----start---- ortho 2/23 ross lameness exam in horses note: you can learn to do lameness exams in horses w/o having prior experience. do not panic. think of a systematic approach to lameness.become a detective to figure out where the lameness is. there are things you can do to exacerbate lameness. we'll see some video as well. lameness: indication of a structural or functional disorder in one or more limbs that is manifested in progression or in the standing position. translation: my leg hurts but I can't tell you where. please find it and fix it for me. MDs have it easy. People tell them where it hurts. We're lookin at a clinical sign and trying to localize the source. basic facts: rules of thumb 1. greater than 75% of lamenesses involve the forelimb because the forelimb sustains more load, esp during TB races. Also, horses that are ridden sustain rider's weight as well. 2. 95% or more of them will be at or below the carpus (knee to ground) 3. suspect the foot first. most common area of lameness in entire population- not true in race horses, though.also we're talking about forelimbs, not hindlimbs. 4. lameness is directly proportional to conformation - this is interesting, correlation of form and function, although isn't always helpful - usually helps to a degree.this is where the experience comes in. 5. area of lameness affected by breed...related to use. if standardbred racehorse is on the line, that indicates something, vs on the shaft, or whatever. some show horse developed the habit of running to the nearest wall and jumping on to it. the horse after 10 minutes would start rearing up and stuff, and everyone thought it had a hindlimb problem. well, why would it rear up if the hindlimbs hurt? they took the horse onto pavement, and it was lame on both front legs. nerve blocks on both front feet stopped the problem. so they think maybe the horse has front foot soreness. 6. 80% of hind limb lamenesses involve the fetlock, hock, or stifle - if you read the book, all hind limb lameness involves the hock - but, really, if you want to be precise, the hock is important for only maybe 40-50%, and the rest is distributed to the lower limb more than the upper limb. slide: racing TB with all weight on one foot. at the end of the race, the center of gravity is way forward, and lots of force is going onto the forelimbs. slide: racing standardbred - cart is behind the horse, and due to gait and equipment, these horses are skewed to hindlimb lamenesses more so than the TB. the racing gait is much more erect than the TB gallop. these horses use a trot or a pace, a two beat gait, distributing forces more equally. standardbreds also get more carpal, hock, and fetlock problems than one might expect in the general equine population. breed/use predispositions: TBP: bucked shins, carpal chips, fx, DJD, bowed tendons, pedal osteitis. TB predisposed to stress problems in long bones (MC3, humerus, tibia) note: standardbred racers have more rear limb lamenesses than the general equine population. STD: hock problems, wear and tear in subchondral bone, chips in carpus, not many stress fx, many suspensory problems, sesamoiddz, DJD QH: naviculardz, ringbone, arthritis, bone spavin, djd. QH tend to have small feet and more foot probs hunter/jumper: older, retired racehorses - navicular dz, djd. Whatdo you do? get a history. history: you want it, but you don't always get it. signalment: age, sex, breed,use past lameness? shoeing, conditioning, diet, surface present lameness - how long, how severe, cause, stumbling, warm out of or into, tx received and response. common TB complaint - horse isn't finishing the mile. does great til the last quarter, then slows a lot. may be due to lameness, may be muscle problem, may be breeding problem. sometimes there are seemingly seasonal lamenesses that are totally unrelated. people think the horse is experiencing an old problem but it's something new. you'd like to do PE prior to AM exercise - examine at rest, in the stall. can't do this at NBC they come in on a trailer. you want to look though to how horse is standing, what the management is like - are nails lying around, or rocks? look for conditions like upward fixation of the patella or stringhalt (hyperflexion of hocks) that are only noticed when horse first starts leaving the stall - they then warm out of the lameness. look for fracture lameness - if horse isn't bearing wt, you have to move on to more serious diagnostics. visual inspection - get signalment,history conformation is very important it determines how a horse moves or progresses abnormality may lead directly to lameness observe from a distance and then closely. he's telling a story of someone who bought a really expensive horse, without ever noticing a grossly visible pelvic deformity due to an old fracture. Point: always look at the big picture. observe from side, front, back,for for conformation, and changes in symmetry. "calf knee" conformation - "back at the knee" - concave dorsal surface to