Rabies in animals

Clinical signs

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

• ‘dumb presentation’ (acting depressed or lame)
• ‘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 display paralysis, which commonly affects the face or neck, often seen as difficulty swallowing
• animals may become excited or aggressive
• animals may attack objects or other animals

Bats and rabies

Only a small proportion of bats are infected with rabies.  However, you can’t 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.

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, and up to 6 months
• 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

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.

Where it’s found

There are many strains, or variants, of rabies virus, each adapted to a particular reservoir species. The reservoir species maintains the presence of the virus in nature.

All variants are capable of causing rabies in other animals.

International

With some exceptions (particularly islands), rabies virus is found worldwide. It results in an estimated 59,000 human deaths each year, almost all associated with dog bites in areas where dog variant rabies (also known as dog-mediated rabies) is present. This variant is not present in Canada. For information on the global impact of rabies, see World Organization for Animal Health (OIE).

Canada

In Canada, there are 5 rabies virus reservoirs:

• artic foxes
• red foxes
• skunks
• raccoons
• bats

The presence of rabies virus in these reservoir species differs across the country and can change over time. The dog rabies variant is not present in Canada. However, there is always the potential for it to re-occur in Canada through the importation of animals from countries in which it is present. For more information, see Rabies cases in Canada (Canadian Food Inspection Agency).

Image 1. Location and species of rabies cases detected in Canada in 2020

View large image to see locations (JPEG, 1.7 MB)

Alberta

In Alberta, bats are the only reservoir of the rabies virus. However, it is possible for other animals to become infected with and transmit bat rabies. Spillover of bat rabies to other animals, which is most commonly observed in cats, generally does not result in sustained outbreaks.

Rabies variants of terrestrial species (that is, mammals other than bats) have been present in Alberta in the past and could be reintroduced in the future. In the 1950s, an epizootic (animal outbreak) of arctic fox rabies variant started at the northern Alberta border and spread rapidly throughout the province.

Through the 1970s, 80s and 90s, epizootics of the prairie skunk rabies variant occurred sporadically. These outbreaks were controlled and eradicated through the work of many individuals and agencies, coordinated through Alberta’s Central Rabies Coordinating Committee.

The skunk rabies variant remains present in Saskatchewan and Montana, providing a potential source of future outbreaks.

Alberta's rabies testing and surveillance program coordinates the testing of animal samples in response to a human or domestic animal exposure, when an animal dies or is euthanized with signs suggestive of rabies, and for the purpose of surveillance in striped skunks.

Importation of rabies

Rabies can also be carried from one area to another by intentional or accidental translocation of animals, or the natural movement of animals that are incubating the virus.

There have been multiple cases of arctic fox variant rabies in dogs translocated from northern Canada, including a puppy from Nunavut (PDF, 136 KB) adopted in Alberta in 2013. Unvaccinated puppies or dogs from Nunavut, Northwest Territories, and northern Quebec should be considered at high risk of having rabies. Animals imported from countries in which dog rabies is present should also be considered at risk.

The relatively long and variable incubation period (typically 3 to 12 weeks in dogs and cats) means infected animals can appear entirely healthy at the time of transport. These cases threaten human and domestic animal health and have the potential to reintroduce arctic fox, canine or other rabies variants into Alberta.