DDX for animals presenting with abnormal gaits
* Musculoskeletal pain or dysfunction
* Neurological conditions
* Intra-abdominal pain
* Skin conditions
What are ways musculoskeletal pain may present?
* poor performance, lameness, reluctance to move, recumbency
Components of a lameness exam
* History, examination of the environment, physical exam, examination of the gait, nerve blocks, imaging, the response to treatment
Most common location of lameness in an adult horse?
Foot and affected sites decrease in frequency as we move up the limb...shoulder lameness is very rare.
What is the most common location of lameness in race horses?
* Fetlock and carpal injuries due to high loads generated in these joints in horses travelling at speed (feet problems are also common)
What is the most common cause of lameness in foals? Yearlings?
Septic arthritis or septic osteitis
** septic focus should be assumed until proven otherwise in any lame foal due to the need for aggressive treatment
** In yearlings developmental condtions are the most common cause of musculoskeletal problems (osteochondrosis & subchondral bone cysts)
Exam question tip
* Which diagnostic techniques you will use
* Mention the nerve blocks even if you aren't going to use them and tell him why you aren't
Challenges with equine lameness
* often few localising signs
* Accurate diagnosis time consuming (come in the morning, often will come back or refer)
* Diagnostic aids often equivocal (none are stand alone, often have to do more than one, prep client)
Locating source of lameness? Diagnostic techniques?
* Pain and swelling...
* Swelling not associated with pain
* No pain and no swelling
How do we localize the source of pain?
How does the stay apparatus affect a lameness exam?
Makes it difficult to localize pain in a horse limb
Diagnostic approach to lameness?
Golden rules of a lameness exam?
History in a lameness exam
* Signalment, duration, onset (associated with work, sudden/ gradual), shoeing, changes with work, response to treatment
Has the owner already tried phenylbutazone? If so, how did it respond?
Clinical exam in a lame horse
1. Examine at rest- quiet place (stable), examine the whole horse: symmetry (muscle mass, conformation, feet), swelling (tendons, synovial structures), feet (shoeing, balance, hoof wall, sole, frog quality, must clean out shoe), palpation (joint capsules, tendons and suspensory ligament, muscles, bony prominence e.g. tubera sacrale, flex and extend, hoof testers
2. Examine moving- gait eval-- straight line, lunge (trot and canter soft ground, hard ground), ridden... which leg is horse unweighting?
3. Flexion Tests- may h ave positive flexion tests, difficult to interpret, not specific- fetlock flexion test stresses all lower joints as well as navicular apparatus
4. Nerve Blocks- only objective means of localising lameness, time consuming
5. Diagnostic imaging
Lameness grading system when trotting!! What do you say when walking?
Mild, moderate or severe when walking
Usual sequence for a pleasure horse for nerve blocks?
* Palmar digital
* Low 4 point
* Sub carpal
Usual sequence for a racehorse with nerve blocks
* Pastern ring block
* Low 4 point
* Midcarpal joint
Show me where you palpate fetlock swelling, midcarpal swelling... etc.
With hoof testers, why unreliable?
* All horses with soft feet will be positive
* All horses with hard feet will be negative
Gait evaluation process
1. Determine the lame leg or legs (have to do this first)- which leg is the horse unweighting? Look at the head. Drop the head, neck and forequarter on the non lame limb.
2. THEN characterise the lameness-- foot flight, length of stride
Worse on the turn and a hard surface?
Generally mean sFoot or pastern problem
What should you look for in terms of gait with hindlimb lameness?
Lift is faster than the drop in the hind quarters... lifts hindquarter on lame limb
** will also look lamb in the ipsilateral forelimb because they use their head as a fulcrum to lift the hind quarters to keep the weight off
What will allow you to evaluate a horse for a longer time when evaluating gait?
* Lower limb injuries often worse
What is the problem with flexion tests?
* not specific
* hard to interpret
* many sound horses have positive flexion tests
Pros and cons of nerve blocks? Preferred?
Cons: time consuming, understand limitations
** Regional vs. intra articular-- complications uncommon but still severe-- painful, more invasive, also don't know what we are blocking
Appropriate time limits for nerve blocks?
Bigger nerves take longer to block-- tibial and peroneal e.g.
What do you need to do with nerve blocks?
Test whether they have worked.... e.g. hoof testers, most horses hate you squeezing suspensory apparatus, skin sensation not a great taste-- we aren't checking the skin
Why different routines for pleasure v. racehorse?
* In practice most common cause of lameness in race horses is carpal lameness... so more efficient
What might you see in a hindlimb bilateral problem?