Systematic Approach to Lameness Localization in Horses PDF

Andy Fiske- Jackson qualified from Systematic approach to localisation of lameness in the the University of Liv...

Andy Fiske- Jackson qualified from Systematic approach to localisation of lameness in the the University of Liverpool in 2004. distal limb of horses Following this he worked for the Society for the Protection of Animals Abroad and then in mixed practice in Somerset, before undertaking an internship at the Liphook Equine Hospital Background: Lameness examination is commonly required in equine veterinary practice, whether followed by an ambulatory it’s to investigate a lameness already identified by the owner, or as part of the investigation of poor position. He has worked for performance. the Royal Veterinary College, London since 2008, where he is now an associate Aim of the article: This article outlines a systematic approach to adopt when presented with a professor in equine surgery lame horse. Although it focuses on examination of the distal limb, the same principles apply when and deputy head of RVC examining the proximal limb. Equine. He is an RCVS- recognised and European Specialist in equine surgery. WHEN it comes to the lameness consult, the order in me about the lameness’ and ‘What concerns you which different components of the examination are most about the lameness?’ To gain further insight, performed will vary between clinicians, according such questions could then be followed by closed to preference, and this is fine provided no steps are questions (ie, those requiring a simple yes or no missed. My preferred order, which is described in answer) such as ‘Does the lameness get better more detail below, is illustrated in Fig 1. with work? Does the lameness affect the canter transitions? History The clinician should also enquire about any Evidence shows that failing to allow clients to voice treatments that have been attempted so far, their concerns at the beginning of an appointment including periods of rest and medications. What can lead to increased client complaints (Dysart and the horses is used for, the client’s goals, and their others 2011). Therefore, it is vital that we give clients budget for investigation and treatment should also the opportunity to share information before asking be established. clarifying questions to gain a better understanding of the problem. Bearing this in mind, when it Observation comes to the equine lameness consult, the clinician This part of the examination is an initial assessment should initially ask open questions, such as ‘Tell without palpation. The overall conformation of the horse and its body condition score should be assessed. The presence of any angular, or flexural, limb deformities should be verified. The KEY LEARNING OUTCOMES hock conformation should be assessed; a straight After reading this article, you should: hock conformation is associated with proximal suspensory ligament desmitis (Fig 2). The carpal F Understand the importance of taking a thorough history conformation is important to assess in racehorses and asking questions which encourage owners to relay their as they are prone to carpal injuries. The horse particular concerns; should be viewed from all four sides while standing F Be able to appreciate the importance of examining the horse square. When viewed from behind, the left and from a distance to allow identification of conformational and right gluteal muscling can be compared; reduced muscling is indicative of a disuse atrophy associated other abnormalities which may contribute to, or be the result of, with chronic lameness in that limb (Fig 3). The distal limb lameness; symmetry of the pelvis should also be assessed, as F Know how to perform and grade gait analysis; an asymmetric tuber coxae height indicates history F Be able to establish a systematic and thorough method of of a pelvic fracture. In the forelimb, a prominent palpating the commonly injured structures of the distal limb; scapula spine on one limb will occur with disuse F Know how to place the three most distal nerve blocks; atrophy of the supra and infraspinatus muscles due to lameness on that limb. The front feet should F Know how to interpret the response to the three most distal be assessed for symmetry, a narrower and more nerve blocks. upright foot suggests current, or historic, lameness 486 October 2023 | IN PRACTICE Fiske-Jackson.indd 486 28/09/2023 11:54:56  20427689, 2023, 8, Downloaded from https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/inpr.362 by National Health And Medical Research Council, Wiley Online Library on [22/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Equine History Observation Gait analysis Excitatory tests Palpation Diagnostic imaging Diagnostic analgesia Fig 1: Steps of the initial examination of a lame horse in that limb (Fig 4). The foot pastern axis should Fig 2: Straight hock conformation should raise Fig 3: Gluteal muscle asymmetry indicating be assessed especially if lameness is subsequently suspicion of proximal suspensory ligament a disuse atrophy associated with chronic localised to the foot. Any swellings should be desmitis lameness in the right hindlimb of this identified, including ‘splint’ exostosis (Fig 5), horse tendon sheath (Fig 6), bursal or joint effusions, as well as periligamentous swellings (eg, over the branches of the suspensory ligaments) and Mediolateral foot imbalance may also be seen; this thickened tendons (eg, superficial digital flexor may indicate the presence of a collateral ligament tendonitis) (Fig 7). It should also be noted if the injury. horse preferentially rests a limb when stationary. In trot Gait evaluation The gait should then be evaluated in trot. If At walking possible, assessment in a straight line followed The horse should be evaluated at walk in a straight by lunging on soft and hard surfaces should be line and stride length, fetlock extension and foot performed. When trotting in a straight line the placement assessed. Reduced fetlock extension can handler should hold the horse loosely to allow free be seen in a lame limb due to the horse attempting movement of the head, otherwise this may impair to unload the limb during weight bearing. However, detection of a forelimb lameness. Consideration loss of suspensory support (as would happen with of the appropriateness of the hard surface should injuries to the suspensory ligament, superficial be made in case the horse, especially an excitable digital flexor tendon and sesamoidean ligaments) horse, slips causing injury. In a straight line, may result in fetlock hyperextension during loading increased speed will mask subtle lameness. In a of the limb. A flat, or even toe-first placement, in the persistently excitable horse, acepromazine can forelimbs can be seen in horses with palmar foot be administered intravenously (0.01 mg/kg) to pain, including injuries to the deep digital flexor facilitate identification of lameness through reduced tendon, as the horse attempts to avoid loading muscle tone (Pilsworth and Dyson 2015). Neither the heel during the first part of the stride cycle. 10 mg acepromazine nor 10 mg detomidine affects (a) (b) (c) Fig 4: Lameness in the right forelimb of this horse. This can be appreciated by (a) the dorsal view showing a narrower and more upright right forefoot and (b) the lateral view and (c) the palmar view showing an increased heel height in the right forefoot IN PRACTICE | October 2023 487 Fiske-Jackson.indd 487 28/09/2023 11:54:58  20427689, 2023, 8, Downloaded from https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/inpr.362 by National Health And Medical Research Council, Wiley Online Library on [22/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Equine Fig 5: Medial proximal ‘splint’ exostosis of Fig 6: Digital flexor tendon sheath effusion of the Fig 7: Palmar bow of the left forelimb the right forelimb right hindlimb metacarpal region consistent with superficial digital flexor tendinitis the degree of lameness in horses (Taintor and A low foot flight, or toe drag, may also be seen. others 2016). The use of low dose xylazine (0.1 to Video recording the lameness can help when 0.2 mg/kg) has also been described for lameness performing this comparison. assessment (Morgan and others 2020) without affecting the lameness grade, although a previous Objective gait analysis study suggested that a higher dose (0.3 mg/kg) may Objective gait analysis (OGA) has increased in have some effect on head movement for forelimb popularity with numerous systems (see useful lameness (Rettig and others 2016). In a straight line resources) now available. Movement of anatomical the horse can be viewed trotting away and towards landmarks (usually poll, tuber sacrale and tuber the observer, or from the side, depending on the coxae) is measured objectively using either clinician’s preference. Head movement is assessed accelerometers attached to the skin over these for the presence of a head nod to detect forelimb landmarks or using intelligent software. Although lameness. The head is raised when the lame limb domain-restricted expertise (ie, getting better with is weight bearing and the head nods down when practice) certainly exists, a bias towards seeing an the