Diseases Your Pets Can Catch from Pests


Rodents, raccoons, skunks, and burrowing animals are not just a danger to your property. They are also a danger to your pets. Here is an A to Z guide to the deadly diseases your pets can catch from pests—with suggestions for disease prevention.


Distemper kills more dogs than any other disease. About 5 to 15 days after a dog is exposed to the distemper virus, it develops a runny noses, mucus-filled eyes, and general lack of appetite and energy. Thick, gooey, yellow mucus are the classic signs of distemper and sign that you need to take your dog to the vet right away. Distemper may also cause diarrhea, dry cough, and blisters on the dog’s stomach.

If your dog has a healthy immune system, he or she may survive the first stage of distemper and go on to lead a healthy life. If your dog has an overactive immune system, however, several months later immune reactions to the virus may affect the brain, causing drooling, slobbering, and seizures. The dog may also develop redness and inflammation around the eyes, pneumonia, and thickened paw pads. At this stage, distemper is very difficult impossible to treat.

Dogs can catch distemper from other dogs when they are puppies. They also can catch distemper as adults from an astonishing range of wild animals including foxes, wolves, coyotes, wolverines, badgers, skunks, and otters.

The single most important thing you can do to protect your dog from distemper is to make sure you go to the vet for vaccinations when your dogs are puppies. In rare instances, the vaccine does not “take.” To prevent distemper and other viral infections later in your dog’s life, make sure your dog stays away from wild animals by installing protecting mesh fencing on and under the perimeter or your lawn or other areas where your dog may play.

Feline panleukopenia virus

Feline panleukopenia virus is a parvovirus that causes bloody diarrhea and low white blood cell counts in cats. It is transmitted from infected skunks and raccoons that feed at the cat’s outdoor bowl. The virus can persist on plastic surfaces for as long as a year, infecting your cat over and over again, until the virus is killed by exposure to bleach. (Be sure to rinse off the bleach before using the bowl again to feed your cat, or simply buy a new bowl.) Joseph K. Gaydos and John R. Fischer have written a case study on this subject if you would like more info.

The key to preventing feline panleukopenia virus infections is taking your outdoor cat’s bowl indoors at night. Since the virus can also be transmitted through feces and urine into the soil, it also helps to use natural control methods to limit the access of skunks and raccoons to your property.


Heartworms are parasitic roundworms that multiply in the right side of the heart and sometimes in the major veins of dogs and sometimes ferrets and cats. These parasites can infect wolves, coyotes, sea lions, otters, and rats. Household pets seldom meat sea lions or otters and usually do not survive encounters with wolves or coyotes. If your cat, dog, or ferret catches and consumes an infected rat, however, heartworm infection may result. Fifty years ago heartworms were essentially unknown outside the the Gulf Coast states of the United States, Texas, Louisiana, Mississippi, Alabama, and Florida, and the parasite is still most common in the immediate coastal areas of these American states. In recent years, however, heartworms have been diagnosed in locations far away from the American South, including Alaska, Canada, South America, southern Europe, Japan, Australia, and the Middle East.

It usually takes about six months for the heartworm parasite to multiply inside the heart. Some heartworms can “get lost” and cause problems in the eyes or skeletal muscles, but most of the time symptoms are heart-related: cough, early exhaustion during exercise, fainting, coughing up blood, and finally congestive heart failure in dogs. Cats are only 1 to 5% as likely to catch the infection and have much more limited symptoms.

Dogs and cats usually can survive heartworm infections with veterinary treatment. (Ferrets usually are not treated because their owners are unaware of the possibility of the disease.) Giving your dog ivermectin will prevent the infection—but you need to give the treatment for 18 continuous months. Fortunately, affordable ivermectin products are available for small, medium, and large dogs with free shipping world-wide.

The most important thing you can do to protect your pets against heartworms is to make sure they are not bitten by the mosquitoes that transmit them. And one of the ways of keeping mosquitoes under control is making sure your yard is an inviting place for insectivorous birds that will devour the mosquitoes before they can infect your pets. Keep egg-eating skunks away from bird habitat with wire mesh or electric fencing. Encourage mosquito-eating birds by putting up a martin house (don’t forget the telescoping pole on which to place it). And keep bird-eating raccoons at bay with Havahart traps.

Lyme disease

Lyme disease is not just a disease of people. It is also an increasingly common infection in dogs. Lyme disease is dogs causes swollen joints and chronic arthritis, along with bouts of fever and loss of appetite. As in people, dogs acquire Lyme disease from a bite of a deer tick, a tiny eight-legged arthropod about the size of a sesame seed.

