Veterinary · Clinical · also MSVE VSR-511
Fractures and their fixation, joint, tendon and ligament disease, lameness examination in horses and cattle, hoof and claw disorders, diagnostic nerve blocks and rehabilitation.
In the exams: ICAR AIEEA-PG 13 (Surgery & Radiology); NAVLE equine 14.7% and bovine 13.3% species weighting
Veterinary orthopaedics is the study and treatment of the musculoskeletal system: bones, joints, tendons, ligaments and, in the ungulates, the hoof and claw. Lameness is its commonest clinical expression. A lame animal is one whose gait is altered because of pain, mechanical restriction or neurological deficit, and the job of the clinician is to find which limb, which region and which structure, then decide whether the problem can be fixed, managed or must be accepted.
The subject matters because lameness is one of the largest welfare and economic problems in veterinary practice. In dairy herds it reduces milk yield, fertility and cull value, and farmers routinely underestimate how many cows are lame. In dogs, cranial cruciate ligament disease, hip and elbow dysplasia and osteoarthritis fill orthopaedic caseloads worldwide.
Examiners treat this subject in three ways. Indian postgraduate and civil-service papers (ICAR AIEEA-PG, AICE-JRF/SRF, state public service commissions) ask for classification, named signs, grading scales and the names of procedures. Licensing exams such as NAVLE, BCSE, RCVS SME, AVE and SAVC use clinical vignettes: a lame horse that blocks sound to one nerve block, a dog with a positive tibial compression test, a cow with a swollen interdigital space. Specialist boards expect biomechanics, strain theory and the evidence behind competing surgical techniques. Drug doses are given only where they are standard textbook values, always followed by a reminder to check the product label and national formulary.
A fracture is a complete or incomplete break in the continuity of bone or cartilage. Fractures are classified so that the clinician can predict stability, choose a fixation method and communicate clearly. The first division is open versus closed. A closed fracture has intact overlying skin. An open (compound) fracture communicates with the outside through a wound and is contaminated from the moment it happens. Veterinary texts grade open fractures in three grades: grade I, a small puncture made from the inside out by a bone spike; grade II, a larger wound with moderate soft-tissue damage, usually made from the outside; grade III, extensive soft-tissue damage or loss, often with comminution, as in gunshot or shearing injuries. Grade III fractures have the highest risk of infection and delayed union.
The second division is by extent: complete fractures break both cortices, incomplete fractures do not. The third is by configuration of the fracture line: transverse (at right angles to the long axis), oblique (short oblique if the line is less than about twice the bone diameter, long oblique if longer), spiral, comminuted (three or more fragments with interconnecting lines), segmental or multiple (separate fracture lines producing a free segment), avulsion (a fragment pulled off by a tendon or ligament, such as the tibial tuberosity or olecranon), impacted and compression fractures.
In immature animals the physis is weaker than the surrounding bone and ligaments, so trauma that would sprain an adult joint often fractures the growth plate. The Salter-Harris classification describes five types. Type I passes entirely through the physis, separating the epiphysis from the metaphysis; the capital femoral physis in young dogs and cats is a classic site. Type II passes through the physis and exits through a small corner of metaphysis; it is the most common type overall, and the distal femoral physis of young dogs is a typical site. Type III passes through the physis and then through the epiphysis into the joint, and type IV crosses epiphysis, physis and metaphysis. Types III and IV are articular fractures and must be anatomically reduced and rigidly fixed, usually with lag screws or pins, to restore the joint surface. Type V is a crushing injury of the physis that is often invisible on the initial radiograph and is diagnosed later when premature closure causes shortening or angular deformity.
The practical consequences are twofold. Physeal fractures heal fast, often within three to four weeks, so fixation needs to hold only briefly and implants that cross the physis should be smooth and parallel so that some growth can continue. Premature closure of one of two paired bones, most famously the distal ulnar physis in the dog, lets the partner bone keep growing and produces angular limb deformity, carpal valgus and elbow or carpal incongruity.
The first priority in a trauma patient is the whole animal, not the bone: airway, breathing, circulation, thoracic injury, bladder rupture and neurological status come first.
Radiographs are taken in at least two views at right angles to each other (orthogonal views) and include the joint above and the joint below the fracture.
The modified Robert Jones bandage, a thick layered cotton bandage compressed with elastic gauze, is effective only for fractures at or below the elbow and stifle. A bandage that ends at mid-humerus or mid-femur acts as a weight on the end of a lever and makes the fracture worse; fractures above these joints are managed with strict rest, analgesia and, for the humerus, a spica splint that extends over the shoulder. Open fractures are covered with a sterile dressing, receive early systemic antimicrobials and are debrided and lavaged as soon as the animal is stable. In horses, correct emergency splinting before transport strongly affects the outcome.
Bone heals by regenerating bone, not by scar, and the route it takes depends on how much the fragments move. Indirect (secondary) healing is the natural route and occurs when there is some movement at the fracture, as with casts, intramedullary pins, external fixators and bridging plates. It passes through four overlapping stages. The inflammatory stage begins with the fracture haematoma; platelets and inflammatory cells release growth factors such as platelet-derived growth factor, transforming growth factor-beta and bone morphogenetic proteins, and mesenchymal cells are recruited. In the reparative stage granulation tissue is replaced by a soft callus of fibrous tissue and cartilage, which then mineralises and is replaced by woven bone through endochondral ossification to give a hard callus that bridges the gap. In the remodelling stage, lasting months to years, woven bone is converted to lamellar bone and the callus is reshaped along the lines of stress, as described by Wolff's law.
Direct (primary) healing occurs only under absolute stability, when the fragments are anatomically reduced and compressed, typically with lag screws and compression plating. There is no visible callus. In contact healing, where fragments touch, cutting cones of osteoclasts followed by osteoblasts tunnel straight across the fracture line and lay down new osteons. In gap healing, where a very small gap remains, lamellar bone first fills the gap at right angles to the long axis and is later remodelled by cutting cones.
