Medical Review: Neospora Myositis
You might be wondering why on Earth I'm talking about Neospora as a small animal vet. (Neospora causes abortion in cattle!) It infects dogs too!! Some of you have seen some positive cases with me throughout 2020 so, I thought it was worthwhile doing a mini-review so we could all brush up on it together.
Etiology: Toxoplasma gondii and Neospora caninum may cause myositis, peripheral neuritis or CNS meningoencephalitis.
Signalment:
Breed: any
Age: may be acquired in utero leading to signs at a very young age (months), or by consuming raw or under cooked meat causing signs at any age. **Adult onset is what I see most commonly. However, the dog pictured above was a puppy that presumably acquired it in utero.
Clinical signs: Stiff gait, muscle pain (myalgia), muscle atrophy. Note: Muscle atrophy can be anywhere including the muscles of mastication. I have been tricked into thinking a dog has MMM when in actuality it had Neospora myositis causing unilateral muscle atrophy in the masticatory muscles.
Diagnostic tests: IFA > 1:200 for Neospora caninum is consistent with an infection, however documentation with a repeated titer is recommended as a confirmatory test. Muscle biopsy showing the encysted organism is definitive but obviously the most invasive route.
Treatment options: Sulfadimethoxazine/ormetoprim (15 mg/kg PO q12h) or clindamycin (10 mg/kg PO q12h) twice daily is recommended for 4-6 weeks, possibly longer. Be aware that sulfa antibiotics can cause idiosyncratic myopathic drug reactions too!
Prognosis: Good, if treatment is started before severe muscle atrophy or fibrosis is present. Prognosis is poor if clinical signs are severe, or chronic.
Frequency: Uncommon, but not unheard of!
Voila! TidBit Tuesday-style update on Neospora caninum. 😊
Final question: When do I run the IFA? Answer: Any dog with a history of muscle pain, muscle atrophy (not explained by neuropathic disease) or an elevated CPK should have a Neospora titer performed. This disease is sneaky so I err on the side of caution and suggest running the test rather than getting caught unawares.
Be safe, be strong and keep those referrals coming!
Heads up for those of you in my referral area: I will be closed Thursday January 28th to celebrate my youngest kiddo turning 5 years old. My, how time flies! I apologize for any inconvenience this may cause and look forward to consulting with you on another day!