Presentation on theme: "Lameness – Part 2: Specific Diseases"— Presentation transcript:
1 Lameness – Part 2: Specific Diseases INAG 120 – Equine Health ManagementNovember 2, 2011
2 Common Lameness Disorders FRONT LIMBShoulderKneeFetlockPasternNavicularHIND LIMBStifleHockFetlockPasternJoints are used to absorb shock, permit frictionless movement, and effectively bear the weight of the horse’s body.Made up of the two bones on either end covered by articular cartilage. Synovial fluid helps to keep the joint properly lubricated
3 Front Limb - Shoulder Signs of shoulder lameness: Head lifts when limb moves forwardLittle flexion of limb (low foot arc)Swinging out of limb to avoid flexionFailure to reach out (shortened cranial phase)Fixation of shoulder joint inability to moveHard or soft ground often has same effect if level (may be slightly worse on soft ground)Stumbling
4 Lameness in the Shoulder Arthritis –Usually caused by traumaPersistent lamenessIn foals, other joints also involvedTx: injections with steroid (usually cortisone) followed by hyaluronic acid
5 Lameness in the Shoulder Sweeny –Atrophy of muscles around shoulderParalysis of suprascapular nerve“Popping” of the shoulder when horse walked toward examinerTrauma to the shoulder damage to the suprascapular nerve that traverses over the top of the neck of the scapula. This nerve innervates the two large muscles of the shoulder blade, the supraspinatus and infraspinatus. If damaged severely enough, nerve quits functioning loss of function and atrophy of the 2 scapular muscles.Clinical Signs:Pain and inflammationmuscular weaknessDenervation atrophy (Within two weeks the shoulder muscles become noticeably shrunken and the central ridge of the shoulder blade bone becomes prominent. Muscular denervation atrophy happens much quicker and more pronounced than with atrophy from disuse which may take weeks or months to develop )Treatment:Wound treatment and reducing inflammation right away (ice packs, DMSO, NSAIDs) absolute stall rest for 14 daysTreatment after the first two weeks should be stall rest with hand walking for 10 minutes twice daily for five weeks.Sweeny with no improvement in five weeks may indicate the need for surgery, where a pressure relieving technique involving creating a notch in the neck of the scapula, underneath the nerve,In cases where surgery is not done the horse should be stall rested for up to 18 months with the daily hand walking. This is done until evidence that the muscles of the shoulder are returning at which time turn out is begun slowly.Prognosis:Prognosis = good but may require prolonged rest. Loss of motor function, evidenced by an outward deviation of the shoulder on weight bearing, for longer than two weeks indicates there is probably complete disruption of the nerve and regrowth will be necessary. This generally occurs at the rate of a millimeter a day (1 inch a month). For severe injury this may be as long as 12 to 18 months.
7 Front Limb - Knee Site of many developmental orthopedic diseases Signs:Stand with knee flexedFailure to reach out in strideLower foot arcStiff-legged paddling gaitCarpal flexion test, joint blocks good tools for diagnosis
9 Lameness in the Knee Anatomy of the knee: Two stacked rows of cuboidal bones (6)Three joint spacesAll held together by intercarpal ligamentsRadius above, cannon below compressive force!Faulty conformation (back at the knee) predisposedDecreased incidence in European racehorses as opposed to American why?European racehorses:Often over at the kneeBegin racing as 3-year olds rather than 2-year olds?Race on Turf as opposed to dirt?Run both clockwise and counter-clockwise?Turns are more subtle than American race courses!
11 Front Limb - FetlockBones of the Fetlock Joint: Cannon, Proximal Sesamoid Bones (2), Long Pastern BoneFracturesFairly common!Usually on the medial side of the long pastern bone, less often on end of cannonFormer seen in race horses on hard surfaces, latter when training beginsLameness most obvious at trot Gets worse with work Usually can’t produce pain with palpation, but can feel heat Use opposite limb as comparison
12 Lameness – Fetlock Fracture of sesamoid bones: Common in racing Thoroughbreds, Standardbreds and Quarter HorsesForelimbs most commonly affected in TB and QH, hindlimbs in STBLameness is very pronounced – often non-weightbearing Swelling, heat, pain Fetlock held rigid during movementThis is the most common type of sesamoid bone fracture. These are typically the result of strain placed on the suspensory apparatus at the level of attachment of the suspensory ligament branch. Injury to the suspensory ligament branch may occur concurrently with the fracture. If significant injury to the suspensory branch is present the prognosis will be poorer.Surgical removal of the apical fragment is the treatment of choice for these fractures. Small fracture fragments may be removed with little damage to the attachment of the suspensory branch. The larger the fracture fragment that is removed, the more disruption of the suspensory branch attachment that occurs and the poorer the prognosis.
