Problem of eating excess grass over years... - Veterinary Practice
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InFocus

Problem of eating excess grass over years…

“MOST cases of laminitis occur
when horses are eating grass, said
Dr Teresa Hollands, a nutritionist
with Dodson & Horrell, speaking at
Laminitis Awareness 2010.

“Pasture-associated laminitis
accounts for 66% of cases occurring in
the UK. But what causes the laminitis?”
she asked.

Experiments have shown that giving
large meals of starch or fructans can
cause laminitis, Dr Hollands said. Large
amounts of these carbohydrates
suddenly arriving in the horse’s large
intestine disrupt the normal population
of bacteria in the gut, leading to a
cascade of inflammatory and toxic
events, but fructans and starch are not
responsible for most cases of laminitis.

She said it had been shown that laminitis could be induced by giving a
large bolus of fructan (5g-12.5g
fructan/kg body weight) – about 3.75kg
fructan for a 500kg horse.

But if a 500kg horse ate an amount
of grass equivalent to 2.5% of his body
weight (12.5kg), his total intake of
fructans would be about 1.9kg.

So the full daily intake falls short of
the levels that have been shown to cause
laminitis, she said.

“We need to move away from
thinking about individual components
of the diet,” Dr Hollands continued.
“In the end it is the calories that are the
main risk factor and grass provides
more than enough calories for most
horses in light work.”

She believed that the slow, insidious
eating of excess grass over years was the
problem.

Make sure horses do not get too
much grass, she said. And make sure
they receive adequate proteins, minerals
and vitamins by feeding a low calorie commercial feed balancer. The solution
is to reduce obesity: ensure nutrition is
optimal, and increase exercise.

Other speakers at Laminitis
Awareness 2010 were Professor Derek
Knottenbelt, Dr John Keen, Dr Cathy
McGowan and Dr Nicola Menzies-
Gow.

The meetings were run by Dodson
& Horrell in association with the
London, Liverpool and Edinburgh
veterinary schools.

  • Dodson & Horrell has produced a
    “fact sheet” with the following
    information:
  1. 66% of laminitis is pasture associated.
  2. Equine Metabolic Syndrome is on the
    increase and with it associated laminitis.
  3. Until recently researchers thought
    that fructans found in grass affected the
    hind gut in a similar manner to an
    overload of starch detrimentally
    changing the fermentation in the hind
    gut. However recent work has shown
    that the fructans do not reach the hind gut but are fermented in the small
    intestine of the horse.
  4. Laminitics have three times the levels
    of free radicals compared to non
    laminitics.
  5. Horses and ponies with a fat score
    >3.7 (0-5modified score) are at greater
    risk of laminitis and foot-related
    problems.
  6. It is likely that if amareisonadiet
    deficient in protein, vitamins and
    minerals (sub-optimum nutrition in utero)
    her foal will be born with insulin
    resistance.
  7. If fed in excess, high fat diets
    predispose a pony to insulin resistance
    more than high sugar diets.
  8. Ponies and horses with insulin
    resistance are at a higher risk of
    laminitis.
  9. Restricting a horse’s dry matter intake
    increases the risk of stereotypy, colics
    and gastric ulcers.
  10. Exercise is protective against insulin
    resistance.

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