##################### Bovine Spongiform Encephalopathy #####################
Describe mechanisms of CWD transmission between infected and ...
Selective Predation by Mountain Lions on CWD-Infected Mule Deer
In addition to direct effects on the habitats used by the natural cervid hosts of CWD,
urbanization could affect the ecology of systems where CWD may be introduced or has
become established. Because land use patterns may alter the abundance and activity of
large predators (e.g., mountain lions), we have been studying the potential role of
selective predation in CWD ecology. Our specific objectives are to:
1. test for evidence of selective predation by mountain lions on CWD-infected
2. collect data to help assess the broader ecological question of whether
mountain lions selectively prey on debilitated or compromised animals rather
than healthy ones;
3. continue refining and assessing the adequacy of field sampling techniques for
studying selective predation on CWD-infected mule deer; and
4. evaluate and compare the performance of Lotek Wireless GPS4000 and
GPS4400 collars and Tevevilt GPS-Simplex collars in a study of selective
predation by mountain lions under field conditions.
To test for evidence of selective predation, we will compare prevalence of CWD among
puma-killed mule deer to prevalence among mule deer harvested or randomly culled by
humans within home ranges of collared mountain lions. A total of eight adult mountain
lions have been collared, resulting in 39 collared cat months between 2001 and present.
Sampling of predator-killed deer is ongoing. ...
Susceptibility of mountain lions to chronic wasting disease
M. W. Miller, L. L. Wolfe, and T. R. Davis
Chronic wasting disease (CWD) naturally infects free-ranging deer
(Odocoileus spp.) and elk (Cervus elaphus nelsoni) in northeastern
Colorado and adjacent jurisdictions (Miller et al. 2000). Because
CWD has the potential to destabilize affected cervid populations
(Miller et al. 2000, Gross and Miller 2001), management efforts have
been initiated to achieve goals of containing CWD and reducing its
prevalence (Colorado Wildlife Commission 2001). Modeling studies
have indicated that selective population control on affected
populations may be most effective in controlling CWD (Gross and
Miller 2001). It follows that processes fostering selective removal
of affected individuals, like test-and-slaughter or predation,
should be carefully evaluated in the context of CWD management.
Although the host range of CWD appears to be limited to deer and elk,
several predatory species (including humans) may be exposed to
prpCWD via consumption of infected carcasses. Because mountain lions
(Felis concolor) are the most consistent predator of mule deer
(0. hemionus) in the foothills of northeastern Colorado and
southeastern Wyoming where CWD is most prevalent, they are
undoubtedly exposed to CWD in areas where it occurs. To date,
spongiform encephalopathy has not been detected in local
mountain lion populations (M. W. Miller, unpubl. data). However,
more formal studies of exposure rates (Krurnm and Miller 2002) and
susceptibility of mountain lions to CWD are needed to clarify the
role that mountain lions may play in helping manage CWD. Moreover,
because mountain lions (Willoughby et al. 1992) and other
wild felids (Kirkwood and Cunningham 1999) showed susceptibility
to bovine spongiform encephalopathy (BSE) similar to that of
humans (Will et al. 1996), understanding mountain lion
susceptibility to CWD may provide insights into potential human
susceptibility to CWD as well. Here, we describe plans for a
study to evaluate natural susceptibility of captive mountain
lions to CWD under conditions of prolonged exposure via
consumption of infected mule deer carcasses.
Our specific objective is to evaluate the potential susceptibility of
mountain lions to CWD using a natural exposure route under
controlled laboratory conditions.
Three young (-4-6-week-old) mountain lions originating from near
Chugwater, Wyoming were obtained opportunistically from the Wyoming
Game and Fish Department in October 2001; these cubs were slated for
euthanasia because no suitable rehabilitation destination was
available to provide for their care. All 3 cubs have been
maintained together at the CDOW Foothills Wildlife Research Facility
in indoor or outdoor pens since that time. To date, their diet has
consisted mainly of a commercial horse meat product (Dallas Crown,
Inc., Kaufman, Texas) and healthy mule deer, supplemented
occasionally with cottontail rabbits and house mice. In December
2001, we began operant conditioning training with all 3 cubs both
to facilitate long-term tractability and veterinary care, and to
provide behavioral enrichment; individual responses to this
training also will serve as a baseline for evaluating behavioral
changes that could be early clinical signs of CWD. In addition,
the 2 male cubs were castrated and the female was spayed to
further facilitate long-term tractability and to minimize
potential for aggression, both intraspecific and toward caretakers.
