Over the past five years, vet Stephen Ashdown has written many
articles, spoken on equine matters and contributed widely to horse
Here he reproduces
in the form of questions and answers about 100 topics, all of
them common problems which afflict horses.
Topics click on Vet Advice Menu.
by grass sickness
Q. In September last year I lost my horse to grass sickness. Her
symptoms started in the morning and by evening she was put to sleep.
a 'good doer' and at the time was being grazed in a sparse paddock
along with a Shetland pony. My horse was fit and healthy 16 year
old mare, who had never suffered a bout of colic in the 10 years
I owned her. Do you have any more information about this condition?
A. It is very
sad to hear you have lost your horse to grass sickness. Unfortunately,
the cause of this disease is unknown, but it is thought that it
may be due to a toxin that damages the nerve supply to the bowel
and other organs. The origin of this toxin is most likely to be
in the pasture, but, as with your Shetland pony your horse shared
the field with, it only affects certain individuals. Most case occur
during the summer among horses in good condition which have recently
been stressed (any form of stress weakens the immune system). Mild
forms of grass sickness result in weight loss and mild tremors,
but in its worst form it causes severe pain, shaking and regurgitation.
At this stage the most likely action, in order to avoid suffering,
It is often
difficult to know how to treat cases of grass sickness effectively,
and it requires careful nursing and fluid therapy. Some vets may
give drugs to help the bowel work more effectively and probiotics
may be useful. Antioxidant supplements
can aid recovery and strengthen the immune system to prevent the
If you suspect
that a horse has grass sickness, particularly if he is on grazing
land where it has happened before, a vet should be contacted
as prompt action is vital. However, don't worry too much, as it
is unlikely that a case of colic will turn out to be grass sickness.
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