Transmission and Symptoms of Canine Neosporosis

Canine neosporosis is a parasitic disease that gets its name from the protozoan that causes it, Neospora caninum. Among dogs, it mainly affects puppies.

It's characterized by neuromuscular symptoms that usually cause paralysis, starting in the hind legs, which can progress. It's a condition that can even prove fatal, hence the importance of seeing the vet and starting treatment early.

What Is Neosporosis?

Neosporosis is a condition caused by a parasite, specifically a protozoan called Neospora caninum. To survive, it needs to live inside the cells of the animals it parasitizes, mainly dogs, but also cattle. This is important to keep in mind for prevention.

At first it was treated as a new genus of coccidia, which was also found in dogs, hence its name. The discovery specifically happened in puppies that showed paralysis and eventually death.

But shortly after, it was also discovered in cattle. Neospora tends to attack the central nervous system, hence the typically neurological and muscular symptoms.

The Life Cycle of Neospora Caninum

Nowadays it's been established that the definitive hosts of neospora are dogs, coyotes, dingoes, and gray wolves. But it's also known that, for this protozoan to complete its life cycle, it needs the presence of what are known as intermediate hosts.

These are ruminants, wild ungulates, rodents, and birds. When a dog is infected with neospora, it sheds the parasite in its feces. This is how contamination reaches water, pastures, or the bedding set up for livestock.

This is how transmission occurs. In turn, if a dog eats a contaminated product from livestock or any other intermediate host, such as a placenta, it will become infected.

Symptoms of Neosporosis in Dogs

Neosporosis isn't a very common disease. The sign that can make us suspect its presence is paralysis of the hind legs. Although this symptom is shared with other diseases, if these are ruled out and we're dealing with a young dog, neosporosis should be considered. Other symptoms that can be detected include the following:

• Neuromuscular disorders that generally show rapid progression.
• In this regard, the most common sign is paralysis of the hind legs, which follows an ascending pattern.
• Difficulty swallowing.
• Jaw paralysis.
• Muscle flaccidity and atrophy.
• Heart failure.
• Myocarditis, or inflammation of the heart muscle.
• Pneumonia.
• Polymyositis, or inflammation of muscle fibers and skin.
• Enlarged liver.
• Seizures.
• Behavioral changes.
• Listlessness.
• Loss of appetite.
• Dermatitis, which is linked to the immunosuppression the sick dog experiences, although this is an uncommon symptom.
• Sometimes, dogs carrying neospora will remain asymptomatic. These dogs could show the clinical picture described if, for any reason, their immune system becomes weakened.

How Is Neosporosis Transmitted?

Besides contact with water or contaminated remains, females can transmit it directly to their puppies. It's not known exactly how this transmission occurs. The disease in dogs infected this way shows up more severely.

Which Dogs Get Neosporosis?

All dogs are susceptible to catching neospora, but a higher incidence has been found in those under one year old. Dogs in contact with livestock or any of the other intermediate hosts will also be at higher risk.

How Is Neosporosis Diagnosed?

Since this is an uncommon disease, other conditions are usually considered first. Only once these are ruled out is the possibility of neosporosis considered. Other times, especially if the dog is considered part of a risk group or ascending paralysis occurs, neosporosis can be suspected directly.

There's a rapid test to confirm or rule out this parasite. It's also common to run bloodwork to get general information about the animal's condition. Liver values may be altered.

What Is the Treatment for Neosporosis?

To treat this disease, the vet will prescribe antiprotozoal drugs to eliminate the parasite. Antibiotics are also prescribed, mainly to prevent opportunistic secondary infections.

There's no vaccine that can help prevent it. To minimize risks, we can prevent, as much as possible, contact between the dog and intermediate hosts or potentially contaminated remains.

Prognosis for Neosporosis

This is a treatable disease, but we should keep in mind that, despite treatment, not every affected dog manages to overcome it. Death results from respiratory, heart, or liver complications.

The prognosis will largely depend on when treatment begins. The characteristics of the damage neospora has already caused also play a role. Generally, we can say this is guarded.

Bibliography Dubey and Lindsay (1993): Neosporosis. Parasitology today, 9 (12): 452-458.