Perren's interfragmentary strain theory explains why some fractures heal and others do not. Strain is the change in the width of the fracture gap divided by the original gap width. Each tissue tolerates a different strain before it fails: granulation tissue tolerates about 100 per cent, fibrous tissue and fibrocartilage about 10 per cent, and lamellar bone only about 2 per cent. Bone can only form in the gap once strain has fallen below what bone can tolerate. Healing therefore proceeds as a cascade in which each tissue stiffens the gap enough for the next, stiffer tissue to form.
Two consequences follow. First, a very small gap with movement produces very high strain, which is why a simple transverse fracture fixed with a slightly unstable implant may fail to heal, while a comminuted fracture bridged by the same implant heals well, because the same movement is shared across a longer zone. Fixation strategy is therefore chosen either for absolute stability, reconstructing simple fractures anatomically, or for relative stability, bridging comminuted fractures without disturbing the fragments. The second approach, often called biological osteosynthesis, uses minimally invasive or open-but-do-not-touch techniques to preserve the fracture haematoma and the soft-tissue blood supply.
A delayed union is a fracture that has not healed in the time expected for that fracture in that patient but still shows biological activity. A non-union is one in which healing has stopped. Non-unions are classified, following Weber and Čech, as viable or non-viable. Viable non-unions have a good blood supply and fail because of instability; they include hypertrophic non-union with abundant callus, sometimes called elephant's foot, moderately hypertrophic and oligotrophic types. They usually heal once stability is improved. Non-viable non-unions have poor biological activity and are classified as dystrophic, necrotic, defect and atrophic; they need stabilisation plus biological stimulation, usually an autogenous cancellous bone graft, and removal of dead bone.
Malunion is healing in an abnormal position. It matters when it causes angulation, rotation or shortening that affects joint function. Osteomyelitis after fracture repair is usually bacterial, most often staphylococcal, and is favoured by instability, dead bone and implants; a sequestrum is a fragment of dead bone separated from living bone and surrounded by an involucrum of new bone, and a draining tract that persists until the sequestrum is removed is typical. Fracture disease is the combination of muscle atrophy, joint stiffness, cartilage degeneration and osteoporosis caused by prolonged immobilisation. A severe form in young dogs is quadriceps contracture after distal femoral fracture, in which the stifle becomes fixed in extension; it is prevented by stable fixation and early active use rather than by prolonged immobilisation.
Every fracture must be protected against the forces that act on it during weight bearing and muscle pull: bending, rotation (torsion), axial compression (which causes shortening or collapse) and tension (distraction). An implant is chosen by asking which of these it resists. The AO (Arbeitsgemeinschaft für Osteosynthesefragen) principles, adopted in veterinary surgery, state four goals: reduction and fixation that restore anatomy, fixation that gives the stability that the fracture and patient need, preservation of blood supply by gentle technique, and early, safe mobilisation of the limb and patient.
Fracture assessment brings together three groups of factors. Mechanical factors include the patient's size, the number of limbs injured and whether the fracture can be reconstructed so that the bone shares load with the implant. Biological factors include age, health, soft-tissue damage and whether the fracture is open or high-velocity. Clinical factors include the patient's temperament, the owner's ability to manage aftercare and the cost.
Casts and splints are external coaptation. They work best for stable, closed fractures distal to the elbow and stifle, in young animals, and must immobilise the joint above and the joint below. Cattle, sheep, goats and calves tolerate casts well.
An intramedullary pin, placed along the medullary canal, resists bending well in all directions but gives almost no resistance to rotation or axial collapse, so it is always combined with cerclage wires, an external fixator or a plate. When used alone a pin is commonly sized to fill about 60 to 75 per cent of the narrowest part of the canal; in plate-rod constructs a smaller pin of about 35 to 50 per cent is used. A pin is not placed in the canine radius, whose canal is narrow and whose ends are articular. Cerclage wires encircle the bone and are used only on long oblique or spiral fractures where the fracture line is at least twice the bone diameter and the bone column can be reconstructed completely. At least two wires are placed, spaced roughly half to one bone diameter apart and not too close to the fracture ends, and they must be tight. Tension-band wiring, two pins with a figure-of-eight wire, converts the pull of a tendon into compression and is used for olecranon, greater trochanter, tibial tuberosity and calcaneal avulsions.
External skeletal fixators use pins through the bone joined outside the limb by connecting bars or acrylic. Type Ia is unilateral and uniplanar, type Ib unilateral and biplanar, type II bilateral and uniplanar, and type III bilateral and biplanar; circular (ring) and hybrid fixators are also used. Stiffness rises from type I to type III. Threaded positive-profile pins resist loosening better than smooth pins, and pin diameter is kept to about a quarter of bone diameter or less to avoid fracture through the pin hole.
Bone plates have three functions. A compression plate compresses a transverse or short oblique fracture, using eccentric screw placement in dynamic compression holes. A neutralisation (protection) plate protects a fracture that has already been reconstructed with lag screws. A bridging (buttress) plate spans a comminuted zone that cannot be reconstructed and carries the full load until callus forms. Locking plates have threaded holes so that the screw heads lock into the plate, creating a fixed-angle construct that does not rely on friction between plate and bone. A common rule in dogs and cats is at least three bicortical screws, engaging six cortices, in each main fragment.
A lag screw compresses two fragments by gripping only the far one. With a cortical screw this is achieved by drilling a glide hole in the near cortex equal to the thread diameter and a smaller pilot hole in the far cortex equal to the core diameter, which is then tapped. For a 3.5 mm cortical screw the pilot hole is 2.5 mm, and for a 4.5 mm cortical screw it is 3.2 mm.