front leg.what does this mean? well, this horse is prone to carpal chip fxs, b/c they occur in dorsal carpus, where this horse will putting lots of load.this is bad for a TB racehorse, but not so big a deal in STD racers. Bench knee - offset knees - looks like canon bone is offset laterally, but radiographically, the entire carpus if offset laterally - at the radiocarpal joint. this predisposes to carpal problems. not desirable. looking from behind - don't forget to look at the pelvis! from side - posty legs, straight in the hocks. might predispose to hock, stifle, fetlock problems. from back - right hip looks lower than left hip. or left side is higher. hard to say. they used to call this sacroiliac subluxation - but we now know it's more likely a right broken tuber sacrale than a left subluxation. you also have to evaluate bilateral muscle development. atrophy may indicate nerve damage, EPM, lower motorneuron disease, disuse, chronic lameness exam/palpation - palpate before you watch them go. why? you get an idea of what's going on in the legs without being biased first. lots of horses are lame only at high speed, so then you have to rely more on palpation. start at distal frontlimb - most common site of injury - and so forth.end with hind limbs - start at top b/c horses don't like hind feet messed with. foot: assess conformation, symmetry. if one is smaller than the other, it may have been born that way, or may not have been used as much and has gotten contracted due to lack of use. in older horses w/chronic lameness usually refereable to the foot,not always, but... feel for heat, warmth, swelling, sensitivity. get your fingers on as much as possible. see if you provoke pain response. slide: laminitis/founder - conformation of hoof is wrong. there's dorsal concavity, dishing. there are non-parallel rings that diverge at the heel. the foot has grown abnormally. pick up foot - assess balance, assess length of heels, assess width of foot. chronic imbalance situation may be the source of the whole problem. slide: looking at sole - dropped sole - if you see this,it means there has been ventral rotation of P3 palpate the extensor tendons and push on one side - see if fluid wave pushes out to the other side.increased fluid indicates synovitis, inflammation, etc. feel digital pulses - is it bounding? foot pain will cause increased pulse pressure. effusion - excess joint filling with fluid - often associated with osteoarthritis/DJD. palpate the back of the leg - the tendons - from external to deep - superficial flexor, deep flexor, suspensory ligament, and distal check or accessory ligament of deep digital flexor slide: bowed tendon - horses w/tendonitis of superficial digital flexor tendon show this puffiness. tendon gets so big that movement is restricted by annular ligament- might want to cut annular lig and superior check ligament. slide: normal looking leg - minor minor contour change in the tendon region. you have to really try to feel these differences. but with riding horses/hunters/jumpers, there is often a false positive response to palpation - not with racehorses. bump on front of canonbone - bucked shin, or flex the carpus, feel ROM,palpate for effusions.try to push different spots and see if you can pinpoint areas of pain. picking horse's leg up, squeezing it really hard along back - do both sides to see if horse reacts to both sizes. also squeeze then trot off - if horse gets lamer, may be source of problem there. sometimes there are fx at source of suspensory lig - you can't feel them, but you can elicit a strong pain response. moving up front limb - most problems are below knee, but you have to assess upper limb also. sweeny - suprascapular nerve injury, atrophy of supra/infraspinatus muscles, resulting in lateral subluxation of shoulder joint. horse runs into fence, tramatizes nerve, loses muscle tone, develops problem. sometimes they get better. ---break--- start at LF, work up, RF, work up, palpate over back and pelvis for pain and assymetry, don't zoom in too close, look from far out also. palpate greater trochanter of proximal femur - soreness occurs at gluteal attachment. muscle soreness is often secondary to a lower HL lameness. feel femoropatellar joints, look for fluid - osteochondrosis, DJD. palpate down over hocks, for pain, heat, swelling. yearling w/tarso-crural effusion. what's this? OCD. must examine lower HL even though horse doesn't like it. be careful. proliferative change over dorsal aspect of P1 and pain associated with it can tip you off to P1 fx - this horse has a midsagital P1 fx they picked up this way. hoof testers - a lameness exam isn't complete without an adequate hoof tester exam. develop a system and use it. there are different types of hoof testers. look at shoes for signs of abnormal wear. hold horse's foot comfortably, make sure horse can pull foot if you hurt it. you need to clean foot with hoofpick first so you can see it and test appropriately. use your tester to squeeze all around