Surprising Problems From Ticks and Fleas

Medically Reviewed by Amy Flowers, DVM on May 14, 2023
3 min read

Fleas and ticks are tops among the list of concerns for pet owners. But these tiny pests, which bite and feed on your animal’s blood, may do much more than just make them itch. They also can spread a long list of diseases that can sicken your furry companions.

Anaplasmosis. Symptoms of this bacterial infection can look very similar to those of Lyme disease, including fever and lack of energy. Your pet may stop eating or be unable to stand or walk. Some dogs and cats with anaplasma can also have nosebleeds or other bleeding problems.

Babesiosis. This is when parasites destroy your dog’s red blood cells. It’s not been reported in cats in the U.S. The animal’s gums may be pale and the whites of their eyes may look yellow-orange. They also may get weak, have a fever, and lose weight.

Ehrlichiosis. Like Lyme disease, this most often comes from the bite of a tick. Like anaplasmosis, it can make your dog or cat vomit, avoid food, and have nosebleeds. Symptoms pop up 1 to 3 weeks after the bite. It can be treated if caught early.

Hepatozoonosis. This severe and sometimes deadly disease doesn’t come from a tick bite. It happens if your dog or cat eats an infected tick or something infested with it. Talk to your vet if your pet doesn’t want to stand or move, or seems to lack muscle strength.

Lyme disease. Just like people, dogs can get it from the bite of a tick. This infectious disease is so common that more than half the dogs in New England have had it. Cats can also get infected with Lyme, but not as frequently as dogs. Only about one in 10 dogs with Lyme have symptoms like fever, sluggishness, and lameness that require treatment.

Rocky Mountain spotted fever. Despite its name, Rocky Mountain spotted fever affects dogs (and people) -- but no other animals -- all over the country. Mice, rats, rabbits and other small mammals carry the bacteria. Ticks feed on them, and then spread the disease through bites. Common symptoms of a mild case include coughing, diarrhea, and vomiting. If your dog has a severe case, you may see redness in the eyes, nosebleeds, blood in the urine or stool, and problems standing or walking.

Cytauxzoonosis. This comes from ticks that feed on bobcats. Cytauxzoonosis doesn’t affect dogs, but it can be deadly to cats. It spreads quickly and leads to breathing problems, loss of appetite, jaundice, and coma.

Dermatitis. Strange but true: Some dogs and cats are allergic to the saliva of fleas. Dermatitis, or inflammation of the skin, is an allergic reaction to fleabites. It can make your pet’s skin red, scabbed, and very itchy.

Tapeworms. Your dog or cat could get them from eating a flea or something else that has tapeworm eggs. These parasites live in your pet’s small intestine and steal nutrients from everything you feed it. Tapeworms eventually pass through poop, but they rarely make your pet sick. Your pet should be treated, though.

Hair loss. It’s not from the fleas themselves, but from all the itching and biting. Fleas can trigger allergies that make your pet so itchy that they scratch their fur into bald spots.

Bartonella. It’s better known as cat scratch disease, but it infects both cats and dogs. Bartonella spreads through ticks, fleas, and sand flies. Look for fever, joint pain, and any unusual behaviors.

Fleas love dark, moist areas. Once a week, groom your pet with a flea comb and wash its bedding. Ask your vet about the best flea control product for your pet.

Some flea medication also controls ticks. Be consistent about tick prevention medication. Wear gloves to check your pet for ticks regularly, especially after spending time in wooded areas. If your pet’s exposure to ticks is high, talk to your vet about vaccines that prevent Lyme disease.