Diagnosis, treatment and control of left displaced abomasum in cattle Karin Mueller.pdf

Farm animal practice Karin Mueller Left displaced abomasum remains an important disease in dairy cows during the early postpartum period. The condition is multifactorial in nature, so it is important to carry out a thorough clinical examination and consider the influence of concurrent disease on m...

Farm animal practice Karin Mueller Left displaced abomasum remains an important disease in dairy cows during the early postpartum period. The condition is multifactorial in nature, so it is important to carry out a thorough clinical examination and consider the influence of concurrent disease on management. This article outlines the clinical findings that aid diagnosis, and describes the treatment options available and the relative merits of each. In addition, it reviews the potential risk factors that might be involved and highlights some predictive indicators cited in the literature that may find practical application in the future. Karin Mueller graduated from the University of Giessen in Germany in 1991, after which she completed a residency in farm animal medicine at Leahurst. She subsequently worked in private practice and academia in both the UK and New Zealand, and led the farm animal section at Cambridge Veterinary School for several years. She is now based at Dick White Referrals as a consultant in camelid medicine. She holds European and RCVS diplomas in bovine/cattle health and a MVSc in theriogenology. Incidence The annual worldwide incidence of a displaced abomasum in cattle is 0·05 to 5·8 per cent. In individual herds, incidence can range from zero to approximately 25 per cent. The condition is more common in adult female cattle than male animals or calves. In bulls and calves, the ratio of left- to right-sided displacement is roughly equal. In female cattle, left displaced abomasum (LDA) (Fig 1) is more common than right displaced abomasum (RDA), with LDA:RDA ratios of 2·5:1 to 7:1. Diagnosis Signalment Around 90 per cent of animals with LDA are nonpregnant cows. They typically present in the first month postpartum, with a high proportion occurring in the first 14 days in-milk. The highest risk period is in parities 3 to 5. doi:10.1136/inp.d6079 Dairy breeds are more commonly affected than beef breeds. This may be largely due to management and metabolic demands. Body shape may also play a role, as abdominal depth and contour has changed in dairy cows over the past 70 years, resulting in a greater distance between the ventral abomasal body and duodenum. This distance has been found to be higher in cows with LDA than in control cows (Wittek and Barrett 2009), probably resulting in reduced abomasal emptying. Within dairy breeds, there is a decreasing susceptibility from Guernsey to Holstein Friesian to Brown Swiss cows. Family susceptibility has been recognised in Holstein Friesian cattle, with a moderate hereditability of 0·24 estimated in German cattle and 0·28 in Canadian cattle. However, other studies suggest that hereditability is lower at 0·03 to 0·09. General clinical findings Unsatisfactory milk yield is a common presenting sign. Selective inappetence is often apparent, with continued intake of forage but refusal of concentrates. Z O R X O O D R X B Fig 1: Position of left displaced abomasum in a cow viewed from the (a) rear, and (b) left side (ie, the animal’s head would be to the left). O Greater omentum, X abomasum, R rumen, D duodenum, Z 13th rib A 470 In Practice October 2011 | Volume 33 | 470–481 Fig 2: Arched back in a cow with left displaced abomasum, indicating abdominal pain. This is atypical, and suggests that abomasal wall pathology is present (eg, ulceration), or that the animal is suffering from a concurrent painful condition (eg, peritonitis or metritis) In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Diagnosis, treatment and control of left displaced abomasum in cattle Farm animal practice Condition Differentiation from left displaced abomasum Rumen collapse syndrome Resonance is very similar to that of LDA, but typically occurs more caudally – that is, over the main part of the flank rather than close to or over the last rib. The area of resonance is typically larger. The small size of the rumen and collapsed dorsal sacs may be appreciated on rectal examination Rumen tympany Distension of the left flank is evident, with dull, drum-like resonance. Free gas bloat can be confirmed by passing a stomach tube to release the gas Peritonitis Bilateral resonance with diffuse peritonitis. Alternatively, localised resonance may occur, but not necessarily at the typical site of LDA. Vital signs are changed, and will include signs of toxaemia. Affected animals react positively to abdominal pain tests. Emphysema may be appreciated on rectal examination Pneumoperitoneum Resonance typically occurs high in the abdomen, and is bilateral, extending over a large area. Animals have a history of recent laparotomy Z Fig 3: View of the left flank of a cow with left displaced abomasum showing a discrete swelling (arrows) caused by the displaced abomasum. Z 13th rib Vital signs are typically within normal ranges to slightly raised, unless the abomasum is very distended or there is concurrent abomasal wall pathology leading to discomfort (Fig 2). Rumen activity tends to be normal, but this may not be appreciated on clinical examination, with the rumen being pushed medially by the displaced abomasum. This medial displacement of the rumen is why the flank typically appears sunken rather than distended. A discrete swelling may be palpable just caudal to the last rib (Fig 3). In cases of more than three days duration, watery, and