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JOHNE ’ S D I SEASE
Veterinary Surgeon
Keith Cutler
XLVets Practice
Endell Veterinary Group
WORKING
TOGETHER
FOR A HEALTHIER FUTURE...
23
LIVESTOCK MATTERS
K E I TH CUT L E R ,
ENDE L L V E T E R I NARY GROUP
If you don't know the Johne's disease status of your dairy or beef
herd, then you need to ask your vet to investigate for you. If it is
present, then control strategies need to be adopted to protect future
herd performance and health. Whatever the case, biosecurity
controls to protect against it are also required, along with ongoing
screening for the disease.
That's the message from Endell Veterinary
Group's Keith Cutler, a member of the
National Johne's Disease Action Group,
and a director of CHeCS (Cattle Health
Certification Standards Board). Keith is
concerned that the financial impact of this
particular infectious disease, and its long term
effects in the herd, are not being fully
recognised by farmers.
Keith explains: ‘Johne's disease can remain
undetected in herds for many years, as there
is a long incubation period between infection
and clinical signs being seen. However, it's
thought that at least one third of dairy herds
are infected with the disease. It's also present
in beef herds.’
Signs of Johne's disease
The cause of Johne's disease - mycobacterium
avium subspecies paratuberculosis (Map) -
can infect many species, particularly
ruminants. Infection, over time, creates an
inflamed intestinal (or gut) wall. This effect
is gradual, chronic, and irreversible.
So the classic signs of clinical Johne's disease
are weight loss and scouring, as the gut wall
becomes less able to absorb nutrients and
fluid. However, these signs are not usually
seen until the animal is between two and six
years of age.
Infection usually occurs early in life; young
calves within the first days and weeks of
birth are the most susceptible. Transmission is
usually faeco-oral, but can also occur via
colostrum or milk from infected cows.
Because the bacterium's effect on the gut is
gradual, then for some time before clinical
signs are seen, there will have been a
negative impact on cow fertility and milk
yields in infected animals. These animals are
also likely to have a higher incidence of many
other diseases, lameness for example, than
uninfected herd contemporaries.
Keith explains: ‘Herds, in which Johne's
disease is present, will usually have higher
culling rates. But the possibility of the disease
being the cause is often overlooked. A farm
might cull a few cows each year because
they are always a 'bit loose' and never seem
to put on any condition - but actually these
animals could be infected with Johne's
disease. And they will have been spreading
the infection around the farm.
‘So it's essential for all dairy and beef farmers
to establish whether Johne's disease is present
on the farm or not. Admittedly, this takes time
and effort and does cost money. But ignoring
the possibility of infection can cost more
money, as the disease can spread and levels
escalate within a herd until the magnitude of
the problem makes it difficult to address.’
Is
Johne's disease
in your herd?