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EQU INE INF LUENZA
Paul May BVMS MRCVS
Paragon Veterinary Group
CASE REPORT...
Case Study:
Equine influenza
Dandy,
an eight year old
16.2hh gelding had been
stabled on a competition
yard for four years and was
coming back into work
after recovering from a
tendon injury.
During his convalescence from the injury
he had missed a booster dose of influenza
vaccine so had been restarted to bring his
immunity up to date. At the time of his illness
he had received the first of the two influenza
vaccinations required to restart.
Dandy became ill one afternoon, presenting
to the owners as a case of colic. He was
uneasy, wanting to lie down and digging at
his bed. An examination by the vet found
that his heart and respiratory rates were
significantly increased, he was quite
uncomfortable but he was passing droppings.
He was found to have an enlarged spleen
which was unusual, but more significantly he
had a raised temperature. He was treated
with antibiotics and an anti-inflammatory (pain
relief) and with this treatment, he settled down
nicely. He was moved immediately into quar-
antine away from the other horses in case of
a transmissible infectious disease.
Over the next few days Dandy recovered well
but took time to come back to full appetite.
He never coughed and developed only the
slightest of discharges at his nose (Figure 1).
At this time the younger horses on the yard
developed nasal discharges and some began
coughing on exercise. Their exercise was
reduced and they were put onto medication
until they improved.
Blood samples were taken from Dandy at
the time he first became ill, and they showed
changes that could be consistent with a viral
challenge. All of his other biochemistry tests
were in the normal range. As he had lost
quite a lot of weight during his illness and he
was anaemic, it was decided to turn him
away for some time.
The spring grass had started to come through
and all agreed that turnout to pasture would
be the best for him (Figure 2).
His blood test was repeated a month later
and the samples were sent to the Animal
Health Trust Laboratory. There they can carry
out a screening for viruses to look for possible
causes for this illness. Comparing the two
samples showed a significant rise in the
antibody level to a particular strain of the
Equine Influenza virus. This evidence was
sufficient to suggest that the yard had been
affected by the influenza virus.
It was assumed that the level of protection
was good enough in most of the horses to
prevent them from showing signs of illness
and the vaccine being used did cover the
strain of virus in question. It is not unusual for
young horses in this situation to show the
worst signs but what was alarming was how
little protection Dandy appeared to have. The
gap in his vaccination programme allowed
the virus to overcome what protection he had.
It took several months for him to put the
weight back on but, happily, he has made a
full recovery. The yard owners have had to
consider the impact of the influenza virus on
the performance of their horses. Needless
to say there have been lessons to learn,
particularly in this case with a horse that
was away from the yard at the time that his
vaccination was due.
Figure 1:
Little discharge despite evidence of
influenza infection
Veterinary surgeon
Paul May
XLVets Equine practice
Paragon Veterinary
Group
Figure 2:
Rest and nutrition are vital for
recovery
SPRING 2014 ISSUE
EQUINE MATTERS
16