often malodorous diarrhoea may be present. Specific examination In about 50 per cent of cases, LDA can be detected by auscultation of the left flank alone, with high-pitched gurgling sounds being present intermittently and not associated with obvious rumen contractions. For more reliable detection, simultaneous percussion and auscultation over the left flank will reveal an area of high-pitched ‘pinging’, similar to the sound of a bouncing basketball or water trickling into a metal bucket. This ‘pinging’ can be due to a number of conditions and must be differentiated from LDA (Table 1). Displacement tends to start in the reticulorumen groove, so the area on a line from one hand-width behind the left elbow to the left tuber coxae should be percussed. Typically, the ‘ping’ can be heard just over or just behind the last rib, about one-third down the flank. Simultaneous ballottement and percussion may reveal a similar sound. On rectal examination, the displaced abomasum can only rarely be felt in the left abdomen, but medial displacement of the rumen may be appreciated (resulting in a palpable gap between the rumen and the left body wall). LDA can be confirmed by: ■■ Centesis over the area of the ping. Abomasal fluid will have a pH of 2 to 3, whereas the pH of rumen fluid will be 6 to 8; ■■ Passing a stomach tube into the rumen, with an assistant blowing air down the tube while the clinician listens at the left flank. In the case of LDA, the bubbling caused by the air would not be audible. This technique is advocated in some texts, but it is quite difficult to interpret the findings unless the procedure is performed regularly; LDA Left displaced abomasum ■■ Ultrasonography of the left flank. Again, this tech- nique needs to be undertaken regularly to achieve confidence in interpreting the images produced. At least 50 per cent of cattle with LDA will be suffering from concurrent illness, such as metritis or mastitis. A thorough clinical examination must be performed to detect any additional problems that may influence prognosis, treatment approach and aftercare. Treatment Conservative treatment Conservative treatment involves rolling the animal without anchoring the abomasum while providing supportive therapy. The cow is cast into right lateral recumbency, and slowly rolled into dorsal recumbency while the abdomen is kneaded to correct the displaced abomasum. The animal is held in the dorsal position for several minutes and auscultation used to confirm the abomasum has returned to its correct position. After rolling the cow into left lateral recumbency, it is held down for a few more minutes and then allowed to rise. Surgery A number of surgical methods can be used to correct LDA and include: ■■ Percutaneous fixation, which can be carried out using the Grymer-Sterner toggle technique (Fig 4, A B Fig 4: (a) Instruments required for the Grymer-Sterner toggle technique (Grymer and Sterner 2002) (from left to right): handle, trocar, suture push-rod, two toggle sutures, and two artery forceps. (b) Assembled instrument. The push-rod is inserted as for toggle suture advancement. Additional equipment, including a halter, casting and leg ropes, clippers, disinfectant, 20 to 40 ml of local anaesthetic, sterile gloves, stethoscope, and a pair of scissors, will also be required In Practice October 2011 | Volume 33 | 470–481 471 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Table 1: Main differential diagnoses for a ‘ping’ in the left flank Farm animal practice Step 1. Cast the cow into right lateral recumbency on a soft surface. Sedation should only be used if necessary for the safety of the animal or the operator. The only licensed sedatives are alpha-2 agonists, which have an undesirable effect on abomasal tone (especially xylazine) Step 5. Gradually roll the cow into dorsal recumbency while kneading the left flank to encourage the abomasum to resume its normal position. Once in dorsal recumbency, auscultate the area around the midline for a high-pitched ‘ping’ indicating the location of the abomasum. Here, it is helpful to have an assistant kneel in front of the udder to exert pressure on to the abdomen to keep the abomasum close to the body wall Step 2. Keep the cow in right lateral recumbency for steps 2 to 4. Clip the area between the xiphisternum and umbilicus to the right of the midline. The back legs are tied together for restraint and safety Step 6. Once the abomasum has been identified, push the trocar through the body wall into the abomasum. The trocar must be placed into the area with the high resonance ‘ping’. For the caudal toggle, the ideal site is one hand-width cranial to the umbilicus, to the right of the midline Box 1) (Grymer and Sterner 2002), which has generally superseded blind fixation by passing a large curved needle through the body wall into the abomasum. Severe concurrent disease or late pregnancy render patients unsuitable candidates for the Grymer-Sterner toggle technique. In a small-scale study carried out by the author, ultrasonography using a linear probe was not found to be helpful for identifying the abomasum with certainty for guiding toggle placement. Interpretation of the images obtained in this study was also difficult. ■■ Paramedian laparotomy with ventral abomasopexy or omentopexy (Box 2), under local infiltration anaesthesia; ■■ Left flank laparotomy with ventral abomasopexy or omentopexy (‘Utrecht method’) (Box 3), under paravertebral or local infiltration anaesthesia; Step 7. Taking care not to allow too much gas to escape, push the toggle suture through the trocar with the help of the push-rod. Remove the trocar and push-rod, and clamp the suture end with a pair of forceps. The pH of