An autogenous cancellous bone graft is the gold standard graft because it provides all three properties: osteogenesis (living cells that form bone), osteoinduction (growth factors that recruit and differentiate precursors) and osteoconduction (a scaffold). Common donor sites in the dog are the proximal humerus, proximal tibia and wing of the ilium.
In adult horses, fractures of long bones above the carpus and tarsus often carry a poor prognosis because of body weight, the danger of recovery from anaesthesia and the risk of supporting-limb laminitis in the opposite foot. Condylar fractures of the third metacarpal bone and sagittal fractures of the proximal phalanx in racehorses are routinely repaired with lag screws.
A synovial joint consists of articular (hyaline) cartilage over subchondral bone, a joint capsule lined by synovial membrane, and synovial fluid.
Osteoarthritis (degenerative joint disease) is the commonest joint disease in every species. It is a disease of the whole joint, not only of cartilage. Loss of proteoglycan from the matrix, driven by enzymes such as matrix metalloproteinases and aggrecanases and by inflammatory mediators including interleukin-1 and prostaglandin E2, softens the cartilage, which then fibrillates and erodes. Subchondral bone becomes sclerotic, osteophytes form at the joint margins and enthesophytes at capsular attachments, and the capsule thickens and becomes fibrotic, reducing range of motion. In dogs most osteoarthritis is secondary to developmental disease or injury, such as hip and elbow dysplasia, cruciate rupture and patellar luxation.
Management is multimodal: weight control, which is the most effective single measure in overweight dogs, controlled exercise, non-steroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclo-oxygenase, the prostaglandin EP4 receptor antagonist grapiprant, monoclonal antibodies against nerve growth factor licensed in some countries for dogs and cats, intra-articular corticosteroids or hyaluronan in horses, and polysulphated glycosaminoglycans.
Septic arthritis is an emergency because bacterial enzymes and the inflammatory response destroy cartilage within days. It arises from penetrating wounds, spread from adjacent infection, injection into the joint, surgery or, in neonates, blood-borne spread. In foals, haematogenous septic arthritis and osteomyelitis are linked with failure of passive transfer of maternal antibody and are classified as S-type (synovial only), E-type (epiphyseal), P-type (physeal) and T-type (involving the cuboidal bones of the carpus or tarsus).
Diagnosis rests on arthrocentesis. Normal synovial fluid is clear, pale yellow and viscous, with a low nucleated cell count made up mostly of mononuclear cells and a low protein content. Septic fluid is turbid, watery and has a very high nucleated cell count dominated by neutrophils. In horses, a total nucleated cell count above about 30,000 cells per microlitre with more than about 80 per cent neutrophils and a total protein above about 4 g/dL is commonly cited as strongly suggestive of sepsis, but reference values vary by laboratory and species, and a negative culture does not rule infection out. Treatment is joint lavage (through-and-through needle lavage or arthroscopic), systemic antimicrobials chosen by culture where possible, local delivery by intra-articular injection or regional limb perfusion under a tourniquet, and anti-inflammatory analgesia.
Immune-mediated polyarthritis in dogs is classified as erosive or non-erosive. Erosive disease, which includes a rheumatoid-like arthritis, destroys subchondral bone visible on radiographs. Non-erosive disease is more common and includes idiopathic polyarthritis, arthritis associated with systemic lupus erythematosus and reactive polyarthritis secondary to infection, neoplasia or drugs. Infectious causes such as tick-borne organisms must be excluded before immunosuppressive treatment with glucocorticoids.
Osteochondrosis is a disturbance of endochondral ossification in the growing articular-epiphyseal cartilage. Cartilage fails to convert to bone and remains thickened; a flap may separate, when the condition becomes osteochondritis dissecans (OCD), or a cyst-like lesion may form in subchondral bone. It is multifactorial: genetics, rapid growth, nutrition and trauma all contribute. In dogs it is typical of large, fast-growing breeds, and the commonest sites are the caudal aspect of the humeral head, the medial part of the humeral condyle, the lateral (and less often medial) femoral condyle and the medial trochlear ridge of the talus. In horses, common sites include the distal intermediate ridge of the tibia in the tarsocrural joint, the lateral trochlear ridge of the femur in the femoropatellar joint and the sagittal ridge of the third metacarpal or metatarsal bone in the fetlock. Subchondral cystic lesions are common in the medial femoral condyle. Treatment of clinically significant OCD is usually arthroscopic removal of the flap and debridement.
Several classic equine osteoarthritic conditions carry traditional names that examiners still use. Bone spavin is osteoarthritis of the distal intertarsal and tarsometatarsal joints; it causes hindlimb lameness worsened by upper-limb (spavin) flexion, is diagnosed by intra-articular anaesthesia and radiography, and is managed with intra-articular medication, NSAIDs, corrective farriery and, in refractory cases, facilitated ankylosis by surgical or chemical means. Ringbone is new bone around the pastern: high ringbone involves the proximal interphalangeal (pastern) joint and low ringbone the distal interphalangeal (coffin) joint.
Cranial cruciate ligament (CrCL) disease is the commonest cause of hindlimb lameness in dogs. The CrCL prevents cranial translation of the tibia relative to the femur, limits internal rotation and prevents hyperextension. In most dogs the ligament degenerates over months or years before it fails, often bilaterally, so the disease is better thought of as a degenerative condition than as a purely traumatic rupture.
The diagnostic tests are the cranial drawer test and the tibial compression (tibial thrust) test. In the drawer test the examiner holds the femur with one hand and the tibia with the other and tries to move the tibia cranially. Young dogs have a small drawer movement with an abrupt stop, which is normal. A partial tear may produce drawer only in flexion, and chronic cases may show little drawer because of periarticular fibrosis, which is palpable as a firm medial swelling called a medial buttress. Radiographs show effusion, displacing the infrapatellar fat pad, and osteophytes; they support but do not prove the diagnosis. The medial meniscus, especially its caudal horn, is commonly torn because it is firmly attached to the tibia and gets crushed as the femur slides caudally.
