Neospora caninum is not a virus found in dogs, but instead a protozoa, a parasite. This parasite causes the neosporosis infection in canines, which effects the brain and muscles. Neosporosis is the clinical word for what happens when the Neospora caninum parasite invades the host and begins to destroy, or necrotize, the cells and tissues in the muscles and nerves. The life cycle of the parasite for dogs, though unknown, is hazarded to move from canine to herbivore and back again, or canine to canine, through digestion and emission. Though found mostly in young puppies, dogs of any age can become infected and even die from the parasite. Though similar to symptoms surrounding infections of other protozoa such as Toxoplasma gondii, Neospora caninum's symptoms are more severe.
Stiffness and Muscle Atrophy
In puppies younger than 6 months old, one major symptom is stiffness in the hind limbs, or outright paralysis as the parasite attacks the muscles and nerves. In either case, atrophy of the muscles occurs so that the limbs contract rigidly without moving and stay that way.
Seizures and Tremors
Because a dog of any age can fall victim to Neopsora caninum, when it appears in older dogs the central nervous system is often where symptoms revolve. These symptoms include seizures and violent tremors not just in the hind limbs but throughout the body.
Also prevalent in older dogs, and related to tremors and seizures, is how the parasite steadily will weaken the dog's muscles. These muscles are not just those around the spine, but also the heart muscle, causing cardiovascular and respiratory failure. This symptom develops slowly with time.
Dysphagia and Dermatitis
When the parasites attack the muscles around the neck, a dog will be unable to hold up his head. The muscles of the esophagus will weaken so that the dog can no longer swallow, a condition called dysphagia. Other than these symptoms, older dogs can suffer from blindness, behavioral changes and dermatitis. Some tissue cysts that develop do so on the skin itself rather than in the muscles.
Treatment and Prognosis
Neospora caninum is a lethal parasitic infection when left untreated. Even with treatment, death can occur. Treatments do exist to control the problems. See your vet if your dog shows signs of the illness. Treatmen often includes Clindamycin and Trimethoprim sulfadiazine in combination with pyrimethamine. Treatment optimally begins before the onset of contraction and paralysis. Dogs can pass this parasite onto pups -- do not breed bitches who have had or shown signs of the infection in the past. Dogs who survive have a good prognosis for health afterward.
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