the escaping gas can be checked during this step before suture placement. Correct placement into the abomasum is confirmed by a pH of less than 4. Checking acidity by smell is often difficult due to the presence of other smells (eg, from disinfectant) ■■ Right flank laparotomy with right-sided omento­ pexy or pyloropexy (Box 4), under paravertebral or local infiltration anaesthesia; ■■ Bilateral laparotomy with right-sided omentopexy or pyloropexy. This technique is essentially the same as the right-flank approach, but with a second surgeon repositioning the abomasum through an additional incision in the left flank. Practitioner preference, and patient and farm circumstances (eg, concurrent problems and available resources) will affect the decision of which surgical technique to use. When using surgical treatment, it is important to anchor the correct part of the abomasum (in a physiological sense), depending on the approach used. For example, the greater curvature of the abomasum when using a technique with ventral abdominal anchorage (eg, the Utrecht method) versus the pyloric Continued on page 476 472 In Practice October 2011 | Volume 33 | 470–481 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Box 1: Grymer-Sterner toggle technique Farm animal practice Step 3. Apply surgical disinfectant (eg, povidoneiodine) to the clipped area A B Step 8. Repeat steps 6 and 7 at the cranial site, ideally one hand-width (7 to 8 cm) cranial to the first toggle (resulting in this toggle sitting one hand-width caudal to the xiphisternum), with (a) auscultation to locate the abdomen and (b) placing the trocar. After pushing the toggle suture through, allow as much gas as possible to escape before removing the trocar at this second site. Steps 5 to 8 should be carried out rapidly once the animal is in dorsal recumbency to prevent too much gas from escaping while the first toggle suture is placed. Allow as much gas as possible to escape once the second toggle has been placed Step 9. Tie together the two suture ends, leaving one hand-width of space between the body wall and the knot. A toggle button can be used to spread the pressure created by the sutures. A pack of gauze swabs may be placed underneath the suture for the same purpose, but creates a more contaminated environment around the sutures. Roll the cow into left lateral recumbency and keep it in that position for five to 10 minutes, before allowing it to rise. A course of antibiotics (eg, penicillinbased) is advisable and should ideally be started before the procedure is undertaken. Supportive therapy for ketosis and other concurrent problems should be given, as appropriate Box 2: Paramedian laparotomy with ventral abomasopexy or omentopexy A (a) Cast the cow into right lateral recumbency on a soft surface. Only use sedation if necessary for the safety of the animal or operator (see Grymer-Sterner toggle method [Box 1] ). Gradually roll the cow into dorsal recumbency while kneading the left flank to encourage the abomasum to resume its normal position. Once in dorsal recumbency, clip an area to the right of the midline between the umbilicus and xiphisternum and prepare it for surgery. Make a longitudinal incision through the body wall, large enough to insert your hand. (b) Identify the abomasum (arrow) and pull it up to the incision. Either suture the abomasal wall to the body wall just inside the incision, or incorporate the omentum close to the abomasum into the abdominal wall closure. (Pictures, N. D. Sargison) B In Practice October 2011 | Volume 33 | 470–481 473 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Step 4. Infiltrate two sites of the abdominal wall with 10 to 20 ml of local anaesthetic each (eg, procaine hydrochloride). The first should be one hand-width cranial to the umbilicus and the other one handwidth caudal to the xiphisternum, both to the right of the midline. The use of local anaesthetic makes the procedure safer for the operator Farm animal practice A B Step 1. (a) Clip the area to the right of the midline between the umbilicus (white arrow) and xiphisternum (blue arrow). After applying surgical spirit, infiltrate two sites of the abdominal wall with 10 ml of local anaesthetic each (eg, procaine hydrochloride). The first should be one handwidth cranial to the umbilicus to the right of the midline and the other one hand-width cranial to the first site. (b) Both sites may be marked with ‘blue spray’ or similar indicator to aid later identification of the sites by the assistant (the arrow indicates a blood vessel) O X R X Step 4. The abomasum (X) can typically be visualised just cranial to the incision. Aside from palpation, it can be distinguished from the greyish rumen (R) by its more pinkcoloured serosa A Step 5. Insert your right hand into the flank incision. Grasp a fold of greater omentum at the level of the 11th to 12th rib and pull it into the incision B Step 6. Place an absorbable suture at least two metres long into the abomasum (X) or the omentum (O) (the more commonly used site), very close and parallel to its abomasal attachment using a continuous horizontal mattress pattern, taking 4 to 5 bites. Leave a roughly equal length of suture material at either end of the suture line. The diagram shows the left flank, with the suture in green C Step 8. Using a flat hand and the lower arm, create downward pressure on the abomasum and push it towards the right of the midline while rotating it anticlockwise. This results in the greater curvature of the abomasum moving into the normal ventral position again. In most cases, pressure from the hand and arm is sufficient to deflate the abomasum. In rare cases, a needle and tube may need to be placed into