Equine Lameness Flashcards
What are 4 metabolic causes of laminitis (Founder)?
- obese or overweight horses
- metabolic-prone breeds - Morgans, ponies, minis
- Equine Cushing’s disease
- excess grass intake, especially in the spring time
What are 3 endotoxemic diseases that can cause laminitis (Founder)?
- grain overload
- colitis
- retained fetal membranes
What is a common iatrogenic cause of laminitis (Founder)?
steroid use
What is the pathogenesis of laminitis (Founder)?
- an inflammatory cascade is set off
- this causes laminar projections in the hoof capsule to become inflamed and weaken
- pull of the DDFT on the coffin joint’s weak laminae causes the coffin bone to rotate the toe palmar toward the ground
- the toe can also sink lower in the hoof due to weight-bearing forces on the weak laminae
What feet are most commonly affected by laminitis (Founder)? What are common clinical signs?
front
- increased digital pulses + heat in hooves
- rocked back stance (“walking on eggshells”)
- difficulty picking up hoof due to painful weight being on other hoof
- total or significantly increased recumbecy
- hoof tester positive at the the toe
What is most commonly seen on radiographs in cases of laminitis? What is a chronic change?
coffin bone rotated toward the ground and decreased sole depth under point of the coffin bone
osteophyte “ski-tip” at point of coffin bone due to chronic trauma
Are nerve blocks used to diagnose laminitis?
NO –> contraindicated due to increased temporary weight bearing
(technically improves with abaxial nerve block)
What treatments are recommended in the initial stages of laminitis? What medication can be given?
icing or cooling feet + anti-inflammatories
phenoxybenzamine - vasodilation improves circulation to hooves (true benefit unknown)
What are some lifestyle changes to decrease the effects of laminitis?
- deeply bedded stalls with sand bedding
- cushioned boots or styrofoam on hooves
- trim over time to de-rotate - bring back the toe and square off to decrease the heel angle
What treatment is recommended for chronic cases of laminitis not responding well to traditional treatment?
DDFT tenotomy - relieves pull of tendon on coffin bone
What are 3 long-term changes used to decrease effects of laminitis?
- weight loss
- diet changes for low sugar and low starch hay/grain
- soaking hay in water to remove sugars before feeding
What breeds are overrepresented for developing navicular syndrome?
Paints, Quarter Horses –> small feet
What is navicular syndrome? What is a common secondary cause of pain associated with this syndrome?
any source of pain from the navicular bone or attached ligaments
osteophytes on the navicular cause pressure and grating action on the DDFT where it attached to the bottom of the coffin bone in the hoof capsule
What is a characteristic sign of navicular syndrome? What are some other signs?
horse switches lameness to opposite foot after initial lameness is blocked –> navicular syndrome most commonly bilaterally affects the front hooves
- sound at a walk, lame at a trot
- hoof tester positive at the heels
What nerve block does navicular syndrome react to?
palmar digital
What does the navicular bone usually look like on radiographs? How is it affected by navicular syndrome?
“reverse oreo” - central medulla is darker and less dense with 3-4 small nutrient foramen and a solid, outer cortex
- enlarged and increased nutrient foramen (lollipops)
- increased density of medulla - poor distinction between it and cortex
- osteophytosis
What are 3 methods of treating navicular syndrome?
- trimming and shoeing - reduce toe to improve breakover, increase heel angle to take pressure off tendons at heel (wedge of heel pad, eddbar shoe)
- OsPhos or Tildren - bisphosphonate injection to decrease osteoclast action, allowing for more balanced osteoblast activity
- anti-inflammatories
What 3 tendons are most commonly affected by tendonitis? What is the pathogenesis?
- suspensory ligament - especially proximally
- DDFT
- SDFT
acute trauma or chronic weakening of overuse
What is degenerative suspensory ligament desmitis/disease? What does it result in? What breed is it most commonly seen in?
progressive failure of collagen fiber repair in the suspensory ligament apparatus (NOT an athletic injury)
gradual enlargement, but weakening of the suspensory ligament leads to a significant fetlock drop and positive flexion
Paso Finos
What is the best way of diagnosing suspensory ligament desmitis/disease?
U/S - focal anechoic lesions +/- chronic abnormal fiber patterns
(MRI may be necessary for tears in the hoof capsule)
What is the difference between high and low ringbone?
HIGH = pastern joint OA
LOW = coffin join OA
What is the difference between bone and bog spavin?
BONE SPAVIN = hock (intertarsal) joint OA
BOG SPAVIN = tibiotarsal joint effusion
What are 2 of the most common radiographic signs of osteoarthritis in horses? What joints are most commonly affected?
- osteophytes
- narrowing or bridging of joints (can become completely fused at end stage, which can improve comfort)
hocks and coffin joints –> performance horse
carpus –> aged horses
What clincial signs are associated with hoof abscesses in horses?
- lameness - often acutely and nearly non-weight bearing
- increased digital pulse
- positive to hoof testers throughout the hoof and more so at specific site of abscess
- soft, sensitive coronary band
- grey or white purulent material draining from an open abscess
What are the most common clinical signs associated with osteochondritis dissecans? What is seen on radiographs?
- lameness at the trot, mild or absent lameness in young horses –> more likely to form OA or lameness at a later age
- joint effusion
subchondral radiolucency at articular surface
What joints are most commonly affected by congenital flexural limb deformities in foals? What are the 2 major types?
carpus and fetlock - often bilateral
- CONTRACTION - physically unable to extend limn, may knuckle over
- EXTENSION - most common at the fetlock, walk on heels with toe in air and abrade palmar/plantar fetlock on the ground
