A severe, invariably fatal viral encephalitis, rabies is infectious to mammals, including dogs, ferrets, and even humans. The virus enters the body through a wound (usually from a bite of a rabid animal) or via mucous membranes. It then travels quickly along the neural pathways into the central nervous system and later to other organs. 

Fortunately, the prevalence of rabies in ferrets is low. In fact, there have been fewer than 20 cases of rabies in ferrets in the United States since 1954. However, rabies can be found in much of the world.

Symptoms and Types

In the United States, four strains are endemic within fox, raccoon, skunk, and bat populations -- all of which can be transmitted to ferrets. The clinical signs of rabies are typically mild at first and progress. These include anxiety, lethargy, and posterior partial paralysis. The furious form of rabies seen in other mammals is unusual in ferrets, but can occur. Other symptoms include:

• Disorientation and seizures
• Change in attitude—apprehension, nervousness, irritability
• Erratic behavior—biting or snapping, biting at cage, wandering and roaming, excitability

Causes

The rabies virus is a single-stranded RNA virus of the genus Lyssavirus, in the family Rhabdoviridae. It is transmitted through the exchange of blood or saliva from an infected animal, often from bites or scratches from unvaccinated dogs, cats, or wild animals. Although rare, ferrets can also be infected through breathing in the escaping gasses from decomposing animal carcasses, such as in a cave with large populations of infected bats.

Diagnosis

If you suspect your ferret has rabies, call your veterinarian immediately. If your pet is behaving viciously, or is trying to attack, and you feel you are at risk of being bitten or scratched, you must contact animal control to catch your ferret for you.

Your veterinarian will keep your ferret quarantined in a locked cage for 10 days. This is the only acceptable method for confirming suspected rabies infection. Rabies can be confused with other conditions that cause aggressive behavior, so a laboratory blood analysis must be conducted to confirm the presence of the virus. However, blood testing for the virus is not veterinary procedure.

Diagnosis in the U.S. is done using a post-mortem direct fluorescence antibody test performed by a state-approved laboratory for rabies diagnosis. Your veterinarian will collect fluid samples if your ferret dies while in quarantine, or if it begins showing progressive signs of rabies; in which case, your veterinarian will opt to put your ferret to sleep (or euthanize it).