the lumen to release excess gas before repositioning. (a) The assistant takes up the slack in the sutures (as shown). Repositioning of the abomasum is done by you, not by the assistant pulling on the sutures. Check that the abomasum is lying tightly against the body wall (ie, there should be no more than 1 to 2 cm of free suture between omentum and body wall) and hold the abomasum in place, while (b) the assistant ties off the two sutures against each other. (c) The assistant cuts the sutures several centimetres below the knot 474 In Practice October 2011 | Volume 33 | 470–481 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Box 3: Left flank laparotomy with ventral abomasopexy or omentopexy (Utrecht method) Farm animal practice Y Step 3. Make a routine left-flank incision close to the last rib, long enough to insert your entire arm. A typical dorsal starting point for the incision is one-and-a-half hand-widths below the transverse processes, but this should be adjusted depending on the length of your arm and the cow’s height. You need to be able to reach to the right of the midline inside the cow’s abdomen Step 2. Clip the left flank between the 12th rib (Y) and the tuber coxae (T), and prepare the area for surgery A B C Step 7. Attach the caudal suture end to a 10 to 12 cm long cutting needle. (a) Cupping the needle in the right hand, advance your hand along the inner body wall to the right of the midline. (b) An assistant should be asked to push a closed pair of artery forceps up on to the body wall at the caudal, previously marked point on the ventral abdomen. Identify the resulting elevation in the body wall and push the needle point into the body wall. This should be done quickly to prevent omentum or intestine from becoming ensnared. The assistant should watch your movements and provide guidance away from any larger blood vessels if necessary. Push the needle all the way through the body wall, aided by the assistant creating counterpressure. (c) Once the needle has emerged, the assistant applies a temporary clamp to the suture. Repeat steps a to c for the cranial suture. To avoid entanglement in the first suture inside the abdomen, it helps to first advance your hand cranially along the inside of the ribcage, before moving towards the ventral body wall D R X O Step 9. The abomasum (X) now lies in its correct position and is anchored at the ventral abdominal wall. O Greater omentum, R rumen, D duodenum Step 10. Close the flank incision in a routine manner. Apply fly repellent if necessary. Note the image shows a cow after caesarean section – that is, the incision is more caudal and longer than a typical approach for LDA correction. After 12 to 14 days, cut the abomasal sutures close to the body wall and remove the flank skin sutures In Practice October 2011 | Volume 33 | 470–481 475 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. T Farm animal practice Laparoscopy Laparoscopy offers a minimally invasive method of correction, but with visual control. The two-step method consists of placing two toggle sutures into the displaced abomasum through two keyhole incisions in the left flank, followed by retrieval of those sutures through two ventral incisions with the cow now in dorsal recumbency (van Leeuwen and others 2009). One-step methods have also been described (Newman and others 2008). Aftercare ■■ Routine antibiosis and analgesia (non-steroidal anti-inflammatory drugs, unless corticosteroids are used [see below]) should be given after surgical correction. The author also prefers to use both after toggle fixation; ■■ Various drugs have been investigated for a potential positive effect on abomasal motility and emptying (Table 3); ■■ Cases of LDA will either be ketotic or at high risk of developing ketosis. Oral administration of propylene glycol and offering palatable food will help to correct this. The advantage of corticosteroids in correcting ketosis versus their disadvantage of potentially interfering with wound healing has to be considered on a case by case basis; ■■ If animals remain ketotic, blood analysis for liver function/fatty liver necrosis is useful as a prognostic indicator (measure bile acids, glutamate dehydroge- Box 4: Right flank laparotomy with right omentopexy or pyloropexy Step 1. After clipping and surgical preparation, make a routine rightflank incision close to the last rib, long enough to insert your entire arm. A typical dorsal starting point for the incision is one-and-a-half hand-widths below the transverse processes, but this should be adjusted depending on the length of your arm and the cow’s height. You need to be able to reach the midline inside the cow’s abdomen A Step 2. Reposition the abomasum into its correct position. This can be facilitated by previous deflation using a 19 gauge needle with attached tubing. Advance your hand over the dorsal rumen across to the left side of the cow’s abdomen, and insert the needle into the dorsal distended abomasum B Step 3. Reposition the abomasum into its ventral position by a combination of dorsal pressure with a hand advanced over the rumen, and by pulling ventrally on the greater omentum near its attachment on the abomasum. (a) Either attach the abomasum near the pylorus to the body wall just cranial to the flank incision, or incorporate a fold of omentum close to the pylorus into the first layer of the flank closure (the more common procedure). (b) Identify the correct part of the omentum by an omental flap several centimetres long, also called the ‘sow’s ear’. (Pictures, J. M. Roberts) 476 In Practice October 2011 | Volume 33 | 470–481 Step 4. Close the flank incision in a routine manner. Apply fly repellent if necessary. Remove the