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The
goat industry has made good progress in recognizing and controlling a number
of important infections. We must apply the same approach to another
infection that many do not consider a problem for goats: Johne’s disease.
Johne’s disease is more prevalent in goats than many people realize and
once it is established in a herd it can be difficult to eradicate. The
organism can infect any ruminant species, so if you keep sheep or cattle
too, they are all equally at risk.
Caused
by a mycobacterium in the same family as those successful pathogens that
cause tuberculosis and leprosy in humans, this fatal infection is not treatable
and can be challenging to detect until late phases of the disease.
Goats get infected as kids but stay healthy for months to years which is
why it is easy to sell a goat and have no idea it was infected until the
new owner calls you a few years later. Goats eventually starve to
death when the organism and the immune cells fighting the organism pack
the gastrointestinal tract and prevent the goat from getting any nutrition
from its feed. Goats in the clinical phases of Johne’s disease look
thin, scruffy, might (or might not) have diarrhea, are hungry, eat eagerly
but waste away.
The
infected goat is contagious throughout its life, even while free of clinical
signs of the infection. The infection is usually spread by fecal-oral
contact, meaning that anything that has been contaminated by pellets from
an infected goat (water, feed, teats, mineral blocks, etc.) that might
be licked or mouthed by a kid may spread the infection. A doe does
not have to have Johne's disease for her kid(s) to get it – she just has
to lie down in a barnyard or pasture housing infected animals, thus getting
the Johne's bacteria on her udder for the kids to suck off. Other methods
include kids nibbling grain, hay, berries (you know how goat kids are!)
or other interesting "goodies" off contaminated ground. BABIES are
the most susceptible age group for this disease – and you won’t know if
they’ve been infected until months or years later.
The
infection can spread silently in your herd as goats without symptoms contaminate
your premises. The organism is very hardy and can remain for months,
although it does die off eventually and adult goats can be exposed to a
low dose of the organism and not become infected. Using disinfectants
labeled as “tuberculocidal” as directed (meaning wash the mangers and non-porous
surfaces such as metal feeders and fencing etc. first) helps get rid of
the organism faster. These products are not of any use for your pastures
or dirt barn floors, however.
There
are as many methods to managing this infection as there are goat owners.
The approach will be very different for owners that have had multiple cases
of the disease vs. those that have had just one case or who want to establish
that their herd is free of the infection. Some people “take no prisoners”
and aggressively test, cull, and sanitize. Some owners move test-positive
goats to a separate paddock, stop breeding them, ensure that there is no
contact with other animals and let them live out their lives. The best
approach for you is the one that balances the resources (time, land, and
money) you have, the reasons you own goats, the amount of animal exchange
you do, other herd health issues and the level of M. paratuberculosis infection
in the herd.
That
being said, how do you determine if your herd is infected? Not everyone
needs to test but you might consider it if you have ever introduced a goat
into your herd without knowing the Johne’s disease status of the source
herd and have had a goat die with the vague signs of weight loss and perhaps
diarrhea. The first case of Johne’s disease usually comes as a surprise.
Think back ? have any of your goats just wasted away? These cases
are not all due to parasites, although that’s what we usually think it
is. It is always a good idea to determine the cause of any death,
especially when the cause might be a slowly developing herd problem like
Johne’s disease.
There
are a number of diagnostic tests that are helpful in establishing the presence
of the infection in adult goats (don’t bother testing until kids reach
18 months or so). They include blood tests (AGID, ELISA) and a culture
test that can be used to isolate the organism from fecal pellets or tissue
samples. Each test has its strong points and its deficits because
of the biology of the infection, and be aware that there may be times that
a truly infected goat may be test-negative. Your veterinarian can
help you pick the best testing protocol for your herd, and can then help
you use the results to set up a management program focusing on sanitation
and biosecurity that can improve herd health from the standpoint of other
diseases as well, not just Johne’s disease. Methods to keep the infection
from spreading once introduced into a herd are all based on one concept:
keep kids away from anything contaminated by the organism, realizing that
you may not know which adult goats are doing the contaminating. This
may include using feeders that keep pellets out of food and water, pasteurization
of milk (the organism can be shed into milk by infected does) for bottle-feeding,
separating test-positives from test-negatives at kidding time, etc.
Testing
without intending to make management changes to limit the spread of the
infection will just be a waste of time for you.
Of
course, the best approach of all is to keep the infection out of your herd.
If Johne's disease gets a strong grip on your herd, controlling it can
be a major task. This is where we as an industry can help each other out
by encouraging folks to establish their freedom from infection so we can
trade animals with confidence instead of trepidation. We can limit
the spread of the infection by encouraging open discussions, just as we
do with CL and CAE and by encouraging testing. If you are lucky enough
to live in Wisconsin, Alaska or one of a very few other states, you can
get the costs of diagnostic tests reimbursed to you by the state’s Johne’s
control program! In some states, the testing is entirely free to the breeder.
Encourage your state to include goats in its Johne’s disease control program
instead of just cattle. You are better off buying a goat from a herd
that knows its Johne’s disease status even if they have had a case or two
than from one that has never tested. Ignoring the subject will not
make it all go away – in fact the opposite will happen just as has occurred
for the Holstein industry where the prevalence of Johne’s disease is now
estimated at 80% of herds.
This
infection is not going to go away by our ignoring it. HEADS UP, PEOPLE!
It is time to “come up for air” and talk about it since it's safe to say
no one wants Johne's disease in his or her herd. And I believe as
well that no one wants to inadvertently pass Johne's along to other herds.
The only way to prevent this is to know the status of your own herd and
the status of those from whom you buy. Have necropsies done when
a goat dies of an unexplained cause. Watch the clinical status of
your animals, keep Johne’s disease “on your radar screen” and test if you
have any suspicions. If you know your herd has had cases in the past
and kids were in contact with those infected animals, test your herd annually.
Do your part to keep this disease from becoming as prevalent in goats as
it already is in cattle. As goat breeders we can limit the spread
of this infection and the heartache it can cause if we open our eyes to
the problem now.
Deb
Frost
Spring
Promise Pygmies
Test
Negative for Johne's annually sinec 2002!
Meadow
Lakes, AK
Dfrost@customcpu.com
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SPRING PROMISE HERD & JOHNE'S DISEASE
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