Treatment choices include conservative management for small dogs, lateral extracapsular (fabellotibial) suture, tibial plateau levelling osteotomy (TPLO) and tibial tuberosity advancement (TTA). TPLO rotates the tibial plateau to a slope of roughly five to six degrees so that cranial tibial thrust is neutralised during weight bearing. TTA moves the tibial tuberosity forward so the patellar tendon is perpendicular to the tibial plateau. Meniscal tears are treated by partial meniscectomy.
Patellar luxation is displacement of the patella out of the femoral trochlear groove. Medial luxation is by far the more common, especially in toy and small breeds, while lateral luxation is proportionally more common in large and giant breeds. It is usually developmental and associated with a shallow trochlear groove, medial displacement of the tibial tuberosity, distal femoral varus, internal torsion of the tibia and, in some dogs, coxa vara.
The widely used grading system has four grades. In grade I the patella can be luxated manually but returns to the groove when released. In grade II the patella luxates with stifle flexion or manipulation and stays out until the stifle is extended or the patella is replaced. In grade III the patella is luxated most of the time but can be reduced manually, after which it luxates again. In grade IV the patella is permanently luxated and cannot be reduced, and the limb is often severely deformed.
Surgery is recommended for clinical lameness, usually from grade II upwards, and for young dogs with deforming grade III or IV luxation. The procedures are combined as needed: deepening of the trochlear groove by wedge or block recession trochleoplasty, transposition of the tibial tuberosity to realign the quadriceps mechanism, release of the tight soft tissues on the side towards which the patella luxates and imbrication of the lax side.
Canine hip dysplasia is a developmental disease in which laxity of the coxofemoral joint leads to subluxation, abnormal loading, remodelling and osteoarthritis. It is polygenic with environmental modifiers, especially rapid growth and excess weight. The Ortolani sign, elicited under sedation, is a palpable clunk as a subluxated femoral head drops back into the acetabulum when the adducted limb is pushed dorsally and then abducted.
Screening schemes differ by country. The British and Irish scheme scores nine features per hip from 0 to 53, giving a total of 0 to 106, lower being better. The North American Orthopedic Foundation for Animals scheme grades hips in seven categories from excellent to severe. The FCI scheme used in much of Europe grades A to E. PennHIP measures passive laxity as a distraction index from 0 to 1 under anaesthesia, and a lower index means a lower risk of osteoarthritis. The Norberg angle, measured on the extended ventrodorsal view, is regarded as normal at about 105 degrees or more.
Treatment depends on age and joint damage. Juvenile pubic symphysiodesis must be performed early, before about five months of age. Double or triple pelvic osteotomy rotates the acetabulum in young dogs with laxity but no significant arthritis. Total hip replacement is the definitive treatment for severe disease, and femoral head and neck excision creates a fibrous false joint that works best in small dogs and cats.
Traumatic hip luxation is most often craniodorsal: the limb appears shorter and is held adducted with the stifle rotated outward. After closed reduction an Ehmer sling is used for craniodorsal luxation, while ventral luxation is supported with hobbles. Legg-Calvé-Perthes disease is avascular necrosis of the femoral head in toy and small breeds under about a year old; femoral head and neck excision is the usual treatment.
Elbow dysplasia is an umbrella term, defined by the International Elbow Working Group, for fragmented medial coronoid process of the ulna, ununited anconeal process, osteochondrosis of the medial humeral condyle and joint incongruity. Medial coronoid disease is the commonest component. Affected dogs are usually large breeds and show forelimb lameness from about five to twelve months of age, often bilateral, with elbow effusion and pain on flexion and extension. Radiographs may show osteophytes and sclerosis under the trochlear notch, but a fragmented coronoid is often invisible, and computed tomography or arthroscopy is more sensitive. The anconeal process normally fuses with the ulna by about five months; a separate process after that age, typical in German Shepherd Dogs, is an ununited anconeal process. Treatments include arthroscopic fragment removal, subtotal coronoid ostectomy, proximal ulnar osteotomy to relieve incongruity and, for the anconeal process, removal or lag-screw fixation often with ulnar osteotomy.
Tendons connect muscle to bone and ligaments connect bone to bone. Tendons heal slowly through three overlapping phases. In the inflammatory phase, over the first days, haemorrhage and oedema fill the lesion and inflammatory cells remove debris. In the proliferative or reparative phase, over several weeks, fibroblasts lay down disorganised collagen rich in type III. In the remodelling phase, which lasts many months, collagen is converted towards type I and becomes aligned along lines of tension, but the scar never regains the structure and elasticity of normal tendon, so reinjury is common.
Severed tendons in small animals and horses are repaired with tendon-holding suture patterns such as the locking-loop (modified Kessler) and three-loop pulley patterns, using strong monofilament non-absorbable or slowly absorbable material, followed by immobilisation of the repair in a relaxed position for several weeks and a gradual return to load. In dogs, rupture or laceration of the common calcaneal (Achilles) tendon produces a plantigrade stance with the hock dropped; if the gastrocnemius part is ruptured but the superficial digital flexor tendon is intact, the toes are held flexed in a characteristic claw-like posture. Repair is protected by a calcaneotibial screw, transarticular external fixator or splint holding the hock in extension.
