L17: Equine acute laminitis (copy)

What is the importance of laminitis

• 1.5-34% prevalence

• 7.4% deaths due to laminitis

• extremely painful

• frequently recurrent

• Huge welfare implications

What does this show

Lamellar interdigitations

What is the basement membrane anchored by

hemidesmosomes

What are the forces acting on the pedal bone

What is the aetiology for laminitis

• syndrome not a disease

• Associated with systemic disease or excessive weight bearing

What are the three forms of laminitis

• Sepsis associated

• endocrinopathic

• Excessive weight bearing (SLL)

TRUE OR FALSE

The overall end of laminitis is similar regardless of aetiology

TRUE

What does morphological derangement cause

• Loss of the strength of the lamellar attachment

• Distal phalanx no longer suspended in the hoof capsule

• pain

What is sepsis associated laminitis associated with disease wise

• Associated with

  • GI disease

  • Pneumonia

  • Septic metritis

• Similar to SIRS

  • Laminitis= end organ dysfunction

• Two experimental models

  • Carbohydrate overload

  • black walnut

What is the mechanism for sepsis associated laminitis

• Evidence of

  • systemic inflammation

  • endothelial activation

  • Leucocyte adhnesion and emigration

  • Cytokine expression

  • oxidative injury

• MMP activation not initiating event

• Failure of critical LBEC functions

  • caused by inflammatory and/or hypoxic cellular injury

What is endocrinopathic laminitis associated with

• EMS

• PPID

• Glucocorticoids

what is the pathogenesis for endocrinopathic laminitis

• Association recognised for many years

• Linking factor discovered with hyperinsulinaemia model

• Prolonged hyperinsulinaemia

• Inflammation not a major feature

• Not systemic or GI inflammation

• Different histological changes

what type of laminitis does this show

insulin model

What type of laminitis does this show

sepsis model

What is the mechanism for endocrinopathic laminitis

• Not inflammation

• Not ECM degeneration

• Not glucose toxicity/depravation

• Inappropriate IGF-1R stimulation

• Endothelial dysfunction

• Altered adipokines

• Altered proteostasis

What are the key features of equine metabolic syndrome

• Insulin dysregulation

  • Hyperinsulinaemia

  • Excess insulin response to oral carbohydrate

What are some additional features of equine metabolic syndrome

• Increased fasting

• altered adipokines

• obesity

What is the sequence of events in endocrinopathic laminitis

what causes insulin dysregulation in equine metabolic syndrome

• Genetics

• Epigenetics

• Microbiome

• Obesity

• Diet

• Endocrine disrupting chemicals

What is PPID

• Loss of dopaminergic inhibition

• Excessive production of pi hormones

• Cortisol, CLIP, b tropin + others affect insulin

• Hyperinsulinaemia → laminitis

How can exogenous glucocorticoids cause laminitis

• cortisol antagonises insulin

• retrospective studies

  • Only animals with pre-existing laminitis risk factors

  • Prednisolone only increase risk of recurrent not initial episodes

• Prospective study

  • Same frequency as in untreated populations

  • Same risk factors as in untreated populations

what is supporting limb laminitis

• Prevalence 0.02%

• Severity and duration of lameness risk factors

• High mortality

• Little primary research

• Mechanism

  • not direct mechanical overload

  • inadequate perfusion

What are the 3 stages of laminitis

• Developmental

• Acute laminitis

• Resolution or chronic laminitis

What happens in the developmental stage

Contact with trigger- lasts up to 72 hours

What happens in resolution or chronic laminitis stage

• Pedal bone movement

• Pedal bone remodelling

what are the aims when approaching a suspected laminitis case

• Make a definitive diagnosis

• Determine underlying cause

• determine if likely to recover to expected level of soundness

how do you diagnose laminitis

• Clinical signs

• ± radiography

• ± endocrine tests

What are the clinical signs of laminitis

• Lameness affecting two or more limbs

• Characteristic stance

• Bounding digital pulses

• increased hoof wall temperature

• Pain on hoof tester pressure at the region of the point of the frog

• Palpable depression at the coronary band

when do you radiograph laminitis