Deer ticks are tiny but “sociable” creatures. Ticks meet on large animals to mate, each female tick bearing hundreds of eggs that later hatch into larvae smaller than the period at the end of this sentence. The larvae are born free of Lyme disease, but can acquire it if their very first meal is the blood of a mouse, rat, groundhog, or squirrel that is infected with the disease. The tick will feed only one or two more times in its life, and can transmit the infection through its saliva during those feedings.

Making sure your dogs don’t wander through tall grass will keep them from picking up ticks, but keeping keeping mice, rats, gophers, and squirrels under control will keep ticks from carrying the disease in the first place. It also helps to keep your lawn mowed and to make sure leaf litter does not accumulate on your property. Composting leaves for garden fertilizer is an effective way to get rid of the ticks. An interesting method of natural control is to acquire pet guinea fowl (which have to be protected from skunks and raccoons from late afternoon to early morning). Guinea fowl eat ticks. Two guinea fowls can eliminate ticks from up to two acres (about a hectare) every year.

North American guinea worms

North American guinea worms work their way into a dog’s body through the soft space between the muscles of its upper hind leg. They can burrow their way back to the dog’s abdomen and groin. North American guinea worm infections are usually not fatal, but they can cause a great deal of pain as the adult worm creates a blister in the skin to escape and infect another host.

In Canada, up to 80% of otters are infected with guinea worms. In New York state, the parasite is most common in raccoons. Dogs are only at risk for catching the parasite from their encounters with raccoons for a few weeks of the year, in late spring and early summer, when the worm “breaks out” of its host to lay its eggs. Should your dog become infected, it will display signs of pain in its legs and eventually become immobile. It will scratch and bite its own skin where female guinea worms seek to escape.

The most important thing homeowners can do to protect pets from guinea worm infections is to keep raccoons off their property. This means making sure raccoons can’t use your garbage bins as an all-you-can-eat buffet. Buy garbage cans with secure lids. Keep your lawn mowed to deprive raccoons of nighttime cover. And consider electric fencing around your dog’s run to keep it away from parasite-infested pests.


Parvovirus is deadly for puppies. Even when vaccinated, puppies sometimes succumb to this infection. Causing deadly symptoms in dogs, this virus causes only mild symptoms in raccoons, which may transmit the infection to your dogs through contact with their feces.

The most important thing you can do to protect dogs, especially puppies, against parvovirus is to make sure they get all their shots. It is also important to remove raccoon scat from your yard whenever you find it (wear gloves). Raccoon feces typically contains undigested seeds, berries, feathers, or hair. Natural exclusion methods that keep raccoons off your property will also protect your pets.


Rabies is a viral infection that works its way from the site of the bite of an infected animal slowly up the peripheral nervous system. When the virus reaches the spinal cord, it can then quickly and fatally infect the brain. Only two human beings have ever survived rabies after the virus reached the spinal cord, and both of them underwent heroic and extremely expensive medical procedures. Pets never survive rabies.

While humans are most likely to contract rabies from dogs or bats, in most of North America dogs and cats are most likely to contract rabies from skunks. Getting sprayed by a skunk makes your pet extremely smelly but does not cause any risk of the disease. Only a bite from the skunk (not a scratch) can transmit the virus. In the southeastern United States, rabid raccoons transmit the disease more frequently than skunks. Raccoons that have rabies are likely to be aggressive during the day, but skunks  that have rabies are usually docile.

The most important protection for your pet is a rabies vaccination. But to make absolutely sure your pets do not encounter skunks or raccoons that could give them rabies, make your pet’s outdoor space a pest-exclusion zone with electric fencing or protective mesh wire dug into the ground on all sides of the lawn.

Rocky Mountain spotted fever

Rocky Mountain spotted fever is a bacterial infection spread by ticks from infected ground squirrels and prairie dogs to dogs and people. It is actually not especially prevalent in the Rocky Mountains; most cases occur in the Plains states of the US and in the states of North Carolina and Virginia. The infection causes muscle pain, fever, nausea, and vomiting. The dog (or person) may become sensitive to light and break out in a rash.

Limiting the population of ground squirrels reduces risk to pets and people. Ground-level electrical fences are a good idea if large numbers of ground squirrels live near your property, as is mesh fencing dug into the ground around portions of your lawn you want to keep safe for your dogs.


Roundworms are potentially deadly infection in both pets and people. Typically a skunk or a raccoon becomes infected with roundworms that lay eggs in its gut. The infected animal then defecates on your lawn or garden. The eggs “ripen” in the soil for two to three weeks, during which time any evidence of the animal scat may disappear. A dog or cat then digs in or rolls on the dirt and picks up the parasite, infecting itself when it licks its coat.

