Arthur's Veterinary Reproduction and Obstetrics 8th Edition PDF

SAUNDERS A n imprint of Elsevier Lunned e EIS(:vit.'r Limih.'l.1200 1. All righ t" reserved. The riJ::hr of Davtd Noakt'S. l1 mllthy Parkinson and G uy England ro he identified as authors{.( this work ~l-' been asserted hy them in acco rdance with th e Copvrtghr. Dcsi~, and Parent... Act 19M No r a...

SAUNDERS A n imprint of Elsevier Lunned e EIS(:vit.'r Limih.'l.1200 1. All righ t" reserved. The riJ::hr of Davtd Noakt'S. l1 mllthy Parkinson and G uy England ro he identified as authors{.( this work ~l-' been asserted hy them in acco rdance with th e Copvrtghr. Dcsi~, and Parent... Act 19M No r art of rhi-, r uhlic:lrion 1I1;1) ' h:- reproduced. stored in a re tr ieva l sv-te m, tIT tr ansmitted in an y form or I:>y i lll)' mean s, elec tronic , mec ha nica l, phor ocopv irur, rcc ordma or ot h erwise , with ou t eit her the prio r permission of the pu blishers or a licence pe rmit ting restrict ed ( I'\flying in th e U n ucd Kingdom i~'o.'llt."l.l t-.y th e C 'l' yrighr Licen -mg A /.'t.'n q, 90 Tonen ham Court Rlllbhl."\1 19 38 a-, Veterinary O bsremcs hy F. Benesch Second ed itio n 1951 a.. Vcrcnnarv Oh.tetric... hy F. I'\enex-:h and J. G. Wri ~ht Third edmon 1964 a'" Wri~h t'~ Verennarv Ob-temcs by G. H. A rthur Fourt h edinon 19i ; as Vercnnarv Reprod uct ion and Obsrctrtcs bvG. I I. A rthur Fifth edmon 1982 a..Vercrinarv Rep r oduct ion and O h. tetrics hy G. H. Arthur. D. E. N uak~ anJ H. Pear-on Sixth edmon 1989 a.. Verennarv Reprod uction and Obstetrics hy G. I I. Arthur. D. E. NO;lk~ and H. Pear-on Repr inted 199 2 Seventh edmon 1996 ,h Vercn narv Reproducnon and O h. letr ic.y G. H. Arthur, D. E. Noa kes. H. Pearson and T. J. Par kinson Repnm ed 1998. 1999 Eight h edmon 200 1 a" A rth ur's Vcrcnnarv Rep rod uc tion and O bsrctrtcs h~' D. E. Noakes, T. J. Parkin-on and G. C. W. England Reprinted Z003 {twice). Z(\..1.+. ZOO;. 2007. 2C\.-18 ISBN, 978 0 7010 2\ \ 6 I British Lib rary Catalllj..'Uinl-: in Publicat ion Data A cata logu e rec ord (or th is hook is availa ble from th e Bnush l.Ihrarv Library of Conl-:rc!'l~ Cata loging in Publication D ata A cmalo/,.' record fllr Ihil 29 M 4018 8.0 2.0 calvings in the USA, dystocia was recorded > 29 F 4027 4.4 0.7 according to whether it was necessary for some 208  GENERAL CONDITIONS 8 calf mortality rates and reduced fertility. For this Table 8.4 Relative frequency of severity of reason, the author’s view is that it is unethical dystocia and birth weight and sex of calf (Berger et al 1992) to breed from such animals when it is known that there will be a high probability of severe Birth Sex of Total number % Some % dystocia and the need for an elective caesarean weight calf of calvings assistance Difficult (kg) operation. 20 M 23 949 11.3 2.2 20 F 25 069 6.4 1.1 Sheep and goats 21–25 M 3085 5.9 1.0 The incidence of dystocia is influenced by breed 21–25 F 5588 3.9 0.4 (Table 8.5), ranging from 1% in Scottish Blackface (Whitelaw and Watchorn, 1975) to 26–30 M 13 023 9.3 1.3 77% in the Texel (Grommers, 1977). In the goat, 26–30 F 19 118 6.6 0.8 the frequency of dystocia is generally low, being 31–35 M 21 165 16.4 3.5 comparable with that of the Scottish Blackface: 31–35 F 19 368 11.5 2.2 between 2–3%. Faulty fetal disposition can cause 36–40 M 10 372 29.0 10.1 dystocia. In a study by Wallace (1949), it was 36–40 F 5007 23.7 7.0 found that 94.5% of presentations were anterior longitudinal and only 3.6% were posterior. The 40 M 2164 33.6 27.8 commonest faulty disposition was unilateral 40 F 542 30.0 20.6 flexion of one forelimb; if the lamb is small, this may not result in dystocia (Table 8.6). breeds in particular have been bred in the last two decades. The highest frequency occurs in the Horses Belgian Blue and Piedmont breeds, in which there is a higher proportion of the expensive cuts There are relatively few studies which provide reli- of meat of high lean content and of high quality. able information on the incidence and causes of However, the frequency of dystocia is very high, dystocia in the horse. In general, it can be stated and with it the undesirable consequences of high that despite being a monotocous species, where Table 8.5 Incidence of dystocia (assisted births) in sheep Author(s) Year Country Breed Total no. of % Dystocia parturitions Laing 1949 NZ Suffolk NS 70 Gunn 1968 UK Blackface 15 584 2.5 Cheviot 4.2 George 1975 NZ Merino 1510 4.2 Whitelaw and SC Cheviots 1009 12 Watchorn 1975 UK NC Cheviots 569 2 Blackface 433 1 George 1976 NZ Dorset Horn 1509 34 Grommers 1977 Netherlands Texel NS 77 Wooliams et al. 1983 UK Blackface Cheviot 2000+ 5.3 Welsh NS = not stated 209 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION consequences, by the induction of farrowing (see Table 8.6 Classification of ovine births according Chapter 6). Figures of 2.9% in 103 farrowings to the type of presentation. (Data from Wallace, 1949) (Randall, 1972), 0.25% in 772 farrowings (Jones, 1966) and 0.25–1% (Jackson, 1995) have been Presentation Number reported in the literature. Anterior, with head and both forefeet 191 (69.5%) extended Dogs and cats Anterior, with head and one foreleg 49 (17.8%) normal, other leg retained Details concerning the frequency of dystocia Anterior, with head presented and both 18 (6.5%) in the dog are few; this is because of the wide forelegs retained between-breed variations and the tendency for Anterior, with forefeet presented and 2 (0.7%) breeders to intervene, in some cases prematurely head retained and unnecessarily. In addition, there are some Breech presentation – both hind legs 7 (2.5%) retained breeds which are achondroplastic and brachy- Posterior – lamb being right way up and 2 (0.7%) cephalic, where normal birth rarely if ever occurs, both hind legs presented and elective caesarean operations are the routine. Posterior – lamb upside down, i.e. 1 (0.4%) A retrospective study by Walett-Darvelid and ventrosacral position Linde-Forsberg (1994) of 182 cases of dystocia Other miscellaneous types 5 (1.8%) found that 42% of bitches that had whelped Total 275 (100%) before had previously suffered from dystocia. In one of the few studies of the frequency of dystocia in the cat (Gunn-Moore and Thrusfield, the fetus is relatively large in comparison with the 1995), dystocia was reported to have occurred in dam (unlike the situation in polytocous species), 5.8% of 2928 litters involving 735 queens. There the incidence of dystocia is low. There are large were some interesting breed differences; for breed variations. For example, Vandeplassche example, in a large colony of cats of mixed breeding (1993) quotes 4% for thoroughbreds and trotters; the frequency was 0.4%, whereas in litters of Devon 10% in Belgian draft horses, this relatively high Rex it was 18.2%. Pedigree litters were at a signifi- level being due to fetal muscular hypertrophy; and cantly higher risk than cats of mixed breeding (odds 8% in Shetland ponies because of a large skull. ratio being 22.6). Dolichocephalic and brachy- However, in many breeds of pony the incidence is cephalic types were found to have a significantly 2%. In an interesting on-farm study, involving 517 higher level of dystocia than mesocephalic types. spontaneous foalings and including a wide variety of breeds (quarter horses, standardbreds, thor- oughbreds and miniature horses), the total number of dystocias was 517 (11.2%), ranging from 8–19% PREVENTION OF DYSTOCIA on different farms. When the details for the differ- ent breeds are examined, then the incidences were As with all diseases and disorders, veterinarians 16%, 10.5%, 8.9% and 19% for the quarter horses, should be endeavouring to prevent and reduce the standardbreds, thoroughbreds and miniature incidence of dystocia. For certain categories, such horses, respectively (Ginther and Williams, 1996). as faulty fetal disposition, our knowledge of the All studies have shown that dystocia occurs more mechanisms that occur during the first stage of frequently in primipara than in pluripara. parturition, that are responsible for ensuring that the fetus assumes the correct disposition for its normal expulsion, is very incomplete. However, Pigs there are some types of dystocia which can be In the pig, dystocia is generally considered to be reduced significantly; these are invariably based less common than in the monotocous species. on good husbandry. The principal one is fetoma- In addition, many large intensive breeding units ternal disproportion. It has been known for some attempt to reduce dystocia, or certainly reduce its time, largely based on anecdotal evidence, that 210  GENERAL CONDITIONS 8 the pelvic canal size varies between breeds. For – namely, faulty disposition of the fetus. It is example, in cows of the Channel Island breeds the unlikely that its aetiology will be clarified until the pelvic canal is relatively much larger than in other normal birth mechanism involved in parturient breeds, and cows of these breeds will readily give extension of the limbs from the flexed gestational birth unaided when they are pregnant as embryo position is understood. It seems likely to the author transfer recipients with calves of breeds with mus- that the uterus, through its myometrial activity, cular hypertrophy. There are two approaches to plays a