Rabies in animals

Clinical signs

The presence of abnormal behaviour is the key sign in an animal with rabies. The effects of the disease can appear differently:

• ‘dumb presentation’ (acting depressed displaying lameness or incoordination)
• ‘furious presentation’ (showing excitement or aggression)
• a combination of the two

For example:

• domestic animals may become depressed and try to hide in isolated places
• wild animals may lose their fear of humans and appear unusually friendly
• wild animals that usually come out at night may be out during the day
• animals may become excited or aggressive and may attack objects or other animals
• animals may display paralysis of the face or neck, often seen as difficulty swallowing and excessive drooling
• weakness or paralysis of the limbs may result in an inability to walk normally
• animals may display convulsion or seizures

Bats and rabies

Only a small proportion of bats are infected with rabies. However, you cannot tell if a bat has rabies just by looking at it, so a bite or scratch should always be managed as a potential exposure. Follow the steps listed on the If you suspect rabies page if you have come into contact with a bat.

For more information on bats, see:

• Bats and rabies in Alberta
• Bats and public health

For information about bat conservation, see:

• Alberta Community Bat Program
• Bat Conservation International

Report rabies exposure or disease

Find out more about what to do if you suspect rabies and how to prevent it.

Learn more about the distribution of rabies.

Incubation period

The time between the introduction of the virus into the body and the appearance of the first clinical signs of rabies infection is known as the incubation period. During this time, the animal will appear clinically healthy.

Typical incubation periods in animals are:

• Dogs and cats: 3 to 12 weeks, but up to 6 months is possible
• Other species (less well documented): for most mammals, the incubation period appears to be similar to cats and dogs
• Common livestock species: less than 60 days
• Bats: incubation periods are highly variable – from weeks to months

Period of communicability

Rabies virus transmission occurs when virus-laden saliva of a rabies-infected animal is introduced by a bite, scratch, or other break in the skin (or, rarely, through intact mucous membranes).

Based on experimental data, dogs, cats and domestic ferrets may have rabies virus present in the saliva 3 to 4 days prior to onset of clinical signs. Some studies suggest it could be up to 10 days prior.

Once the virus reaches the saliva of the infected animal, it is present until the animal’s death. With this in mind, a clinically healthy pet dog, cat, or ferret that bites a person should be confined and observed for 10 full days. Animals that remain healthy at the end of this 10-day period would not have been shedding rabies in their saliva at the time of the bite.

The period of communicability is not well documented in most species and may vary. It is assumed that all mammals can have the rabies virus in their saliva for a short period prior to specific clinical signs of rabies.

Bats can be extremely variable in their period of communicability and their subsequent time to death.

Diagnosis

In animals, rabies is diagnosed when the virus is detected in samples of brain and spinal cord taken after death.

The main test used, the fluorescent antibody test, has a sensitivity and specificity close to 100% for a sample that is in good condition. This test is performed on fresh tissue; samples should be kept refrigerated and should not be fixed in formalin or other preservatives. Samples can be frozen if necessary, but testing may be delayed while they thaw.

Animals that may require rabies testing should not be dispatched by gunshot or other trauma to the head. Capture bats gently and, if testing is required, contact your veterinarian or Alberta rabies program staff to arrange for euthanasia (humane death). See If you suspect rabies for more information.