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Living with Wildlife
Wildlife Diseases
Some pathogens (bacteria and viruses, for example) can spread between wildlife, domestic animals and people. Many of these pathogens cause disease, sometimes with serious consequences.
The best way to prevent exposure to any wildlife diseases is to avoid approaching and handling wild animals. If your pet comes in contact with a wild animal, contact your veterinarian for the appropriate next steps. If you or another person comes in contact with a wild animal, contact your medical doctor or your local public health department.
Woman walking on a trail
Prevent Disease
There are several steps you can take to help prevent the spread of disease. It is best to avoid dead animals and handling animals. It is natural to want to help sick or injured wildlife, but it's not worth endangering yourself or your pets. Where possible, call your nearest Colorado Parks and Wildlife office for help.
Report Signs of Sickness
If you or your pets are experiencing any of the symptoms listed above, especially after any contact with wildlife, please seek care from your doctor or veterinarian. Report your conditions or interactions to the proper agencies so they can better track potential outbreaks.
Contact Your Doctor or Veterinarian
Contact your doctor or veterinarian immediately if you or your pet suffers a bite, scratch or other contact from a wild animal, or if you or your pet become ill or develop skin lesions following contact with wild animals, ticks or biting insects such as fleas.
Report Sick Wildlife
Any wild animal that appears sick or is acting strange or aggressive should be reported to the nearest CPW office and your local animal control agency.
Contact a CPW OfficeDiseases in Humans and Pets
Avian Botulism
Avian botulism is caused by a toxin released into water by bacteria. The disease mostly affects waterfowl and other bird species. It spreads during summer months when birds feed in contaminated water, often causing large die-offs of ducks and geese.
Avian botulism does not typically cause human disease. It’s rare for domestic dogs and cats to become infected, but cases have been reported. As a precaution, do not let your pet drink from water where you see multiple dead ducks and geese.
What to Look For in Wild Birds
- Large numbers of dead or sick waterfowl, especially mallard ducks, near or in a body of wate
- Weak or unable to move, stand, walk or fly
- Unable to lift the head
Canine Distemper
Canine distemper is a viral disease of wild and domestic carnivores. Coyotes, foxes, raccoons, skunks and black-footed ferrets are the most commonly infected animals in Colorado. Because the virus does not survive long outside the body, it spreads mainly through direct contact. Canine distemper can cause a wide range of symptoms and, normally, is fatal. Signs of canine distemper are often indistinguishable from rabies; animals suspected of canine distemper are often humanely euthanized and tested for both.
Canine distemper cannot infect humans, but it can infect unvaccinated domestic dogs. Please follow your verterinarian’s recommendations on vaccines to prevent infection. Always report contact between pets and wild animals to your veterinarian.
What to Look For in Wild Animals
- Strange behavior
- Lack of coordination, seizures
- Weakness, slow movement
- Crusting around eyes and nose
- Coughing, sneezing, nasal discharge
- Diarrhea
- Vomiting
- Thickened paw pads
Highly Pathogenic Avian Influenza
HPAI is a viral disease known as “avian influenza” that causes illness in birds and mammals. Some species of ducks, shorebirds and other wild birds naturally carry the virus without getting sick — they have the infection but not the disease. But some of these viruses can cause disease in other bird species, including swans, turkeys, grouse, quail, diving ducks, gulls, geese, grebes, raptors, vultures, cranes and terns. In Colorado, HPAI has been detected in some mammals, including foxes, skunks, bobcats, mountain lions and bears.
What to Look For in Wild Birds
- Swimming in circles
- Head tilting
- Lack of coordination
- Swollen head
- Diarrhea
- Moving slowly
- Ruffled feathers
- Respiratory signs
- Found dead
What to look for in Wild Mammals
- Lack of coordination (dragging feet, falling from side to side)
- Loss of fear of humans
HPAI is highly infectious to domestic poultry and pet birds. Use proper prevention methods (such as footbaths and dedicated footwear and clothing) and minimize contact between wild birds and any domestic birds in your care. Pets should not be allowed to interact with or eat sick or dead birds. Although rare, some strains of HPAI can infect humans. Avoid handling sick or dead birds and keep your distance from wildlife.