part in this limb extension; postural defects reducing the frequency and the severity of dysto- are more common with twins and with premature cia. Firstly, the size of the birth canal should be births, and in both of these instances a degree of adequate, secondly, the size and conformation of uterine inertia is commonly present. Hormone the calf should be such that it can pass through changes, ratios and concentrations (particularly the birth canal. that of progesterone), which occur as a result of the For some years, since the early attempts to meas- cascade which stimulates the onset of parturition ure the size of the pelvic canal, there has been con- (see Chapter 6), are probably important in deter- siderable interest in using this measurement as a mining limb posture. method of predicting ease of calving. There are For example, Jöchle et al. (1972) have found differences of opinion as to its value, largely based that when progesterone was given to cows in on the accuracy of measuring the pelvic area using which labour had been induced by flumethasone, pelvimeters inserted in the rectum. Deutscher there was a high incidence of dystocia due to pos- (1995) is of the opinion that pelvic area is moder- tural deviation. This may be related to the influ- ately to highly heritable, and can be increased in a ence of the endocrine changes on myometrial herd by the selection of breeding heifers and bulls. activity (see Chapter 6). He found that yearling heifers should have a pelvic area of at least 120 sq cm to deliver a 27 kg calf at 2 years of age. The pelvic area:birth weight (in lb) OBSTETRICAL TERMINOLOGY ratio should be 2:1. Similarly, Gaines et al. (1993) found that the ratio of the pelvic area at calving and We have used the term faulty or abnormal fetal dis- calf birth weight significantly affected (P < 0.01) position to describe the situation where the fetus the incidence of dystocia, but the pelvic area before has failed to assume the disposition which enables calving was not an accurate predictor. Others have it to be expelled unaided per vaginam. In order to doubted its true value (van Donkersgoed et al., be able to provide a description of the disposition 1993). Although excess body condition score has which any veterinarian will understand, there is an been considered to increase the incidence of dysto- agreed terminology first defined by Benesch. This cia, because of the presence of large amounts of involves the use of the terms presentation, position retroperitoneal fat in the pelvic canal, not all studies and posture, each of which has a specific meaning have confirmed this. It is likely that only very fat in relation to veterinary obstetrics. cows will have problems, and it is good husbandry Presentation signifies the relation between the practice to ensure that this does not occur. longitudinal axis of the fetus and the maternal The selection of sires which result in a low dys- birth canal. It includes longitudinal presentation, tocia frequency due to fetomaternal disproportion which can be anterior or posterior depending on has been recognised for many years, as illustrated which fetal extremity is entering the pelvis; trans- by the use of breeds such as the Angus and verse presentation, ventral or dorsal according to Hereford as sires for dairy heifers. Other aspects whether the dorsal or ventral aspect of the trunk of good husbandry can prevent dystocia due to is presented; and vertical presentation, ventral or fetomaternal disproportion or reduce the adverse dorsal. Vertical presentation is very rare, and only consequences if it occurs; this is discussed in the obliquely vertical ‘dog-sitting’ presentation in detail in Chapter 11. the horse needs to be considered. Little attention has been paid to the study of the Position indicates the surface of the maternal basic causes of the other large category of dystocia birth canal to which the fetal vertebral column is 211 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION applied. It can be dorsal, ventral and left and right Surprisingly, cows in high-condition score at lateral. calving have been shown to produce heavier Posture refers to the disposition of the movable calves, but without an increase in dystocia appendages of the fetus and involves flexion or (Spitzer et al. 1995). extension of the cervical or limb joints: for example, Dystocia due to faulty fetal disposition at the lateral flexion of the neck or hock flexion posture. time of calving is lower, i.e. 26% (Sloss and Johnston, 1967 – Table 8.7). A survey of 3873 calv- ings over a 21-year period in Colorado, USA, TYPES OF DYSTOCIA WITHIN SPECIES showed that in 96% of the calvings the fetus was in normal disposition; in the remaining 4% the dis- Cattle position was abnormal. In these 4% (155 in total), 72.8% of the fetuses were in posterior presentation For many years it has been customary to classify and dorsal posture, 11.4% had unilateral carpal or fetal oversize into absolute and relative; the former shoulder flexion, in 8.2% the calf was a breech, in describes an abnormally large fetus, whilst the 2.5% there was lateral deviation of the head, 1.9% latter refers to a normal-sized fetus but where the had incomplete extension of the elbow, in 1.35% maternal pelvis is smaller than normal. A more the calf was in posterior longitudinal presentation appropriate terminology is fetomaternal or feto- and ventral position, in 1.35% it was in transverse pelvic disproportion; the former of these two terms presentation, and in 0.6% it was in oblique ventro- will be used in this book. Fetomaternal dispropor- vertical presentation/position. tion is the commonest cause of dystocia in cattle The incidence of fetal monsters is relatively (Table 8.7). The incidence of which is dependent high in the cow; they are generally of the distorted on such factors as: and celosomian types, schistosoma reflexus and breed, being especially common in those with a perosomus elumbis being commonest (see Chapter high incidence of muscular hypertrophy; this can 4). In a survey by 21 veterinarians from 1966–85 be compounded in a breed such as the Belgian in the state of Victoria, Australia, 1.3% of the dys- Blue where there is also a small pelvic inlet tocias attended were due to schistosoma reflexus immaturity of the dam at the time of breeding, (Knight, 1996). In a survey in Poland from and hence calving 1970–74, 115 or 12.9% of 891 fetuses or newborn the use of an inappropriate sire either without calves with developmental congenital abnormal- or within the breed ities were also due to this abnormality; all resulted the use of embryos derived from in vitro in dystocia (Cawlikowski, 1993). Achondroplastic fertilisation (IVF). calves, typified by the ‘bulldog’ calf of the Dexter– Kerry breed, are also encountered. Departures from longitudinal presentation are Table 8.7 Causes of dystocia in 635 beef cattle uncommon, because the anatomical arrangement (after Sloss and Johnston, 1967) of the uterine cornua and the absence of a distinct Cause % All dystocias uterine body do not favour transverse present- ation. Postural irregularities of the head and limbs Fetomaternal disproportion 46 are common, particularly carpal flexion, lateral Faulty fetal disposition 26 deviation of the head and ‘breech presentation’. Incomplete cervical and vaginal dilatation 9 Simultaneous presentation of twins is a well- Uterine inertia 5 recognised cause of bovine dystocia, and one of Uterine torsion 3 the first duties of the obstetrician when proceed- Cervical prolapse 3 ing to manipulative delivery is to ensure that the Pelvic fracture 2 presenting limbs belong to the same fetus. Uterine Uterine rupture 2 inertia, often associated with hypocalcaemia, is Cervical neoplasia 0.5 well known, particularly in pluriparous Jersey Fetal abnormalities 5 cows; uterine torsion has its highest incidence in 212  GENERAL CONDITIONS 8 cattle, while instances of incomplete dilatation of referred to clinics. In a study by Ginther and the cervix are occasionally seen. Williams (1996), details were collected from eight stud farms involving four different breeds of horse; again the study shows that faulty disposi- Mare tion of the fetus was responsible for causing 69% According to Vandeplassche (1972), only about of the dystocias. Of these, flexion and retention of 5% of the more serious equine dystocias are of one forelimb accounted for 13 of the 40 cases. maternal origin, and they are mainly uterine tor- Examination of the causes of dystocia when fetal sions. Most cases result from irregularity of pre- disposition was normal shows that fetomaternal sentation, position and posture of the fetus, of disproportion occurred in 5, weak contraction in which the commonest single cause is lateral devi- 5, a small or previously broken pelvis in 2 and ation of the head. Fetomaternal disproportion and hiplock in 2 of the 18 cases. uterine inertia are rare, except in some draught Failure of the fetus to rotate into the dorsal breeds. Transverse presentation of the foal across position, and its consequent engagement at the the uterine body (either dorsotransverse or ven- maternal pelvis in the ventral or lateral position, trotransverse) is well known, and another form of are often encountered. They may be complicated transverse