Following recent outbreaks of Distemper (Hondesiekte in Afrikaans) in Kwa Zulu Natal and Gauteng, it is important to have an understanding of this disease which is fatal in half of all cases of dogs that contract the disease.
What causes Distemper?
Distemper is a virus disease caused by the Canine Distemper Virus or CDV. This virus is a morbillivirus in the Paramyxoviridae family which is a virus group that affects humans, vertebrates and birds. This specific virus is not transmissible to humans but specifically targets dogs hence the name “Canine” Distemper Virus. The virus is closely related to measles virus in humans, and also to rinderpest virus in cattle, which at the beginning of the previous century almost killed the entire cattle population of Southern Africa. It’s a nasty virus.
What are the symptoms of Distemper?
The virus attacks mainly the respiratory system (from the nose right into the lungs), the gastro-intestinal system (from the mouth, through the stomach into the small and large intestines) and the central nervous system (mainly the brain). This means that the symptoms associated with the disease will be related to problems with these three main systems. In acute to subacute infections the dog will usually develop a fever within a day or two from being infected. The dog will go off its food and become weak and lethargic
Respiratory system symptoms may include a clogged up nose typically with mucous or slime that becomes hard, and hardening of the nose itself. This is a very telling symptom of Distemper but is by no means the only, or most typical, presentation of the disease. A dog with distemper may have a perfectly normal nose and still have the disease. Many times there will also be a discharge in the corners of the eyes. Other respiratory symptoms include coughing, sneezing and difficult breathing if the virus attacks the lungs.
If the gastrointestinal systems is affected you may see vomiting and/or diarrhoea.
If the central nervous system is involved you may have muscle tremors, a dog which seems disorientated and walks around as if they are drunk (ataxia), hind limbs which are dragged or seem lazy (paresis), a dog which cannot get up or falls down when they do get up (paralysis), and even seizures. Other symptoms which are not immediately visible and which only the vet may be able to pick up are lesions on the retina at the back of the eye, or an inflammation in the front of the eye called anterior uveitis. Hardening of the footpads (hyperkeratosis) was previously quite common because of the strains of virus involved, but seem to be less common these days.
How is Distemper diagnosed?
There are several blood tests which can be done by the vet, but it is a difficult disease to diagnose because unlike a disease like biliary or tick fever in dogs where you can see the parasite in the blood with a bloodsmear, in Distemper, as with all other virus diseases, you cannot see the virus as it is simply too small. The trouble with the blood tests are that they are often not conclusive. The reason for this is that some of the tests, test if the dog is building up antibodies (“soldier”) against the virus. However a dog that may previously have been vaccinated may show antibodies and not have the disease. Sometimes the dog may die acutely before the body was able to produce neutralising antibodies, so in that case the test may be negative, yet the dog still had the disease.
Another type of blood test where the white and red blood cells are counted and where the white cells are less than usual, called lymphopenia, may give an indication that the dog has a virus disease but it will not tell which virus the dog has.
If the dog has central nervous system symptoms, the fluid around the brain and spine called Cerebro Spinal Fluid (CSF) may contain antibodies but once again it may not be 100% diagnostic. There are other tests which can be run on the CSF (cell or protein content) which may be indicative, but does not conclusively confirm that the dog has Distemper.
There are a number of other diseases which can present with similar symptoms which the vet will have to rule out. On the respiratory side there is Kennel Cough or other upper respiratory tract infections. On the intestinal side there is Parvovirus and Coronavirus, parasitism like worms or Giardia, bacterial infections, toxin ingestion or inflammatory bowel disease. On the neurological side there is granulomatous meningoencephalitis, protozoal encephalitis (toxoplasmosis, neosporosis, babesia), cryptococcus or other infections (meningitis, Ehrlichiosis), pug dog encephalitis and lead or other poisoning.
Clearly Distemper is not a simple disease to diagnose and the vet will often have to rely on the age of the dog, its history, the results of the clinical tests and the appearance of the clinical symptoms, to make a diagnosis of Distemper.
How is Distemper transferred?
The virus is typically inhaled through the air from other sick dogs and also from physical contact with infected animals. The virus can survive for a period of time in the environment and if a dog which carries the virus sniffed around or spent time in a certain environment, it will leave tiny, tiny droplets (aerosol) which contain the virus in that area, which can then infect other dogs. A dog which is infected will inhale or ingest the virus and the virus will quickly spread through the mucous membranes to the local lymphnodes (these are like the remote “army bases” of the body which has to protect the body against invasions) where it will multiply and within one week the whole body will be infected.
How is Distemper treated?
Vets have over the years tried antiviral drugs of which there are very few anyway, and none have been effective. As with almost all virus diseases one has to support the body in its own fight against the virus because it is only once the body has been successful to produce antibodies (the “soldier cells” which kill the “terrorist” or virus), that the dog will be able to overcome the disease. Often, when the body is attacked by viruses and the immune system is fighting hard to overcome the infection, bacteria will cause a secondary infection and make the whole situation worse. Therefore antibiotics are often administered even though it will do nothing against the virus, but at least it will help the body fight off opportunistic bacterial infections and help the body to overcome the disease. Other treatment depends largely on which systems are affected and to what extent. The vet will typically give symptomatic treatment, for example if the dog has seizures, the vet may administer a drug to help contain the seizures and make them less violent. Certain drugs should not be given and it is important to consult with the vet in case you think your dog may suffer from Distemper.
Can Distemper spread to humans or cats?
In the past it was suspected that the Canine Distemper Virus can cause Multiple Sclerosis in humans. However this has been proven NOT to be the case and as far as we know the disease cannot spread from dogs to humans. Similarly, as far as we know, this disease cannot be transferred to domestic cats.
What is the prognosis should my dog contract Distemper?
Unfortunately the prognosis is not good and the mortality rate is 50%. It will be very difficult for the vet to tell whether your dog will fall in the 50% that will survive or the 50% that will not make it. The vet will have to assess the extent and severity of the clinical symptoms and the progression of the disease and based on that, will advise you whether treatment has any chance of success or not. An important thing to remember is that even though the disease may not appear to be very far advanced when you first present your dog to the vet, and there seems to be early good response to treatment, like the clogging of the nose and the discharge in the eyes clearing up, the dog may still develop fatal central nervous system signs later on. It is important to understand that the vet has no control over which way the disease may go and will do his or her best with your animal’s best interest at heart, when recommending treatment or not.
Can Distemper be prevented?
A resounding yes! Vaccination has been hugely effective in almost eradicating this disease and all dogs should be vaccinated, preferably yearly at the same time as their annual health exam. Your vet will give you more specific advice related to the area you live in and the risk factors involved and should the vet think that annual vaccination is not necessary, the vet will advise you accordingly.
Puppies and old dogs are more commonly affected and all puppies should go through an initial vaccination program from 6 weeks onwards to provide protection. Puppies born from mothers who were vaccinated and had antibodies will get this protection from the initial milk or colostrum from the mother in the first few days after birth. The protection provided through the mother’s milk will start waning after six weeks and this is why vets normally start vaccinating at this time, and repeating the vaccination three or four times with booster vaccinations with monthly intervals and then yearly thereafter.
What do I do if I suspect my dog to have Distemper?
Get them to the vet as soon as you can. Home remedies or treatment is unlikely to give your dog a fighting chance. Proper supportive and secondary infection treatment remains the mainstay of treatment.
Most importantly, have your dog vaccinated. Prevention is always better than cure!
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