Distemper Vaccine Reactions and Anaphylaxis
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For vaccinations available for your ferret in late 2014, go here
Ron Hines DVM PhD
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You may want to read a companion article to this one, Vaccinations to Give Your Ferret . Distemper that ferrets occasionally contract is actually a disease of dogs. The form of distemper that cats contract will not infect ferrets. Although dogs often recover from distemper, the disease is usually fatal in ferrets. Ferrets that contract distemper have been exposed to a dog that was incubating the distemper virus or recently recovered from an infection. Young, unvaccinated dogs in a rural setting are the principal carriers of the distemper virus. The chances that your household ferret - that never leaves the home will contract distemper are very, very low.
The distemper virus does not survive long in the environment. Sunlight and drying quickly kill the virus, as do common household disinfectants. In my youth working at a veterinary hospital, I saw many cases of distemper every week. But it has become a rare disease in urban America because so many dogs are now vaccinated and immune to the disease.
Distemper incubation time in ferrets is 7 - 10 days. Infected dogs shed this virus through their respiratory tract, urine and feces. But ferrets usually get infected from a sneeze or a cough when the inquisitive pets meet. After it enters the ferret, the virus multiplies in the lymphatic tissue surrounding the pet's respiratory tract.
What Are The Signs Of Distemper That I Might See?
When ferrets contract distemper, the first signs are loss of appetite, lethargy and depression. Fever, skin rash and a clear to pussy eye and nose discharge soon follow. The characteristic rash of distemper in ferrets is present on the chin and between the rear legs. Many ferrets develop a dry cough, which soon becomes a moist cough as secondary bacterial pneumonia develops. Their eyes and nose become caked with brownish crusts and scabs. After this respiratory phase of the disease, the distemper virus invades the ferret’s nervous system causing twisted neck, cross-eyed gaze, muscular twitching, convulsions and incoordination. Some ferrets develop brown tarry stools and diarrhea. In some, the skin of the foot pads thicken and harden.
Early in the disease, distemper can be confused with human influenza to which ferrets are also susceptible. One can try to support ferrets, sick with distemper, with antibiotics and intravenous fluids but there is little chance of their survival. Ferrets usually die 12-14 days into the diseases. A few will appear to be on the road to recovery only to develop nervous deterioration several weeks to months later.
How Can I Protect My Ferret?
Although there is no effective treatment for ferrets that contract distemper, vaccines on the market are very effective in preventing the disease. Immunity in ferrets, as in dogs, is probably much longer than a single year. So yearly vaccinations are probably unnecessary. I vaccinate my own ferrets every three years. If your ferret will be exposed to young, unvaccinated dogs, vaccination every second year might be more appropriate until we have more scientific data on the length of vaccine immunity. You can read online about some of the problems that over-vaccination is thought to cause in pets.
Which Vaccine Is Best?
My preference is to use Purevax Ferret Distemper Vaccine. It is manufactured by Merial. Inc. If you have specific questions about the vaccine, you can call them at (678) 638 3000. The vaccine maker suggests that it be given to your pet at 8, 11 and 14 weeks of age and yearly thereafter. However, I feel that this is too often. I think the problems of over-vaccination occur in ferrets just like it does in dogs and cats. There are a lot of financial incentives for over-vaccination that I am concerned about. I have never seen a case of canine distemper in a ferret or dog that received even one vaccination after the age of 14 weeks. The company will say that if you wait until 14 weeks of age, your ferret might encounter the distemper virus and become infected. That is true. But a solution is to keep your ferret at home and not exposed to other animals until it receives its 14-week vaccination. I give the vaccination at 10 and 14 weeks and feel quite confident. Never vaccinate pregnant female ferrets.
Throughout 2013 and 2014, veterinarians experienced long periods when Merial's PUREVAX® FERRET distemper vaccine was unavailable. As of September, 2014, We do not know when (or if) it will return to the market. During this period, many veterinarians have switched to immunizing ferrets with Merck's Nobivac® Puppy-DPv, a vaccine that has been used successfully in ferrets in Europe and the UK for many years.
What if My Pet Has A Reaction To The Distemper Vaccine?
Anaphylaxis refers to a sudden and severe allergic reaction that causes a crisis in many body systems. It occurs in all species of mammals as well as in human beings. Some signs of vaccine reaction that ferrets experience are rapid breathing, redness or blushing of its ears, restlessness, vomiting and mucus diarrhea - both of which can contain blood, collapse, seizures and even death. I would refuse to revacinate a ferret that ever experienced any of these signs, no matter how mild. Each time the reaction is likely to be more severe. Anaphylaxis is an immunologic event in that portions of the immune system are responsible for all the events that occur. The immune system of ferrets and other animals contain memory cells that recognize things foreign to the body. To gain immunologic memory the body must be exposed to the agent once, to know it, and then a second time to remember it. Because of this the ferret’s first distemper shot never causes a problem.
When the ferret is exposed to the vaccine a second or third or fourth time the foreign protein (antigen or allergen) causes the release of dangerous mediator chemicals called histamines, leukotrienes, prostaglandins and tryptase. The ferret’s blood cells that are responsible for the release of these chemicals are called basophils and mast cells. These four chemicals cause the smooth muscle within the respiratory and digestive tract to contract and smooth muscle surrounding the blood vessels to relax. Blood vessels also begin to leak. This causes the respiratory distress and shock-like drop in blood pressure characteristic of anaphylaxis in ferrets. Histamine released into the skin causes the hives we see frequently in dogs and humans undergoing an anaphylactic reaction. In people, the most common cause of anaphylaxis are antibiotics, peanuts and bee stings.
It is safest if your pet does not receive more than one vaccination in a given week. After it receives it shot, stay in the waiting room for at least a twenty minutes and observe your pet to be sure it is OK. While you are waiting, do not let the ferret roam around the waiting room or introduce itself to other pets.
When I was using the old Fervac-D vaccine to vaccinate ferrets, I became all too familiar with anaphylaxis in ferrets. Within two minutes or less following vaccination, some ferrets would salivate and begin to hyperventilate. They would often void their urine and bowels. Some turned blue. I saw so many reactions that I began giving all ferrets a small (0.2ml) dose of chlorpheniramine maleate or benedryl antihistamine about twenty minutes before giving the vaccine. I never let ferrets leave the office until thirty minutes after receiving a vaccination. The company that produced this vaccine never admitted to problems.
Ferrets that show any signs of an impending vaccine reaction immediately receive an injection of epinephrine and oxygen via a face mask.
acute allergies or anaphylactic reactions are due to the ferret’s
body becoming sensitized to ingredients in the vaccine. It is not
the actual virus protein, needed to immunize the ferret, that causes
the reaction but other ingredients used in the propagation of the
distemper virus or used to preserve and fortify the vaccine.
My suggestions are for owners of pet ferrets in typical household situations. They are not for ferret breeders or people who keep large numbers of ferrets , nor for pet shops, ranchers, shelter or pet show conditions. In those situations, the likelyhood of exposure is much greater, the likelihood of a weakened immune system is greater and distemper virus exposure can be massive enough to override the animal's immunity.