Other details of husbandry and care are described in FWRF Standard
Upon approval of this study plan, we will begin feeding all 3 cubs
portioned carcasses from CWD-infected mule deer, such that at
least 20% of their collective annual diet will be comprised of
tissues from test-positive deer. This exposure level is about 33%
higher than the highest mean CWD prevalence observed in
northeastern Colorado (15% in GMU 9; Miller et al. 2000), thereby
representing a substantial but not overwhelming treatment.
Infected deer carcasses will be obtained opportunistically from
captive and free-ranging sources in conjunction with ongoing
research, surveillance, and management programs. All suspect
carcasses will be confirmed via immunohistochemistry (IHC) or
immunodotblot of brain and/or lymphoid tissues (Miller et al.
2000, Miller & Williams 2002, M. W. Miller unpubl. data).
Carcasses will be prepared to specifically preserve central
nervous system, gut, lymphoid, and muscle tissues, as well as
other organ tissues, using an established protocol (Appendix A).
Respective portions of each carcass will be identified and
stored frozen until used. We will maintain a daily log of
specific carcass portions fed and consumed, and will remove and
dispose of uneaten portions at regular intervals.
Our study is planned to be descriptive, and consequently no
experimental control will be maintained because spongiform
encephalopathy does not appear to occur naturally in mountain
lions (Williams et al. 2000). Instead, each lion will serve
as its own control. We will monitor changes in body condition
and behavior as indicators of clinical CWD in subject animals
(Willoughby et al. 1992). Each lion will be weighed monthly
and its responses to a series of routine training exercises
scored subjectively. Persistent weight loss and/or other
signs of disease will be evaluated, and treated as needed,
by an attending veterinarian (Wolfe, Miller). If health
problems become progressive and a lion fails to respond to
treatment, that individual will be euthanized and subjected
to a complete necropsy and diagnostic evaluation to rule out
spongiform encephalopathy as the cause of illness. Similarly,
any lion that dies will be subjected to complete necropsy
and diagnostic evaluation. All 3 lions will be maintained
for the duration of their lives under the foregoing
We will document the extent of CWD exposure to CWD-infected
mule deer, and will summarize onset, signs, and pathology of
CWD in mountain lions in the unlikely event that illness
occurs. Results will be described, but no analyses are
Personal services $ 10,500
Operating $ 10,800
Gross, J. E., and M. W. Miller. 2001. Chronic wasting disease
in mule deer: A model of disease dynamics, control options,
and population consequences. J. Wildl. Manage., in press.
Kirkwood, J. K., and A. A. Cunningham. 1999. Scrapie-like
spongiform encephalopathies (prion diseases) in nondomesticated
species. In Zoo and wild animal medicine, 3rd edition. M. E.
Fowler and R. E. Miller, eds., W. B. Saunders, Philadelphia,
Pennsylvania, pp. 662-668.
Krumm, C. T., and M. W. Miller. 2002. Study plan: Selective predation
by mountain lions on chronic-wasting disease-infected mule deer. In
Miller, M. W., E. S. Williams, C. W. McCarty, T. R. Spraker, T. J.
Kreeger, C. T. Larsen, and E. T. Thorne. 2000. Epizootiology
of chronic wasting disease in free-ranging cervids in Colorado and
Wyoming. Journal of Wildlife Diseases 38:676-690.
Will, R. G., J. W. Ironside, M. Zeidler, S. N. Cousens, K. Estibeiro,
A. Alperovitch, S. Poser, M. Pocchiari, A. Hoffman, and P. G. Smith.
1996. A new variant of Creutzfeldt-Jakob disease in the UK. Lancet
Willoughby, K., D. F. Kelly, D. G. Lyon, and G. A. H. Wells. 1992.
Spongiform encephalopathy in a captive puma (Felis concolor).
Veterinary Record 13 l:431-434.
Williams, E. S., J. A. Kirkwood, and M. W. Miller. 2000. Transmissible
spongiform encephalopathies. In Infectious diseases of wild mammals,
3rd edition. E. S. Williams and I. K. Barker, eds. Iowa State
University press, Ames, Iowa, pp. 292-301.
Carcass Processing for Mountain Lions
I. Carcass labeling and CWD Tissue Sampling:
1) Carcasses intended for the lions should be labeled to avoid mixing
them up with those intended for necropsy. Lion carcasses must be
labeled "Lions", dated, and assigned a CWD case number when they come
in (please use wire twist labels and a permanent marker). If the
animal is a known positive or negative CWD animal, please indicate
this also on the tag. Whoever removes the head from the carcass for
CWD sampling is also responsible for bagging and labeling it with all
of the above information.