flank skin sutures after 12 to 14 days In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Continued from page 472 region when anchoring in the right flank. No significant difference has been found between omentopexy and abomasopexy in anchoring success. The right flank method can be slightly modified by first rolling the cow to reposition the abomasum, followed by right flank laparotomy to anchor it. This is especially useful in large patients. Table 2 compares the surgical techniques discussed above and outlines the criteria for each. Farm animal practice injection of calcium borogluconate. The author typically administers calcium routinely to higher parity cases; ■■ Intravenous sodium chloride (isotonic or hypertonic) should be considered in long-standing cases in which dehydration with hypochloraemia, hypokalaemia Table 2: Comparison of surgical techniques to correct left displaced abomasum Criterion Grymer-Sterner toggle Paramedian laparotomy abomaso/omentopexy Left flank with ventral abomaso/omentopexy Right flank pyloro/ omentopexy Bilateral approach Position of patient Dorsal recumbency. Risk of regurgitation, more stressful. Contraindicated in pregnant animals. Care required in compromised animals (eg, in cases of toxaemia) Standing Standing Standing Identification of abomasum + +++ +++ ++ +++ Detection of ulcers and adhesions – Ulcers ++ Adhesions – +++ + Treatment not possible +++ Decompression ++ After repositioning ++ Rolling +++ Manual or needle ++ Needle or rolling +++ Manual or needle Replacement +++ Usually resumes normal position +++ Usually resumes normal position +++ Easy + Difficult in large animals. Risk of trauma to abomasum or omentum +++ Easy Anchorage ++ Omentopexy ++ Abomasopexy +++ ++ +++ +++ Wound N/A Risk of venepuncture, cellulitis + High risk of contamination. Serious complications in the event of a breakdown +++ Small risk of contamination +++ Small risk of contamination + Two incisions. Little risk of contamination Other areas examinable – + Possibly liver ++ Rumen, reticulum, uterus ++ Liver, intestine, caecum, uterus +++ Most organs Number of surgeons 1 1 1 1 2 Non-vet assistants 2 to 3 2 to 3 1 1 0 to 1 Technical difficulty Moderate Easy Moderate Moderate Easy Problems Adhesions prevent replacement, identification of abomasum, wrong organ toggled Adhesions prevent replacement Reaching ventral abdomen, snaring omentum/ intestine Unable to reposition abomasum, trauma, adhesions prevent replacement Potential complications Peritonitis, torsion if second toggle fails Wound infection, peritonitis Wound infection, peritonitis Wound infection, peritonitis, torsion Wound infection, peritonitis, torsion Time ++ +++ +++ +++ +++ Cost ++ +++ +++ +++ ++++ – Not possible, + Poor, ++ Moderate, +++ Good/high, ++++ Highest Table 3: Drugs that may have a positive effect on abomasal tone and emptying Drug Proposed action Suggested dose Evidence found Erythromycin* Increased abomasal emptying and milk yield immediately after surgery 10 mg/kg intramuscularly once before surgery Yes. Controlled study Flunixin meglumine Rumen rate strongly increased at one day after surgery Label dose Yes. Controlled study Dexamethasone or vitamin C Prevention of reperfusion injury and oxidative stress Hyoscine-butylbromide* (Buscopan; Boehringer Ingelheim) Agonist to atropine. Atropine abolishes myoelectric activity in abomasum Metoclopramide† Effect on pyloric antrum No effect in healthy heifers Bethanechol† Effect on pyloric antrum No effect in healthy heifers Atipamezole† Reversal of α2 drugs (eg, xylazine) Some support. Milk yield one day postoperatively higher in treated versus untreated cows with abomasal volvulus Label dose every eight hours Label dose. α2 drugs prerolling and atipamezole 20 minutes after Case reports Accelerated contractile motility of abomasum in healthy cows *Off-label use of drug, †Off-cascade use In Practice October 2011 | Volume 33 | 470–481 477 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. nase, gamma glutamyl transpeptidase, non-esterified fatty acids). Insulin Lente at 200 iu every 48 hours has shown some promise in refractory cases of ketosis (this represents off-cascade use of this drug); ■■ Hypocalcaemia is also common in cases of LDA, and can be treated by intravenous or subcutaneous Farm animal practice Direct costs (eg, for treatment and medicines), as well as indirect costs, may be associated with LDA, resulting in a suggested loss of £250 to £500 per case for that lactation. ■■ Milk is lost because of drug withholding periods. Overall milk yield is also reduced. In one study, an average reduction of 550 kg was seen between calving and 60 days after LDA diagnosis. Thirty per cent of this loss occurred before LDA diagnosis. Another study reported a 360 kg reduction in lactation yield. ■■ The degree of ketosis plays a role in reduced milk yield. A total of 1·9 kg/day of milk was lost if the b-hydroxy­butyrate level was above 1·4 mmol/litre, rising to 3·3 kg/day if the level was above 2 mmol/litre. ■■ LDA may affect fertility. Studies report the time from calving to first service as being increased by 10 and 17 days, and the calving interval by 24 and 33 days, compared with normal cows. and metabolic alkalosis is present. The potassium imbalance usually resolves once hydration status and acid-base balance have been corrected; ■■ The dietary regimen following correction of LDA consists of providing best quality forage. ●● Concentrates should be reintroduced at 0·5 to 1 kg twice a day and gradually increased to reach the desired total amount after seven days. Sugar beet pulp and maize flakes are useful in inappetent animals, as is a small amount of molasses; ●● One study found