Laminitis Flashcards
Obj: Understand the pathogenesis of laminitis and how they are related to the associated causes
Obj: CLinical signs and diagnosis of laminitis
Obj: Most important treatment aspects of laminitis and rationale
What is laminitis? Why is it important?
- Inflammation of the laminae
- Characterized by degeneration, necrosis, and inflammation of the dermal & epidermal laminae in the hoof wall
- Importance:
- severely debilitating, career threatening and often life ending disease
- up to 15% of horses will develop laminitis over their lifetime
- up to 75% of them will be euthanized
What is the pathophysiology of Laminitis?
- Due to several processes:
- Inflammation: Systemic Inflammatory Response to underlying illnesses, that inflammation also occurs in the foot
- Ischemia/Endothelial cell dysfunction:
- venous vasoconstriction and edema, lack of blood flow to the laminae
- Insulin: hyperinsulinemia has experimentally resulted in laminitis
- Enzyme pathways
- excessive activation of metalloproteinase enzymes
- destruction of laminae
- excessive activation of metalloproteinase enzymes
- mechanical trauma
After the laminae is weakened, what are the possible outcomes?
- Laminitis w/out displacement of P3 from hoof wall:
- no mechanical failure - but laminae are week
- better prognosis
- Rotation of P3 away from the dorsal hoof wall:
- most common type of displacement/mechanical failure
- DDF tendon pulls tip of P3 distally
- Sinking/Vertical Displacement:
- most severe
- P3 displaced vertically/distally in the hoof wall
- P3 ‘falls’ through hoof
- palpable ridge at coronary band
What diseases/syndromes/toxins are associated with laminitis?
- Carbohydrate overload
- Black Walnut toxin
- Systemic Diseases associated with endotoxin
- colitis
- retained fetal membranes
- Endocrine disease
- PPID
- EMS
- Exogenous steroids
- Grass Founder
- Support Limb laminitis
- Road Founder
- Idiopathic
What are the clinical signs of laminitis?
- Lameness
- increased digital pulse
- warm dorsal hoof wall
- sensitivity to hoof testers over toe
- Depression at the coronary band - sinking
- Hoof changes - rings, ‘slippers for feet’
What is the Obel lameness scale?
- Obel 1 - least severe, not lame at walk, lame at trot
- Obel 2 - walk with stilted gait
- Obel 3 - move reluctantly and resist lifting foot
- Obel 4 - Refusing to move unless forced
How is laminitis diagnosed?
- Clinical signs
- Nerve blocks
- abaxial - anesthesia of the entire foot ⇢ significant improvement to lameness
- Radiographs - lateral view best
- Thickness of dorsal hoof wall to dorsal P3 (Normal 18mm)
- Measurement of rotation
- Modeling of the toe or dorsal wall of P3 implies previous disease
- Vertical displacement of P3
What are the goals of laminitis treatment?
- ID/Treat underlying cause
- Reduce Pain
- Reduce inflammation
- Reduce mechanical forces and stabilize distal phalanx
- Others:
- Improve perfusion
- Inhibit enzymatic pathways
What medications are used in horses to reduce pain due to laminitis?
- NSAIDs - phenylbutazone
- Opioids - butorphanol, morphine
- Detomidine, ketamine, lidocaine CRI for severe pain
How to reduce mechanical forces/stabilize the distal phalanx in lamanitic horses
- No forced exercise
- deeply bedded stalls - sand
- Acute stages:
- frog support - reduce tension on laminae
- Chronic Cases:
- corrective shoeing
- DDF tenotomy
What medications are used to improve blood flow to the digit in laminitis cases? MOA?
-
Pentoxifylline - phosphodiesterase inhibitor
- anti-inflammatory properties
- improves RBC deformability
- Does NOT increase digital blood flow
- Aspirin - blood thinner
-
Heparin - improve blood flow
- problems with microagglutination and decrease in PCV
What methods can be tried to prevent laminitis?
- Cooling of limbs:
- for 72hrs during ‘at risk’ time
- experimentally shown