sound limb is weight bearing. Increased tuber improvement in a lameness following diagnostic coxae excursion is seen on the side of the lame analgesia has been demonstrated with subjective limb in hindlimb lameness. A significant hindlimb assessments (Arkell and others 2006). OGA removes lameness can cause a referred lameness on the the potential for this bias and assists the decision ipsilateral forelimb. making process when working up a lameness. However, OGA should never replace a visual On the lunge assessment of the whole horse by the clinician. Forelimb lameness on the lunge is assessed in a Following the gait evaluation three questions similar fashion with observation of a head nod. should be answered: Hindlimb lameness can be more challenging to Is lameness present? identify on the lunge. Tuber coxae movement can In which leg? still be compared for the few strides they are visible How lame is the horse? (Box 1) on the arc of the lunge when the horse is trotting away from the observer; the horse will be leaning Further gait analysis in towards the centre of the circle and this must be Lunging with side reins can precipitate lameness, taken into consideration during assessment. For the especially if it’s related to caudal cervical articular rest of the circle, the evenness of the tuber sacrale process joint osteoarthritis. Side reins can also excursion can be assessed alongside the rhythm steady the head allowing a more consistent head of the trot. Comparing the tuber coxae movement nod to be observed. A ridden assessment can also between reins can also be useful; for example, be very useful, especially if the owner has noticed comparing inside tuber coxae movement on the left the lameness when the horse is exercising under and right reins. Evenness of stride length can also saddle. The rider should be encouraged to trot on be assessed, although it should be kept in mind both the correct and incorrect diagonals, and give that, on a circle, the inside leg stride length will feedback to the clinician on how the horse feels, naturally be shorter than the outside leg. including any reluctance to go forwards, saddle slip 488 October 2023 | IN PRACTICE Fiske-Jackson.indd 488 28/09/2023 11:54:59  20427689, 2023, 8, Downloaded from https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/inpr.362 by National Health And Medical Research Council, Wiley Online Library on [22/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Equine in one direction and evenness of rein contact. If a BOX 1: SCALES FOR ASSESSING LAMENESS IN HORSES ridden assessment is to be performed before and after diagnostic analgesia, the same rider should The lameness scale devised by the American Association of Equine perform the assessment. A more experienced Practitioners is as follows: 0: Lameness not perceptible under any circumstances rider could be considered to rule out training/ behavioural issues. 1:Lameness is difficult to observe and is not consistently apparent, regardless of circumstances (eg, under saddle, circling, inclines, hard Flexion tests surface) Following a gait evaluation, flexion tests can 2: Lameness is difficult to observe at a walk or when trotting in a straight be used to further localise the lameness. In the line but is consistently apparent under certain circumstances (eg, weight- forelimb, proximal and distal limb flexion tests are carrying, circling, inclines, hard surface) easily separated. In the hindlimb this is less easy 3: Lameness is consistently observable at a trot under all circumstances due to the reciprocal apparatus, but it can still be 4: Lameness is obvious at a walk achieved in a compliant horse by keeping the distal limb close to the ground during distal limb flexion 5:Lameness produces minimal weight bearing in motion and/or at rest or a (Fig 8). complete inability to move Flexion tests should be performed for 45 seconds to 1 minute and the response compared with the In the UK, the following 0 to 10 lameness scale is commonly used. With this equivalent region on the contralateral limb. The scale the grade of lameness can be assigned separately for walk, trot in a sound leg should be flexed first in case flexion of the straight line and again for each rein when lunged. lame leg results in a sustained level of discomfort. 0: Sound The same person should perform the flexion tests 1–3: Mild lameness to try to standardise the amount of force applied. 