no difference in recurrence rates between cows fed either a diet of hay and 16 per cent crude protein concentrates, or maize silage and 26 per cent crude protein concentrates; ●● In animals with rumen stasis and continuing inappetence, transfaunation is indicated. This involves administering 2 to 3 litres of fresh rumen fluid from a healthy donor once a day for several days; ■■ Any concurrent disease must be treated appropriately and aggressively; ■■ Clients should be encouraged to report further unsatisfactory appetite or milk yield immediately, which should initiate a prompt re-examination of the animal. Control Control of LDA is centred on avoiding known or suspected risk factors (Geishauser 1995, Shaver 1997) (see Table 4 on page 479). Contributing factors will vary from herd to herd, and several elements may play a role. A thorough investigation of dry and early lactation cow management, combined with metabolic profiling, faecal scoring, diet analysis, and butterfat and milk protein patterns will usually highlight the most relevant factors in a problem herd. Prediction of risk Several studies (including LeBlanc and others 2005, Lyons and others 2009) have investigated whether there are predictive indicators for LDA in individual cows (Table 5 below). Although some results look promising, it must be remembered that the herd incidence affects how many animals will be wrongly diagnosed. These predictive tests are only worthwhile if the incidence of LDA is high, the cost of the test is low, the sensitivity and specificity of the test are as high as possible, and effective preventive measures can be instigated. One study found postpartum serum or milk b-hydroxybutyrate to be a better predictor than prepartum non-esterified fatty acids. Cholesterol, glucose, urea, calcium and phosphorus levels were not found to be useful predictors. The following indicators have been suggested for predicting the risk at herd level: ■■ As milk protein concentration is linked to energy intake, there should be concern if more than 20 per cent of early lactation cows have a milk protein concentration below 2·9 per cent; ■■ Cows that mobilise body fat may show an increased butterfat level. Butterfat concentration should be less than 5·5 per cent at the cow’s first post-calving recording (ideally carried out before 15 days inmilk). If more than 20 per cent of the herd have a butterfat concentration above 5·5 per cent, there is cause for concern; ■■ Butterfat is an indication of effective fibre levels in the diet (low butterfat indicates insufficient fibre); ■■ Using bulk milk analysis, the calculated result of butterfat percentage minus protein percentage should ideally be less than 1·5. Using a value of 1·4 or above as a cut-off, the positive predictive value for a cow having LDA was found to be 80 per cent; Table 5: Potential predictive indicators for the risk of developing left displaced abomasum Parameter Point of determination Cut-off level Risk associated with level PPV False positive AST 1st week postpartum >102 IU/litre Odds of 3:1 61% 46% AST 2nd week postpartum >102 IU/litre Odds of 8:1 79% 31% BHB (serum) 1st week postpartum >1 mmol/litre Odds of 2:1 61% 38% BHB (serum) 2nd week postpartum >1 mmol/litre Odds of 4:1 64% 31% BHB (serum) 1st week postpartum >1·2 mmol/litre Odds ratio 2·6 BHB (serum) 2nd week postpartum >1·8 mmol/litre Odds ratio 6·2 46% 19% BHB (serum) Postpartum >1·2 mmol/litre Odds of 8:1 BHB (milk K) Week 1 to 2 postpartum >100 μmol/litre Odds of 3:1 BHB (milk) Postpartum >200 μmol/litre Odds of 3·4:1 NEFA One to six days prepartum >0·5 mmol/litre Odds of 3·6:1 Likelihood ratio 2·6 Sensitivity 46% Specificity 82% AST Aspartate amino transferase, BHB b-hydroxybutyrate, K Ketolac (Hoechst), NEFA non-esterified fatty acids, PPV positive predictive value 478 In Practice October 2011 | Volume 33 | 470–481 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Box 5: Financial implications of left displaced abomasum Farm animal practice Risk factor Details Abomasal wall pathology For example, mucosal erosion or ulceration, oedema and adhesions from previous episodes of peritonitis (eg, after caesarean section). Diagnosis of these conditions is difficult. Melaena may be present in cases with abomasal ulceration Contractility is significantly inhibited in animals with left- or right-sided displacement versus control animals. This appears to be due to malfunction of neurally mediated reflexes Volatile fatty acids No difference found in abomasal VFA concentrations between healthy and LDA cows No difference in abomasal VFA levels after a concentrate feed versus a high-fibre feed Rumen total VFA levels are higher in cows without LDA compared with those one day before the occurrence of LDA (diet of maize silage and 26 per cent crude protein concentrate) In contrast, infusion of VFA solution into the abomasum caused hypomotility and markedly delayed emptying Fibre Maintaining a high rumen fibre effect is thought to be important Unless straw in a dry cow diet is chopped to a length of 2 to 5 cm, cows will sort it, and an intake of no more than 2 kg/head/day should be assumed in ration analysis. If chopped, 4 to 5 kg/head/day have been suggested Nutrition in early dry period Overfeeding leads to increased fat mobilisation in the periparturient period Nutrition in transition period A study in the USA of 12,000 multiparous cows in 67 herds showed that the risk of LDA increased 2·5 to three times for any of the following: a negative energy balance prepartum (ie, increased serum NEFA levels), high BCS, poor feed-face management (eg, trough space, not ad libitum, staleness, sorting), a prepartum diet containing more than 1·65 Mcal net energy