Trichinellosis in dogs, also known as trichinosis, is caused by the parasitic nematode Trichinella spiralis. These worms are found in most carnivorous mammals in the wild, as well as in domestic animals such as dogs and pigs. The infection can be transmitted to humans too, when infected and undercooked meat is consumed. Pork is the usual source of infection in people.
Cysts that contain the larvae of the worm are found embedded in the muscle tissue of the infected animals. Dogs get the infection when they eat the flesh of other infected animals. Inside the new host, the larvae come out of the cyst and spread to different parts of the body. As they mature, they make new cysts in the muscles within which the larvae survive for several years. They become active, and complete the rest of their development, only when the cysts get eaten by the next host. If the larvae are excreted along with the feces, they can infect other animals directly too.
Trichenellosis is usually asymptomatic in most animals including dogs. The disease goes undiagnosed in most cases until it becomes too severe and fatal. Dogs that eat the raw meat of rodents and other prey have very high chance of harboring the parasite. Severe infections may cause serious disease in people, sometimes culminating in death.
In dogs, prevention of the disease is more practical than treating it. This can be achieved by providing only well-cooked meat to the dogs, and not allowing it to eat wild animals and carcasses as they may be carrying viable cysts.