Sarcocystis neurona is a parasitic apicomplexan, a microscopic organism that can feed off a number of different species, including both dogs and humans. It goes through a number of hosts throughout its life cycle, and while many hosts may be asymptomatic, the disease can sometimes cause serious symptoms and even death.
Life Cycle of Sarcocystis
In its juvenile form, Sarcocystis is eaten by prey animals such as horses, cattle, sheep and birds. The infection then forms into cysts in the muscle tissue. When a predator species, such as dogs, snakes or humans, eat the infected muscle tissue, the parasitic protist is passed on. The Sarcocystis then grow in the capillaries, muscle fibers and lymph nods. The juveniles are shed in the feces of the predator and picked up by prey species to continue the cycle.
Pathology of Sarcocystis
In many cases Sarcocystis can remain completely asymptomatic. Cattle species are often not diagnosed until they are slaughtered and the meat is examined. The species that is passed on specifically in dog feces can be more dangerous to cattle, producing diseases in calves and inducing stillbirths and spontaneous abortion in pregnant cows. Dogs who do show symptoms may have fever, muscle pain and low levels of platelets and white blood cells.
Sarcocystis Neurona-Related Encephalitis
One of the more serious and rare symptoms of Sarcocystis neurona in dogs is encephalitits, swelling of the brain, due to the presence of infection around the nerves and brain tissue. The swelling can cause weakness and partial paralysis in a dog's hind legs, behavior changes, hypersensitivity to sensory input and aggression. Dogs unfortunately are sometimes euthanized for this aggressive behavior before the cause can be found and treated.
Preventing Sarcocystis neurona infection is the best way to protect your dog. Avoid offering him raw meat -- either cook any meat he does eat at 158 degrees Fahrenheit for 15 minutes or freeze it at 24.8 degrees Fahrenheit for two days. If your dog is showing symptoms, your vet may recommend a medication like clindamycin and decoquinate to eliminate the infection. If serious organ damage occurs, the infection may still leave lasting damage or even be fatal.