Equine Flash Notes - Laminitis vs Navicular Disease

Question 1

what is laminitis?

Answer 1

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

Question 2

what are the main causes of laminitis in horses?

Answer 2

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

Question 3

what are the 4 types of laminitis?

Answer 3

1. predisposing conditions
2. acute laminitis
3. refractory laminitis
4. chronic - rotation of P3

Question 4

what are the laminitis lameness grades?

Answer 4

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

Question 5

T/F: laminitis is usually not diagnosed until a horse reaches grade 3

Answer 5

true

Question 6

what is the classic case presentation of acute laminitis? chronic?

Answer 6

hoof tester positive over toes, alterations in digital pulses

refractory - lack of response to treatment

chronic - dropped sole & see toe of P3 through sole

Question 7

what is seen on rads of laminitis?

Answer 7

acutely for baseline

early - widening between P3 & dorsal hoof wall, roughening of dorsal P3, distal displacement of P3, rotation of distal phalanx

Question 8

what is the prognosis for laminitis in horses?

Answer 8

always guarded - 30% return to soundness

lower grade = greater chance of recovery

Question 9

what stance is seen in horses with acute laminitis?

Answer 9

leaning back - pain posture

Question 10

what nerve block is done to eliminate laminitis pain?

Answer 10

pastern/foot block

Question 11

what causes 1/3rd of all forelimb lameness in horses? what is the number 1 cause of chronic intermittent forelimb lameness?

Answer 11

navicular disease

Question 12

what is navicular disease?

Answer 12

chronic, progressive, painful syndrome due to problems of the navicular bone, navicular bursa, coffin joint, hoof, DDF tendon, & associated structures

Question 13

what horses are often affected by navicular syndrome?

Answer 13

athletes - quarter horses, thoroughbreds, & warmbloods

Question 14

what are predisposing factors to navicular disease?

Answer 14

unbalanced foot

concussion

conformation - break in foot/pastern axis

small feet

large, heavy bodies

inadequate heel support

poor conditioning

Question 15

what is the proposed etiology navicular syndrome?

Answer 15

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

Question 16

what is the common owner complaint for a horse with navicular syndrome?

Answer 16

believes there is pain in the shoulder - tied up in the shoulder

Question 17

what is the classic case presentation of navicular syndrome?

Answer 17

chronic, insidious low grade shifting lameness, pointing toes, intermittent lameness, stiff gait where the horse lands on their toes with a shortened stride & stumbling

Question 18

what are sequelae to navicular disease?

Answer 18

contracted heels & increased concavity to sole

toe bruises from landing on toe

foot changes - wears down toe & grows at heel

Question 19

how is navicular disease diagnosed?

Answer 19

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

Question 20

what diagnostic is indicated for navicular syndrome?

Answer 20

positive rad findings are supportive of diagnosis but are NOT diagnostic

need 5 views for standard navicular series

1. 60 DP
2. lateral
3. flexor view
   4 & 5 - 2 obliques 60 to horizontal

Question 21

what radiographic changes are seen in a horse with navicular syndrome?

Answer 21

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

Question 22

what is the goal of treatment of navicular disease?

Answer 22

manage - impossible to cure

Question 23

what medical treatment is used for navicular disease?

Answer 23

stall rest, controlled exercise program, corrective trimming, corrective shoeing, & PBZ for 10 days

Question 24

when is a digital neurectomy done for a horse with navicular syndrome?

Answer 24

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

Question 25

T/F: a heel block predicts the effect of neurectomy in a horse with navicular syndrome

Answer 25

true - horse should show improvement if it is a navicular problem

Question 26

what is the prognosis of navicular syndrome? why?

Answer 26

guarded - progressive degeneration & chronic disease