Neosporum Parasite and Neosporosis in DogsLast updated: March 24, 2021
Neosporum or neospora caninum in dogs is a coccidian parasite causing the infection called neosporosis. This one-celled parasite is most commonly seen in dogs and cattle and causes damage to the muscles and nervous system. It is similar to toxoplasmosis, the disease feared by pregnant women handling cat litter.
Causes of Neosporum in DogsNeospora in dogs can be contracted by drinking infected water, eating infected raw meat, or placentas from livestock. Mother dogs can transmit the parasite to their pups through the placenta or through the milk. This is one of the reasons we discourage feeding raw meat diets to females in breeding programs. Even if you are not currently feeding a raw meat diet, your dams can harbor the parasite. Then, pregnancy can initiate parasite multiplication, followed by transmission thought the placenta and into the fetus. Adults may have the parasite but not have symptoms.
Puppies under six months of age are the most commonly affected group. Adult dogs rarely show symptoms. Within five to eight days of exposure, nerve tissues die, interrupting nerve impulses, and causing clinical signs.
Life Cycle of Neospora in Dogs
Image courtesy: Agricultural Research Service- U.S. Department of Agriculture
Neosporosis Symptoms in DogsNeosporosis in dogs symptoms and clinical signs include hyper-reactivity, muscle swelling or muscle atrophy in very young puppies. Puppies may have pneumonia, respiratory distress, heart disease, diarrhea, difficulty swallowing, neck weakness, incoordination, joint abnormalities, paralysis of all four legs with the rear legs most severely affected, rigid legs, or death. The animal may be down or alert on presentation. Progressive incoordination and weakness, weight loss, loss of appetite, circling, fast heart rate, head tilt, abnormal eye movement, high stepping walking, head tremors, delayed placing movements, cranial nerve dysfunction, unequal pupils, paralysis, cervical hyperesthesia, and seizures have also been reported. In other words, neurologic disorders or many other symptoms can be associated with a neosporum infection.
How to DiagnoseTo diagnose neosporosis in dogs, blood work at your veterinary clinic (CBC and chemistry panel) will not have specific changes, in other words, typical bloodwork won't show this parasite. A PCR assay or titer or test specifically looking for the antibodies of the neosporum parasite is most helpful. However, it can take over three weeks to get the results. The most effective way to test is to run two samples three weeks apart to compare results, looking for a rise in the antibody test indicating recent active infection. When checking for chronic disease, an indirect fluorescent antibody test (IFAT) is the test of choice. Antibody tests can be used to differentiate toxoplasmosis from neosporosis. Fecal tests are not generally useful as the eggs are not typically shed in the stools.
Imaging such as x-rays and MRI do not yield specific findings. Tissue samples are also not definitive. Rarely a CSF (Cerebrospinal fluid tap) is diagnostic.
Neosporosis in Dogs Treatment and PreventionNeosporosis treatment in dogs consists of using two antibiotics, clindamycin combined with trimethoprim/sulfonamide for four to eight weeks. Treatment is most effective if started early, even if neosporum is suspected but while waiting for test results to return. Waiting until muscle contracture occurs may make treatment unsuccessful. Other treatments may consist of pyrimethamine and ponazuril (an extra-label drug use). Avoid the use of any immunosuppressive drugs.
If one puppy is diagnosed with the parasite, other litter mates should be tested and/or treated as well. The prognosis is poor to guarded.
Prevention is best achieved by avoiding feeding raw or undercooked meat, avoiding contact with placentas on farms, and removing feces. There has not been any indication of human disease.
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Marty Greer, Doctor of Veterinary Medicine, Director of Veterinary Services at Revival Animal Health
Marty Greer, Doctor of Veterinary Medicine, has 35+ years' experience in veterinary medicine, with special interests in canine reproduction and pediatrics. She received her Doctor of Veterinary Medicine from Iowa State University in 1981. She's served as Revival's Director of Veterinary Services since 2019.
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