Roundworms often cause minimal symptoms in both pets and people. The worm lodges in muscle tissue and then goes into a kind of hibernation by forming a cyst. The cyst may trigger allergic reactions of its own and heighten allergic reactions to other substances, but causes relatively little damage. When cysts lodge in the eyes or brains of either pets or people, however, they can cause blindness, seizures, and even death.

Pets that are infected with roundworms usually tilt their heads to one side. They may become docile and lose their appetite. Later symptoms range from sneezing to seizures.

The most important thing you can do to protect your pets and your family from roundworms is to keep skunks and raccoons off your property. You can do this with properly placed electric fences or narrow-gauge mesh fencing. If you are unable to keep these wild animals off your lawn, then you can do the next best thing and encourage the useful bacteria and molds that that break down their eggs in the soil, with products such as Medina Soil Activator and Medina Hasta Gro.

Squirrel pox

Squirrel pox is a viral disease in the same family that causes chicken pox and smallpox in humans. Red squirrels are especially susceptible to the disease and usually die when they contract it, but the larger gray squirrels usually survive the disease and transmit it to other animals.

The only pet that can catch squirrel pox is the rabbit. Simply keeping your rabbit caged and away from direct contact with sick squirrels or squirrel carcases is adequate protection. Humans do not catch squirrel pox.


Tapeworms are an especially icky parasite that can infect both dogs and people through infected meat or contact with feces of infected animals. Tapeworm eggs lodge in the digestive tract of dogs, where they grow and release their eggs into feces. Tapeworm eggs swallowed by humans that survive the acid environment of the stomach can enter the body through the hepatic portal vein and later form cysts in organs all over the body.

The most important thing you can do to prevent your dog from becoming infected with tapeworms is to prevent contact with infected wild animals. In Australia, a form of tapeworm infection is transmitted by  kangaroos, wallabies, wombats, and foxes. In North America, a different tapeworm is transmitted to dogs from infected moose, elk, caribou, wolves, cattle, and sheep.

The key to preventing tapeworm infection in your pets is keeping them away from the carcasses of dead animals. Your best protection is a strong fence that keeps pets in and pests out to protect both your pet and your family, along with making sure you and every member of your family never handle doggy doo with bare hands.


Toxoplasmosis is a parasitic infection that cats can pass to humans. People who handle kitty litter with bare hands sometimes acquire the parasite and then develop flu-like symptoms that just won’t entirely go away. Women infected with the parasite during the first trimester of pregnancy sometimes miscarry the baby. Chronic toxoplasmosis infection can result in the parasite’s forming cysts in muscle or nerve tissue. Medical researchers have identified possible links between toxoplasmosis and sudden-onset depression or schizophrenia.

Cats acquire toxoplasmosis by eating infected mice and rats. In the cat, the parasite may not cause any symptoms at all, or the cat may experience lethargy, fever, and abnormal reactions of the eyes to light. The cat may twitch its ears, circle, or press its head against soft objects, all compulsively.  Toxoplasmosis is not usually fatal unless the cat has some kind of compromise of the immune system. Cats that have feline leukemia are especially susceptible the most severe consequences of the disease, which include seizures, uncontrollable diarrhea, and eventual death by dehydration. Toxoplasmosis can be controlled with any of several antibiotics, but a veterinarian has to administer them.

The best way to protect your pet from toxoplasmosis is to let traps do the work of controlling rats and mice. It’s never a good idea to leave your cat in a room full of rats—the rats will win any fight with your cat and your cat will idea. But it’s not even a good idea to to let your cat roam where there are mice. Protect both your cat and your home with ultrasound repellents, mouse cubes, and rat traps that are covered so your cat cannot reach inside.

Have a read here for more pest control techniques, tips and a review of the different products.


Mark has a strong background in Engineering and a huge interest in Pest Control as a way of getting rid of rodents and other unwanted pests who can cause a nuisance in your home and garden. You can subscribe to his free daily paper on Pest Control Solutions and follow him on Facebook or Twitter

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  • Ah, I forgot to mention this. Even though the Martin birds don't eat mosquitos and can eat desirable bugs like butterflies, bees (not so great for bee keeping, though I consider bees to be pests) and dragonflies, clearing unnecessary brush and eliminating sources of standing water after it rains is your best bet for reducing mosquito counts (and other bugs). I've also read that you can grow mosquito repelling plants in your yard if your are supports their growth, but I have not fact-checked that one.

  • Uhm, I hate to break it to you, but Martin birds don't eat mosquitos. That's a myth started by a sales guy back in the day who made his living by selling pole-top martin houses. Google it. They do eat bees and other pest bugs, but also eat dragonflies and butterflies.

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