on the hoof. find or detect areas of pain - foot abscess may be detected this way - you'd feel heat, bounding pulse, sore area - use knife to pare out area and pus will come out. hammer on the nails with your tester - see if that causes pain. then watch the horse go. 1. observe at walk - away from you, toward you, from side 2. observe at trot - trot away from you. find the baseline lameness. this is the lameness you observe at the trot. a right forelimb lameness shows up, and that's your baseline lameness,that you're going to try to resolve. if you block that lameness,and horse switches to L forelimb lameness then what? you can block that too. but your baseline lameness is the RF leg. also, if you do a flexion test or something,and cause a response, that's not your baseline lameness. you want to see why the horse was lame that day. next most important thing is what happens with your diagnostic blocks. if you inject and lameness resolves or switches, you've confirmed the source of the original problem. all the other induced lamenesses may be influencing the baseline lamenesses, but they aren't the bottom line problem. 3. lame limb 4. use eyes and ears 5. see top line, head, hip note: lameness is scored at a trot in hand. if you say horse is 2/5 degrees lame, that means a 2/5 at a trot in hand. score from 0 to 5 at a trot. examination at work: 1. forelimb - down sound 2. hindlimb - pelvic hike - lame leg weight bearing. say horse is lame in RF. horse will elevate up on lame leg, and bob down on the sound leg. when you see the head/neck bob down, it's doing that when the sound leg is hitting the ground. head and neck go down on the sound side. for hindlimb. if animal is lame in RH, it elevates pelvis with R leg, and drops it with sound leg. when lame leg hits ground, the pelvis hikes up, b/c horse wants to get off that leg asap. you have to fix your gaze on one part of pelvis. what about horse with severe HL lameness? now, you see not only pelvic hike up, but also head bob down with opposite leg hitting ground. as horse is trying to elevate pelvis up off right HL lame leg, head and neck are nodding down as left fore hits ground. video: he showed us some horses trotting, that allegedly displayed head bobs and pelvic hikes. I do not believe these horses were really lame. I think he's just trying to make us feel inferior. classifying lameness: supporting limb (painful type) swinging limb (nonpainful as with fibrotic myopathy - goosestepping) mixed - horses will alter strides when they're painful. complimentary special exams: increase lameness flexion extension wedge moving on turns, hills movement on hard or soft surface. you know baseline lameness, you know degree - now you have to localize it. you want to try to block it out - improve gait with diagnostic anesthesia - regional nerveblocks or intraarticular blocks. sometimes you block everything and horse is still lame. at least you've ruled a lot of stuff out. if you do block out a lameness with a nerve block, you now know for sure where horse is lame.then you use imaging to refine source of lameness. main things: know where baseline lameness is, and block it out. everything else we do, hoof testers, flexion tests, riding horse, moving on hills - we do all these things to exacerbate baseline lameness - but they may induce other lamenesses that have nothing to do with the baseline lameness. see handout for details. your flexion tests are all intended to exacerbate your baseline lameness. lower limb flexion - positive response doesn't mean much unless dramatic. compare lame leg to sound leg. lower limb flexion isn't same as fetlock flexion - it's hard to flex fetlock without flexing the other lower limb joints. flexing upper hind limb - flexes stifle, fetlock - hard flexion on hock and stifle. this is an upper limb flexion test or spavin test or hock flexion test even though it isn't specific to the hock - positive response could indicate stifle or even lower limb problem. best way to ensure you know where problem is is to block it with anesthetic. stifle valgus stress test - may worsen lameness in stifle, or in hock. using nerve or intraarticular anesthetic is required. common nerve block - inject local into palmar digital nerve - desensitizes back of foot, about 2/3 of foot. you start distally. wait to see if it blocks lameness. if you see improvement,then you know the baseline lameness was there. then you refine dx with imaging. if no response, block higher up. can't start high and work low. once you localize the lameness, you do radiographs and so forth. stress this fact - you can take an xray on any horse and find a problem and it has nothing to do with anything. you need to know where the lameness is. there may be mild degenerative changes in carpus, and a broken phalanx in same leg. much more important to know where lameness is than to have a radiographic change. an xray with no blocking history isn't that valuable. u/s is useful arthroscopic evaluation useful. ---end---