74 Mountain Lions of the Black Hills
1% of tested samples). Therefore, although deaths of Florida panthers had been asso-
ciated with the disease (Brown et al. 2008), we did not expect it to negatively affect
the population of mountain lions inhabiting the Black Hills.
We also documented low exposure to feline herpes virus, a disease that can cause
conjunctivitis. This disease was of interest, since mountain lions at the time were
affected by cloudy- eye syndrome and 1–3% of lions did show titers for exposure to the
disease. As with other potential pathogens, if cloudy- eye syndrome resulted from lion-
specific interactions with infected domestic species, feline herpes virus, together
with feline calicivirus, could explain the prevalence of cloudy eyes in the Black Hills
mountain lion population. It also could explain the disappearance of the disease once
the population began to decline because of harvest. Again, we were unable to verify
the causative agent associated with this eye malady, and therefore the suggestion of a
feline herpes virus effect is circumstantial at best. Furthermore, although 19% of
58 mountain lions tested for feline herpes virus in California showed titers indicating
exposure (Paul- Murphy et al. 1994), eye characteristics indicating cloudiness were
not reported.
The death of a National Park Ser vice employee in Grand Canyon National Park
from exposure to plague (Yersinia pestis) (Paul- Murphy et al. 1994), bobcat exposure
to plague in North Dakota (D. M. Fecske, North Dakota Game and Fish Department,
unpublished data), and the fact that the disease had been documented in black- tailed
prairie dog (Cynomys ludovicianus) towns in southwestern South Dakota, prompted us
to test for exposure to plague and proceed cautiously when conducting necropsies
of mountain lion mortalities. Of the 68 mountain lions tested for exposure, none
was positive. Those results were in ter est ing, since the disease was documented within
the region, and since lions immigrating to the Black Hills from west of the region,
where the disease was more common, could have exposed Black Hills lions to the
disease. However, because exposure to the disease is believed to increase with age
(allowing more time for lions to come in contact with infected prey) and could be
higher in female than in male mountain lions (Biek et al. 2006), our evaluation of this
disease may have preceded its entry into the Black Hills system.
Another disease organism that has been associated with eye inflammation (fig. 5.3)
is toxoplasma (e.g., Toxoplasma gondii), a parasitic protozoan (Dardé, Ajzenberg, and
Smith 2011). In fact, that disease is closely associated with felids, which are the only
known definitive hosts, and because it is common in domestic cats, it is of concern
with regard to previously unexposed pregnant women. Because of this close associa-
tion between the disease and cat species, and because we documented lions feeding
on domestic cats, we expected that tests for exposure of lions to the disease would be
positive. Of 97 mountain lions tested, 53% were positive for exposure ( table 5.3).
Other species also can carry this disease, and therefore, mountain lions could have
become exposed via consumption of domestic pigs, for example. Further, there could
be regional variation in mountain lions’ susceptibility to the disease, based on the