13 Front Limb – Pastern Joints TWO joints (Long pastern-short pastern and short pastern-coffin bone)RingboneNew bone growth on bones of pastern joint(s) leading to arthritis and fusion of jointsHigh = top jointLow = bottom jointCommonly caused by trauma strain on collateral ligaments, joint capsule attachments to bone, wire cuts; or direct trauma leads to trauma to periosteum and bone formationBase-wide conformation strain on medial surfaces and base-narrow lateral surfaces toe-in or out increases forces
14 Pastern Joint - Ringbone Articular vs. Non-articularNon-articular due to inflammation of the periosteumMost common in non-speed horses with coarse boxy pasternsHorses with high heels and short toes with trappy gaitsPeri-articular often doesn’t cause lameness; after rest, may also lack heat, pain or swelling;Articular chronic lameness with variable degrees of swelling heat and pain; lateral movements such as longeing = intensified pain; lack of flexion with high ringboneNonarticular ringbone doesn’t involve joint surface, most common as high ringbone
15 Pastern Joint – Ringbone Articular High ringboneHorse used for high speed that make quick stops, short turns or rapid twisting movementsOverly upright pasterns increased concussion on jointSigns of lameness are not specificFusion of pastern joint commonIf high articular ringbone – lameness present until fusion takes place.Surgical fusion may be performed (screws + cast from knee to cover foot for 6-7 weeks; then bandage support when fusion is complete, stall confinement for 8 weeks hand-walking) no free exercise until after 16 weeks (may need up to 1 year, though!)If coffin bone involved BAD NEWS! Probably never get a sound riding horseLow ringbone may lead to “buttress foot”
16 Diagnosis: early using thermal imaging (will show increased heat in the pastern); radiology is definitive diagnostic tool.Treatment: guarded prognosis for return to athletic endeavors – pt and modified training (non-articular is obviousy better)Early prior to bone growth – robert jones bandage or light cast; warm moist heat/cold therapy to decrease inflammation; light therapy to increase circulation; proper shoeing and modification of training technique.Chronic cases: pain releiving drugs, stall rest, nervingHigh articular ringbone: systemic/intra-articular therapies; surgical invovlvement possible (fusing)Chronic articular: surgical fusing and post-surgical castingRockered toed shoes
18 Front Limb – Navicular Bone “Navicular Syndrome” aka PodotrochleosisMost common cause of intermittent, shifting forelimb lamenessMost common in horses years oldMost common lameness of horses between 4 and 9 yoHereditary (small feet, faulty conformation)Highest incidences in Quarter Horses and StandardbredsGeldings > Stallions > MaresLameness exhibits as heel painBroad spectrum of conditions which affect the navicular bone
19 Navicular Syndrome Predisposing factors: @ walk and trot Poor conformationUpright pasternsInappropriate exerciseResilient surfacesImproper/irregular trimmingLong toe-low heel (broken-back axis)@ walk and trotLands toe first excessive wear of the toe, bruisingLower limb flexion test aggravates 80% of horsesStiff shuffling gait with high head and rigid neckWhen circled, limb on inside will be worse, head held to outside of circleWas originally thought to be an arthiritic condition of the bone itself and it’s consequential effects on the bursa and flexor tendonsHorse with laminitis is similar except that it lands heel first!Distinguish from bruising, SSD (sheared heels, etc.)If chronic and long-present -> foot will change shape (heels contract and rise to keep pressure off frog), sole becomes more concave and a narrowing in the quarters; if only one foot affected – it will be smallerTreatment: Corrective trimming and shoeing; drugs that may affect vascularization of foot (isoxuprine and dicumorol); pain alleviation
20 Hind Limb – Stifle Bones involved: femur, tibia, patella (knee cap) Most commonly mis-diagnosed lameness area (overdiagnosed)Hard to discern differences due to stifle vs. hockCommon Problems:DOD …Upward Fixation of the PatellaArthritis and inflammation (gonitis)
21 Upward Fixation of the Patella Locked StiflesMiddle and medial patellar ligaments get “caught” on the femurPatella should be able to slide during movement, if ligaments stuck, patella can’t moveMay be intermittent or completeAcute = hindlimb locked in extensionStifle and hock can’t flex (but fetlock can)Catching (not complete locking) also possible
22 Upward Fixation of the Patella Diagnosis:Catching most noticeable when horse is turned in a tight circle towards affected limbWalk up and down slope – crouched position going up, jerky gait downToe drag if limb lockedPalpation – patella locked in extensionTreatment:Training to improve muscle toneAvoid exercise in soft areasSurgery as last resort
24 Stifle – Arthritis and Gonitis Gonitis = inflammationMany causesDistension of the stifle jointGluteal muscles may be atrophiedWearing of toes in the hind end (toe drag)More lame when ligaments or cartilage involvedShortened stride (failure to reach forward)Hip hikeArthritis = bony changes
25 When the stifle flexes the hock also flexes and vice versa! Hind Limb – HockBone spavinBog spavinFracturesCurbStringhaltShiversCapped HockSoft TissueDOD (Nutrition Course)When the stifle flexes the hock also flexes and vice versa!
