Lamanitis Flashcards
laminitis
inflammation of soft tissues (laminae) of equine foot, ultimately leading to separation of epidermis from dermis and hoof wall from phalanx
hoof anatomy
- primary and secondary dermal epidermal lamellae interdigitate to coffin bone, hoof capsule, and sole
- tendons and ligaments can be pulled and rotated
- vascular supply of corium; arteries and veins crushed when bone rotates
- 60-65% of weight bearing is on front feet
coffin bone
- conforms to shape of hoof wall
- attached to hoof wall via dermis
- porous to allow blood vessels through overlying dermis
hoof wall
- grows from epithelium
- horn tubules cover dermis covering coffin bone
hoof, top to bottom, front to back external anatomy
-coronary, sensitive laminae, sole, bulbs
general points of laminitis
- complex, occurs mostly in adults and ponies (ponies any age, breed, or use)
- 15% of all horses develop laminitis, 75% of which will develop chronic debilitating disease requiring euthanasia
- treatment must be aggressive and early
- all 4 feet affected, but usually front feet since they are weight bearing
acute vs chronic lamanitis
- occurs in stages
- chronic/founder associated with physical evidence of rotational or vertical displacement of third phalanx
- chronic follows acute
clinical signs of acute laminitis
-very painful, caused by bruising, inflammation, abscess formation
-unwilling to move, lameness
-rock backwards, shifting weight on rear legs
-exaggerated lifting of legs
-anxiety, sweating, increased heart and resp rate
-sweeling of coronet band
-unwillingness to lift leg for cleaning
-sensitive to hoof testers
rotation indicated by depression of coronet band, bulging sole
conditions associated with laminitis
acute GIT diseases like colitis, strangulation
- carb overload with fructans
- endocrine and metabolic diseases: increased steroids in blood/glucotoxicity
- endotoxemia or sepsis
- fractures
- obesity
theories on pathogenesis
- vascular, lack of oxygen to digit
- toxic metabolism, damage to epithelial cells of laminae result in vascular lesions
- both lead to death of laminae cells, causing hoof wall to separate from dermis and phalanx
3 forms of laminitis
- insulin resistance: CHO overload from derangement of glucose regulation
- mechanical trauma
- secondary result of systemic inflamm response syndrome (SEPSIS) or endotoxemia
insulin resistance
- found in horses with pituitary pars intermedia dysfunction (cushings)
- experimentally induced by HYPERINSULINEMIA
- common in horses on PASTURE due to high level of fructans in grass, which may lead to increase in insulin resistance and high blood glucose
mechanical trauma
- reduces blood flow to laminae
- caused by support limb laminitis or long trailers rides
- inflamm results in swelling, damage to vessels and loss of laminae
- cows deal with it better because they can lie down
endotoxemia or SEPSIS
- models using grain overload as model of laminitis show damage to lining of gut allows microbial products to enter blood stream
- gram -ve bac cell walls contain toxins
- reults in vasodilation and unresponsive vessels, blood shunts away from crucial tissues, damaging walls and clots
diagnosis
- history
- radiographic evidence may see P3 (coffin bone) starting to sink