Guidelines for prepartum feeding include limiting concentrate levels to 0·5 to 0·75 per cent bodyweight Concentrate feeding is important in the dry period as it increases the rumen papillae area, which, in turn, increases the capacity for VFA absorption. Papillae development takes five weeks The forage:concentrate ratio should ideally be 60:40, but a minimum of 40:60. There is a risk of exceeding this ratio if not using a TMR. Dry matter intake can drop by 30 per cent in the last days of pregnancy, leading to a relative overfeeding of concentrate Concentrates postpartum Feed the transition period quantity for the first four days postpartum, then increase by 250 g/day until the peak yield/desired amount is reached. This allows lactase converters to catch up with lactate producers, which increase in numbers more quickly after the introduction of a starch-rich diet. This gradual introduction is especially important in first-calving heifers. In contrast, one study found no effect on antroduodenal myoelectric activity when diet was abruptly changed to concentrates Particular feedstuffs Increased risk with feeding large amounts of maize silage Dietary fat probably does not influence the risk of LDA Body condition score Risk of LDA is lower if no loss of body condition between calving to four weeks postpartum Incidence of LDA versus actual BCS was 3·1 per cent for cows with low BCS (2·75/5 to 3·25/5), 6·3 per cent for moderate BCS (3·25/5 to 4/5), and 8·2 per cent for high BCS (>4/5) In contrast, one study did not find a difference in BCS of affected versus control cows Hormones Oestrogens can increase triglycerine deposition in the liver, leading to a higher risk of fatty liver necrosis The role of insulin is unclear. It influences abomasal emptying and has been found to be higher in cows with LDA (versus healthy cows) There is no evidence that either prostaglandins or gastrin play an important role in the occurrence of LDA Opioids reduce gastrointestinal tract motility, and are increased in the last month of pregnancy and the first 48 hours postpartum, but their role in LDA aetiology has not been investigated further Housing type There is no direct association with a particular type of housing and LDA risk, but poor housing, especially poor cubicles, increases the risk Hypocalcaemia Findings of studies on the effect of clinical hypocalcaemia are ambiguous There was a direct relationship between low calcium and LDA in Canadian herds, with an odds ratio of 2·6 In New York State herds, no link to calcium or phosphorus levels was found A plasma calcium level of 1·25 mmol/litres resulted in a reduction in abomasal motility by 70 per cent and in the strength of contractions by 50 per cent (at a level of 1·8 mmol/litres, the reduction was 30 and 25 per cent, respectively) Liver function compromise The odds ratio of a cow with ketosis developing LDA is 4·5 to 11, compared with cows without ketosis. Equally, LDA increases the risk of ketosis There is a high risk of LDA with fatty liver necrosis. Cows developing LDA at a later date showed a three-fold increase in liver triglyceride concentrations at the time of calving Mastitis Mastitis does not appear to increase the risk of a cow developing LDA Escherichia coli endotoxin was shown to cause hypomotility and markedly reduced abomasal emptying Milk yield There is no direct link between milk yield and LDA risk – that is, a high-yielding cow is not automatically at greater risk. This is also reflected in there being no association with previous lactation milk yield. The genetic milk yield potential is not different between cows with LDA compared with normal cows. However, a higher persistency in milk yield over the lactation carries a higher risk of displaced abomasum. High-yielding herds have a higher incidence of LDA, presumably because of a variety of management factors, including breed type selection. Reproductive tract problems Metritis leading to LDA has an odds ratio of about 4·5. The suggested pathophysiology involves endotoxin release from the uterus, which reduces abomasal emptying. Equally, the risk of developing metritis seems to be higher in cows with LDA Cows with retained fetal membranes have been shown to have just over twice the risk of LDA compared with normal cows, and an odds ratio ranging from 3·6 to 8 has been determined for retained fetal membrane cases Giving birth to twins and stillbirth appear to be linked to a higher risk of developing LDA Time of year In New York State, there was a 1·5-fold risk of LDA during the months of March to May In Michigan, winter and summer months carried a higher risk. A possible explanation for this may be heat stress in summer leading to reduced dry matter intake, and increased usage of energy for thermoregulation in winter No seasonal pattern could be found in herds in Canada Other factors Bullying. Increases the risk of LDA in heifers, and careful introduction to the herd is advised Lameness. The odds ratio of cows with foul-in-the-foot developing LDA was 2 to 3 in herds in Canada. Other associations with lameness have not been found Dry period length. Although pre- and postpartum NEFA levels differed between the two groups, no difference in incidence of LDA was found in cows with a dry period of either 34 or 55 days Abomasal impaction or foreign bodies, vagal nerve damage, or vitamin A deficiency. There is no evidence that these factors directly influence the occurrence of LDA BCS Body condition score, LDA left displaced abomasum, NEFA non-esterified fatty acids, TMR total mixed ration, VFA volatile fatty acids In Practice October 2011 | Volume 33 | 470–481 479 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Table 4: Risk factors