The protozoa named Toxoplasma gondii is the parasite that causes toxoplasmosis in dogs. It can cause the disease in most warm blooded animals including humans.
The parasite has a definitive host in animals belonging to the cat family. They act as a reservoir of Toxoplasma, spreading it to other domestic animals and to people too. Dogs may develop toxoplasmosis when the protozoa entering the body through the oral route infect various tissues including the brain.
Most healthy dogs have sufficient immunity against the protozoa; hence they may be able to fight off its spread. But puppies may develop widespread infection, resulting in various general symptoms such as fever, respiratory distress accompanied by cough, as well as diarrhea and jaundice. They may develop seizures and succumb to the infection. The infection is usually fatal to immune-compromised dogs too, as they may develop the symptoms suddenly.
The disease may get resolved without any treatment in most cases. The veterinarian may give antibiotics to the dog if necessary. Seizures may have to be controlled with anticonvulsant drugs. If the dog is extremely dehydrated or weak, fluids and nutritional supplementation may be administered intravenously.