Canine Diseases Caused by Dog Fleas

Dog fleas cause more than just itchiness. Fleas and their larger counterparts, ticks, can bring a variety of diseases that can cause serious illnesses in their hosts. Therefore, it is important that fleas are vigorously controlled and eliminated once they are discovered on a dog.

Flea Allergy Dermatitis

A dog can develop dermatitis (skin irritation) from a flea bite. Some dogs are allergic to the saliva left behind on his skin after a flea bites him. An allergic reaction to a flea bite may come in the form of hot spots, hair loss, constant licking or scratching of the skin, hives, a rash or red bumps on the skin, or skin that is wounded and oozing.

Flea Anemia

A dog can become anemic if he has a large flea infestation. The great number of fleas on a canine can drink so much of the dog's blood that it makes him weak. Young dogs and senior dogs that spend a lot of time outside are more prone to becoming anemic from fleas. Flea anemia is common and often is hard to detect.


As strange as it seems, fleas can be hosts to parasites that will also infect dogs. A dog becomes infected with tapeworms after the flea becomes infected. First, tapeworm eggs need to be consumed by flea larvae. This encounter usually happens when carpet or pet bedding is infested with both. The dog then ingests the infected fleas. The tapeworm eggs hatch within the dog and latch themselves on to the intestine and lay eggs. The eggs are then passed with a dog’s bowel movement, only to start the process all over again. A dog with tapeworms may experience weakness, weight loss and vomiting.

Lyme Disease

Ticks, which are big fleas, can infect dogs with Lyme disease. A tick can transmit this disease when it carries the disease-bearing bacteria, Borrelia burgdorferi. Lyme disease is then transmitted to a dog after a tick latches on to him and begins to drink his blood.

A dog with Lyme disease will develop a fever, body and joint pains, enlarged lymph nodes, have a lack of energy and appetite, and a cough. Serious conditions of the heart or kidneys may ail a dog if left untreated, but this is a rare occurrence.  

Rocky Mountain Spotted Fever

Rocky Mountain spotted fever, another disease caused by ticks, is transmitted by the Rickettsia rickettsii organism that can infest a tick. The disease is transmitted to dogs when the tick bites him. Symptoms of Rocky Mountain spotted fever include inflammation of the inside of a dog’s eye, lack of appetite, joints that are painful and swollen, and a high fever.

Because of all the diseases a dog can get from fleas, it is crucial for a pet owner to exercise proper and consistent flea control. This means not just making sure a dog wears a flea collar. The area where a dog lives must be clean and a dog should have regular baths per a veterinarian’s instructions. Fleas will not just cause a dog to be itchy; they can be the cause of serious canine diseases.