4–6: Moderate lameness During the process, the clinician performing the test will be able to gauge the level of comfort and may 7–10: Severe lameness need to reduce the force being applied in order to complete the test. Such information may inform on the site of (a) (b) pathology. The response to flexion has been shown to be dependent on the force and time applied (Keg and others 1997). As the limb is released the horse is trotted in a straight line on a hard surface and assessed for any exacerbation of lameness; the first four to five strides should be ignored unless the response is severe. The metacarpo-/ metatarsophalangeal joint (and surrounding structures) contribute most to a positive distal limb flexion test. Stabled (rested) horses or horses resting at pasture are less likely to have a positive flexion test than working horses. Palpation I prefer to perform palpation after the gait evaluation as it allows a more targeted palpation of Fig 8: (a) Distal limb flexion test of the left forelimb. Note the limb is held as low as possible the lame limb and, if positive to flexion, a specific to reduce flexion of the carpus, elbow and shoulder joints. (b) Distal limb flexion of the left part of the limb. However, all limbs should be hindlimb. Note the limb is held as low as possible to reduce flexion of the hock, stifle and hip joints palpated as well as the neck, back and pelvis, as appropriate. Application of hoof testers is mandatory to rule out solar pain. In thin-soled horses a response may should be revisited to ensure it is repeatable and a be seen across all four feet. If a focal response to comparison made with the contralateral limb. Based hoof testers is identified, a detailed examination of on a thorough anatomical knowledge, individual the hoof is required. This will involve removing the structures should be palpated. Tendons should shoe and paring out any region of discoloured sole, be assessed for enlargement, reduced suppleness, particularly in the region where the response was heat and pain, while ligaments also tend to seen. develop periligamentous oedema and subsequently When palpating the limb, I start distally and fibrosis when injured. Joints should be assessed move proximally, first with the limb weight bearing for synovial distension, heat and reduced range then with the limb raised. Areas of sensitivity, of motion which may generate a pain response. swelling and heat should be noted. Any response For each abnormality, the opposite limb provides 490 October 2023 | IN PRACTICE Fiske-Jackson.indd 490 28/09/2023 11:55:41  20427689, 2023, 8, Downloaded from https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/inpr.362 by National Health And Medical Research Council, Wiley Online Library on [22/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Equine an opportunity for comparison. There is no doubt that lighter breeds, such as thoroughbreds and Arabians, are easier to palpate than thick-skinned and feathered breeds. However, a meticulous approach to palpation will be time well spent and is an important skill to develop. Diagnostic analgesia Diagnostic analgesia of the distal limb, commonly referred to as nerve and joint blocks, are probably the most valuable tool available to the clinician when assessing equine lameness. They involve minimal expense and can be performed swiftly and on site. To allow accurate interpretation, a consistent baseline lameness is essential alongside a knowledge of what structures each nerve block will desensitise. Accurate placement requires Fig 9: Medial plantar metatarsal nerve block being sound anatomical knowledge. All findings before placed with narrow bore and after the block should be recorded in the case extension set attached record; I recommend video recording all lameness examinations as this will facilitate comparison of the gait before and after blocking. Interpretation approximately 10 minutes, whereas deep pain can bias is a risk whereby, subjectively, the clinician is take 36 minutes (range 11 to 62 minutes) to resolve inclined to view an improvement after the nerve following blocking with mepivacaine (Hoerdemann block even when none has occurred (Arkell and and others 2017). Therefore, if a lameness has others 2006); this again highlights how OGA could not resolved following assessment at 10 minutes, be used to avoid this bias. Nerve blocks should the clinician should consider waiting another 20 never be placed if there is suspicion of fracture to 30 minutes to see if an improvement is seen. (severe lameness) nor in the presence of cellulitis. However, during this time, diffusion will occur which could result in more proximal structures Preparation being desensitised, thereby confusing interpretation Clipping of the hair is not always performed, of the block. I always assess lameness 10 minutes especially