Animals get rabies when the saliva of an infected mammal enters their body, almost always through a bite wound. The virus lives in saliva and needs a direct path into muscle or nerve tissue to establish an infection. Once inside, it travels along nerves toward the brain, where it causes the fatal inflammation that defines the disease.
Bites Are the Primary Route
A bite from a rabid animal is by far the most common way any animal contracts rabies. When an infected animal’s teeth break the skin, virus-laden saliva gets deposited deep into tissue where nerves are accessible. The deeper the bite and the closer it is to the brain, the faster the infection progresses.
Scratches can also transmit the virus, though less efficiently. If a rabid animal’s claws have been contaminated with its own saliva (from grooming or drooling), a scratch that breaks the skin creates an opening for the virus. Contact between infectious saliva and any existing wound, cut, or mucous membrane (eyes, nose, mouth) is another possible route, though this is far less common than a direct bite.
Which Wildlife Species Carry Rabies
Wild animals account for more than 90% of reported rabies cases in the United States. The four main carriers are bats (responsible for about 35% of reported wildlife cases), raccoons (29%), skunks (17%), and foxes (8%). Each species tends to dominate in a particular region.
Bats are the most widespread carrier, found rabid in every U.S. state except Hawaii. Raccoons serve as the primary reservoir across the eastern United States, from Canada down to Florida and west to the Appalachian range. Within those areas, roughly 10% of raccoons that bite or scratch a person or pet turn out to be rabid. Skunks carry rabies across most of the Midwest and West, and foxes maintain the virus in the Southwest (gray foxes) and Alaska (arctic foxes). Both skunks and foxes pose a higher per-encounter risk: more than 20% of individuals that expose people or pets test positive.
In Puerto Rico, mongooses are the dominant carrier. Over 80% of mongooses that bite or scratch people or pets have rabies, making them the highest-risk exposure on the island. They also frequently infect stray, unvaccinated dogs.
How Rabies Jumps From Wildlife to Pets
Domestic animals typically get rabies through encounters with infected wildlife, a process called spillover. A dog nosing around a raccoon den, a cat catching a bat, or a curious pet approaching a sick skunk can all lead to a bite that transmits the virus. Raccoon rabies produces the highest rate of spillover infections to domestic animals and other wildlife of any reservoir in the country, largely because raccoons thrive in suburban areas where pets roam.
These encounters often happen at night or in the early morning, when wildlife is most active. Animals that spend time outdoors unsupervised face the greatest risk, especially in regions with known wildlife reservoirs. Unvaccinated dogs and cats have no immune defense if exposed, which is why vaccination remains the single most effective prevention tool for pets.
What Happens Inside the Body
Once the virus enters through a wound, it doesn’t immediately enter the bloodstream. Instead, it attaches to nerve endings near the bite site and begins a slow journey along peripheral nerves toward the spinal cord and brain. This nerve-traveling phase is what makes the incubation period so variable. A bite on the face or neck gives the virus a short path to the brain, potentially producing symptoms in weeks. A bite on a hind leg means the virus has much farther to travel, and symptoms may not appear for months.
During this incubation period, the animal appears completely normal. It eats, plays, and behaves as expected. The virus is silently replicating and advancing along nerve fibers without triggering any visible signs.
When an Infected Animal Becomes Contagious
Dogs, cats, and domestic ferrets can begin shedding the rabies virus in their saliva three to six days before any clinical signs appear. This is a critical detail: an animal can look and act perfectly healthy while already being capable of transmitting the virus. Once symptoms do appear, the animal typically lives only a few more days. This narrow window is the basis for the standard 10-day quarantine observation period used for dogs and cats that bite someone.
Stages of Rabies in Animals
Rabies progresses through three recognizable stages, though not every animal goes through all of them.
The first stage, lasting roughly one to three days, involves subtle behavioral shifts. A normally friendly pet may become irritable or withdrawn. A wild animal may lose its fear of humans, appear active during daylight hours when it’s normally nocturnal, or show unusual changes in appetite. These early signs are easy to miss or dismiss.
The second stage is the one most people picture when they think of rabies. The animal becomes severely agitated and aggressive, biting at anything nearby, including objects, other animals, or its own body. Rabid dogs often develop a distinctive high-pitched bark during this phase. Some animals die from seizures during this stage without ever progressing further.
The final stage is characterized by paralysis. The animal loses the ability to swallow, which causes the classic sign of foaming or drooling saliva. Paralysis often begins in the hind legs and spreads forward. Complete paralysis leads to death, usually within a few days. Some animals, particularly livestock, skip the aggressive stage entirely and present only with paralysis, which can make rabies harder to recognize.
Animals That Cannot Carry Rabies
Rabies is exclusively a mammalian disease. Birds, reptiles, amphibians, and fish cannot be infected. Among mammals, small rodents like squirrels, hamsters, guinea pigs, chipmunks, rats, and mice are rarely found with rabies and are not considered a significant risk. Rabbits similarly pose very low risk. The animals that matter most are medium to large wild mammals (especially the four main reservoir species) and any unvaccinated domestic dogs or cats that encounter them.