26 The Hock Joint 6 cuboidal bones, tibia, cannon, 4 joints Hock works as a hingeMost movement occurs between the tibia and the tibial tarsal boneHock is the pivotal hind limb joint – all equine exercise disciplines rely on it for performanceThe hock absorbs most concussive forcesMost common site of stress related injuries!
27 Hock LamenessFirst noticeable sign is stiffness/soreness in lumbar region of backPoorly trained chiropractors may “adjust” a horse that really has a primary hock problem!Pain around inside splint boneSwelling and pain in the joint itself
28 Specific Conditions Bone Spavin: General term for degenerative joint disease or osteoarthritis in the hock jointOften in both hocksHistory = back stiffness/soreness with lameness that may go away with exerciseExcessive wear on the outside of the shoe/hoofBony enlargement just below and behind the chestnutFlexion test!
29 Specific Conditions Bog Spavin: Curbed Hock General term for distension of joint capsulePresent on inside front of the hock!Usually representative of an underlying hock problem!Curbed HockSprain of the ligament that runs down the back of the hockCommon in horses with sickle-hocked conformation
30 Specific Conditions Capped Hock Stringhalt Hematoma at the point of the hockOften due to trauma (kicking walls, etc.)Avoid drainage due to potential for infectionStringhaltExcessive involuntary flexion of the hock jointUsually isolatedCauses unknown
31 Specific Conditions Stringhalt Study in Australia: Appears in Late Summer peaking in FebruaryAssociated with droughty summersAll breeds affected but TBs more, ponies lessRecover when removed from paddocks containing catsear or dandelionCases appear from late summer with a peak in February and are often associated with drier than normal summers. All breeds may be affected by Australian Stringhalt, although thoroughbreds seem to be more susceptible and ponies less susceptible. Horses will usually recover if moved to a paddock where they are not grazing Catsear or Dandelion. Recovery can take a few days or up to 18 months. The average recovery period is 6-12 months. The anticonvulsant drug Dilantin® does ease the signs of the disease and can help to hasten recovery. Some severe cases that have not responded to being removed from pasture can have a surgical treatment. The surgery involves removing the lateral digital extensor tendon in the hind leg. This treatment has variable results but in some cases has proven to be very worthwhile
32 Specific Conditions Shivers Involuntary muscle movements of limbs and tailMay be caused by EPSM – most other causes unknownUsually most visible when trying to back a horseJerks foot and holds it above the ground in flexed positionEPMS – Equine Polysaccharide Storage MyophathyUsually affects heavy breed horses. EPSM is a genetic predisposition to fail to digest grains properly in the horse. The result leads to damage to muscle tissue during exertion.The Quarter Horse community calls the condition PSSM (Polysaccharide Storage Myopathy).
33 Treatment Terminology Rest with Controlled Exercise:Out of work (time off!); moderate controlled exercise such as daily hand-walkingPhysiotherapy:HydrotherapyCOLD – up to 48 hours post-injury to reduce inflammationHOT – 48 hours after injury to reduce tension, relieve pain
34 Treatment Terminology Joint Lavage:Washing dead tissue out of joint with large amounts of sterile fluidDMSO (dimethyl sulfoxide):Topical application can reduce joint inflammationWear gloves!Corticosteroids:Anti-inflammatory – helps reduce harmful enzymes in synovial fluidUsually directly injected into joint
35 Treatment Terminology NSAIDs:Non-steroidal anti-inflammatory pain relief for soft tissue injuries (Bute, Banamine, Aspirin)Hyaluronic Acid (HA):Natural part of synovial fluid used to treat synovitis injected directly into joint (after steroids)Horses often show immediate, long-lasting reliefJoint Fusion:Surgical repair of arthritis
36 Treatment Terminology Counterirritation:Blistering, firing, ultrasound to speed healing