Polymyositis in Cats
Key takeaways
Polymyositis is a rare condition in cats which affects the way nerves interact with muscles, characterized by inflammation of one or more muscle groups.
- Long term inflammation results in damage to the muscle tissue
- Primary polymyositis is an immune-mediated condition, with no identifiable underlying cause
- Secondary polymyositis can be caused by a range of underlying conditions and risk factors, including cancer, immune disorders, and infections
- Diagnosis is based on physical examination, blood tests, diagnosing imaging, and muscle biopsy
- Once diagnosed, treatment varies depending on the underlying condition causing the polymyositis
- In all cases, supportive care is required
- Prognosis varies and depends on the underlying condition and the timing of treatment
- While generally good with proper treatment, cats suffering from FIV or cancer have a guarded prognosis
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A closer look: Polymyositis in Cats
Polymyositis refers to chronic inflammation of muscles. Ongoing inflammation leads to tissue damage which ultimately reduces function of the affected muscle groups.
If a cat develops symptoms of polymyositis, prompt medical attention is crucial. Left untreated, polymyositis may lead to megaesophagus, which can be life threatening.
Polymyositis is either primary or secondary. Primary polymyositis is immune-mediated, meaning the body’s immune system is attacking its own tissues. Secondary polymyositis is a complication of other conditions.
Toxoplasmosis is the most common cause of polymyositis in cats. However, polymyositis is not the most common manifestation of toxoplasmosis.
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Risk factors
Polymyositis is a rare condition in cats. While generally treatable with proper medical attention, some underlying conditions that cause polymyositis carry a poor prognosis.
Cats diagnosed with FIV, cancer, and toxoplasmosis are at higher risk of developing polymyositis.
Cats with polymyositis can develop acquired megaesophagus, a dilation of the esophagus that interferes with regular feeding. Severe cases of megaesophagus may lead to aspiration pneumonia, which is life threatening.
Possible causes
Polymyositis can be caused by a number of underlying conditions and risk factors.
Immune-mediated primary polymyositis can have no identifiable underlying cause, or can be associated with cancers (such as thymoma).
Main symptoms
Testing and diagnosis
Animals presenting with symptoms of polymyositis generally undergo the following diagnostics:
- Physical examination
- Blood tests
- Tests for specific infectious agents
- Diagnostic imaging, such as X-rays and ultrasound
- Muscle biopsy
- Electromyography
Steps to Recovery
Once diagnosed, treatment depends on the underlying condition causing polymyositis. Specific treatment options include:
- Immunosuppressants: in the case of immune-mediated polymyositis
- Antibiotics: in the case of bacterial infections Antifungal medication
- Anti-parasitic medication
Regardless of the underlying condition, supportive care involves:
- Physical therapy
- Pain medication
- Rotating the patient frequently to prevent pressure sores if they are unable to stand
Prognosis of polymyositis varies according to the underlying condition and the timing of treatment.
With proper treatment, toxoplasmosis-associated polymyositis generally carries a good prognosis and improves within a few days of starting treatment.
Cats diagnosed with thymoma carry a guarded prognosis, as only a small number of affected cats react well to surgery.
In the majority of cases, cats suffering from FIV that develop polymyositis have a poor prognosis.
Immune-mediated polymyositis has a good to fair prognosis, depending on the success of treatment.
Prevention
Infectious polymyositis can be caused by parasitic, viral, or bacterial infections. Strategies to decrease the likelihood of developing infectious polymyositis include:
- Avoiding contact between infected and non-infected cats
- Screening cats for contagious diseases before introducing them into a home with other animals
- Keeping up-to-date with annual vaccinations and external parasite control
- Regular veterinary checkups
Immune-mediated polymyositis is a non-infectious idiopathic condition with no identifiable cause. Regular annual veterinarian checkups can help maintain general health and increase the likelihood of early detection.
Is Polymyositis in Cats common?
Polymyositis is a rare condition in cats.
Typical Treatment
- Physical therapy
- Pain medication
- Immunosuppressants
- Antibiotics
- Antifungal medication
- Antiparasitic medication
- Supportive care