Tendon and ligament injuries are a leading cause of lost training days in performance horses. Superficial digital flexor tendinopathy, often called a bowed tendon because of the palmar swelling, is typical of racehorses and eventers and most often affects the mid-metacarpal region of the forelimb. It usually follows cumulative degeneration, possibly worsened by heat generated in the tendon core, so a central hypoechoic core lesion on ultrasound is characteristic. Management is controlled exercise: box rest with hand walking initially, then a gradually increasing programme of walking, trotting and cantering over nine to twelve months or more, adjusted according to repeat ultrasound examinations. Intralesional injections of platelet-rich plasma or mesenchymal stem cells are widely used, but the evidence on their benefit is still debated, and the high rate of reinjury remains the main problem.
Suspensory ligament desmitis may affect the proximal part (proximal suspensory desmitis, common in the hindlimbs of dressage horses), the body or the branches. Rupture of the peroneus tertius, part of the reciprocal apparatus, allows the hock to be extended while the stifle is flexed, and the common calcanean tendon appears dimpled when the limb is pulled backwards.
Flexural deformities, often loosely called contracted tendons, are a failure to extend a joint fully. Congenital forms in foals and calves range from mild to severe; intravenous oxytetracycline is used in neonatal foals to induce relaxation of the musculotendinous unit, with attention to renal function. Acquired flexural deformity of the distal interphalangeal joint in growing foals produces a club foot and involves the deep digital flexor unit; if farriery and management fail, desmotomy of the accessory ligament of the deep digital flexor tendon (inferior check desmotomy) is performed. Acquired flexural deformity of the fetlock involves mainly the superficial digital flexor unit and the suspensory ligament.
Upward fixation of the patella occurs in horses, cattle and buffaloes, and in working bullocks it is a common reason for presentation in South Asia. The medial patellar ligament hooks over the medial trochlear ridge of the femur, locking the stifle and therefore the hock in extension through the reciprocal apparatus, while the fetlock remains flexed. The animal drags the limb behind it with the toe on the ground. Conservative treatment includes conditioning exercise in horses, but the definitive surgical treatment in cattle and in refractory horses is medial patellar desmotomy under local anaesthesia, cutting the medial patellar ligament near its tibial attachment. In horses desmotomy has been linked to later fragmentation of the patella, so conditioning is tried first.
A lameness examination follows the same order every time so that nothing is missed. The history covers the horse's use, the duration and onset of lameness, response to rest or medication, shoeing, recent work and previous problems. The horse is then inspected standing on a level surface, from a distance and close up, for conformation, muscle symmetry, swelling, hoof shape and balance, and how weight is carried.
Palpation is systematic, from the foot upwards on every limb, with the limb weight-bearing and then lifted. The examiner feels the digital pulses, which are increased with inflammation in the foot, feels for heat and effusion in joints and tendon sheaths, palpates tendons and ligaments along their length and flexes joints to assess range of motion and pain. Hoof testers are applied systematically over the sole, frog and wall; a consistent, repeatable response over a small area suggests a focal problem such as a subsolar abscess, and a response over the central third of the frog is associated with pain in the navicular region.
Flexion tests hold a region flexed, commonly for about thirty to sixty seconds, and the horse is trotted off immediately. A test is positive if lameness is worsened. Flexion tests are not specific, because distal limb flexion stresses several joints and soft tissues at once, and the force applied varies between examiners, so results are interpreted alongside the rest of the examination.
The horse is observed at walk and trot in a straight line on a firm, level surface, then on the lunge or in circles on both hard and soft surfaces, and ridden if necessary. Forelimb lameness is recognised by a head nod: the head and neck rise as the lame forelimb bears weight and fall when the sound forelimb lands, which is remembered as down on sound. Hindlimb lameness is recognised by asymmetric pelvic movement: the tuber coxae on the lame side moves through a greater vertical excursion (a hip hike), and the horse may shorten the cranial phase of the stride.
Lameness can be classed as supporting-limb lameness, seen when the limb bears weight, and swinging-limb lameness, seen during protraction, and many horses show both. A primary hindlimb lameness can produce a compensatory head nod that mimics lameness in the forelimb on the same side, and a primary forelimb lameness can mimic lameness in the opposite hindlimb. Blocking the true source removes the apparent secondary lameness.
The American Association of Equine Practitioners scale grades lameness from 0 to 5. Grade 0 means lameness is not perceptible under any circumstances. Grade 1 is difficult to observe and not consistent. Grade 2 is difficult to observe at walk or trot in a straight line but consistent under certain circumstances such as weight carrying, circling or inclines. Grade 3 is consistently observable at a trot under all circumstances. Grade 4 is obvious at the walk. Grade 5 means minimal weight bearing in motion or at rest, or complete inability to move.
Beyond the foot conditions described later, several lamenesses are seen in every equine practice. Dorsal metacarpal disease, called sore or bucked shins, is a stress-related periostitis of the dorsal cortex of the third metacarpal bone in young racehorses early in training; it can progress to a dorsal cortical stress fracture. Sesamoiditis and proximal sesamoid fractures occur in racehorses, and fractures of both proximal sesamoid bones with suspensory apparatus failure are catastrophic.
Carpal chip fractures and fetlock joint disease are common in racehorses, and distal hock pain and proximal suspensory desmitis in sport horses.
Imaging completes the examination. Radiography is the first imaging method for bone and joint disease, ultrasonography for tendons and ligaments, nuclear scintigraphy for stress fractures and when the site cannot be localised, and magnetic resonance imaging and computed tomography for the foot and distal limb. Imaging should normally follow localisation by diagnostic anaesthesia, because many sound horses have radiographic abnormalities of no clinical significance.
Diagnostic anaesthesia, the use of local anaesthetic to abolish pain in a region temporarily, is the most useful tool for localising lameness in horses. If the lameness improves substantially after a block, the source lies in the region anaesthetised. Perineural blocks deposit anaesthetic over nerves, and intrasynovial blocks put it into a joint, tendon sheath or bursa. Blocks are performed from distal to proximal, because a proximal block anaesthetises everything below it, and the horse is re-examined after a suitable interval, usually several minutes for distal blocks and longer for proximal ones. Mepivacaine is preferred by many clinicians because it causes less tissue irritation than lidocaine; bupivacaine lasts longer and is used when a long duration is needed.
