Disseminated idiopathic myofascitis (DIM) is a disease of unknown cause in pet ferrets that targets their muscle function. Ferrets affected by DIM are usually less than 18 months old, however, some cases have been seen in adults over 2 years of age. The disease occurs in both males and females and does not seem to be influenced by whether or not the animal is spayed or neutered. It has not been shown to be contagious to other pets in the household, including other ferrets.
Signs of DIM in Ferrets
The signs of DIM appear suddenly and can worsen rapidly. A ferret can behave perfectly normally one day and show severe signs of DIM the next. Signs are variable, but they commonly include a lack of energy and appetite, weight loss, nausea and vomiting, fever, depression, and/or weakness that can impair their ability to walk. Other signs commonly seen that are not specific to just DIM include excess mucus around their eyes and nose, increased heart rate breathing rate, and changes to the skin. Ferrets with DIM are often found lying down, are reluctant to move and react painfully to touch, especially around their back.
Diagnosing DIM can be challenging because the signs are commonly seen with many other diseases and we do not fully understand what causes it. There is no definitive diagnosis for DIM, which means there is no test to determine with 100% certainty whether or not your pet has this disease. If your ferret shows a combination of these signs, your veterinarian will most likely complete blood and urine tests, radiographs, and possibly an ultrasound to assess the severity of the disease progression and try to rule out other potential causes. DIM is a diagnosis of exclusion, which means your veterinarian will run many tests to rule out other potential causes before concluding that your pet has DIM. The primary tool used for diagnosing DIM is a muscle biopsy where a small piece of muscle will be removed while the animal is sedated to look for signs of inflammation or infection within the tissue. However, the small section of muscle removed may not be representative of the entire muscle tissue, so a biopsy that is negative for inflammation does not guarantee that other muscles are not being affected by the disease.
Treatment and Prognosis
Unfortunately, due to the complexity of the disease, a general lack of response to treatment is one of the ways that DIM is diagnosed. Some veterinarians have had success treating this. Due to suspicion that DIM could be an immune-mediated disease, recent recommendations include treating suspected DIM ferrets with corticosteroids (such as prednisolone) and other immune system suppressants. A treatment protocol of prednisolone, chloramphenicol, and cyclophosphamide may suppress overall inflammation and auto-immune activity, and potentially, further progression of the disease. This protocol is recommended by the American Ferret Association, and continued research needs to be done to determine overall treatment effectiveness.
Supportive care is also very important and involves things like hand feeding, fluid therapy, pain medicine, and general antibiotics. Supportive care is meant to help relieve some of the patient's symptoms and suffering, but it has not been shown to effectively stop the progression of the disease.
DIM, unfortunately, still has a poor prognosis in ferrets. Since it was first described in 2003, DIM has been considered a fatal disease, as most of the cases confirmed by muscle biopsy resulted in death within several weeks. However, more ferrets are now surviving this condition with improved treatment. Veterinarians and researchers are actively studying these cases and the treatments used to help develop the most effective treatment possible for improving the prognosis of patients with DIM.