myopathy

Neospora in Adult Dogs

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.

Limber Tail?

Limber tail, or cold tail, is known medically as coccygeal myopathy and is a poorly characterized condition associated with acute onset tail flaccidity and pain. Working dogs are more commonly associated with the disease, especially hunting breed dogs. I recently evaluated a patient with suspected "limber tail" and thought it might be fun for us all to review this unusual disease. The most recent study published was 2016, so I'll reference data from that study in this TidBit Tuesday. Reference at the end. 

What is the pathology associated with limber tail?

Limber tail is a self-resolving disease, usually within 10 days of the onset of signs, therefore very little pathology has been described for the problem. One study from Norway in 1999 identified inflammatory cells in the coccygeal muscles along with evidence of myofiber damage and elevated CK in dogs with clinical evidence of limber tail, compared to breed matched control (nonclinical) dogs. 


What are common triggers?

In a questionnaire to dog owners in the UK (2016) the following triggers were queried and the responses are as follows:

  • Swimming (29 yes, 9 no)

  • Exposure to cold weather ( 19 yes, 19 no)

  • Exposure to wet weather (11 yes, 26 no, 1 unsure)

  • Vigorous exercise (18 yes, 18 no, 2 unsure)

  • Confinement (5 crate, 1 car, 31 no, 1 unsure)

Some triggers appeared to be dual, such as swimming on a cold day. Increasing latitude has been identified as a risk factor, which is assumed to be linked to colder temperatures. They determined that while swimming was not a necessary precursor to the development of limber tail, it appeared to be a risk factor. The odds ratio of a swimming case compared to control was 4.7. Furthermore, cases were more related (had common ancestors) compared to controls and this was more than is expected for random selection. Otherwise, a similar distribution between cases and controls was noted for neuter status, coat color, height, weight, exercise levels, household type, and smoking vs non-smoking in the home. 

Do you need to treat it?

The self-resolving nature has made treatment protocols difficult to evaluate. Pain management in the early phases, as needed, is appropriate. This could include anti-inflammatory medications such as NSAIDs, but probably doesn't need to rise to the level of steroids in most dogs. Pain modulation with gabapentin, narcotics if severe pain is noted, or muscle relaxants could be utilized. If clinical signs have not resolved by day 10, additional diagnostic testing such as MRI of the lumbo-coccygeal region, electrodiagnostic testing or both may be indicated. 

I hope you enjoyed Labor Day holiday and weekend and have a great week! I am in town this week but leaving for a few days over next weekend to speak at IVECCs in beautiful Denver Colorado. I will have limited email and telephone access Monday-Tuesday September 11-12th due to travel and speaking hours. Please pardon my delay in response if you reach out on those days. Thanks for reading!

Reference: https://bvajournals.onlinelibrary.wiley.com/doi/epdf/10.1136/vr.103729