in thin-haired horses but, in many cases, after blocking with further assessments made on a I prefer to clip as it facilitates subsequent cleaning case-by-case basis. Hoerdemann and others (2017) and allows easier identification of anatomical also found that complete return of the original level landmarks. I use a chlorhexidine scrub followed by of lameness took an average of six hours, which 70 per cent alcohol rinse. Some horses are poorly realistically means that the clinician may need to tolerant of placement of nerve and joint blocks and wait until the following day for the effect of a nerve the safety of the clinician should always outweigh block to wear off. the benefit of placing a block; to this end, it is prudent to wear a safety helmet when performing Palmar digital nerve block diagnostic analgesia. If the horse is deemed too In the forelimb, in the absence of any other dangerous to block then an alternative diagnostic localising sign, the first nerve block most commonly route should be pursued. There are various methods performed is the palmar digital nerve block of restraining or distracting an anxious horse to (Fig 10). This block is performed medially and facilitate the procedure, including feeding the laterally at the level of the ungular cartilages. A horse, offering it a molasses-flavoured lick, applying 25 G, 1.5 cm needle is inserted axial to the palpable a neck or nose twitch, holding up the contra- or neurovascular bundle and directed distally with ipsilateral limb, or sedating with an α-2 agonist the aim of depositing the local anaesthetic in (eg, xylazine or detomidine); this has been shown the subcutaneous space; I use 2 ml mepivacaine. not to affect the level of lameness (Taintor and Following an accurately placed block, heel bulb others 2016). For nerve blocks performed with the sensation should be lost. limb weight bearing, a narrow bore extension set Typically, the palmar digital nerve block can be used to allow safer injection and provides removes sensation to the entire foot except the some protection against the needle becoming dorsal coronary band and laminae. The distal dislodged if the horse moves its leg (Fig 9). interphalangeal joint is desensitised (Easter and others 2000) and it can also remove sensation to Interpretation the proximal interphalangeal joint if the block A recent study has shown that skin sensation is placed proximal to the proximal margin of the is lost following distal limb nerve blocks after ungular cartilages (Schumacher and others 2004). 492 October 2023 | IN PRACTICE Fiske-Jackson.indd 492 28/09/2023 13:31:00  20427689, 2023, 8, Downloaded from https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/inpr.362 by National Health And Medical Research Council, Wiley Online Library on [22/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Equine In addition, the distal third of the proximal phalanx (Nagy and others 2009) or fetlock joint (Contino and others 2012) can be desensitised. This is more likely if higher volumes of local anaesthetic are used, or the block is placed too proximally. Movement also encourages diffusion. Abaxial sesamoid nerve block The abaxial sesamoid nerve block is placed at the level of the proximal sesamoid bones, both medially and laterally (Fig 11). A 25 G, 1.5 cm needle is inserted axial to the neurovascular bundle and directed distally, with the aim of depositing 2 ml local anaesthetic in the subcutaneous space. I place the block at the level of the widest point of the fetlock to avoid the fetlock joint and digital flexor tendon sheath pouches. Heel bulb sensation should be lost with a successful block; coronary band Fig 10: Palmar digital nerve block being placed Fig 11: Abaxial sesamoid nerve block being sensation will also be lost, and this can be tested if a placed palmar digital nerve block is already in place. The abaxial sesamoid nerve block desensitises the foot, the proximal interphalangeal joint, the middle phalanx and associated soft tissues, the distal and palmar aspects of the proximal phalanx and will variably remove sensation to the fetlock joint (Dyson and Murray 2006, Ross and Dyson 2010). Low four-point nerve block In the hindlimb, in the absence of localising signs, the low four-point nerve block is often the first block performed. The low four-point nerve block desensitises the lateral and medial palmar/ plantar nerves and the lateral and medial palmar metacarpal/plantar metatarsal nerves. The lateral and medial palmar metacarpal/ plantar metatarsal nerves course distally on the axial aspect of the splint bones and are blocked Fig 12: Lateral palmar metacarpal