Mange
Sarcoptic mange is a skin infection caused by microscopic mites. Infected animals experience hair loss and severe skin irritation. Mange is highly contagious and can be spread by skin-to-skin contact or by contact with infected material, such as bedding. In Colorado, coyotes and foxes are most commonly affected by mange; however, other species such as black bears, porcupines and squirrels may also be affected. Severe cases may result in excessive weight loss and death.
Mange can spread between wildlife, domestic animals and humans, although a severe infection typically occurs only when an animal contracts it from another of the same species.
Pets can be protected from infection by preventing contact with wildlife and using mite-controlling products prescribed by a veterinarian. Infections in humans are usually mild and resolve on their own, but some individuals may require medical intervention.
What to Look For
- Hair loss, especially over the lower legs and tail (giving the animal a “rat-tail” appearance)
- Thick crusting or scaling of the skin
- Intense itching and scratching
- Thin, debilitated animals
New World Screwworm
New World screwworm (NWS) is a foreign animal disease caused by an infestation of larvae, or maggots, laid by adult flies (Cochliomyia hominivorax). NWS can infect all warm-blooded animals, including wildlife, livestock, companion animals, birds and humans. Unlike maggots that feed on dead tissue, NWS maggots are generally found feeding on live tissues of living (or recently deceased) animals. On June 3, 2026, the presence of NWS in the United States was confirmed in a domestic calf in Texas. The United States Department of Agriculture and state officials are closely monitoring the disease.
What to Look for in Wild Animals
Commonly affected wild animals species include deer, rabbits, small mammals and turkeys; however, all warm-blooded animals can be affected. Look for these signs:
- NWS maggots feeding on live tissue in living animals or animals recently killed/harvested
- Open wounds or fresh wounds with live maggots
Domestic Animals and Humans
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NWS is a threat to the livestock industry. Report any possible cases in domestic animals, including pets, to the Colorado Department of Agriculture.
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Though the risk of infection is low, NWS can affect humans. Direct all questions and report any possible cases in humans to the Colorado Department of Public Health and Environment.
Plague
Plague is a bacterial disease that most commonly affects prairie dogs. The disease is spread by flea bites, contact with infected fluids or dead animals, and by breathing in bacterial particles that are coughed or sneezed by an infected animal. In Colorado, the fleas that commonly spread plague bacteria are specifically adapted to prairie dogs as their host; however, they can also spread the disease to other rodents, such as mice and ground squirrels, and other animals. Cats, both domestic and wild (bobcats, mountain lions), are particularly susceptible to plague and can become infected through flea bites or by eating infected rodents.
Plague can infect both people and pets. Domestic cats with outdoor access pose a high risk to humans — cats should not be allowed to interact with prairie dogs or other wild rodents. Flea prevention products for domestic cats and dogs are recommended. To protect yourself from possible infection, wear insect repellent and protective clothing when recreating outdoors.
Plague infections can be fatal if not treated immediately. Contact your doctor immediately if you experience flu-like symptoms following contact with wild mammals or fleas. Contact your veterinarian if your pet is exposed to wildlife, particularly prairie dogs or other rodents.
What to Look For in Wild Animals
- Multiple dead prairie dogs in the same area or decreased prairie dog activity at an active colony
- One or more rodents or rabbits found dead in a similar area
What to Look for in Domestic Animals
- -Swollen lymph nodes on cats
- Fever or other general signs of illness in pet dogs, cats or other animals with access to prairie dog habitats
Rabies
Rabies is a fatal viral disease that attacks the brain and can infect any mammal. Because the virus is transmitted through the saliva, rabies is most commonly spread by the bite of an infected animal. The virus can also spread if infected saliva comes in contact with the eyes, nose or mouth of another mammal or human. Rabies is rare in all mammals in Colorado, but bats and skunks are the most commonly infected.
