Infectious diseases

Viral infections

Rabies (hydrophobia) is a fatal viral disease that can affect any mammal, although the close relationship of dogs with humans makes canine rabies a zoonotic concern. Vaccination of dogs for rabies is commonly required by law. Please see the article dog health for information on this disease in dogs.
Canine parvovirus is a sometimes fatal gastrointestinal infection that mainly affects puppies. It occurs worldwide.
Canine coronavirus is a gastrointestinal disease that is usually asymptomatic or with mild clinical signs. The signs are worse in puppies.
Canine distemper is an often fatal infectious disease that mainly has respiratory and neurologic signs.
Kennel cough is an infectious respiratory disease which can be caused by one of several viruses or by Bordetella bronchiseptica. It most commonly occurs in dogs in close confinement such as kennels.
Canine influenza is a newly emerging infectious respiratory disease. Up to 80 percent of dogs infected will have symptoms, but the mortality rate is only 5 to 8 percent.
Infectious canine hepatitis is a sometimes fatal infectious disease of the liver.
Canine herpesvirus is an infectious disease that is a common cause of death in puppies less than three weeks old.
Pseudorabies is an infectious disease that primarily affects swine, but can also cause a fatal disease in dogs with signs similar to rabies.
Canine minute virus is an infectious disease that can cause respiratory and gastrointestinal signs in young puppies.

Bacterial infections

Brucellosis is a sexually transmitted bacterial disease that can cause uveitis, abortion, and orchitis in dogs.
Leptospirosis is an infectious disease caused by a spirochaete. Symptoms include liver and kidney failure and vasculitis.
Lyme disease is a disease caused by Borrelia burgdorferi, a spirochaete, and spread by ticks of the genus Ixodes. Symptoms in dogs include acute arthritis, anorexia, and lethargy. There is no rash as is typically seen in humans.
Ehrlichiosis is a disease caused by Ehrlichia canis and spread by the brown dog tick, Rhipicephalus sanguineous. Signs include fever, vasculitis, and low blood counts.
Rocky Mountain spotted fever is a rickettsial disease that occurs in dogs and humans. It is caused by Rickettsia rickettsii and spread by ticks of the genus Dermacentor. Signs are similar to human disease, including anorexia, fever, and thrombocytopenia.
Clostridium species are a potential cause of diarrhea in dogs. Associated species include C. perfringens and C. difficile.

Fungal infections

Blastomycosis is a fungal disease caused by Blastomyces dermatitidis that affects both dogs and humans. Dogs are ten times more likely to be infected than humans. The disease in dogs can affect the eyes, brain, lungs, skin, or bones.
Histoplasmosis is a fungal disease caused by Histoplasma capsulatum that affects both dogs and humans. The disease in dogs usually affects the lungs and small intestine.
Coccidioidomycosis is a fungal disease caused by Coccidioides immitis that affects both dogs and humans. In dogs signs include coughing, fever, lethargy, and anorexia. Many cases include lameness due to bome lesions.
Cryptococcosis is a fungal disease caused by Cryptococcus neoformans that affects both dogs and humans. It is a rare disease in dogs, with cats seven to ten times more likely to be infected. The disease in dogs can affect the lungs and skin, but more commonly the eye and central nervous system.
Ringworm is a fungal skin disease that in dogs is caused by Microsporum canis (70%), Microsporum gypseum (20%), and Trichophyton mentagrophytes (10%). Typical signs in dogs include hair loss and scaly skin.
Sporotrichosis is a fungal disease caused by Sporothrix schenckii that affects both dogs and humans. It is a rare disease in dogs, with cat and horse infections predominating in veterinary medicine. The disease in dogs is usually nodular skin lesions of the head and trunk.
Aspergillosis is a fungal disease that in dogs is caused primarily by Aspergillus fumigatus. Infection is usually in the nasal cavity. Typical signs in dogs include sneezing, nasal discharge, bleeding from the nose, and ulcerations of the nose.
Pythiosis is a disease cause by a water mould of the genus Pythium, P. insidiosum. It occurs primarily in dogs and horses, but can also affect humans. In dogs it affects the gastrointestinal system and lymph nodes, and rarely the skin.
Phycomycosis is a collection of fungal and mold diseases in dogs including pythiosis, zygomycosis, and lagenidiosis that affect the gastrointestinal tract and skin.

Protozoal diseases

Giardiasis is an intestinal infection in dogs caused by the protozoa Giardia lamblia. The most common symptom is diarrhea. The zoonotic potential of giardiasis is controversial.
Coccidiosis can be caused by a variety of coccidian organisms in dogs, most commonly Isospora. There are usually no symptoms, but diarrhea and weight loss may occur.
Leishmaniasis is spread by the sandfly, and in the dog as well as human has both cutaneous and visceral forms. The dog is considered to be the reservoir for human disease in the Americas.
Babesiosis is spread by members of the family Ixodidae, or hard ticks. The two species of the genus Babesia that affect dogs are B. canis and B. gibsoni. Babesiosis can cause hemolytic anemia in dogs.
Neosporosis is caused by Neospora caninum.

Other infections

Protothecosis in dogs is caused by a mutant form of green algae and is usually disseminated. Symptoms include weight loss, uveitis, and retinal detachment.