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Caveat:
most information on M. paratuberculosis infection and Johnes
disease has been obtained through studies on domestic species (for
example cattle, sheep, goats). While it is believed that this information
likely is applicable to non-domestic species as well, there may
be some facets that differ for which we do not yet have a good understanding.
Please bear this in mind as you use this website. We welcome any
experience/information you may wish to share about this disease
in non-domestic species: please feel free to contact us at johnes@johnes.vetmed.wisc.edu.



What
is your diagnosis?
An
adult female addra gazelle (Gazella dama) had been losing weight
despite intake of sufficient rations plus repeated treatment for
gastrointestinal parasites. She intermittently had soft, clumpy
stool. The animals sharing the enclosure included other addra gazelles,
Thomson gazelles, white-bearded wildebeest, and Burchell's zebras.
Some of these animals were acquired at less than 1 year of age.
No immature animals were in this enclosure at the time the addra
became ill.
What
should be done at this point?


M. paratuberculosis was isolated by radiometric culture from
a fecal sample collected from a 10 year old captive-bred male addax
(Addax nasomaculatus). This animal was in good clinical condition
and no other indication of Johnes disease had been found previously
for this animal or for animals sharing its exhibit. However, the
infection was well-established in neighboring exhibits. The animal
was housed alone. During subsequent months, additional fecal cultures,
serology, semen culture, and tissue biopsy for histopathology and
culture were completed. No further ante-mortem evidence for the
infection was found in this addax. Euthanasia was elected and multiple
tissues were collected for both culture and histopathology. No acid-fast
organisms nor lesions were seen on histopathologic examination.
M. paratuberculosis was isolated from eight different tissues.
Case lessons:
| 1. |
Despite
scant antemortem and no postmortem histopathologic evidence
of Johnes disease, a disseminated infection may still
exist. |
| 2. |
Take
a single test-positive result seriously, especially if the infection
has been confirmed in other animals on site. |


During routine surveillance of the artiodactylid collection at a
zoo with no prior history of Johnes disease, M. paratuberculosis
was isolated from a fecal sample collected from a clinically normal
adult female oryx . She was the herd dam and had been on site for
more than 7 years. Two of her now adult calves remained in the herd.
A
year later, a second isolation was made. No change in her clinical condition had
occurred. She was isolated from the group at that time. After approximately six
months, she began to lose weight. She was euthanized and while no gross evidence
of the infection was found, the histopathologic lesions were consistent with Johnes
disease (both acid-fast rods and a granulomatous infiltrate were seen) and the
organism was isolated from numerous tissues, both within and beyond the gastrointestinal
tract.
Case lessons
| 1. |
Captive
hoofstock collections with no prior history of Johnes
disease with animal transfers made years ago may still harbor
an infected animal. |
| 2. |
In some
cases, there will be no sign of the infection at gross necropsy.
Effective surveillance for this easily missed infection requires
culture and microscopic evaluation of even normal appearing
relevant tissues (ileum, mesenteric lymph nodes) for all hoofstock
dying on site. |
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