Rabies can infect both pets and people. If you or your pet suffers a bite or a scratch, or has some other physical contact with a wild mammal, contact your doctor or veterinarian immediately — a post-exposure vaccination may be necessary. Bat bites and scratches can be easily missed; if you find a bat in a room with a pet or a nonverbal person, contact your veterinarian or doctor immediately.
If a human or animal is exposed to rabies and is not treated, the infection will be fatal. All pets and other domestic animals (such as horses) should be vaccinated against rabies as a precaution.
What to Look For in Animals
- Aggression, no fear of humans, nonreactive (if paralysis has set in)
- Disorientation, lethargy
- Difficulty walking (signs of paralysis, lack of muscle coordination)
- Excessive salivation
- Strange behavior for the species (such as a bat flying around in the middle of the day)
Tularemia
Tularemia is a fatal bacterial disease that infects rodents (particularly beavers), rabbits and hares; it can also infect humans and domestic animals. Infection is usually transmitted through ticks, biting flies and fleas, or by breathing in infectious droplets from soil or contaminated water.
What to Look For in Wild Animals
- One or more sick or dead beavers in one area
- Multiple sick or dead rabbits or rodents in one area
- Pinpoint white spots throughout the liver and spleen of an animal
Tularemia can infect both people and pets. Do not allow pets to interact with or consume sick or dead wildlife. Leave dead wildlife alone and report it to your local CPW office.
Infections with tularemia can be fatal if not treated promptly. Contact your doctor immediately if you feel ill or develop skin lesions following contact with wild animals, fleas, flies, other biting insects or ticks.
Preventing Disease in Pets
You can prevent disease in pets by:
- Keeping pets in yards, kennels or on a leash. Pets that are allowed to run loose are more likely to come in contact with infected animals or disease-carrying pests that they can bring into your home.
- Do not allow free-roaming pets to sleep on your bed.
- Use flea, tick and mite preventatives on your pets.
- Pets should not be allowed to consume or interact with dead wildlife.
Parasites and Tapeworms in Pets
Dogs and cats can become infected with tapeworms if they eat infected wildlife.
Tapeworms are common parasites of cottontail and jackrabbits. These types of tapeworms don’t infect humans, but dogs and cats may experience intestinal infections if they eat an infected animal.
What to Look For in Wild Rabbits
- Fluid-filled cysts, each containing a floating white dot, in the belly or chest of a rabbit or hare
- Thick, white spots or lines on the liver of a rabbit or hare
Hydatid cysts, found on the lungs and liver of infected moose or elk, are large, fluid-filled cysts containing young tapeworms. Moose and elk can become infected by eating coyote, fox, wolf or domestic dog feces while grazing.
Cysts on harvested elk and moose organs are not dangerous to people but can infect domestic dogs if eaten, and the disease can spread to humans through pet waste. Do not allow dogs to consume raw meat or organs from wildlife. Consult your veterinarian for regular deworming of pets.
What to Look For in Wild Moose and Elk
- Large, fluid-filled cysts that contain hundreds of tiny white grains in lungs or liver of moose, elk and, less commonly, deer
The most common parasites that big-game hunters observe in their harvested animals are the tapeworms that cause cysticercosis, which affects deer, elk, moose, bighorn sheep and pronghorn. These worms live in the intestines of wild carnivores such as coyotes, foxes, mountain lions and bobcats. When these carnivores defecate, tapeworm eggs get onto the ground and the grass; big-game animals then swallow the eggs as they graze, leading to infection.
Cysticercosis does not pose a risk to human health, but may cause intestinal infections if eaten by domestic dogs or cats.
What to Look For
- Large (1-inch) fluid-filled cysts, each containing a floating white dot, in the belly or chest
- Small (1/4-inch) fluid-filled cysts, each containing a floating white dot, in the muscle tissue