Disease Ecol ogy of Mountain Lions 73indicating lions were ill or that could be used to document the progression of disease
within individual lions.
Another factor that increased our awareness of the implications of disease in moun-
tain lions was a suit brought against the state of South Dakota by the Mountain Lion
Foundation of California. A witness for the plaintiff stated that mountain lions could
harbor diseases that, in concert with harvest, would drive the population to extinc-
tion. At the time, we had no information about disease exposure and assumed that
these lions were healthy based on external characteristics and nutritional condition
information obtained during necropsies (see chapter 6). However, our experience with
cloudy- eye syndrome increased our suspicion that diseases, some associated with
domestic species, began to affect mountain lions in the Black Hills as the species ex-
panded into areas occupied by humans (and vice versa), likely from lions killing and
consuming domestic pets (i.e., cats and dogs). For example, exposure to feline immu-
nodeficiency virus (FIV) (Biek et al. 2006) averaged 12% in mountain lions in the Black
Hills ( table 5.2). This disease also is associated with domestic cats and has been docu-
mented in lions throughout Montana (25% of 352 lions [Biek et al. 2006]) and in Wash-
ington (Evermann et al. 1997). It has been suggested that both mountain lions and
African lions (Panthera leo) had been exposed to FIV longer than domestic cats had
been, providing a long period of coevolution between pathogen and host. What was
in ter est ing was that this long period of evolution might explain the lack of pathogenic
effects of the disease on large felids like mountain lions (Carpenter et al. 1996; Cul-
ver 2010). Therefore, despite the implications that this disease might contribute to the
mortality of mountain lions, there likely are no effects of it that could contribute to
population decline and extirpation of lions within the Black Hills region. In any
case, the exposure rate was rather low compared to that in other mountain lion
populations.
More telling was that 81% of the sampled mountain lions showed titers for feline/
canine nonspecific parvo virus, and 18% showed exposure to canine distemper virus
( table 5.2). In addition, a much stronger association between feline calicivirus and
cloudy- eye syndrome was seen with the results of serum analyses: 27% of mountain
lions in the Black Hills were exposed to the disease—as mentioned, the estimated pro-
portion of mountains with this eye disease was between 5% and 10%. Although not
confirmatory, such a high percentage of positive animals was unexpected at this time.
These findings further implicate interactions with domestic cats and dogs as the source
of at least some of the exposure to these diseases.
During our studies of mountain lions, we did not collect information on clinical
signs of diseases such as feline leukemia; collection of clinical characteristics requires
frequent interactions with animals as well as laboratory analyses to confirm diseased
lymph nodes, low red blood cell count, and septicemia. However, feline leukemia was
not documented in lions in California (Paul- Murphy et al. 1994) or in early work on
Florida panthers (Cunningham et al. 2008). Exposure to feline leukemia was low (about