disposition in which the extremities of by laceration of the dorsal wall of the vagina and the fetus occupy the uterine horns is notorious even of the rectum and anus. and peculiar to the equine species. In respect of All forms of postural irregularity occur in the the influence of presentation of the fetus on dys- mare. The head and neck may be displaced later- tocia, Vandeplassche (1993) summarises the pre- ally or downwards between the forelegs. Such sentations in 170 000 normal equine births in displacements may be further complicated by Belgium, compared with the presentations diag- rotation of the cervical joints. The limbs are fre- nosed in 601 dystocia cases brought to his clinic quently presented abnormally; one, several or all in Ghent (Table 8.8). Whereas posterior and of the joints of the limbs may be flexed, and the transverse presentations occurred in only 1.0% irregularities are classified according to their and 0.1%, respectively, of normal births, they clinical significance as carpal flexion, shoulder were present in 16% and 16% of dystocia cases. flexion, hock flexion and hip flexion. Bilateral hip An obliquely vertical or ‘dog-sitting’ position of flexion is known as breech presentation. An the fetus is another well-known dystocia peculiar exceptional equine postural abnormality, which to horses. In a more recent study, Leidl et al. occurs in anterior presentation, is displacement of (1993), from the Munich Veterinary School, one or both extended forelimbs above the fetal examined the causes of 100 dystocia cases neck (foot-nape posture). referred to their clinic. They found that 61 were Gross fetal monstrosities are rare, but occa- due to faulty fetal disposition, 17 due to uterine sional developmental anomalies which cause torsion, 10 due to fetomaternal disproportion, 4 dystocia are wryneck (fixed lateral deviation) and associated with twins, 4 due to incomplete dilata- hydrocephalus. Wryneck is likely to occur with tion of the birth canal and 3 due to uterine ventral transverse bicornual pregnancy. deflection. These detailed studies involve cases Sheep and goat Wallace (1949) provided a useful basis for under- Table 8.8 Influence of fetal presentation on standing the causes of sheep dystocia by observing dystocia in the mare (Vandeplassche, 1993) all parturitions (275) in a single flock (Table 8.6). Presentation Normal foalings Dystocia cases He found 94.5% anterior presentations and 3.6% posterior, strikingly similar figures to those for Anterior 168 130 (98.9%) 408 (68%) bovine parturitions. Gunn (1968) collected data Posterior 1700 (1.0%) 95 (16%) from 15 584 births in Scottish hill flocks, and Transverse 170 (0.1%) 98 (16%) reported a dystocia incidence of 3.1% (3.5% with 213 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION singles and 1.3% with twins), but McSporran Only the more difficult dystocias are referred for et al. (1977) recorded 20–31% of difficult lamb- treatment to veterinary surgeons, and in veterinary ings in a particular flock of Romney sheep in lists of assisted lambings the incidence of particular which fetopelvic disproportion was prevalent. types of dystocia varies with the prevalent breed and It is uniformly believed that in sheep popula- with flock management. In Ellis’s (1958) series of tions, irrespective of breed and age, fetopelvic dis- 1200 cases of sheep dystocia attended in a North proportion is the commonest cause of dystocia, Wales practice over a 10-year period, lateral dev- that its incidence varies with breed and that it fre- iation of the head was the commonest type, whereas quently occurs where there is crossing of disparate in Wallace’s (1949) and Blackmore’s (1960) reports breeds for commercial lamb production. Also, it was cervical non-dilatation (32 and 15%, respec- assistance at lambing for this type of dystocia tively). Next after these two types in the veterinary is more frequently required in primipara; male surveys came shoulder flexion, carpal flexion, lambs, which are larger, predispose to it. Where simultaneous presentation of twins, breech pre- pelvic size of the ewe is the major factor in the dis- sentation and fetal oversize. Other occasional proportion, there is likely to be repeated dystocia. causes of severe sheep dystocia are uterine torsion, McSporran et al. (1977) have demonstrated that monstrosities (including schistosoma reflexus), fetal its incidence can be markedly reduced (from 31% duplication, fetal oedema and perosomus elumbis. to 3.3% in a period of 4 years) – the level in Similarly, in Thomas’s (1990) survey the number of Gunn’s (1968) survey for Scottish hill sheep – by dystocias due to fetomaternal disproportion was culling ewes that had required assistance at con- small (3%) because, unless it is very severe, such secutive parturitions, and by breeding to rams forms of dystocia can be dealt with by the shepherd. that had sired lambs of lower birth weight. Similarly in this same survey, the large number of In certain breeds and flocks, the incidence of other causes were due to those disorders such as dystocia due to maldisposition exceeds that due to incomplete dilatation of the cervix which may fetopelvic disproportion; for example, in Gunn’s require veterinary intervention such as a caesarean survey it was more than 60% (Table 8.9). It is operation (see Table 8.9). more common in pluripara than primipara, and is It appeared from Gunn’s (1968) data, and from more frequent with twins than with single births. other reports, that twinning does not significantly Among maldisposition dystocias, shoulder flexion increase sheep dystocia overall. The explanation is commonest, followed by carpal flexion, breech for this is that whereas twins increase maldis- presentation, lateral deviation of the head and position dystocia, there is a reduced incidence of transverse presentation. Ewes with unilateral fetopelvic disproportion dystocia because of their shoulder flexion often lamb spontaneously. smaller individual size. Table 8.9 Frequency of the main causes of dystocia in sheep Author(s) Year Country Breed(s) Total no. of % Disproportion % Disposition % Other dystocias Wallace 1949 NZ Romney 100 32 53 15 Gunn 1968 Cheviot UK 477 35 65 0 Blackface George 1975 Australia Merino 63 77 23 0 Whitelaw 1975 Cheviot UK 50 76 24 0 and Watchorn Blackface George 1976 Australia Dorset 513 57 43 0 Thomas* 1990 UK Mixed 328 3 42 55 * Veterinary practice-based survey 214  GENERAL CONDITIONS 8 There is no doubt from all published work that dimension from the sacrum to the pubic bone, posterior presentation markedly predisposes to and thus reduces the size of the pelvic canal. In difficult births. brachycephalic breeds the head is very broad. In a study involving 155 cases of dystocia in Pig bitches, which included 65 different breeds ranging in age from 1 to 11 years, 75.3% of the causes of The types of dystocia encountered in the sow dystocia were maternal in origin, and 24.7 fetal in resemble more closely those of the bitch than origin (Walett-Darvelid and Linde-Forsberg, those of the monotocous species, maternal forms 1994). A further breakdown of the various sub- being almost twice as common as fetal forms. In causes is shown in Table 8.10. This shows that Jackson’s (1972) series of 202 dystocias, 37% were uterine inertia was responsible for 72% of all dys- caused by uterine inertia, 13% by obstruction of tocias. The authors of this paper used the term the birth canal and 9% by downward deviation of ‘primary complete uterine inertia’ to indicate when the uterus, whereas 14.5% were caused by breech the bitch failed to expel any pups, comparable with presentation, 10% by simultaneous presentation, the classical definition of primary uterine inertia, 3.5% by downward deviation of head and 4% by and ‘primary partial uterine inertia’ to indicate fetal oversize. The incidence of fetal dystocia where the bitch gave birth to at least one pup and increases when the litter is small, for in these the then stopped before whelping was complete, more size of the individual tends to be large and obstruc- comparable with secondary uterine inertia. tion may result. Irregularities of limb posture, and The dachshund and Aberdeen terrier are parti- even uncomplicated posterior presentation, often cularly prone to primary uterine inertia. The cause dystocia when the litter is small, whereas had corgi shows extreme variation in the size of its the litter been large and its individuals small, these puppies and hence fetomaternal disproportion irregularities would not have interfered with may occur. Brachycephalic breeds, together with normal expulsion. Monstrosities are not uncom- the Sealyham and Scottish terrier, are prone to mon; they are generally of the double type but obstructive dystocia due to the fetuses having schistosomes, perosomes and hydrocephalic speci- comparatively large heads and the dams having mens also occur. Together, bladder flexion and vaginal prolapse were reported to be the third most common causes of dystocia in a study in Germany Table 8.10 Frequency of the cause in 182 cases (Schulz and Bostedt, 1995), whilst hypocalcaemia of dystocia in bitches (Walett-Darvelid and should also be considered as a cause of uterine Linde-Forsberg, 1994) inertia (Framstad et al., 1989). Cause Number % Among