associated with left displaced abomasum Farm animal practice The table below shows the results of published follow-up or comparison studies for different LDA correction techniques (Saint Jean and others 1987). One study found that 10 per cent of animals were culled before the next herd test day after LDA correction. In another study, the risk of culling was found to be 1·8-fold higher in cows following LDA than control cows for the current lactation. The culling risk in subsequent lactations was not different from control cows. Other prognostic findings suggest that: ■■ The long-term success of rolling is poor, with a 60 to 70 per cent recurrence rate within a few days; ■■ Recurrence of LDA in subsequent lactations is rare. An economic analysis of LDA correction techniques concluded that surgical intervention provided the best financial return, closely followed by toggling (on the basis of a 90 per cent success rate for surgery, 85 per cent for a closed technique and 30 per cent for rolling). Rolling gave greater financial return than culling the cow straight away (Ruegg and Carpenter 1989). A higher cost:benefit of surgery over toggling was also found by Gordon (2009). Published success rates measured by cow survival for different correction techniques for left displaced abomasum Number of animals Technique 250 RFO versus LAP 147 RFO 86% Recurrence rate 4 per cent. Main risk was sutures placed too caudal or dorsal from the pylorus 50 RFO 90% Recurrence rate 4 per cent. Main risk was sutures placed too caudal or dorsal from the pylorus Success rate Comments Milk yield and rumen rate increased faster after LAP. There was no difference in appetite or milk yield at seven days, relapse at 60 days after surgery, comfort or cull rate. LAP was much quicker to perform (36 versus 74 minutes) 120 LFO 86% 14 LFA 100% 45 LFA 80% Unknown PARA 86·5%, 92%, 94% 27 Toggle 81·5% 44 Toggle 84% 104 Toggle 86% 59 Toggle versus Sx 72 versus 77% Not statistically significant 810 Vet-T versus Herd-T versus Sx Survival at 14 days after surgery: 87 versus 81 versus 85% Survival at 60 days after surgery: 79 versus 71 versus 73% Failure risks included mastitis, previous history of LDA, correction by herdsman, high preoperative risk Herd-T Toggle performed by herdsman, LAP laparoscopy, LFA left flank and ventral abomasopexy, LFO left flank and ventral omentopexy, PARA paramedian, RFO right flank omentopexy, Sx laparotomy, Vet-T toggle performed by vet however, the false-positive rate was also high at 31 per cent; ■■ In one study, the above changes (ie, reduced milk yield and milk protein, and increased butterfat and percentage differences) were also evident in affected cows at one to three weeks before LDA diagnosis. Summary LDA remains a multifactorial condition, and its control and prevention will differ between herds and continue to present a challenge. Predictive parameters of the condition have been investigated, but values currently remain too low for practical application. Several options for LDA correction are available, with surgical methods typically offering the highest cost:benefit ratio. While veterinary surgeons should be aware of the particular advantages and disadvantages of each method, their preference and experience, the available resources and the presence of concurrent disease will also influence the decision of which treatment option is chosen. References Geishauser, T. (1995) Abomasal displacement in the bovine – a review on character, occurrence, aetiology and pathogenesis. Journal of Veterinary Medicine, Series A 42, 229-251 Gordon, P. (2009) Roll and toggle correction of left displaced abomasum (LDA) – practical tips for success. Cattle Practice 17, 128-130 GRYMER, J. & STERNER, K. E. (2002) Grymer/Sterner toggle suture. Online resource and reference site for veterinarians. www.ldatogglesuture.com. Accessed August 19, 2011 LeBlanc, S., Leslie, K. & Duffield, T. (2005) Metabolic predictors of displaced abomasum in dairy cattle. Journal of Dairy Science 88, 159-170 Lyons, N. A., Brickell, J. S., Wilson, S. & Wathes, D. C. (2009) Association between postpartum concentrations of plasma IGF-I, left displacement of the abomasum and subsequent fertility in the dairy cow. Cattle Practice 17, 131-135 Newman, K. D., Harvey, D. & Roy, J. P. (2008) Minimally invasive field abomasopexy techniques for correction and fixation of left displacement of the abomasum in dairy cows. Veterinary Clinics of North America: Food Animal Practice 24, 359-382 Ruegg, P. L. & Carpenter, T. E. (1989) Decision-tree analysis of treatment alternatives for left displaced abomasum. Journal of the American Veterinary Medical Association 195, 464-467 Saint Jean, G. D., Hull, B. L., Hoffsis, G. F. & Rings, M. D. (1987) Comparison of different surgical techniques for correction of abomasal problems. Compendium on Continuing Education for the Practicing Veterinarian 9, F377-F382 Shaver, R. D. (1997) Nutritional risk factors in the etiology of left displaced abomasum in dairy cows: a review. Journal of Dairy Science 80, 2449-2453 Van Leeuwen, E., Mensink, M. G. S. & de Bont, M. F. P. M. (2009) Laparoscopic reposition and fixation of the left displaced abomasum in dairy cattle practice – ten years of experience under field conditions in the Netherlands. Cattle Practice 17, 123-127 Wittek, T. & Barrett, D. C. (2009) An update on the aetiology and pathogenesis of abomasal displacement. Cattle Practice 17, 117-122 In Practice October 2011 | Volume 33 | 470–481 481 In Practice: first published as 10.1136/inp.d6079 on 21 October 2011. Downloaded from http://inpractice.bmj.com/ on November 1, 2019 at University of Liverpool Library. Protected by copyright. Box 6: Prognosis