Blocks are not performed where a fracture is suspected, because abolishing pain may cause the horse to load and displace an incomplete fracture; a horse that is severely lame, or has focal bone pain after a fall or race, is radiographed first.
Interpretation needs care. Local anaesthetic diffuses, so a perineural block may anaesthetise structures beyond the intended area, and an intrasynovial block may affect nearby nerves; for example, anaesthesia of the distal interphalangeal joint can relieve pain from the sole and navicular region. A partial response may mean incomplete anaesthesia, more than one source of pain, or a source partly in the blocked region.
The palmar (plantar) digital nerve block is placed on the medial and lateral palmar digital nerves at the palmar aspect of the pastern, just above the collateral cartilages. It anaesthetises the palmar part of the foot: the navicular bone and bursa, the heels, the frog and much of the sole, with variable effect on the distal interphalangeal joint. The abaxial sesamoid block, over the palmar nerves at the base of the proximal sesamoid bones, anaesthetises the whole foot and much of the pastern. The low four-point (low palmar) block anaesthetises the medial and lateral palmar nerves between the suspensory ligament and the deep digital flexor tendon, and the medial and lateral palmar metacarpal nerves just distal to the ends of the splint bones; it removes pain from the fetlock and everything below. In the hindlimb the equivalent low six-point block also anaesthetises the dorsal metatarsal nerves. The high four-point (high palmar) block, placed in the proximal metacarpus, anaesthetises the metacarpal region including most of the suspensory ligament and flexor tendons. Other blocks include the lateral palmar nerve block and the deep branch of the lateral plantar nerve block for proximal suspensory pain, the median, ulnar and musculocutaneous nerve blocks for the carpus and distal forearm, and the tibial and fibular (peroneal) nerve blocks for the hock and below.
Common intrasynovial blocks are the distal interphalangeal joint, navicular bursa, fetlock joint, digital flexor tendon sheath, carpal joints, tarsal joints (the tarsometatarsal and distal intertarsal joints for spavin), femoropatellar and femorotibial joints.
Surgery of the bovine digit, such as claw amputation, debridement of deep digital sepsis or treatment of a painful sole ulcer, is routinely carried out under intravenous regional anaesthesia, also called the Bier block. A tourniquet is applied above the fetlock or in the metacarpal or metatarsal region, a superficial vein distal to it is found, and local anaesthetic is injected into the vein. In adult cattle textbooks describe about 20 to 30 mL of 2% lidocaine without adrenaline for the distal limb — confirm against the product label and your national formulary. Analgesia develops within minutes and persists while the tourniquet is on. The tourniquet should not normally remain for more than about an hour and a half to two hours, and it is released after the procedure; local anaesthetic toxicity is unlikely when it is released after at least twenty minutes.
In dogs and cats, local and regional anaesthesia is used for analgesia during orthopaedic surgery rather than for diagnosis. Peripheral nerve blocks guided by a nerve stimulator or ultrasound include the combined radial, ulnar, musculocutaneous and median nerve block at the humerus, the brachial plexus block and the femoral and sciatic nerve blocks. These techniques reduce the need for systemic opioids and improve recovery.
Lameness is one of the three most important health problems of dairy cattle, with mastitis and infertility. It causes pain and so is a major welfare issue, and it reduces milk yield, fertility and body condition and increases culling. Reported prevalence varies widely between countries, housing systems and studies; many surveys of housed dairy herds in Europe and North America have reported mean prevalences in the range of roughly 20 to 30 per cent, with some herds far higher and well-managed grazing herds much lower. Farmers consistently underestimate lameness in their own herds, so structured scoring by a trained observer is more reliable than the farmer's estimate.
Most bovine lameness, around 90 per cent in most studies, originates in the foot, and most foot lesions are in the hind feet, particularly the lateral claw. The lateral hind claw carries more load than the medial, especially on hard floors, and grows more horn in response, which increases the imbalance. In the front feet the medial claw is the larger and more commonly affected. Lesions are grouped as non-infectious claw horn disruption lesions, chiefly sole haemorrhage, sole ulcer and white line disease, and infectious lesions, chiefly digital dermatitis, interdigital phlegmon and heel horn erosion. Risk factors include the period around calving, when the digital cushion is thin and the claw suspensory apparatus is weaker, long standing times on concrete, poor cubicle comfort that reduces lying time, slurry-covered floors, poor claw trimming and, historically, feeding that leads to subacute ruminal acidosis, although the role of nutrition in so-called laminitis is now debated.
Locomotion scoring classifies cows by how they stand and walk. A widely used five-point scale, published by Sprecher and colleagues, rates cows from 1 to 5. Score 1, normal, has a level back standing and walking. Score 2, mildly lame, stands with a level back but arches the back while walking, and the gait is slightly abnormal. Score 3, moderately lame, has an arched back standing and walking, with short strides in one or more limbs. Score 4, lame, has an arched back and takes deliberate steps, favouring one or more limbs. Score 5, severely lame, has an arched back and is unable or very reluctant to bear weight on one or more limbs.
In the United Kingdom and some other countries the four-point mobility score from 0 to 3 is used: 0 good mobility, 1 imperfect mobility, 2 impaired mobility and 3 severely impaired mobility. Cows scoring 2 should be examined and treated promptly, and cows scoring 3 urgently.
Scoring is best done as cows walk on a flat, non-slip surface, such as when leaving the parlour, by the same trained observer at regular intervals.
The individual cow is observed standing and walking. Swelling above the coronary band suggests deep infection.