nerve block Fig 13: Lateral palmar nerve block being where they emerge immediately distal to the being placed placed button of the splints (Fig 12). A 25 G, 1.5 cm needle is directed perpendicular to the skin (or even proximally) to avoid inadvertent penetration of the palmar nerves and is often palpable subcutaneously palmar/plantar pouch of the fetlock joint. Although on the palmar aspect of the metacarpus. This the block can be performed with the limb lifted, I communication carries sensory impulses in both prefer to perform it with the limb weight bearing directions. Therefore, the medial and lateral as the landmarks are easier to palpate and uptake palmar nerve must be anaesthetised distal to the of the block seems to be more reliable. Historically, ramus communicans. In the hindlimb, the ramus in the hindlimb, it was deemed necessary to block communicans is usually rudimentary or absent, the dorsal branches of the peroneal nerve abaxial but it may be worth palpating the area to confirm to the long digital extensor tendon on the dorsal this. In fractious horses this, and other blocks, can metatarsus (the low six-point nerve block), but be performed using a narrow bore extension set, this is now deemed unnecessary to fully block the prefilled with local anaesthetic, to allow injection fetlock joint (Coleridge and others 2020). from a safe distance (Fig 9). The lateral and medial palmar/plantar nerves The low four-point nerve block will block fetlock lie in the groove between the suspensory ligament region pain; both palmar/plantar nerves and and the deep digital flexor tendon (DDFT) with the palmar metacarpal/plantar metatarsal nerves nerve lying on the dorsal surface of the DDFT. A provide innervation to the fetlock joint. The block 25 G, 1.5 cm needle is directed distally to deposit can be divided into parts to improve its specificity, 2 ml local anaesthetic adjacent to the dorsal surface particularly if a site of pathology is suspected. An of the DDFT (Fig 13). In the forelimb, the ramus example would be blocking the palmar/plantar communicans connects the medial and lateral nerves proximal to the digital flexor tendon sheath IN PRACTICE | October 2023 493 Fiske-Jackson.indd 493 28/09/2023 13:31:02  20427689, 2023, 8, Downloaded from https://bvajournals.onlinelibrary.wiley.com/doi/10.1002/inpr.362 by National Health And Medical Research Council, Wiley Online Library on [22/03/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License Equine (DFTS) as manica flexoria tears often do not block References completely to anaesthesia of the DFTS (Fiske- ARKELL, M., ARCHER, R. M., GUITIAN, F. J. & MAY, S. A. (2006) Jackson and others 2013). This block will remove Evidence of bias affecting the interpretation of the results of local anaesthetic nerve blocks when assessing lameness in horses. Vet sensation to the fetlock joint, pastern and foot. The Record 159, 346–348 low four-point nerve block can diffuse proximally COLERIDGE, M., SCHUMACHER, J. & DEGRAVES, F. (2020) to partially desensitise the proximal suspensory Comparison of lameness scores after a low 4-point nerve block to lameness scores after additional desensitisation of the dorsal ligament; this should be borne in mind during its metatarsal nerves in horses with experimentally induced pain in interpretation. the metatarsophalangeal joint. Equine Veterinary Education 32, Subchondral bone injury of the distal 199–203 CONTINO, E. K., WERPY, N. M., MORTON, A. J. & MCILWRAITH, C. W. metacarpus/metatarsus is effectively blocked with (2012) Metacarpophalangeal joint lesions identified on magnetic just the palmar metacarpal/plantar metatarsal nerve resonance imaging with lameness that resolved using palmar digital block. To improve specificity further, the medial nerve and intra-articular analgesia. In Proceedings of the Annual Convention of the American Association of Equine Practitioners. branch in the forelimb and the lateral branch in the Anaheim, USA, 5 December 2012. p 534 hindlimb can be effective as a single block based on DYSART, L. M. A., COE, J. B. & ADAMS, C. L. (2011) Analysis of the typical location of this injury. solicitation of client concerns in companion animal practice. Journal of the American Veterinary Medical Association 238, 1609–1615 To avoid inadvertent penetration of the DFTS it DYSON, S. J. & MURRAY, R. (2006) Osseous trauma in the fetlock is necessary to place the palmar block proximal region of mature sports horses. In Proceedings of the Annual Convention of the American Association of Equine Practitioners. San to the DFTS. This may result in the lateral palmar Antonio USA, 6 December 