litters of sows attended for dystocia, of cases there is a collective stillbirth rate of about 20%, as Maternal compared with 6% in sows which farrow unaided. Primary complete uterine inertia 89 48.9 Primary partial uterine inertia 42 23.1 Dog and cat Narrow birth canal 2 1.1 It is difficult to collect meaningful data on causes Uterine torsion 2 1.1 of dystocia in the bitch and queen, firstly, because Hydallantois 1 0.5 some experienced dog and cat breeders will be Vaginal septum formation 1 0.5 capable of treating all but the most severe causes. Total 137 75.3 Secondly, many breeds of dog, and to a lesser Fetal extent cat, suffer from severe congenital deform- Faulty disposition 28 15.4 ities such as achondroplasia and brachycephal- Fetomaternal disproportion 12 6.6 icism which can exert a major influence on the Fetal monsters 3 1.6 birth process. The data will be influenced greatly Fetal death 2 1.1 by the population of animals in the study. Total 45 24.7 Achondroplasia results in a reduction in the 215 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION narrow pelves. Large fetuses, causing fetomater- study also shows the influence of breed on dystocia nal disproportion, are commonly encountered in (Table 8.12). bitches gravid with only one or two young; dis- proportion may also result from a fetal monster. A primigravid bitch of the small breeds often has Table 8.11 Causes of dystocia in queens (Ekstrand and Linde-Forsberg, 1994) trouble expelling her first puppy, but provided timely assistance is forthcoming she usually Cause Number % expels the remainder of her litter normally. If, of cases however, assistance is delayed, the onset of sec- Maternal ondary inertia may make the outcome serious. Uterine prolapse 1 0.6 Irregularities of limb posture are generally of little Uterine strangulation 1 0.6 importance provided the puppy is of normal size. Narrow birth canal (fetomaternal 8 5.2 In fact, many puppies are born with their fore- or disproportion) hindlimbs flexed. However, when the fetus is rel- Uterine inertia 94 60.6 atively large, these postural deviations are often Subtotal 104 67.1 the factor that causes dystocia. Not infrequently Fetal a bitch or cat, in attempting to expel a fetus with Faulty disposition 24 15.5 its forelimbs retained, partially succeeds in that Fetal congenital defects 12 7.7 the head is born but the thorax with the limbs Fetomaternal disproportion 3 1.9 becomes obstructed in the maternal pelvic inlet. Fetal death 7 4.5 Similarly a puppy or kitten may have its hindparts Subtotal 46 29.7 born while its distended thorax is obstructed. Irregularities of head posture are common, and Other causes 5 3.2 vertex (‘butt’) presentation and lateral deviation Total 155 100 of the head are frequently encountered. An inter- esting feature of the latter abnormality is that it often involves the last puppy to be born. Fetal hydrocephalus and anasarca occasionally Table 8.12 Relative frequency of cat breeds with dystocia (Ekstrand and Linde-Forsberg, 1994) occur, but other forms of monster are rare. In the achondroplastic types and in the kitten, gross Breed Number % Queens umbilical hernia (schistocormus) is seen, but it is Short-haired seldom a cause of dystocia. British short-hair 2 1.3 Abnormalities of position are common in both Devon rex 2 1.3 anterior and posterior presentation and are them- Russian blue 2 1.3 selves a cause of obstruction. Failure of the fetus to Burmese 7 4.5 rotate prior to presentation results in its engaging in Foreign short-hair 1 0.6 the pelvic inlet in the ventral or lateral position. Siamese 10 6.5 Traverse presentation is rare. When it occurs the bitch is generally gravid with a single fetus Semi-long-haired only and gestation is of the bicornual type. It is Balinese 3 1.9 generally accompanied by uterine inertia. Norwegian forest cat 2 1.3 In the cat, maternal causes of dystocia are more Birman 6 3.9 common, particularly uterine inertia. Fetomaternal Long-haired disproportion and faulty disposition are the most Persian 58 37.4 common fetal causes. These are illustrated in Table 8.11, from a paper by Ekstrand and Linde- Others Forsberg (1994); the authors used the same class- Household cat 62 40.0 ification for uterine inertia as described above Total 155 100 (Walett-Darvelid and Linde-Forsberg, 1994). This 216  GENERAL CONDITIONS 8 REFERENCES Azzam, S. M., Kinder, J. E., Nielsen, M. K. et al. (1993) Kossaibati, M. A. and Esslemont, R. J. (1995) Daisy – the J. Anim. Sci., 71, 282. Dairy Information System, report no. 4. Reading: Berger, P. J., Cubas, A. C., Koehler, K. J. and Healey, M. H. University of Reading. (1992) J. Anim. Sci., 70, 1775. Laing, A. D. M. G. (1949) N. Z. J. Agric., 79, 11. Blackmore, D. K. (1960) Vet. Rec., 72, 631. Leidl, W., Stolla, R. and Schmid, G. (1993) Tierärztliche Carr, J. (1998) In: Garth Pig Stockmanship Standards, p. 4. Umschau, 48, 408. Sheffield: 5M. McDermott, J. J., Allen, O. B., Martin, S. W. and Alves, D. M. Cawlikowski, J. (1993) Zeszyty Naukowe Academii Rolniczej w (1992) Can. J.Vet. Res., 56, 47. Szczecinie, Zootechnika, 29, 52. McEarlane, D. (1961) Aust.Vet. J., 37, 105. Collery, P., Bradley, J., Fagan, J., Jones, P., Redehan, E. and McSporran, K. D., Buchanan, R. and Fielden, E. D. (1977) Weavers, E. (1996) Irish Vet. J., 49, 491. N. Z.Vet. J., 25, 247. Dennis, S. M. and Nairn, M. E. (1970) Aust.Vet. J., 46, Miller, G.Y. and Dorn, C. R. (1990) Prev.Vet. Med., 8, 171. 272. Moule, G. R. (1954) Aust.Vet. J., 30, 153. Deutscher, G. H. (1995) Agri-practice, 16, 751. Randall, G. C. B. (1972) Vet. Rec., 90, 178. Drew, B. (1986–1987) Proc. BCVA, 143. Salman, M. D., King, M. E., Odde, K. G. and Mortimer, Edwards, S. A. (1979) J. Agr. Sci. Camb., 93, 359. R. G. (1991) J. Am.Vet. Med. Ass., 198, 1739. Ekstrand, C. and Linde-Forsberg, C. (1994) J. Small Animal Sauerer, G., Averdunk, G., Matzke, P. and Bogner, H. (1988) Practice, 35, 459. Bayerisches Landwirtschaftliches Jahrbuch, 65, 969. Ellis, T. H. (1958) Vet. Rec., 70, 952. Schulz, S. and Bostedt, S. (1995) Tierärztliche Praxis, 23, 139. Framstad, T., Krovel, A., Okkenhaug, H., Aass, R. A., Sloss, V. and Johnston, D. E. (1967) Aust.Vet. J., 43, 13. Kjelvik, O. and Hektoen, H. (1989) Norsk Sloss, V. and Dufty, J. H. (1980) Handbook of Bovine Veterinaertidsskrift, 101, 579. Obstetrics. Baltimore: Williams and Wilkins. Gaines, J. D., Peschel, D., Kauffman, R. C. et al. (1993) Spitzer, J. C., Morrison, D. G., Wettermann, R. P. and Theriogenology, 40, 33. Faulkner, L. C. (1995) J. Anim. Sci., 73, 1251. George, J. M. (1975) Aust.Vet. J., 51, 262. Thomas, J. O. (1990) Vet. Rec., 127, 574. George, J. M. (1976) Aust.Vet. J., 52, 519. Vandeplassche, M. (1972) Personal communication. Ginther, O. J. and Williams, D. (1996) J. Equine Vet. Sci., 16, Vandeplassche, M. (1993) Equine Reproduction. Philadelphia: 159. Lea and Febiger. Grommers, F. J. (1977) Tijdschr. Diergeneeskd., 92, 222. Van Donkersgoed, J. Ribble, C. S., Booker, C. W., Gunn, R. G. (1968) Anim. Prod., 10, 213. McCartney, D. and Janzen, E. D. (1993) Can. J.Vet. Res., Gunn-Moore, D. A. and Thrusfield, M. V. (1995) Vet. Rec., 57, 170. 136, 350. Walett-Darvelid, A. and Linde-Forsberg, C. (1994) J. Small Haas, S. D., Bristol, F. and Card, C. F. (1996) Can.Vet. J., 37, Animal Practice, 35, 402. 91. Wallace, L. R. (1949) Proc. N.Z. Soc. Anim. Prod., 85. Hight, G. K. and Jury, K. E. (1969) N. Z. Soc. Anim. Prod., Welmer, G., Wooliams, C. and Macleod, N. S. M. (1983) 29, 219. J. Agric. Sci. Camb., 100, 539. Jackson, P. G. G. (1995) In: Handbook of Veterinary Obstetrics, Whitelaw, A. and Watchorn, P. (1975) Vet. Rec., 97, 489. p. 105. London: W. B. Saunders. Wilsmore, A. J. (1986) Br.Vet. J., 142, 233. Jöchle, W., Esparza, P., Gimenez, T. and Hidalgo, M. A. Wittum, T. E., Salman, M. D., King, M. E., Mortimer, R. G., (1972) J. Reprod. Fertil., 28, 407. Odde, K. G. and Morris, D. L. (1994) Prev.Vet. Med., 19, 1. Jones, J. E. T. (1966) Brit.Vet. J., 122, 420. Wooliams, C., Welmer, G. and Macleod, N. S. M. (1983) J. Knight, R. P. (1996) Aust. Vet. J., 73, 105. Agric Sci. Camb., 100, 553.  