Introduction to Laminitis

Question 1

what are the 4 stages of laminitis

Answer 1

1. developmental phase: inciting cause, presence of foot pain, we often miss
2. acute phase: within 72 hours of onset of clinical signs, no P3 displacement
3. subacute phase: greater than 72 hour duration; no P3 displacement
4. chronic phase: P3 displacement

Question 2

what are the 4 predisposing/triggering factors of laminitis?

Answer 2

1. dietary: excessive ingestion of non-structural carbohydrates leads to large amounts of starch in hindgut and lactic acid production, causes hindgut bacteria death and toxin release/absorption and endotoxemia/SIRS
2. inflam/infectious/toxic
   -GI: enteritis, colitis
   -non GI: pneumonia/pleuropneumonia, septic metritis, septicemia
3. endocrine dysfunction: most common cause currently!
   -hyperinsulinemia/insulin resistance: equine metabolic syndrome. pituitary pars media dysfunction
4. mechanical/support limb: excessive weight bearing, lack of perfusion/ischemia

Question 3

describe the 2 classifications of laminitis

Answer 3

1. rotational: P3 shifted towards ground, due to compromised lamina allowing stronger pull of DDFT to override pull of CDE
2. distal displacement: whole bone column displaces
   -symmetrical: whole column sinks closer to ground together; look at how much of P2 sitting within hoof capsule versus normal
   -asymmetrical: one side versus the other; medial sinks alone or lateral sinks alone

Question 4

describe laminitis diagnostics (5)

Answer 4

1. clinical signs: vary with stage/severity and number of feet affected
2. acute phase: increased hoof wall temperature, increased intensity of digital pulses, hoof tester response (like abscess, variable)
3. chronic stage: hoof capsule changes; ski slope, stretching of white line area on bottom of foot
4. diagnostic imaging:
   -radiographs: standard, lateromedial view, dorsopalmar/dorsoplantar views will give a good idea of what going on with hoof capsule for laminitis bases
   -use the foramen that run through P3 as landmarks to draw a line through to the ground and joint distance between medial and lateral aspect of coffin joint
5. can do a venogram; backfill venous blood flow to get an idea of what going on with blood supply

Question 5

describe endocrine testing for laminitis

Answer 5

need to get endocrine under control or won’t win battle with feet
1. measure ACTH: if increased indicates PPID/cushing’s; usually older horses

2. insulin and leptin: check for equine metabolic syndrome; usually fatter younger horses

Question 6

describe treatment and management of acute laminitis goals

Answer 6

treatment goals:
1. individualized treatment plan
2. identify predisposing factors
3. treat/eliminate these factors

overarching goals:
1. prevent further lamellae damage
2. maintain/improve blood supply to dermis of hoof
3. prevent P3 displacement
4. reduce pain and inflammation

Question 7

describe 5 treatment modalities for acute laminitis

Answer 7

1. cryotherapy:
   -interrupt inflammatory signaling pathways and increase expression of anti-inflammatory IL-10
   -initially vasoconstriction, but overall vasodilatory affect, decreases cellular metabolism when used long term (ice on constantly for 48-72 hours)
   -numbs feet so horse is more comfy
2. appropriate confinement:
   -stall size: enough room?
   -stall bedding: hella important!! soft and thick; not sand (pressure sores)
3. systemic pharmocologic therapy:
   -on farm: NSAIDs, acetaminophen
   -hospital: opioids, systemic lidocaine, ketamine
4. surgical treatment:
   -DDF tenotomy: remove pulling force all together; for unathletic horses; midmetacarpal approach or pastern approach
5. farriery: primary goal is to improve comfort, do literally whatever works
   -for lamellar pain: alter load bearing, redistribute forces, decrease DDFT tension
   -for solar pain: reduce/eliminate pressure under sensitive areas (wood clogs!)