by Simon Thomas BSc BVetMed CVR CSAO MRCVS, Gatehouse Veterinary Hospital, Bradford
Between 1993 and 1996 cases of a seemingly new disease in ferrets appeared in North America. It swept through rescue and rehoming centres and other places where ferrets were kept, affecting up to 100% of the ferrets in many establishments. It caused green, slimy diarrhoea and some (about 5%) died. The disease was given the name epizootic catarrhal enteritis (ECE). The cause of the disease is a virus called ferret coronavirus.
During April 2010 I treated a group of ferrets with a similar disease. Thirteen ferrets from a group of fifty two ferrets from a rescue and rehoming centre in Yorkshire under my care became ill. Nine of them died, two had to be put to sleep, and two recovered.
At first I was unsure what was causing the problem. Their keeper had been in contact with another ferret keeper about two weeks earlier. The person she had been in contact with had had five ferrets die around that time. My client had also been in contact with a third person who had lost ferrets and been told they were dying of distemper.
When the first two sick ferrets arrived at my surgery and I learned the story we suspected the problem might be distemper. We agreed that if either of them died I should carry out a post mortem. I started treating them with fluids and antibiotics but sadly one of them died the same day. The post mortem tests soon showed that the problem was not distemper, but that the ferrets had a form of enteritis.
At first the pathologists could not confirm what germ was causing it. Tests for all the common germs were negative and this definitely ruled out distemper. They suspected it might be coronavirus but it was to be several weeks before tests could actually confirm this.
Meanwhile, over the following days sick ferrets kept arriving and more often than not dying despite whatever treatment I gave them. The illness was very similar in all the ferrets. Most started off by becoming quiet and reluctant to move and producing black sticky faeces that stuck to their tails and bottoms. Often they would continue to eat and drink a bit at first. They would lose weight rapidly and become very weak on their hind legs. When I examined them would be weak and dehydrated.
At first I treated them just with antibiotics and fluids. As it became clearer from the laboratory tests that it was probably a coronavirus that was causing the problem I decided to try using interferon as well. Interferon is a drug that has been used to treat viral infections in humans, dogs and cats. It is licensed to treat coronavirus in cats; it is sold as Virbagen Omega. As it is not licensed for use in ferrets its risks and benefits have not been fully tested, but the manufacturers were able to provide some practical recommendations. On their advice I gave each ferret 2.5 mega units daily, injected under the skin. In theory the drug should work better the sooner it is given and could be given after exposure and before symptoms develop.
The antibiotic I used was a type of penicillin called co-amoxiclav which has several trade names including Noroclav and Synulox. I was worried that the virus might be allowing clostridial bacteria to mutltiply in the intestine and penicillin is the best treatment for clostridia.
Of the two ferrets that became sick and recovered, one was treated with interferon. The other never became very ill, had a more mild green diarrhoea and recovered without treatment. It was only towards the end of the outbreak that I started using interferon so there really is not enough evidence to show whether the cost (around £50 - £60 per ferret) was justified.
The whole outbreak lasted just twenty days from the first to the last case. The ferrets were housed in several groups but they would all have been exposed as the virus spreads easily both by direct contact and on hands or clothes. It is very likely that those that did not become ill have developed an immunity to the virus. Not much is known about whether some infected animals become carriers.
Many species of animals have their own coronaviruses and some species have more than one type of coronavirus. Cattle, dogs and cats all have coronavirus. the common cold in humans is also caused by a coronavirus. There are two licensed vaccines against coronavirus in dogs available in the United Kingdom. According to one of the manufacturers they did carry out a small safety test on six ferrets with the vaccine. Each was given a double dose of the vaccine without any seemingly ill effects. Sadly, there is no information as to whether the dog vaccine would protect ferrets at all; the best information I was able to glean, was probably not.
Nevertheless I know that some ferret owners have had their ferrets vaccinated with the dog vaccine. On the positive side this would have a good chance of protecting against distemper. Distemper largely disappeared from the UK around 18 years ago in 1992 and there is some doubt as to whether there have been any confirmed cases since then.
It is to be greatly hoped that other people do not have the same distressing experience as this group of ferrets. Fluids such as Duphalyte, antibiotics and perhaps Virbagen Omega seems to offer the best hope for treatment at the moment. Early treatment and good nursing are vital.
I would be very interested to hear from anyone whose ferrets have been affected with similar enteritis or with distemper.
Email Simon Thomas