9 The approach to an obstetric case Each case of dystocia is a clinical problem which Is the animal still taking food? may be solved if a correct procedure is followed. In the case of the bitch and cat, has there been The veterinary surgeon arrives with a knowledge of vomiting? the various types of abnormality that may occur in that particular species, and then, by a careful con- By a consideration of the answers to these and sideration of the facts elicited from the owner or similar questions, it is possible to form a fairly attendant and the information obtained from the accurate idea of the case to be dealt with. The methodical examination of the patient, the nature inference to be drawn from many of them is of the abnormality can be ascertained. A correct obvious, but there are several points associated diagnosis is the basis of sound obstetric practice. with them which merit discussion. The greatest attention will be paid to the dura- tion of labour. Calculating the time of onset of first stage is often difficult because, as you will HISTORY OF THE CASE know from reading Chapter 6, the signs are some- times very vague and indistinct. However, the Therefore, before proceeding to examine the onset of vigorous and frequent straining, together animal, a brief history of the case should, when- with the appearance of the amnion, the expulsion ever possible, be obtained. Much of it will be the of fetal fluids, or the appearance of a fetal extrem- outcome of questioning the owner or attendant, ity, indicates the onset of the second stage of but many points will also be elicited from personal labour, and parturition should proceed normally. observation of the animal. If several hours have elapsed since its onset, it is Has full term arrived or is delivery premature? reasonably certain that obstructive dystocia exists. Is the animal a primigravida or multigravida? Nevertheless, it is probable in all species except What is her previous breeding history? the mare that the fetus or fetuses are still living, What has been the general management unless the signs have not been observed and their during pregnancy? significance understood. In the primigravida, par- When did straining begin? What was its nature ticularly the heifer and the bitch, it is often found – slight and intermittent or frequent and that the cause of the dystocia is relatively simple, forceful? such as slight fetomaternal disproportion, and the Has straining ceased? application of a little assistance is all that is Has a water-bag appeared and, if so, when was required. In the mare, the normal course of deli- it first seen? very is so rapid, and separation of the placenta Has there been any escape of fluid? occurs so quickly once the second stage has com- Have any parts of the fetus appeared at the vulva? menced, that any delay generally results in the Has an examination been made and has death of the foal due to anoxia. assistance been attempted? If so, what was its However, when the call for assistance has been nature? delayed 24 or more hours and it is noticed that In the case of the multiparous species, have straining efforts have ceased, it may be assumed any young been born, naturally or otherwise, that the fetus is dead, much of the fluid has been and if so, when? Were they alive at birth? lost, the uterus is exhausted and putrefaction of 219 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION the fetus has begun. These facts in themselves, indicates a grossly delayed case. Where it is clear quite apart from the more detailed features of the from the evidence already obtained that the fetus case, indicate that the prognosis must be guarded. is dead and the uterus grossly infected, the desir- This is especially the case in the polytocous ability of inducing epidural anaesthesia before species, for it is probable that there are several proceeding to a vaginal examination should be fetuses in utero. considered. In this way the risk of infecting the If the history is that efforts to deliver the animal neural canal should spinal anaesthesia later be have already been made, or when such evidence is found to be necessary is reduced. absent but one suspects it to be the case, a search When dealing with the bitch and cat, the degree for injury of the genital canal will be the first of abdominal distension should be observed, for it feature of the detailed examination of the animal. may be possible to make an estimate of the number If any injury is identified then the owner or atten- of fetuses which occupy the uterus. The onset of dant must be informed immediately, and the vomiting, together with a great increase in thirst, likely consequences for the health of the dam should be regarded as grave signs in the bitch. explained. Sometimes, attempts at assistance will be denied; however, it is generally accepted that, with the exception of the mare where the expul- DETAILED EXAMINATION OF THE sive forces during second stage are very powerful, ANIMAL spontaneous injury does not occur. In this case, the honesty or accuracy of the information should Large animals be queried. The animal should be effectively restrained for the safety of both the veterinarian, any assistants and GENERAL EXAMINATION OF THE the animal concerned, in a clean environment. In ANIMAL the case of the mare, cow, ewe and doe goat it is easier if they remain standing; in the sow the The animal’s physical and general condition should examination is best performed with her in lateral be noted. If recumbent, is she merely resting or is recumbency. Very rarely it may be necessary to she exhausted or suffering from a metabolic sedate the dam if she is very fractious. Plentiful disease? Body temperature and pulse rate should supplies of clean hot water with soap or surgical be noted and the significance of abnormalities con- scrub should be available, as well as a table, bench sidered. Particular attention should be paid to the or truss of straw covered with a sterile cloth, on vulva. Parts of a fetus may be protruding and it may which the instruments may be placed. Whilst it is be possible to assess the nature of the dystocia from impossible to perform obstetrical procedures these. Are exposed fetal parts moist or dry? Such aseptically in any species, the amount of contamin- evidence serves not only as a guide to the duration ation of the genital tract should be kept as low as of the condition, but also to the effort that will be possible. A plentiful supply of clean straw should necessary to correct it. Should parts of the amnion be placed under and behind the animal; also, since protrude, what is their condition? Are they moist the floor is often wet and slippery, a prior applica- and glistening and is fluid caught up in their folds? tion of sand or grit is a worthwhile precaution. If so, their exposure is recent and the case is an With an assistant holding the tail to one side, early one. If, however, the membranes are dry and the external genitalia and surrounding parts are dark in colour, it may be taken that the case is thoroughly washed from one bucket, and in the protracted. mare a clean tail bandage applied since the tail Maybe nothing protrudes from the vulva, in hairs are frequently introduced into the vulva and which case particular attention should be paid to vagina and can cause quite severe lacerations. The the nature of the discharge. Fresh blood, espe- operator, having washed his or her hands and cially if profuse, generally indicates recent injury arms from another bucket and after donning a to the birth canal. A dark brown fetid discharge clean disposable plastic sleeve, proceeds to make a 220  THE APPROACH TO AN OBSTETRIC CASE 9 vaginal examination.The introduction of the hand limbs. Recognition of the head is not difficult; the through the vulval labiae almost invariably pro- mouth and tongue, the orbits and the ears are vokes defaecation in the cow and it becomes generally obvious. In the case of a limb, the first necessary to wash the vulva and the operator’s requirement is to ascertain whether it is a fore- arms again. limb or hind-limb. If the plantar aspect of the digit Without the previous induction of epidural is downwards, it is highly probable that it is a fore- anaesthesia and the resultant paralysis of the limb; the converse is equally true. This statement rectum, it is almost impossible to make a vaginal applies with greater force to the cow than the examination in the cow without introducing some mare, for in the latter, presentation of the fetus in faecal contamination. This statement certainly the ventral position is relatively common. Proof is holds true for animals which have been fed on obtained by noting the direction of flexion of the grass and in which faeces are semi-fluid. Usually, limb joints. If the joint immediately above the no serious consequence will result from this fetlock flexes in the same direction as the latter, contamination of the vaginal mucous membrane, the limb is a fore one, and the converse holds true. provided the latter is intact. The beginner may experience some difficulty in If on examination the vagina is found to be recognising the fetal parts being palpated if they empty, attention should be directed to the cervix. are covered by amnion. To overcome this, the torn Is it completely effaced? If it is not, is it partially edges of the amniotic sac should be identified and dilated and is it still occupied by some sticky opened, and the hand inserted so that the fingers mucus? If so, then it may be concluded that the come into direct contact with the fetus. If two first stage of labour is not complete and the second limbs are present, it must be established that they stage of labour has not yet begun, and the animal are both fore or hind, and if they are from the should be given more time. Maybe the case is one same fetus. of uterine torsion. Does the vagina end abruptly at Not infrequently, it is necessary to repel the the pelvic brim and is the mucosa drawn into tight, fetus in the uterus to ascertain the nature and spirally arranged folds? In the event of the vagina direction of displaced parts. If continued straining being occupied by amnion only, the nature of the makes this difficult, the induction of epidural fetal parts presented at the pelvic inlet must be anaesthesia should be considered at once, but it ascertained. Can a fetal tail and anus be identified? should be remembered that the dam’s expulsive If so, it is highly probable that the case is one of effort may be required after