2) If the labeled carcass will be processed within a few days it can
be left in the cooler, otherwise it should go into the freezer to
prevent tissue decomposition. Carcasses will need to be pulled out of
the freezer to thaw two days in advance of processing and should be
placed in the cooler and/or in the necropsy lab.
3) Remove the head and take CWD tissue samples according to WHL
protocol. WHL personnel may have already done this.
4) Most of the carcasses you process will be CWD "unknowns" as test
results are usually necessary to indicate if the carcass is CWD
positive or negative. All heads must be saved until CWD test results
5) Process the carcass and store the tissues according to instructions
6) Enter the case number and all necessary information into the blue
Lion Carcass Notebook.
II. Processing the Carcass;
Processing known negatives (fawns), or "green" carcasses (treat these
1) Skin the carcass and toss out the hide according to WHL disposal
2) The large bones should be removed and saved in a labeled bag (with
or without the hide, and it is good to leave large chunks of meat
3) Cut up meat from each front and hindquarter into approximately fist
size chunks, and mix in chopped pieces of heart, liver, and kidney.
Store in blue tubs or labeled ziplock bags, and fresh freeze. These
tissues will be fed to the lions to supplement our commercial feline
Additional tissues to collect for suspect CWD positive animals:
4) Slice off 2-3 sections of the neck with skin intact and place into
a labeled (twist tie) garbage bag with the processed head and
sections of spine. If WHL personnel processed the head you will need
to find this bag in the freezer (CWD case number on the carcass
should match the one on the bagged head), and add the spine and neck
sections to the same bag. These tissues will be fed to the lions as
part of the study protocol.
5) Open the abdomen and place the following tissues into separately
labeled whirlpacks, and store these in the blue tub labeled "Unknown
CWD Organ Tissues", and fresh freeze.
b.) Lower 10 inches of the colon
d.) Urine (if the carcass is fresh) - store in a labeled plastic
These tissues are set aside for laboratory analysis, and will not be
fed to the lions.
6) Remove the digestive tract and store in a labeled twist tie garbage
bag and fresh freeze. The digestive tract will be fed to the lions.
Additional tissues to collect for known positive CWD animals:
7) Fetuses should be removed, saved in labeled bags, and fresh frozen.
8) Save several cotyledons from the uterus (or the entire repro. tract
if cotyledons are not obvious). Fresh freeze several in labeled
whirlpacks, and store one in a labeled jar with formalin.
9) Ticks and bots should also be fresh frozen, and stored in labeled
These tissues are also set aside for laboratory analysis and will not
be fed to the lions.
10) Please follow instructions below for labeling and storing these
11) Please clean up your work area, and dispose of waste according to
WHL protocols (attached).
III. Tissue Labeling and Tracking Samples:
1) All storage containers and bags must be clearly labeled with:
a. LIONS, or "L"
b. The date the carcass came in
c. The CWD case number
d. The tissue type (meat, bones, head/neckl/spine, organs, gut, fetus,
e. CWD +,-, or unknown.
2) Known CWD positive tissues are color coded green and stored on the
shelves in the NW comer of the freezer.
3) Known negative tissues are color coded blue and stored on the
shelves in the SW comer of the freezer (shelves to the left of the
4) Unknown head/neck/spine sections and gut piles are stored in the
red Rubbermaid bin and are not color coded until CWD test results
5) Unknown (but suspected to be positive) organs are stored in the
blue tub on the SW shelf and the tub is labeled "Unknown CWD Organ
6) When CWD test results come in, WHL personnel will indicate if each
case number is positive or negative in the blue lion carcass
7) Please go through unknown CWD organ tissues (blue tub),
head/neck/spine, and gut contents (red bin) once a week to color
code and separate out.
a. Negative head/neck/spine sections, gut piles and organ tissues
should be tossed out (see WHL lab protocol for disposal). However
we should save a few negative organ tissues for comparative lab
b. Positive head/neck/spine sections, and gut piles should be moved to
the CWD positive section of the freezer (NW comer). Positive organ
tissues should be moved to the green tub labeled "Positive CWD
Organ Tissues" on the NW shelves.
IV. Feeding the lion:
8) All meat and large bones should be saved and fed out regularly.
Lions should also receive one gut pile/week. Meat from known CWD
positive animals is stored in green tubs, meat from known CWD
negative animals is stored in blue tubs. "Unknown" meat is stored in
9) Meat, bones and gut can be fed out even if they are unknowns,
however it is necessary to track these tissues as part of the study
protocol. Please fill out the following information in the blue lion
observation notebook (located in the lion shed) prior to feeding out
any processed tissues or carcasses:
a) tissue type
b) CWD case number
c) CWD +, -, or unknown at the time of feeding
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