pygmy goat herd had been managed as the only hoofstock at a farm for 5 years.
Kids were born and raised on the premises. Additions to the herd were made from
outside sources as well.
Several goats in
the herd were thin and diarrhea was noted in these animals on occasion by the
owner. One goat was sufficiently debilitated to warrant humane euthanasia. This
animal was diagnosed with Johne's disease by histopathology (acid-fast organisms
were observed in lesions consistent with M. paratuberculosis infection)
and the organism was isolated through culture in a number of the goat's tissues.
part of a research project, the adult goats in this herd were tested by two Johne's
disease tests: fecal culture and the ELISA blood test. At the initial testing
screen, positive results were obtained for 12 of 30 goats (40%) from either serum
antibody, fecal culture or both assays. Four of these 12 goats produced positive
results on both tests and 3 of these animals died within four months of the tests.
Johne's disease was confirmed as the cause of death at necropsy for all three.
Of the 18 goats
with negative results on both tests, 12 were test-positive by either fecal culture
ELISA for M. paratuberculosis when tested again within 8 months of the
initial testing screen. Of the 30 animals therefore, 24 (80%) were test-positive
for M. paratuberculosis infection during a one year assessment period.
goats are susceptible to infection by M. paratuberculosis.
and fecal culture diagnostic assays can effectively be used to determine the prevalence
of this disease in a herd.
goat herds with an extensively established infection such as this one, complete
depopulation may be the only effective method of eradicating the infection.
to keep this infection out of your herd are much less costly than attempts to
control it once it is introduced.
owners of a conservancy farm (Bull Thistle Farm, WI*) bought three adult Tennessee
fainting goats (one buck and two does). They were kept in a pasture with other
goats plus another heritage breed (e.g. Jacob sheep) and shared a barn with 60
ewes. The adjoining pen held Highland cattle.
The buck began
to lose weight after being on-site for about 18 months. He was wormed for coccidiosis
and Parelaphostrongylus tenuis [meningeal worm] infection several times
with no response. He developed a rough coat and became increasingly debilitated
although his appetite remained good. No diarrhea was observed. The protein in
the buck's blood was abnormally low (hypoproteinemia) and when a blood test for
Johne's disease was completed (AGID), the result was positive. At necropsy, it
was confirmed that the animal was infected by the organism causing Johne's disease
(i.e. lesions consistent with the infection were found, an acid-fast staining
organism was detected in the tissues and M. paratuberculosis was isolated
from multiple tissues through the culture method).
The owners purchased
more goats from a different source after they had negative test results by AGID.
They kept the kids in the herd which soon grew to 40 animals. Two years later
however, the herd was down to four animals. The adults had tested positive by
AGID for Johne's disease and were culled along with their offspring. (The owner
later learned that, despite her instructions to the auction house that the animals
were to be sold for slaughter, they were sold to other breeders).
The owners had
tested the adults twice a year to make sure they detected goats as soon as they
began to produce antibody to the infection. They no longer keep goats. The sheep
flock and the Highland cattle are also tested annually and have remained test
negative. These herds are now managed on a "closed" basis.
fainting goats can get Johne's disease.
||Symptoms of the
infection are often thought to be due to parasites.
||Diarrhea is not
always a symptom of Johne's disease in goats.
never know what infections may accompany an animal purchased at auction.
infection can be spread from one species (in this case, goats) to other ruminant
species (cattle, sheep). Fortunately, in this case, cross-species transfer
did not occur.
can be years before you learn whether kids/calves/lambs born to infected dams
were infected since the infection takes so long to develop. In this case, the
owners took the conservative step of culling the offspring of test-positive animals
to ensure that the infection was controlled.
*Note: This case
has been reported with permission of the owners who encourage all
heritage breed managers to be aware of Johne's disease as a possible
threat to the health of their animals.