any corrective proce- breech presentation. Is it the flexed neck which is dure has been performed. being palpated? Can the mane be detected? A In the protracted case, assessment of the exact search on one or other side may reveal the ears and nature of the dystocia and methods of correction occiput, the case being one of lateral deviation may be more difficult. Often, particularly in of the head. But what of the forelimbs? Can the heifers, mares and sows the vaginal wall becomes flexed carpi be felt beneath the neck or is there grossly swollen and oedematous so that even the complete retention of the forelimbs in addition to insertion of a hand and arm becomes difficult and the head abnormality? In the mare, complete there is no room in which to carry out manipula- emptiness of the vagina apart from the membranes tions. Loss of fluid has resulted in the mucous may be due to postural defects, as previously out- membrane and the fetal parts becoming dry. lined, but more often indicates a dorsotransverse Contraction of the uterus directly on the irregular presentation. If it is impossible or almost imposs- contour of the fetus makes retropulsion difficult ible to reach any parts of the fetus in this species, or even impossible, in which case a spasmolytic the case is probably one of bicornual gestation. such as clenbuterol may be used, while in many The protrusion of the allantochorion into the cases the fetus has become impacted in the pelvis. vagina and from the vulva – ‘red bag’ – indicates Plenty of obstetrical lubricant is required. placental separation. The assessment of the viability of the presented However, in the majority of cases some part of fetus is necessary at an early stage in the examin- the fetus occupies the vagina – the head, a limb or ation because this will influence the options for 221 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION treatment.This can be done by attempting to elicit cat than the bitch. The case is a simple one; trac- reflexes such as corneal/palpebral, suck, anal if tion on the exposed parts effects delivery without they are in posterior presentation, and limb with- difficulty and, provided this assistance has been drawal. Unfortunately, there is no simple method forthcoming early, it is probable that parturition of determining if other non-presented fetuses in will proceed normally. Occasionally it is found polytocous species are alive or dead. If the fetus is that the vagina is occupied by a fetal head or but- dead, then it may be important to be able to esti- tocks which have become impacted. In the major- mate the time interval since death. When there is ity, however, the pelvic canal is unoccupied and fetal emphysema and detachment of hair, then the obstruction occurs at the inlet. fetus has been dead for at least 24–48 hours. If What is the presentation? If a head, can one after the fetus has been removed there is no detect the mouth? Or is it the occiput with the emphysema and the cornea is cloudy and grey, ears? If the latter, the case is one of vertex present- then it will have been dead for 6–12 hours. ation. Maybe a single limb is felt, but there is no sign of the head; the case is probably one of lateral deviation of the head. Is the presentation poster- Bitch and queen cat ior? Recognition of the tail is generally simple, The bitch, unless an exceptionally large one, should although it may be directed forwards over the fetal be placed standing on a table. It is preferable that a back. Have the hindlimbs entered the pelvis or person with whom the animal is familiar should are they retained? Has the fetus rotated into the hold its head and be warned that even some quiet dorsal position or is the case one of ventral or stoical bitches may resent a vaginal examination. lateral position? Is the uterine body unoccupied? Fetal numbers may be assessed in some bitches by Determination of fetal viability by attempting to gentle abdominal palpation. However, if a B-mode elicit reflexes is unreliable. realtime ultrasound scanner is available then the use of this transabdominally will enable a fairly accurate assessment of fetal numbers, and has the CONSIDERATION OF TREATMENT TO BE added advantage of being able to determine if the ADOPTED pups are alive by identifying the beating fetal heart. At a later stage in the examination, it might also be General necessary to take radiographs. As a general rule, the operator will proceed to The great majority of dystocia cases in the mono- make a digital examination per vaginam, espe- tocous species are fetal in origin, and are the out- cially in early cases in which it is likely that come of either faulty disposition or oversize. In obstruction is the cause of the delay, and also in the former, the first aim of treatment is to convert protracted ones in which it is estimated that a it to normal, and having done this, hasten delivery single fetus only remains unborn. Nevertheless, by relatively gentle traction. Such correction cases will be met in which it is obvious that inertia must, if possible, be performed by manipulation, has supervened and there are several fetuses to be assisted perhaps by the use of simple instruments delivered, in which case an immediate caesarian such as snares and repellers. In cases of oversize of operation or hysterectomy is indicated. the fetus a decision must be made promptly on Whether or not the hair is clipped from the area whether to attempt delivery by traction or by a around the vulva before making a vaginal examin- caesarian operation. Various studies in cattle have ation will depend on the length of the coat. In long- shown that one of the major factors which deter- coated animals it is a great convenience to do so; mines the outcome for the cow and calf in cases of although it is impossible to render the area sterile, a caesarean operation is the degree of traction to it should be thoroughly cleansed beforehand. which the cow was subjected before the decision Sometimes on raising the tail it is seen that part to operate was made. The rationale for the obste- of a fetus, a head or hind parts, is protruding from trician should always be that, if presented with live the vulva. Such a finding is more common in the and viable young at term inside a viable dam, then 222  THE APPROACH TO AN OBSTETRIC CASE 9 the only measure of success is the delivery of live success, the other states described above are pre- and viable young, without compromising the ferable. It is important in such cases that this deci- health or future fertility of the dam. However, the sion be made early, so that the obstetrician shall decision as to whether delivery should be accom- not have become exhausted as the result of pro- plished by traction or a caesarean operation is one longed but futile efforts. of the most difficult facing the obstetrician. In Relatively simple abnormalities, such as carpal addition, veterinarians will sometimes be pres- flexion or lateral or downwards deviation of the surised by owners into performing a caesarean head, can often be corrected using the hand alone, operation when it is not necessary, particularly particularly when the mare is comparatively small in cows with muscular hypertrophic calves or and straining has been eliminated. However, it brachycephalic/achondroplastic bitches, purely must be remembered that the limbs of the thor- because owners want to ensure the birth of live oughbred newborn foal are very long (70% of their offspring. Conversely, owners will sometimes adult length), which requires a substantial amount request the use of severe and prolonged traction of space to facilitate flexion and extension. When, rather than pay for the cost of a caesarean oper- however, one of the more difficult forms is present, ation. In both situations the veterinarian must such as transverse presentation, ventral position or remember that the welfare of both dam and off- impaction of the fetus in the pelvis, or when there spring are paramount, and act accordingly. is laceration of the vagina or vulva, it is generally With the advent of new and safer anaesthetic best to anaesthetise the animal at the outset, par- agents the caesarean operation should not be con- ticularly in a hospital environment. One of the sidered as ‘the last resort’, but an effective method advantages of general anaesthesia is that by chang- of treatment when used appropriately. Fetotomy ing the position of the mare – for example, so that as a method of treating dystocia in large animals she is in dorsal or lateral recumbency, or even sus- still has its place if the fetus is dead. With the pended by her hindlimbs (the anaesthetists will not greater ease and increased effectiveness of the cae- be very enthusiastic about this approach because of sarean operation, however, in many parts of the pressure on the diaphragm) – the change in the world veterinarians have lost the skills that are pressures on the fetus within the uterus can be necessary to perform fetotomy effectively. utilised to facilitate correction. Whenever fetotomy Uncontrolled forcible traction may lead to is required, both sedation and caudal epidural laceration and contusion of maternal soft tissues, anaesthesia should be used. In veterinary hospitals, pelvic nerve damage and occasionally sacral dis- general