The foot is examined lifted, using a crush with a foot-lifting device, a rope or a tilting table depending on facilities. It is washed, the interdigital space inspected for dermatitis, phlegmon or hyperplasia, and each claw examined for shape, overgrowth, cracks and swelling. Hoof testers locate pain and the sole is pared to expose lesions.
Lameness above the foot includes septic arthritis, which often follows umbilical infection in calves, cranial cruciate ligament rupture in adult cattle and bulls, hip luxation, which is often craniodorsal after slipping or mounting, fractures and nerve injuries. Damage to the obturator nerve during calving, to the peroneal nerve from lying on hard surfaces and to the radial nerve from prolonged lateral recumbency gives characteristic postures. Spastic paresis in young cattle, with over-extension of the hock and tension of the gastrocnemius, is a heritable neurological condition that should be recognised so that affected animals are not used for breeding.
The sole ulcer is a full-thickness defect in the sole horn exposing the corium. The typical site is the junction of the sole and heel towards the axial side of the lateral hind claw, beneath the flexor tuberosity of the distal phalanx. Pressure from the sinking distal phalanx crushes the corium and stops horn production. White line disease is separation of the white line, the junction between wall and sole, allowing impaction with dirt and ascending infection; it is most common at the abaxial white line near the heel of the lateral hind claw and may lead to an abscess that discharges at the coronary band. Treatment of claw horn lesions is corrective trimming, removal of loose horn, relief of the affected claw by fitting a block to the healthy partner claw, and NSAIDs — confirm against the product label and your national formulary.
Digital dermatitis is an infectious, painful, ulcerative or proliferative skin lesion, usually on the plantar skin at the back of the interdigital cleft near the heel bulbs. Treponema species are consistently involved. The M-stage system describes the lesion cycle from M0 (normal skin) through M1 (small active lesion), M2 (active ulcerative lesion larger than about 2 cm), M3 (healing, covered by a scab) and M4 (chronic, thickened or proliferative) to M4.1 (chronic with a small active focus). Treatment is topical antimicrobial; herd control relies on footbaths, slurry hygiene and biosecurity. Interdigital phlegmon (foul in the foot) is an acute infection of the interdigital skin and deeper tissues, mainly with Fusobacterium necrophorum often with other anaerobes, causing sudden severe lameness, symmetrical swelling that separates the claws, a fissure with a foul smell and sometimes fever; it needs prompt systemic antimicrobial treatment. Heel horn erosion, associated with Dichelobacter nodosus, produces pits and V-shaped grooves in the heel horn. In sheep, footrot is caused by Dichelobacter nodosus with Fusobacterium necrophorum.
When infection from a sole ulcer, white line abscess or foul extends into deeper structures, it may involve the navicular bursa, the deep flexor tendon, the distal interphalangeal joint or the distal phalanx. Signs are marked lameness, swelling above the coronary band on one claw and sometimes a discharging tract. Treatment options are digit amputation, which is quick and cheap but can shorten the working life of heavy cattle, and resection of the joint with facilitated ankylosis, which preserves the claw but needs longer aftercare.
Functional claw trimming aims to restore normal claw shape and to share weight evenly between and within the claws. The Dutch five-step method is widely taught. Step one trims the reference claw, usually the medial hind claw or lateral front claw, to the correct dorsal wall length, commonly cited as about 7.5 cm in an adult Holstein-Friesian but less in smaller breeds and heifers, leaving an adequate sole thickness at the toe of roughly 5 to 7 mm, which is confirmed by thumb pressure. Step two trims the partner claw to the same length and height so that both claws bear weight equally. Step three shapes or dishes out the sole at the axial side of the typical sole ulcer site so that load moves to the wall and heel. Step four relieves weight from a claw with a lesion by lowering its heel and, when needed, fitting a block to the healthy claw. Step five removes loose and under-run horn and any hard ridges.
Footbaths control infectious lesions. Solutions of copper sulphate, zinc sulphate, formalin and other disinfectants are used, but which products are permitted, and at what concentrations, varies by country, and the environmental and operator-safety effects of copper and formalin are increasingly restricted.
Laminitis is failure of the attachment between the distal phalanx and the inner hoof wall at the lamellae. It has three recognised triggers: endocrinopathic laminitis associated with insulin dysregulation, as in equine metabolic syndrome, and with pituitary pars intermedia dysfunction, now considered the commonest form; laminitis associated with sepsis or systemic inflammation, such as grain overload, colitis or retained fetal membranes; and supporting-limb laminitis in the opposite limb of a horse that cannot bear weight on one leg. The phases are developmental, acute, subacute and chronic. Radiographs measure rotation of the distal phalanx relative to the dorsal hoof wall and sinking, which is increased distance between the coronary band and the extensor process. Management is removal of the cause, digital hypothermia with ice during the developmental phase in at-risk horses with sepsis, deep bedding, frog and sole support, analgesia with NSAIDs (no dose is given here; confirm against the product label and your national formulary), and dietary and endocrine control.
Navicular syndrome, or palmar foot pain, causes a bilateral forelimb lameness with a shortened stride, often worse on hard ground and in circles. It involves the navicular bone, its ligaments, the navicular bursa and the deep digital flexor tendon. It is improved by palmar digital nerve block. Radiographs may show enlarged synovial invaginations, flexor cortex erosion or sclerosis, and MRI shows soft-tissue injury. Management combines corrective farriery to restore a straight hoof-pastern axis and support the heels, NSAIDs, intrasynovial medication and, where licensed, bisphosphonates, with palmar digital neurectomy reserved for refractory cases.
Subsolar abscess is the commonest cause of sudden severe lameness in one foot, with a strong digital pulse and a focal hoof-tester response; it is drained through the sole and the horse's tetanus status is checked.