2006. pp 443–456 nerve being blocked proximal to the communicating EASTER, J. E., WATKINS, J., STEPHENS, S. L., CARTER, G. K., HAGUE, branch (the ramus communicans). Both palmar B., DUTTON, D. W. & HONNAS, C. (2000) Effects of regional anesthesia on experimentally induced coffin joint synovitis. In nerves should be blocked distal to the ramus Proceedings of the Annual Convention of the American Association communicans to avoid leaving non-desensitised of Equine Practitioners. San Antonio, USA, 29 November, 2000. pp sensory nerve fibres passing through this neural 214–216 FISKE-JACKSON, A. R., BARKER, W. H. J., ELIASHAR, E., FOY, K. & connection (Schumacher and others 2013). SMITH, R. K. W. (2013) The use of intrathecal analgesia and contrast Alternatively, the ramus communicans can be radiography as preoperative diagnostic methods for digital flexor blocked specifically by placing local anaesthetic tendon sheath pathology. Equine Veterinary Journal 45, 36–40 HOERDEMANN, M., SMITH, R. L. & HOSGOOD, G. (2017) Duration adjacent to it. of action of mepivacaine and lidocaine in equine palmar digital If the lameness persists following placement of a perineural blocks in an experimental lameness model. Veterinary low four-point nerve block, more proximal blocks Surgery 46, 986–993 KEG, P. R., VAN WEEREN, P. R., BACK, W. & BARNEVELD, A. (1997) will need to be performed. If the lameness blocks Influence of the force applied and its period of application on the to one of the above nerve blocks, either diagnostic outcome of the flexion test of the distal forelimb of the horse. Vet imaging can be undertaken, or further localisation Record 141, 463–466 MORGAN, J. M., ROSS, M. W., LEVINE, D. G., STEFANOVSKI, D., of the lameness can be performed by using synovial YOU, Y., ROBINSON, M. A. & DAVIDSON, E. J. (2020) Effects blocks. of acepromazine and xylazine on subjective and objective assessments of forelimb lameness. Equine Veterinary Journal 52, 593–600 Diagnostic imaging NAGY, A., BODO, G., DYSON, S. J., SZABO, F. & BARR, A. R. S. Following localisation of the lameness using (2009) Diffusion of contrast medium after perineural injection of the palmar nerves: an in vivo and in vitro study. Equine Veterinary perineural anaesthesia, further localisation can Journal 41, 379–383 be achieved with intrasynovial anaesthesia. PILSWORTH, R. & DYSON, S. (2015) Where does it hurt? Problems Alternatively, diagnostic imaging of the region with interpretation of regional and intra-synovial diagnostic analgesia. Equine Veterinary Education 27, 595–603 can be performed to establish the cause of the RETTIG, M. J., LEELAMANKONG, P., RUNGSRI, P. & LISCHER, C. lameness. If the lameness has been localised to J. (2016) Effect of sedation on fore- and hindlimb lameness the foot, radiography is routinely used as a first evaluation using body-mounted inertial sensors. Equine Veterinary Journal 48, 603–607 line, but if insufficient pathology is found to ROSS, M. W. & DYSON, S. J. (2010) Diagnosis and Management of explain the lameness, standing MRI should be Lameness in the Horse. 2nd edn. Elsevier considered. Proximal to the foot, radiography and SCHUMACHER, J., LIVESEY, L., DEGRAVES, F. J., SCHUMACHER, J., SCHRAMME, M. C., HATHCOCK, J. & OTHERS (2004) Effect ultrasonography are the first-line imaging choices. of anaesthesia of the palmar digital nerves on proximal interphalangeal joint pain in the horse. Equine Veterinary Journal Summary 36, 409–414 SCHUMACHER, J., TAINTOR, J., SCHUMACHER, J., DEGRAVES, F., Scan the QR code in Establishing a routine whereby all necessary steps SCHRAMME, M. & WILHITE, R. (2013) Function of the ramus the RCVS 1CPD app to are followed will enable the clinician to localise communicans of the medial and lateral palmar nerves of the horse. log reading this article Equine Veterinary Journal 45, 31–35 the vast majority of distal limb lameness allowing TAINTOR, J., DEGRAVES, F. & SCHUMACHER, J. (2016) Effect of the appropriate area to be imaged with either tranquilization or sedation on the gait of lame horses. Journal of two-dimensional or three-dimensional imaging Equine Veterinary Science 43, 97–100 modalities. With a consistent detectable lameness and a compliant horse, nerve blocks can be Useful resources reliably used to localise the source of pain. A good anatomical knowledge and appreciation of what Objective gait analysis systems: ∙Equinosis: https://equinosis.com structures are anaesthetised by each block allows ∙EquiGait: https://equigait.co.uk accurate interpretation. ∙Sleip: https://sleip.com 494 October 2023 | IN PRACTICE Fiske-Jackson.indd 494 28/09/2023 13:31:02