anaesthesia is preferable since the foal is placement. If the mother survives, a third-degree already dead and will not be affected by transpla- perineal laceration, deformity of the perineum, cental transfer of anaesthetic agents. fistula of the vagina and rectum, or paralysis may In all severe cases, the operator should consider ensue. The obstetrician should seek to avoid these the advisability of seeking the assistance of a col- complications at all costs. league, for it is always possible that the combined efforts of two will succeed where those of one Species-specific alone fail. The value of partial fetotomy as a treatment Mare of equine dystocia where the fetus is dead or The first consideration is whether attempts at cor- deformed has been emphasised by Vandeplassche rection should be made with the animal standing (1972, 1980), but total fetotomy was not recom- or recumbent, or restrained and sedated, or under mended because it usually causes severe damage, caudal epidural, or general anaesthesia. The deci- particularly to the uterus. He pointed out that in sion will be influenced in part by the size and tem- the mare, fetotomy was difficult because of power- perament of the mare, but more especially by the ful straining, long birth canal and early dehiscence type of dystocia. Not infrequently the operator of the placenta. A long Thygesen fetotome was begins manipulative correction with the mare the best instrument. The indications for, and unsedated and standing, but soon realises that, for results of, partial fetotomy are shown in Table 9.1. 223 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION undertake fetotomy or a caesarean operation. If, Table 9.1 Results of fetotomy in mares suffering however, fetal disposition is normal and the case from dystocia (Vandeplassche, 1972 and 1980) is one of simple fetomaternal disproportion, con- Cause of dystocia No. of No. trolled traction will be first attempted, but before mares recovered this is done it is important that the vagina and Reflexion of head and neck 72 67 (93%) those parts of the fetus occupying it shall be lubri- Hydrocephalus of two heads 6 6 (100%) cated as well as possible. For this purpose, one of Breech presentation with ankylosis 17 14 (82%) the proprietary brands of cellulose-based obstetric Partial transverse presentation 25 21 (84%) lubricant should be used. Failing this, the copious Deformity, ankylosis or reflexion 12 11 (92%) application of soap (often in the form of soap of forelegs flakes) and water is indicated, or mucilage of Total 132 119 (90%) linseed or acacia. Traction, however, must be employed with consideration and discretion, for if it is impossible to extract the fetus by this means, Vandeplassche found that 25% of mares retained its continued application makes for more severe the afterbirth after fetotomy compared with 5% impaction and this renders subsequent fetotomy after a normal birth, and that fertility after feto- very difficult or even impossible. In all cases such tomy was 42%.With improved methods of general as these, epidural anaesthesia should be induced anaesthesia and aseptic surgery, the caesarean at the outset, together with the use of a spasmo- operation has a definite place in equine obstetrics, lytic such as clenbuterol. As a result of these treat- particular indications being maternal dystocia due ments, it is generally possible to repel the fetus to bicornual gestation, uterine torsion and narrow sufficiently for the performance of intrauterine or deformed pelvis, as well as those cases of fetal fetotomy. When applying epidural anaesthesia dystocia where there is oversize or faulty fetal dis- subsequent to handling a putrid fetus, great care position combined with maternal injury or where must be taken to ensure that infection is not intro- the uterus has contracted on to a dead emphyse- duced into the neural canal through the medium matous foal. Vandeplassche’s maternal recovery of either the needle or the anaesthetic solution. rates for fetotomy (132 cases) and caesarean oper- However, more often the case will be an early ation (77 cases) were, respectively, 90 and 81%. one; the calf is alive and the uterus healthy. In the Because of early dehiscence of the allantochorion heifer, it is often found that fetal disposition is in mare dystocia, only 30% of foals survived the normal and that obstruction is due to slight caesarean operation (as compared with 85% of fetomaternal disposition. In these cases, it is a calves in the cow). comparatively simple matter to apply snares to the fetal extremities and, following the principles which are described in detail in later chapters, to Cow effect delivery by traction. As a rule, the animal In the cow, delivery per vaginam, is the foremost remains standing during the application of snares consideration. The delay before professional aid is but often goes down during the passage of the sought varies greatly, and this is a factor which calf’s head through the vulva. In the multigravid influences the course to be adopted. In protracted cow, while fetomaternal disproportion is some- cases there is often severe impaction of parts of times encountered, it is more likely that the cause the fetus in the pelvis; the greater part of the fetal of obstruction is faulty fetal disposition. If it is fluids has often been lost and there is insufficient found that the space required for correction is space to repel the fetus; the fetal skin and the continually lost due to the effects of straining or vaginal mucosa have lost their natural lubrication, the contracted uterus, then caudal epidural anaes- while the vagina and vulva are often swollen and thesia and clenbuterol should be given without manipulation is rendered difficult. Correction further waste of effort. A further advantage of of the faulty disposition in such cases may prove epidural anaesthesia is that an animal which has very difficult and may prompt an early decision to become recumbent often rises after its induction, 224  THE APPROACH TO AN OBSTETRIC CASE 9 which invariably makes any manipulative proce- minimal, the use of caudal epidural anaesthesia dures easier because the veterinarian can stand should be used on welfare grounds; because the and the intra-abdominal pressure is reduced. uterus of the ewe is particularly easily torn or rup- If the calf is a monster, e.g. schistosoma reflexus tured it allows a more gentle approach to any presented viscerally, it is almost certain that feto- manipulative procedures and reduces the likelihood tomy will be necessary before it can be delivered via of trauma. In addition, where faulty disposition the vagina. In many, especially schistosoma reflexus involves the limbs or head, reposition after retro- in which the head and limbs are directed towards pulsion is, as a rule, relatively easy. Retropulsion, the pelvic inlet, fetotomy may be extremely diffi- replacement of lost fetal fluids and correction of a cult, and a better means of removing the fetus is by faulty disposition are made much easier by elevating a caesarian operation. the hindquarters of the ewe. This can be done by In cases of fetomaternal disproportion of an oth- rolling her on to her back and getting an assistant to erwise normal calf in normal disposition, the incli- pull both hind legs upwards and forwards. In cases nation of the operator will be to resort to traction. of lateral deviation of the head and breech present- In many cases, this attitude is a proper one, for by ation in which manipulative reposition fails, feto- this means delivery is often effected without the tomy using the guarded wire-saw is indicated. mother sustaining irreparable injury. However, Owing to the smallness of the lamb, the operation is the amount of traction must be limited to that of easier than in the calf. three persons or a calving aid (this will be discussed In the ewe, it is especially important to ensure later) and the progress of the operation must be that the presented parts belong to a single fetus.The very closely scrutinised by the veterinary surgeon, young, in cases of twins and triplets, are small and who will pay due regard to lubrication and to the retropulsion and reposition are seldom difficult. method and direction of traction. If no progress is In ewes in which it is impossible to pass the made after 5 minutes, or if the fetus becomes hand into the uterus, delivery by forceps traction lodged and fails to yield to 5 minutes of further may be possible. The manner of the application of traction, then a caesarian operation should be the forceps is similar to that later described for the performed. bitch. Forceps of the Hobday type, of appropriate Here again, the operator should always consider size and fitted with a ratchet to maintain a secure the advisability of seeking the aid of a colleague. hold when applied, are best for the purpose. Snare forceps of the Roberts’ type or various proprietary fixed snares (see Figure 12.4) are also useful in Ewe head presentations. In this species, the facility with which faulty fetal Great care must be taken during intravaginal disposition can be corrected will depend in large manipulations that the mucous membrane at the measure on the operator’s ability to pass a hand pelvic inlet is not lacerated. It is an accident