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Parasitic Infection (Neosporosis) in Dogs

Neospora Caninum Infection in Dogs

Neospora caninum is a parasite that bears resemblance to Toxoplasma gondii. When examined under a microscope, the N. caninum sporozoite closely mirrors the T. gondii sporozoite, and both diseases exhibit similar symptoms. However, N. caninum infection imposes a more severe toll on a dog’s neurological and muscular systems compared to T. gondii.

This infection leads to neosporosis, a medical condition characterized by cell death and tissue necrosis triggered by the invasion of N. caninum. It involves tissue damage resulting from cyst rupture and the subsequent invasion of tachyzoite microorganisms. This stage denotes rapid multiplication of the sporozoite organism throughout the body tissues.

Although the life cycle of the N. caninum parasite remains unknown, it is transmissible during fetal development and birth. Puppies are the most commonly diagnosed, but hunting dogs also face heightened risks and are frequently documented in medical literature concerning this condition.


The signs of neosporosis closely resemble those of toxoplasmosis, a parasitic disease caused by the protozoan parasite Toxoplasma gondii. In dogs younger than six months, symptoms typically manifest as stiffness in the pelvic limbs (hind legs) and paralysis marked by gradual muscle atrophy, leading to rigid contraction of the limbs.

In older dogs, the central nervous system is more frequently affected, resulting in symptoms such as seizures, tremors, changes in behavior, and blindness. Additional symptoms may include weakness in the cervical muscles (near the neck) and difficulty swallowing, known as dysphagia. These signs progress slowly, and eventual paralysis of the respiratory muscles can result in death. In many instances, the infection spreads throughout the body, impacting various organs, including the skin. Dermatitis is also a common symptom of neosporosis, particularly in older dogs.


Neosporosis stems from the protozoan Neospora caninum, which infiltrates and resides within the host animal’s body. Dogs and coyotes serve as definitive hosts for N. caninum and can transmit the infection through the sporulated oocysts found in their feces. Consumption of these oocysts, such as through contaminated food, can spread neosporosis to animals. Furthermore, the presence of N. caninum cysts in the tissues of an intermediate host, like cattle, can contaminate feeds and lead to infection.

Transmission of N. caninum can also occur transplacentally, meaning it can be passed from mother to offspring through the placenta during fetal development. This may result in congenital infection, where the infection is present at birth. In puppies, N. caninum can form cysts in the developing central nervous system, causing neurological abnormalities.


Your veterinarian will conduct a comprehensive physical examination of your pet, which includes a thorough assessment of its overall health, along with various diagnostic tests. These tests encompass a complete blood profile, a chemical blood profile, a complete blood count, and a urinalysis. Additionally, a fecal sample will be required for laboratory analysis. The presence of oocysts in the feces confirms the diagnosis of neosporosis. Your veterinarian will also analyze your dog’s cerebrospinal fluid, which surrounds the brain and spinal cord, to gauge the extent of neurological involvement. Changes such as a slight increase in protein levels in the cerebrospinal fluid are indicative of neosporosis. Furthermore, a tissue biopsy may be performed to distinguish N. caninum from T. gondii.

Given that various conditions can result in central nervous system dysfunctions, your veterinarian will also need to eliminate these possibilities, particularly those with the highest risk for severe complications. Depending on the symptoms and the environment in which your dog resides, diseases such as rabies, fungal infections, meningitis, and reactions to toxic substances (such as lead or pesticides) may need to be ruled out.


Specific medications may be administered to treat neosporosis, aiming to halt the advancement of the disease and alleviate its symptoms. However, the prognosis for patients is grim once the disease has progressed to the stage where muscle contraction and progressive paralysis have developed.

Recovery and Management

Neosporosis necessitates treatment with the prescribed medications for an extended duration, as advised by your veterinarian. It is crucial to adhere to the proper administration of medications throughout the entire recommended treatment period.


Neosporosis can be prevented by refraining from using contaminated feeds. Other dogs or cattle that might have come into contact with an infected animal should undergo testing for neosporosis and receive prompt treatment to prevent the parasite from spreading systemically.

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