Neospora has become increasingly common in veterinary neurology, especially in the last few years. Neospora is an obligate intracellular parasite that causes notable complications in cattle but is not commonly diagnosed in dogs. Dogs are a definitive host, which means upon infection, they will not pass this infection along to other hosts (unless that new host consumes their meat). In other words, do not eat a dog infected with Neospora (!!).
How do dogs get infected?
The most common transmission is transplacental or juvenile onset neosporosis. Dogs that develop clinical signs at greater than 12 months of age probably have adult onset or the newly acquired form. This form has fecal/oral transmission.
What are the clinical signs of Neosporosis in adult dogs?
There are two forms of disease, which may occur separately or concurrently. First, we can see neuromuscular disease. Signs may include a strict myopathy (difficulty opening the jaw, tetraparesis with normal reflexes), neuromyopathy (myopathy signs plus patchy reduced reflexes) to a full neuropathy (reduced reflexes in multiple limbs along with clinical weakness). The other option is CNS signs, for which cerebellar signs and seizures predominate.
How is it diagnosed?
Adult onset, or acquired neosporosis, is diagnosed via IFA titer. Different papers have listed different “positive” IFA titers. A recent article from Sydney Australia by Kennedy et al(DOI: 10.1111/jvim.17219), listed the positive IFA titer as 1:800. Previous studies have listed anything from 1:200 to 1:800 as the positive titer rate. I typically recommend retesting if you get anything over 1:200. If it goes UP or remains above 1:400 it is likely clinically active and warrants treatment (if clinical signs are present). PCR inconsistently diagnosed Neospora in the recently published study.
How is it treated and do relapses occur?
The first line treatment for most studies is clindamycin (median dose 15 mg/kg PO q12h) x 12-17 weeks. Sulfa antibiotics are the second line of treatment, and several dogs received both drugs in the recently published study. Prednisone is important during active CNS disease to minimize the secondary inflammatory reaction during protozoal die-off. The dose and duration of prednisone is variable, but immunosuppression should be avoided. Relapses were common in the most recent study (9 relapses occurred in 4 dogs) highlighting the need for either longer treatment, or prompt treatment if signs recur. All signs were similar to the initial presenting signs except for one dog.
Take home message?
Remember to test for Neospora caninum when presented with a dog with CNS signs, myopathy, or neuromuscular signs. A simple titer using IFA is the best step, followed by consultation with your local neurologist.
Thanks for reading! I hope you have a wonderful start to November and look forward to working with you soon.