which through the pelvis into the uterus. In the majority may occur quite simply, particularly when a finger of ewes this is possible, but occasionally, especially is being used to lever a head or limb upwards. in primigravid animals of the smaller breeds, it is Such lacerations are usually followed by infection impossible, and delivery per vaginam may fail. and possibly death. The same difficulty arises in cases of incomplete dilatation of the cervix or ‘ringwomb’. In this Sow troublesome condition, unless patient digital and manual efforts to dilate the cervix soon succeed, a In the sow, the ease with which obstructive dysto- caesarean operation must be resorted to. cia can be relieved depends almost entirely on the In cases of fetomaternal disproportion with operator’s ability to pass a hand through the pelvic normal fetal disposition, the application of snares inlet. Provided this is possible, it is usually a rel- after retropulsion of the head or hips from the pelvic atively easy matter to grip the head or hind parts inlet is not difficult, and gentle traction effects deliv- and withdraw the fetus. In small gilts and in ery. Unless the amount of vaginal manipulation is sows of breeds such as the Vietnamese pot-bellied 225 3 DYSTOCIA AND OTHER DISORDERS ASSOCIATED WITH PARTURITION breed, the use of a lambing snare (Figure 12.4) ment. When it is suspected that parturition is may be useful to apply traction to the head. The incomplete, the clinician should pass a hand as far disposition of the limbs is seldom of much conse- as possible into the uterus and sweep it gently quence. When such assistance has been forthcom- about the abdomen in the hope of balloting indi- ing early, i.e. within an hour or two of the onset of rectly a piglet in an adjacent segment of the long second-stage labour, removal of a fetus is often uterine horn. Transabdominal B-mode realtime followed by the normal expulsion of the remain- ultrasonography can be used to locate a retained der. Assistance in the sow is frequently delayed, fetus (see Chapter 3). The presence of retained however, and in these cases the obstetrician will fetal membranes is even more difficult to deter- be well advised to remove as many piglets from mine. Where the clinical manifestations suggest the uterine body and cornua as are within reach. that a fetus (or fetuses) is still retained and there The subsequent course will depend chiefly on the has been no response to the administration of measure of delay and thus the degree of inertia ecbolics, the only approach would be an explor- which has supervened. It may be found in an hour atory laparotomy. Sows and gilts will often survive or so that normal expulsion has recommenced, or the presence of retained piglets which sometimes that on further examination more fetuses are become mummified (see Chapter 4). Since they accessible to manual extraction, and by continued are occasionally seen in the uteri of culled sows attention to the sow in this manner the whole and gilts at the abattoir, it is likely that although litter can be removed. It is worth remembering they survived they were infertile. that intravaginal and intrauterine manipulations will stimulate the release of endogenous oxytocin, Bitch and queen cat and thus stimulate myometrial contractions. Quite often, however, complete inertia has devel- The primary consideration in the management of oped and no further progress follows the removal a case of dystocia in the bitch or queen is – shall of the accessible fetuses. In these, a caesarean one proceed with delivery per vaginam or shall operation is the only means of saving the sow. one immediately resort to laparotomy? Factors The strategic use of oxytocin to induce myo- which will influence the decision are: metrial contractions can be used to treat overt the cause of dystocia, whether obstruction or cases of dystocia, and also to hasten the expulsion primary inertia of piglets if there is an extended time interval the duration of second-stage labour and hence before the arrival of the next, thus preventing still- the condition of the fetuses and the uterine birth. It is important to give low doses of oxytocin muscle initially since it is a potent ecbolic and large dose the number of fetuses retained. rates will cause spasm of the myometrium rather than rhythmical peristaltic-like contractions. In When the case is recent, a matter of a few hours addition, the myometrium will become refractory only, one will proceed to assist the bitch or queen to its effect and it may be necessary to increase the per vaginam. If the cause is a modest degree of feto- dose rate in order to obtain a response. maternal disproportion with the fetus in anterior or In a series of 200 porcine dystocias, Jackson posterior presentation, it is probable that traction, (1996) found that an injection of 1 ml of a solu- using the finger and vectis or forceps (these should tion containing 0.5 mg of ergometrine maleate be used with great care to prevent trauma to both and 5 units of oxytocin gave a better and more dam and offspring), will succeed in effecting deliv- prolonged ecbolic effect. The same author ery and parturition will then proceed normally. observed that the greatest problem in porcine Similarly, in cases of faulty fetal disposition, such as obstetrics was to know when a parturient sow had vertex posture or breech, traction may succeed expelled all her piglets. Good, but not infallible, after correction of the abnormal posture. If, indications of the end of labour are that the sow however, there is gross fetomaternal disproportion, rises, passes a large volume of urine and then and this should be suspected in litters of one or two resumes recumbency in an attitude of content- only, an early caesarian operation is indicated. 226  THE APPROACH TO AN OBSTETRIC CASE 9 In protracted cases of 24 hours or more, a cae- how long after the onset of second-stage labour sarian operation is the primary consideration, for it puppies are likely to remain alive. It is very improb- is probable that secondary inertia has supervened able that the presented fetus will live longer than and removal of the obstructed fetus will not alter the 6–8 hours, for by that time its placenta will have ultimate outcome.The question sometimes arises of completely separated. The remaining fetuses, whether one should first attempt to remove the pre- however, may be alive for much longer periods; it is sented fetus per vaginam before performing surgery. possible that after 36 hours’ delay the presented It is highly likely that this fetus is infected, and inter- fetus may be dead with early signs of emphysema ference with it through an abdominal wound will yet those occupying the anterior parts of the cornua favour the development of peritonitis. There is also, may be alive. After a delay of 48 hours this is highly of course, the possibility that forceps interference unlikely to occur. will subject the bitch to even graver risk. The The respective indications for the two oper- author’s attitude is that when the presented puppy ations, hysterotomy and hysterectomy, will be dis- is impacted in the pelvis, it is best to attempt its cussed in Chapter 21. However, a recent study removal with forceps prior to commencing abdom- involving 37 bitches and 26 queens which were inal operation, but in other situations the presented subjected to ovarohysterectomy found it to be fetus is best removed through laparotomy. safe, with newborn survival rates of 75% for dogs A further question which arises in laparotomy and 42% for cats; these are comparable to those cases – and this has special reference to the influ- published following caesarean operations to treat ence of the anaesthetic agents to be employed – is dystocia (Robbins and Mullen, 1994). REFERENCES Jackson, P. G. G. (1996) In: Handbook of Veterinary Obstetrics. Vandeplassche, M. (1972) Equine Vet. J., 4, 105. London: W. B. Saunders. Vandeplassche, M. (1980) Equine Vet. J., 12, 45. Robbins, M. A. and Mullen, H. S. (1994) Veterinary Surgery, 23, 48. 227 10 Maternal dystocia: causes and treatment Dystocias, which arise in the mother due to Incomplete dilatation of the cervix maternal factors, are caused either by constriction of the birth canal or by a deficiency of expulsive The cervix provides an important protective force; they are set out in Figure 8.1. The constric- physical barrier for the uterus during pregnancy. tive forms, of which the most important are pelvic Several days before, and during, the first stage of inadequacies, incomplete dilatation of the cervix parturition the cervix undergoes considerable and uterine torsion, will be considered first. changes in its structure so that it can dilate, becoming completely effaced and thus allowing the fetus(es) to pass from the uterus into the vagina, and thence to the exterior. The changes in CONSTRICTION OF THE BIRTH CANAL the cervix are described in Chapter 6. Incomplete dilatation occurs in cattle, goats and sheep; in the Pelvic constriction latter species it is one of the commoner causes of Developmental abnormalities of the pelvis are dystocia. The degree of incompleteness of dilata- generally rare in animals, but in the achondro- tion varies from virtually complete closure, to the plastic breeds of dog the pelvic inlet