Page 955 - Clinical Small Animal Internal Medicine

90 Rabies in Dogs and Cats 893

A history that increases the likelihood of rabies may Clinical signs in the prodromal phase are nonspe-
VetBooks.ir include the following. cific. Dogs and cats may have fever, lethargy, dehydra-
tion, anorexia, vomiting or diarrhea. The animal may
Travel. Pet imported within the last six months from a
withdraw and hide, or may appear to become more
●
country where canine rabies is enzootic (includes
many countries in Africa, Asia, and Central and South sociable than usual. They may lick or chew at the site of
the original bite wound. Activation of the autonomic
America). Imported strays or street animals present nervous system may lead to piloerection, drooling, and
especially high risk. See the Public Health Implications dilated pupils.
section below for more information.
Unvaccinated. No rabies vaccination in pet’s history. Furious (excitatory) phase clinical signs may include
● the following.
Dogs and cats that were vaccinated only once or twice
against rabies may not be fully protected. Repeated ● Restlessness. When confined, animals may pace or
vaccination (>2 times) significantly reduces the risk of constantly readjust their body posture. When crouch-
rabies. ing, they may continuously shift the front paws.
Exposure to wild animal or suspected rabid pet. History
● Unconfined animals may walk or run for miles.
of interaction with a wild animal (especially a known ● Hyperreactivity to sounds, movements, and touch.
rabid animal or rabies reservoir species) 10 days to six ● Bizarre behavior. The animal may bite or strike at
months before presentation. Bite from the wild animal unseen things, or stare at things in an unsettling man-
will likely be healed by the time rabies signs begin. ner. Dogs may lick their own urine or eat unusual
Bites inflicted in thick fur or in the oral cavity, or bites objects (pica), and may present with gastrointestinal
from bats, may have gone unrecognized. foreign bodies.
Onset of clinical signs is gradual and steady. Once clin-
● ● Vocalization. Dogs or cats may repeatedly howl, with a
ical signs begin, they worsen over days or hours. noticeable change in voice because of alterations in
Animals are unlikely to be rabid if they have a peracute laryngeal function. Cats may make aggressive screech-
onset of neurologic signs, stabilization or improve- ing sounds, especially in response to stimuli.
ment, or have survived through more than 10 days of ● Aggression. Bites from rabid dogs usually occur with-
overt illness. out warning or behavioral cues (i.e., without snarling,
growling or posturing). Cats may combine striking and
biting. Confined rabid animals may repeatedly bite
Clinical Signs and gnaw at cage doors and walls. Rabies has some-
times been associated with spectacular levels of
Rabies is rarely recognized on physical exam alone. The aggression, with the rabid animal repeatedly attacking
initial clinical signs mimic other diseases and may not even while receiving grave injuries from the bite vic-
seem neurologic. The most consistent finding is a stead- tim. Bites are often firmly inflicted, with the rabid ani-
ily worsening clinical course over hours or days, with an mal latching onto the object or individual.
accumulation of signs that eventually reveal their neuro- ● Grand mal seizures.
logic origins. The pet will not respond to therapy, and ● Fine muscle tremors, especially in cats.
will usually die within 10 days. Close monitoring, with Dumb (paralytic) phase clinical signs may include the
the patient kept in isolation, is the most important pre- following.
mortem clinical tool.
The incubation length is highly variable. Most dogs ● Persistent lethargy.
and cats develop clinical signs within six months after ● Cranial nerve deficits. Pharyngeal paresis may cause a
exposure, but some may become ill in as few as 10 days. change in voice and dysphagia, leading to accumula-
The most common incubation period is 3–12 weeks. tion of saliva in the mouth and drooling. The animal
In general, the clinical signs of rabies may be divided may repeatedly lap at water in unsuccessful attempts
into a prodromal phase, followed by a furious (excita- to drink. Dogs often develop a dropped jaw and hang-
tory or encephalitic) phase, then a dumb (paralytic) ing tongue, and may gag and cough, causing them to
phase, then death. However, the clinical course can appear to be choking on an object.
vary considerably. Phases may be absent or overlap. ● Ataxia.
The majority of cases are associated with a prominent ● A stiff or hunched gait.
furious phase, followed by a short paralytic phase ● Paresis, usually beginning in the body part where the
before respiratory arrest and death. Approximately original bite was inflicted. May be unilateral at first,
20% of cases lack a furious phase (i.e., dumb or para- and the animal may present with an apparent limp.
lytic rabies). Progresses as an ascending flaccid paralysis.