Rehabilitation aims to reduce pain and inflammation, restore range of motion, rebuild muscle strength and proprioception, protect healing tissues from overload and return the animal to its intended function. It begins with a structured assessment: history, gait analysis, joint range of motion measured with a goniometer, muscle mass measured by limb circumference, pain scoring and body condition.
The plan must fit the stage of tissue healing. In the acute inflammatory phase the priorities are analgesia, rest and protection. In the proliferative phase controlled, low-level loading helps align new collagen. In the remodelling phase progressive loading builds strength. After fracture fixation, early controlled use is encouraged because it limits fracture disease, but the loads must match the stability of the repair, and the surgeon and physiotherapist agree limits in advance. After cruciate surgery in dogs, controlled lead walks, passive range of motion and weight-shifting exercises start early, and off-lead activity is restricted until bone healing is confirmed.
Who may provide animal physiotherapy is regulated differently between countries. In some countries it must be done by, or under the direction of, a veterinary surgeon, in others by registered animal physiotherapists after veterinary referral, and national rules should be checked.
Cryotherapy, the application of cold, is used in the first 24 to 72 hours after injury or surgery to reduce pain, swelling and metabolic demand.
Therapeutic exercises include slow lead walking, sit-to-stand exercises, walking up slopes and stairs, cavaletti poles to increase joint flexion, balance boards and weaving through obstacles for proprioception.
Hydrotherapy uses the buoyancy, resistance and hydrostatic pressure of water. An underwater treadmill lets a dog walk with reduced load on its limbs; the higher the water, the less weight is borne, and studies in dogs have shown the reduction to be small at hock level and large at the level of the greater trochanter.
Electrotherapies include transcutaneous electrical nerve stimulation for pain, neuromuscular electrical stimulation to maintain muscle, therapeutic ultrasound for deep heating, low-level laser therapy and extracorporeal shock wave therapy, used in horses for proximal suspensory desmitis and insertional desmopathies and in dogs for some tendon and joint conditions. The evidence base for several of these modalities is limited. Because shock wave therapy is analgesic, many equestrian regulators restrict it before competition.
In dogs, rehabilitation after cruciate surgery, fracture repair and hip replacement, and in the long-term management of osteoarthritis, is the largest part of the caseload. Programmes typically run eight to twelve weeks after surgery, from protected weight bearing to strengthening and return to activity.
In horses, rehabilitation after tendon and ligament injury follows a written programme of box rest, hand walking, then ridden walking, trotting and cantering over many months, with ultrasonographic checks before each increase.
In cattle, rehabilitation is practical and herd-based. A lame cow is moved to a well-bedded straw yard or deep-bedded area close to feed and water, with non-slip flooring and short walking distances. A block on the healthy claw is checked and removed after several weeks, commonly about four to six, once the lesion has healed or before it wears unevenly. NSAIDs are given where legal, and milk and meat withdrawal periods are observed.
A student needs the vocabulary and the order of examination before anything else. Learn to describe a fracture fully from two radiographic views, to name the Salter-Harris types and to say which implant resists which force. Practise the equine lameness examination on sound horses so that you recognise normal head and pelvic movement, and watch nerve blocks being done from distal to proximal. On farm, lift and clean cows' feet, identify sole ulcers, white line disease and digital dermatitis, and score a group of cows for locomotion. In small-animal practice, perform the drawer and tibial compression tests and patellar palpation on many normal dogs so that you can recognise abnormal laxity.
A practitioner five years out handles most first-opinion orthopaedics: stabilising trauma patients, applying Robert Jones bandages and splints, deciding which fractures to refer, diagnosing cruciate disease and patellar luxation, managing osteoarthritis with weight control and multimodal analgesia, and performing lateral suture or referral for osteotomy. In equine practice the daily work is localising lameness with blocks and imaging, treating foot abscesses and laminitis and planning tendon rehabilitation. In farm practice it means treating lame cows, performing digit amputation under IVRA, advising on footbaths and trimming, and setting up regular mobility scoring with the farmer.
A senior clinician with twenty-five years of experience sets systems and makes hard judgements. In a referral hospital this means choosing between compression and bridging fixation, salvaging non-unions and infected fractures, and deciding when euthanasia is kinder than repair of a catastrophic equine fracture. In herd health it means building a lameness control plan with measurable targets for prevalence, time to treatment and lesion types, auditing trimmers and footbath protocols, and linking lameness to fertility and culling costs. Senior clinicians also teach, set practice protocols for analgesia and bandaging, and act as expert witnesses on welfare and fitness to transport lame animals.
A researcher with long clinical experience works on questions that practice cannot answer by observation. Examples are the biology of tendon healing and whether cell-based therapies alter reinjury rates, the mechanics of TPLO versus TTA in controlled trials, the genetics of hip and elbow dysplasia and the value of estimated breeding values, the pathogenesis of claw horn disruption lesions and of endocrinopathic laminitis, and the validity of automated lameness detection with cameras, accelerometers and inertial sensors. Such researchers design randomised trials with objective gait outcomes, contribute to consensus statements and ensure that treatment claims are backed by evidence of adequate quality.
This manual does not yet cover spinal and neurological causes of lameness in detail, orthopaedic oncology (osteosarcoma and other bone tumours), angular limb deformities in foals and their surgical correction, equine distal phalanx fracture types, camelid and small-ruminant orthopaedics beyond footrot, avian and exotic fracture repair, joint replacement techniques, or detailed implant sizing charts. Drug doses are deliberately limited to one standard regional-anaesthesia volume; NSAID, antimicrobial and intra-articular drug doses are not given because they vary by product, species and country. Prevalence figures for bovine lameness are given as broad ranges only, because published values differ widely.
Original practice questions written to the syllabus and pattern of the exams named in each question's examTags. They are not past papers and do not reproduce any board's questions.
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