In the spring of 1993, a brand new disease started to infect ferrets. This infection caused a severe, green, malodorous, mucoid diarrhea. Older ferrets were more prone to serious dehydration, anorexia, and death from this new disease. Young ferrets were more likely to recover, but some continued to have loose feces that looked like “bird seed” for several months. This disease quickly spread from the East Coast to the West Coast. Most ferret owners called this disease the “greenies.”
It took some time before veterinary pathologists, namely Dr. Bruce Williams and Dr. Matti Kiupel, were able to determine that this new ferret disease was caused by a coronavirus. They named this new disease epizootic catarrhal enteritis (ECE). Kiupel and researchers at Michigan State University were eventually able to determine that this was a brand new ferret coronavirus causing ECE.
Almost 10 years later, veterinarians in Spain detected a new syndrome caused by a coronavirus. Instead of staying in the gastrointestinal tract and causing vomiting and profuse, green diarrhea, the virus caused damage to multiple organs, including the liver, spleen, kidneys, lymph nodes, lungs and the central nervous system. This new syndrome was soon reported in America, other countries in Europe, and Japan. The clinical signs could include diarrhea, vomiting, weight loss, tremors, seizures, coughing and labored breathing. Most of these cases were young ferrets, and most of them died soon after getting sick. This is very similar to a disease in cats called feline infectious peritonitis (FIP). Kiupel and the researchers at Michigan State University were again able to sequence the virus. They found another new coronavirus in ferrets, and they named it the ferret systemic coronavirus.
Last year Dr. Gary Whittaker and researchers at Cornell University made a major discovery with the feline coronaviruses. They were able to determine what changes happen that allow the coronavirus of the cat’s GI tract to mutate into the coronavirus that can travel throughout the body and cause fatal FIP. The changes involve proteases, the spike proteins of the coronavirus, and the genes that code for the spike proteins.
Because the ferret coronaviruses cause clinical diseases and pathologic changes that are very similar to the cat coronaviruses, Whittaker and his research team at Cornell University are now looking into the ferret coronaviruses. They want to see if the ferret systemic coronavirus has the same mutations as the cat FIP coronavirus.
They are currently seeking samples (blood, feces and biopsy samples) from ferrets with the systemic FIP-like disease and from healthy housemates (feces). For more information about participating in this important research project, owners and their veterinarian can contact Whittaker’s lab at fcovstudy@Cornell.edu. This will hopefully lead to a better understanding of the ferret coronaviruses and eventually help with the development of better tests, treatments and vaccines.
Since 2006, Dr. Al Legendre and researchers at the University of Tennessee have been studying a new treatment option for cats with the dry form of FIP. They have been using an immune stimulant called Polyprenyl Immunostimulant (PI) to help the cat’s cell-mediated immunity fight the coronavirus. Several ferrets have also been started on this same medication. Based on preliminary data, PI appears to increase survival time and quality of life of ferrets with the systemic coronavirus. Veterinarians can order this product from its distributer.
So far ferrets just have the dry form of FIP. Wet form means there is a lot of fluid that builds up in the abdomen. In cats with the wet form it is easier to diagnose FIP. The dry form does not produce all the free fluid in the abdomen, which makes it more difficult to diagnose. However the dry form responds better to treatment with PI, so it gives a slightly better prognosis.
To definitively diagnose FIP in ferrets takes a few things: an exploratory surgery (or necropsy) with the typical visible lesions, sending a biopsy of the lesion to a pathologist, who sees the typical microscopic lesions (granulomatous inflammation) under the microscope, and then a special test (IHC) that actually stains the coronavirus in the lesion. FIP in ferrets is difficult to diagnose because it requires an exploratory surgery in a ferret that is usually already sick when you suspect FIP, and then some fairly expensive testing.
Currently, Dr. Bob Wagner and researchers at the University of Pittsburgh are working on a coronavirus (ECE) vaccine. This may help prevent ECE and reduce the risk for the more serious systemic FIP-like disease.
In the 20 years since the ferret coronavirus was first discovered, many exciting discoveries have been made. Unfortunately we still do not have an easy test for this viral infection, or a cure for this viral infection, or a vaccine to prevent it. However, great strides are being made in those directions. There is real hope that those break through developments may happen soon.
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