An Observation of Aberrant Behavior in a Raccoon (Procyon
lotor) Infected with Canine Distemper Virus
Sean M. Richards, Katherine A.E. Rainwater, James R. Stephens,
and Thomas R. Rainwater
Southeastern Naturalist, Volume 7, Number 3 (2008): 556–558
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An Observation of Aberrant Behavior in a Raccoon (Procyon
lotor) Infected with Canine Distemper Virus
Sean M. Richards1,*, Katherine A.E. Rainwater2, James R. Stephens3,
and Thomas R. Rainwater4
Abstract - While the occurrence of canine distemper virus (CDV) in Procyon Lotor (Raccoon)
is well documented, detailed descriptions of the behavior of CDV-infected individuals are scant.
Here, we report a sequence of particularly odd behaviors of a CDV-infected Raccoon encountered
in rural Arkansas. These behaviors included lack of fear, apparent loss of coordination
and other actions consistent with a neurologic abnormality. CDV associated encephalitis was
confirmed by histological examination and polymerase chain reaction (PCR).
Procyon lotor (L.) (Raccoon) susceptibility to canine distemper virus (CDV)
infection is well documented (Budd 1970, Deem et al. 2000, Hemboldt and Jungherr
1955, Williams 2001). The incidence of CDV is also well described; the virus is
endemic to North America and has been reported in numerous areas where Raccoon
populations exist (Evans 1984, Hoff et al. 1974, Roscoe 1993). In some areas, up to
50% of the individuals in the Raccoon population have positive CDV titers (Arjo et
al. 2005). In New Jersey, CDV accounted for 50% of debilitating diseases in a population
of Raccoons (Roscoe 1993).
The clinical presentation of neurologic CDV infection is dependent on the region
of the brain that is affected and the severity of the disease (Williams 2001). In general,
the behavior of CDV-infected carnivores has been characterized as abnormal,
lacking fear, and suggestive of rabies (Gillin et al. 2006). In CDV-infected Raccoons,
neurologic signs are described as being similar to that exhibited by infected Canis
familiaris L. (Domestic Dog), which can include abnormally increased sensitivity
to stimuli, rigidity, seizures, impaired balance and coordination, bilateral hindlimb
weakness or weakness in all four limbs, loss of sensory input to appropriately coordinate
muscle activity, and involuntary repetitive rhythmic contractions of muscles
(Greene and Appel 2006, Williams 2001). Budd (1970) described some behavioral
signs of CDV infection in Raccoons including aggressiveness and convulsive movements.
Roscoe (1993) reported the behavior of 124 CDV-infected Raccoons in New
Jersey as lethargic, comatose, or incoordinated.
Although possible behaviors that could be displayed by Raccoons with central
nervous system CDV infection are well described, detailed specific accounts of the
behavior of these animals are scant. Here, we report noteworthy (and different) behavior
of a CDV-infected Raccoon encountered in rural Arkansas.
On 27 December 2002 at approximately 2000 hr, two of us (S.M. Richards and
J.R. Stephens) were approached by an adult male Raccoon while standing next to a
campfire in Washington County, AR (35º58'18.21"N, 94º09'06.20"W). The Raccoon
exhibited no observable fear of us or the fire and appeared indifferent to both. We
stood motionless and observed the Raccoon’s actions. Despite our proximity to the
fire (<1 m), the Raccoon approached us, leisurely grasped one of our pant legs, and
slowly rubbed the fabric between its front paws for approximately 10 seconds. The
Raccoon then released the pant leg, and for the next 20 minutes (approximately)
slowly milled about at our feet (within 1–3 m) in a manner similar to a Felis catus L.
(Domestic Cat). At one point during this period, the Raccoon stopped, sat relatively
motionless, and gazed toward the forest for approximately 2 minutes. Next, the Raccoon
turned and walked to the edge of the campfire. The Raccoon then worked a
Notes of the Southeastern Nat u ral ist, Issue 7/3, 2008
556
2008 Southeastern Naturalist Notes 557
smoldering ember from the fire with its front paws, slowly rolled it backward away
from the fire, sat down, and began rolling the ember up to the middle of its chest,
down, and back again. This behavior continued for approximately 2 minutes. During
this period, the Raccoon continually emitted slow, guttural, grunting vocalizations.
The ember was hot enough to singe the hair on the chest and abdomen, but the animal
did not appear to fl inch or otherwise react to the heat of the ember. Although within
very close proximity, the Raccoon showed no interest in food items at the camp.
We suspected the Raccoon’s aberrant behavior was the result of rabies or other
infectious neurologic disease, and euthanized it with a 0.22-caliber rifle. The carcass
was transported from the camp on ice and next stored at -25 °C until being
shipped to the Arkansas Veterinary Diagnostic Laboratory (Little Rock, AR) for
pathological examination.
The Arkansas Veterinary Diagnostic Laboratory conducted a suite of examinations
on the male Raccoon. A gross (external) pathological examination indicated no
visible lesions. A microscopic examination of tissue sections found that the cerebrum
had a mild lymphocyte aggregation around the vessels of the cerebrum, indicating
infl ammation, and proliferation of neuron support cells common with infl ammation
of the brain that is consistent with viral encephalitis. The lungs displayed a mild
interstitial pneumonia. The heart, liver, gastrointestinal tract, adrenal gland, urinary
bladder, and kidney were unremarkable (aside from bullet damage). Histological
examination of the brain tissue was negative for rabies virus; however, tissue was
positive for CDV based on a polymerase chain reaction assay (PCR primers from
Integrated DNA Technologies, Coralville, IA).
While aberrant behavior of CDV-infected carnivores has been previously
described, most of those accounts were in a controlled laboratory setting or un-substantiated
by pathological diagnosis. The behavior of the Raccoon described herein
is not only unique but directly attributable to a clinically diagnosed CDV infection.
To our knowledge, the present account is the first field description of such unique
behavior (i.e., manipulation of the pant leg and handling of embers) associated with
laboratory-confirmed CDV infection in wild Procyon lotor.
Acknowledgments. We thank J. Britt, D.V.M. for his thorough examination of the
Raccoon.
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1The University of Tennessee at Chattanooga, Department of Biological and Environmental Sciences,
615 McCallie Avenue, Chattanooga, TN 37403. 2University of California Davis School
of Veterinary Medicine, One Shields Avenue, Davis, CA 95616. 3903 Raintree, Siloam Springs,
AR 72761. 4The Institute of Environmental and Human Health, Texas Tech University, PO Box
764, Jefferson, TX 75657. *Corresponding author - seanrichards.utc@gmail.com.