• May take at first presentation if concerned P3 removed

  • Depression at coronary band

  • softening of sole at point of frog

• May take later if not improving

• can be difficult if very painful

  • May have to nerve block

  • Take machine to horse

How do you diagnose via radiography

• Lateromedial radiographs of feet

• Good foot preparation

• Markers

  • dorsal hoof wall, starting at coronary band

  • ± point of frog

• Pedal bone rotation

• Founder distance

How do you diagnose PPID

• Clinical signs

• Basal ACTH

  • Seasonally adjusted reference range

• TRH stim test

How do you diagnose equine metabolic syndrome

• history

• Clinical signs

• demonstration of ID

  • Basal insulin

  • Dynamic test

How do you medially treat laminitis

• Medical emergency

• Treat ASAP

• Changes already occurred in foot

• Analgesia and foot support

what analgesia can you give for laminitis

• NSAIDS

  • PBZ, flunixin

  • IV or oral

• Opiates

  • Morphine, pethidine, fentanyl

  • Controlled drugs, short acting

  • side effects

when do you use digital cryotherapy

• Sepsis associated laminitis

• Endocrinopathic laminitis

• Ice

• chill distal to carpus/tarsus

• 10C

• No complications

what is the role of foot support for treating laminitis

• Essential

• Increase bedding

  • depth, bring to door

• Frog support

  • Bandages, lilypads, NFS etc

• frog and sole support

  • Styrofoam, dental impression material

How do you manage laminitis

• Box rest

• Diet

  • No grass

  • 1.5-2% BW poor quality hay

  • No or minimal concentrates

  • HiFi

  • Unmollassed sugar beet

How do you treat PPID

Peroglide

How do you treat equine metabolic syndrome

• Weight loss

• exercise

• ± pharmacological agents

How do you determine the prognosis of laminitis

Clinical signs

• Depression extends all way round coronary band suggests sinker = 20% survival

• Evidence of previous attacks = success rate decreased by 20%

Radiographs

• Rotation >11.5o significantly reduced

• D >15mm 40% chance of returning to soundness after treatment.

What is the number one priority in preventing endocrinopathic laminitis

• Minimise consumption of NSC

  • Fructan + starch + sugar

• NSC = energy for growth of plants

• NSC content of pasture fluctuates widely

• Decreases when plant growing

• Increases when plant photosynthesising

  • High light intensity, low temp, lack of water

What does NSC content affected by and what does the NSC of hay/haylage depend on

• NSC content also affected by season

  • Low early spring, greater late spring

• NSC of hay depends on content of grass

• NSC of haylage generally low

  • More palatable

  • Provokes a greater insulin response

How do you determine NSC content

• Can only determine NSC content accurately by analysis

• Should manage pasture to encourage growth

  • Fertiliser, regularly topped

• Ideally hay made from mature crop post seed dispersal

  • Want <10% NSC

• Cannot reliably reduce content by soaking, but it will help

How do you formulate a diet for preventing endocrinopathic laminitis

• Base diet on forage/fibre, not sugar/starch

• If need extra energy use oil or unmollassed beet pulp

  • Beet pulp 0.2-0.7kg/day

  • Vegetable oil; max 1ml/kg/day

• If feed cereals, ensure cooked

  • Makes starch easier to digest in SI

• Small cereal meals

  • <0.5kg/100kg bwt

• Add vit and mineral supplement

What should grazing be like for preventing endocrinopathic laminitis

• Consider zero grazing

• Turn out late night to early am (low NSC)

• Restrict in spring and autumn (growing)

• Avoid if frost with bright sunshine or drought (high NSC)

• Rotate paddocks to keep grass at appropriate height

• Restrict intake: muzzle, strip grazing

• Regular exercise

• Prevent obesity

What are some supplements used to prevent endocrinopathic laminitis

• Commonest = cinnamon, magnesium, chromium, chasteberry

• ? Insulin sensitising

• No equine studies

• Equivocal evidence in humans

What is the prevention/therapy for sepsis associated laminitis

• treat undelying disease

• Anti-endotoxic therapy

• Digital cryotherapy

  • Experimental models

  • clinical cases of colitis

how do you prevent supporting limb laminitis

• Limb cycling important in circulation

• controlled exercise or physiotherapy

• Ideal frequency or duration unknown