Equine Flash Notes - Laminitis vs Navicular Disease Flashcards
what is laminitis?
inflammation of the laminae of the hoof - more common in front feet than hind - can be one or all feet
avascular necrosis of sensitive laminae - medical emergency
what are the main causes of laminitis in horses?
endotoxemia - increased blood flow to the foot but less flow to laminae because of arteriovenous shunting
mechanical overload - can break down connection of sensitive & non-sensitive laminae
what are the 4 types of laminitis?
- predisposing conditions
- acute laminitis
- refractory laminitis
- chronic - rotation of P3
what are the laminitis lameness grades?
grade 1 - lifts feet repeatedly
grade 2 - walks willingly, laminitic gait, doesn’t resist foot lifting
grade 3 - reluctance to move, resists foot lifting
grade 4 - must be forced to move, may be recumbent
T/F: laminitis is usually not diagnosed until a horse reaches grade 3
true
what is the classic case presentation of acute laminitis? chronic?
hoof tester positive over toes, alterations in digital pulses
refractory - lack of response to treatment
chronic - dropped sole & see toe of P3 through sole
what is seen on rads of laminitis?
acutely for baseline
early - widening between P3 & dorsal hoof wall, roughening of dorsal P3, distal displacement of P3, rotation of distal phalanx
what is the prognosis for laminitis in horses?
always guarded - 30% return to soundness
lower grade = greater chance of recovery
what stance is seen in horses with acute laminitis?
leaning back - pain posture
what nerve block is done to eliminate laminitis pain?
pastern/foot block
what causes 1/3rd of all forelimb lameness in horses? what is the number 1 cause of chronic intermittent forelimb lameness?
navicular disease
what is navicular disease?
chronic, progressive, painful syndrome due to problems of the navicular bone, navicular bursa, coffin joint, hoof, DDF tendon, & associated structures
what horses are often affected by navicular syndrome?
athletes - quarter horses, thoroughbreds, & warmbloods
what are predisposing factors to navicular disease?
unbalanced foot
concussion
conformation - break in foot/pastern axis
small feet
large, heavy bodies
inadequate heel support
poor conditioning
what is the proposed etiology navicular syndrome?
concussion causes navicular bursitis due to pressure of DDF resulting in pathological changes
disrupted blood flow leads to arterial thrombosis & ischemic necrosis within the navicular bone
what is the common owner complaint for a horse with navicular syndrome?
believes there is pain in the shoulder - tied up in the shoulder
what is the classic case presentation of navicular syndrome?
chronic, insidious low grade shifting lameness, pointing toes, intermittent lameness, stiff gait where the horse lands on their toes with a shortened stride & stumbling
what are sequelae to navicular disease?
contracted heels & increased concavity to sole
toe bruises from landing on toe
foot changes - wears down toe & grows at heel
how is navicular disease diagnosed?
hoof testers - painful over center 1/3 of frog
at a trot, rigid head bilaterally, nodding on inside limb when lunging, & heel block (PD) partially or total eliminates lameness
what diagnostic is indicated for navicular syndrome?
positive rad findings are supportive of diagnosis but are NOT diagnostic
need 5 views for standard navicular series
- 60 DP
- lateral
- flexor view
4 & 5 - 2 obliques 60 to horizontal
what radiographic changes are seen in a horse with navicular syndrome?
over 7 synovial fossae
lollipops (mushroom shaped synovial fossae)
cysts in medullary cavity
loss of corticomedullary function
thinning/roughening of flexor cortex
flattening of sagittal ridge
enthesiophytes
what is the goal of treatment of navicular disease?
manage - impossible to cure
what medical treatment is used for navicular disease?
stall rest, controlled exercise program, corrective trimming, corrective shoeing, & PBZ for 10 days
when is a digital neurectomy done for a horse with navicular syndrome?
eliminates pain not disease - do if the horse has no improvement from medical therapy in 6-12 weeks
last ditch measure to lengthen athletic life
T/F: a heel block predicts the effect of neurectomy in a horse with navicular syndrome
true - horse should show improvement if it is a navicular problem
what is the prognosis of navicular syndrome? why?
guarded - progressive degeneration & chronic disease
