Distemper is caused by a virus belonging to the same family as the measles virus in humans. It was discovered by Mr. Carre who gave it its name. The distemper virus infects most terrestrial carnivores: canids (dog, jackal), mustelids (ferret, mink), procyonidae (raccoon) and big cats (lion, tiger). You will know the distemper in dogs.
Pathogenesis and epidemiology
The distemper virus envelopes RNA. It means that it is not very resistant in the external environment, and eliminates by most common disinfectants.
Viral excretion is via all the organic secretions of the infected animal: urine, feces, saliva, nasal and ocular discharge. This shedding begins 7 days after infection and can last up to 60-90 days.
Transmission occurs mainly through the nasal route (aerosols) directly from one animal to another. Transplacental infection (from mother to fetus) has describe. Oral route is also possible.
Infection is possible whatever the age of the animal. Most sick dogs are between 3 and 6 months old (puppies during their critical phase, i.e. no longer sufficiently protected by maternal antibodies and not sufficiently protected by vaccines).
The incubation of distemper in dogs is generally long (time between infection and the onset of symptoms) from several days to weeks.
The virus infects certain white blood cells in the body (lymphocytes and macrophages, which involves in the dog’s immune protection and can spread to the spleen and thymus.
Subsequently, the virus reaches the epithelia (ie surfaces) of certain organs: the skin, the respiratory system (nose, larynx, trachea, lungs) and the digestive tract mainly. More rarely, the eye and the nervous system can be affected.
Dog’s immune response
The course of the disease will depend on the dog’s immune response:
- This response may rapid and effective. The virus will not be able to multiply correctly and the symptoms will be frugal. The infection will say to be sub-clinical and concerns approximately more than 50% of dogs;
- This response also may weak, late and ineffective. The spread of the virus will cause severe symptoms which will depend on the location of the viruses, the viral strains and the number of viral particles. This can lead to the death of the animal or lead to neurological sequelae.
Clinical signs and diagnosis
The clinical signs depend on the location of the virus within the organs. And, they usually do not appear at the same time.
In the classic form of distemper, the dog has significant inflammation of the eyes and nose (catarrh) with a viscous, purulent discharge from the eyes and nose, followed by a dry, then oily cough. Due to viral multiplication and immune response, fever is present (> 39.5-40 ° C). Pulmonary bacterial superinfections often complicate the clinical picture.
Of vomiting and diarrhea may occur thereafter. On the skin, redness and pustules are observable, as well as cracking / thickening in the pads and nose
Other eye damage (inflammation of the retina, optic nerve, uvea – area inside the eye) are rarer.
In severe classic forms, neurological signs appear later, suddenly or gradually, and manifest themselves in the form of convulsions, muscle tremors, difficulty moving.
Atypical neurological forms can appear directly and are often severe.
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Outcome of the disease
The outcome of the disease very often results in the death of the animal. When the animal manages to resist the infection, neurological lesions often persist which are disabling and which impair its quality of life: euthanasia may be recommended.
The diagnosis of the disease is first oriented on a combination of clinical signs (respiratory, skin, digestive, nervous). This is frequently a suspicion based on the vaccination status of the animal, its lifestyle and the clinical signs observed.
It is necessary to have recourse to laboratories to confirm the disease. Depending on the clinical signs, your veterinarian may take different samples.
You can check for indirect signs of an infection (i.e. show antibodies) from blood or cerebrospinal fluid (fluid that surrounds the brain). If the animal has vaccinated, interpretation of the results may be tricky.
It is possible to demonstrate the viral particles by a method known as RT-PCR (Reverse Transcription Polymerase Chain Reaction) from blood or cerebrospinal fluid or from conjunctival or oral samples.
Treatment and prevention of distemper
The treatment of the affected animal is mainly symptomatic. The veterinarian will put the animal on a drip to maintain a good state of hydration as well as a correct mineral balance. Anti-emetics as well as intestinal dressings will be administered to him, to limit water loss.
Antibiotic coverage will be put in place, in order to avoid frequent bacterial complications, especially in the lungs and digestive systems. In addition, if the dog has nervous signs, anti-convulsants will be administered.
The prognosis is very reserved, since in general, 50% of affected animals die despite the treatments implemented.
Prevention involves vaccination. The immunity conferred by the vaccines used by your veterinarian is long lasting, often over a year or even several years.
Distemper in dogs can still observe today, linked to the reservoir of wildlife. However, a correct vaccination adapted to the age of your dog will give him immunity that will protect him optimally. Your veterinarian will choose the most suitable vaccination schedule for your dog depending on his age and lifestyle.