Exam 2 - Equine Laminitis Flashcards
what is laminitis?
inflammation of the lamina - disruption/inflammation of the lamina
the lamina hold the distal phalanx to the hoof wall circumferentially, so loss of this attachment results in rotation and/or sinking of the distal phalanx
what is rotation in regards to laminitis?
loss of parallelism of the hoof wall with the dorsal aspect of the distal phalanx causing pinching of the circumflex artery
mild: 3-5°
moderate: 5-10°
severe: >10°
what horses are more commonly affected by laminitis?
minis, ponies, & donkeys
what clinical signs are seen in a horse with acute laminitis?
acute, severe lameness ‘walking on eggshells,’ carrying their weight on the hind end
sensitive to hoof testers over toes
increased to bounding digital pulses
typically bilateral front feet - less common, but can be bilateral hind feet, rare unilateral cases
rare in foals
what are the most important radiographic views for diagnosing laminitis?
lateral & dorsopalmar views
what is founder?
layman’s term for laminitis - sampson reserves this term for laminitis with rotation
how is laminitis diagnosed?
clinical signs - history, physical exam, digital pulses, + hoof testers
block to abaxial nerve - often not needed to diagnose in severe cases, but can confirm with blocking
what block should you use for a horse you suspect has laminitis? why?
abaxial sesamoid block - can use to get better radiographs
sometimes can’t get their feet off the ground to put in soft rides without blocking them
what does an abaxial sesamoid block desensitize? what nerves are you hitting?
entire foot/pastern & part of the fetlock - medial & lateral palmar/plantar nerves
where is an abaxial sesamoid block performed?
lateral & medial palmar aspect of the foot just distal to the fetlock using 2-3 mLs of carbocaine
what are some recognized risk factors for laminitis?
obesity, carbohydrate overload, steroids/systemic steroids, endotoxemia
intra-articular steroids - triamcinolone implicated
PPID, black walnut shavings
trimmed too short
severe lameness in opposite limb - support limb laminitis because of mechanical overload on the contralateral limb
T/F: in laminitis, mild to severe lameness is seen depending on the stage of disease in horses
true
if the front feet of a horse are affected by laminitis, how will they carry their weight?
back end
this stance is characteristic for laminitis in what feet?
front feet - weight is shifted back
what is the pathogenesis of laminitis?
laminar disintegration is mediated by uncontrolled release of excessive activated MMP (strep bovis implicated)
enzymatic destruction of laminae resulting in the loss of basement membrane integrity
ischemic necrosis of laminae - no force to oppose the pull of DDFT
if not controlled, can result in distal phalanx penetrating through the sole at the toe, typically resulting in euthanasia
what is the prognosis of this horse with laminitis that has resulted in sole penetration?
euthanasia
what clinical signs are associated with acute laminitis in horses?
severe lameness
bounding digital pulses
normal external hoof wall
extreme hoof tester sensitivity over toes
walking on egg shells
what clinical signs are associated with chronic laminitis in horses?
variable lameness
increased digital pulses
dished external hoof wall with horizontal rings - foot becomes upright with a tall heel & stretched white line
none to moderate hoof tester sensitivity over the toes
what is the treatment indicated for acute laminitis in horses?
emergency!!!!
soft ride boots - easiest
ice the affected distal limbs - cold stops MMP enzyme activity
phenylbutazone - anti-inflammatory, very important
pentoxyphylline - increases blood flow in tortuous vessels
acepromazine - vasodilation
what is the treatment indicated for chronic laminitis in horses?
shoeing to support caudal half of foot & shorten toe (clogs, heart bar, reverse heart bar shoe)
phenylbutazone or equioxx as needed
manage weight - do not want an obese horse, more risk
manage type/amount of feed - low starch diet
what are the goals of shoeing for managing chronic laminitis?
- unweight the sole at the toe & support the foot at the heel
- increase the heel angle - wedge heel up
- protect the sole of the foot from concussion
what materials are used for shoe management in chronic laminitis horses?
soft ride boots, clogs, heart bar shoes
what shoe material is this?
clogs - has to be screwed on or put on by a farrier or veterinarian
what type of shoe is this? what is it used for?
heart bar shoe - managing chronic laminitis horses
