Canine and feline infectious diseases

Canine Parvovirosis

Canine parvovirosis is also called canine contagious haemorragic gastroenteritis. This is perhaps the most serious and common of canine infectious diseases especially for puppies. This disease is a major problem, with outbreaks still occurring regularly everywhere due to the extreme resistance and contagion of the canine parvovirus responsible for it. The onset is sudden, with vomiting and foul, bloody diarrhea that leads to rapid dehydration and collapse. The heart may also be attacked by the virus. The death of the pet occurs very quickly, sometimes within 24 hours. The younger the affected pet is, the more severe the disease. Some breeds as Rottweilers, Dobermans and Pinschers show an extreme sensitivity to this virus. When in contact with this virus, the disease has a high probability of becoming lethal.

Pets are protected against many infectious diseases by antibodies present in their mother’s milk (colostrum) which they receive in the first few hours of life. This protection from maternal antibodies lasts less generally between 2 and 3 months… that is the reason why puppies become susceptible to parvovirosis around 8 weeks of age. The virus is such resistant that even if the puppy stays at home, the virus can get in and contaminate the house from the outside (shoes, clothes, hands). There is almost no way to apply total disinfection against this virus… so, the contamination of the pup is very likely to occur.

The best protection is vaccination. Parvovirosis vaccines are safe and efficient when they are not neutralized by the remaining maternal antibodies from the colostrum. That is the reason why vaccination schedules cannot be implemented immediately after birth. There are a lot of different vaccines available against parvovirosis but their efficacy can differ strongly.

Canine Infectious Hepatitis

Canine Infectious Hepatitis is a disease due to an adenovirus that attacks the liver and other organs like the kidney. In acute cases the death of the pet can occur within 24-36 hours. When it happens the dog first becomes anorexic, then develops some icterus (yellow coloration of the mucosae) and at the end, a violent haemorragic fever. Those pets that recover from the disease may become carriers and spread the virus via urine during several months potentially infecting other dogs.

Infected dogs and many wild carnivores like foxes can spread the virus via urine. This virus is very resistant in the environment and dogs can contaminate by just walking through an area polluted by contaminated urine.

Vaccination against canine adenovirosis induces quickly an extremely strong protection against canine hepatitis.

Canine Distemper

Canine Distemper is also called canine measles. This disease is highly contagious and often fatal. The different symptoms are respiratory distress, nasal and ocular discharge, gastroenteritis and nervous troubles. When pets survive the initial viral attack they are often left with permanent disability such as deformed teeth, nervous twitches or a predisposition to distressing epileptic fits. Treatment is often unsuccessful as the incubation period is long – often about three weeks – it is usually too late to vaccinate when an outbreak occurs.

Distemper cases are more frequently reported on wet and cold weather conditions (the dog can be contaminated by contact with distemper virus on the street as the virus can survive outside in such conditions). Furthermore dogs can carry the virus and directly contaminate other dogs whatever the environmental conditions.

There is no way to treat the disease when it happens and if a dog recovers, some sequelae remain. The only good protection goes though prevention by vaccination.

Leptospirosis

Canine leptospirosis is a disease caused by a bacteria called Leptospira that lives in contaminated water. There are several strains of Leptospira that are pathogenic in dogs and some strains induce more severe disease than others. The main symptoms appear 3 to 5 days after contamination. It first looks like a fever syndrome with anorexia and depression, then it becomes painful and the dog is reluctant to move. In the most severe cases the dog dies from an hemorrhagic syndrome and kidney failure after a few days. The diagnostic is difficult to make.

Most Leptospira are excreted by rodents and dogs when they urinate. The bacteria crosses the skin of the dog while walking in contaminated water by rat’s urine.

Vaccination can protect against the most pathogenic strains of Leptospira in dogs. But there is no vaccine able to protect against all strains. The criteria for a good vaccine choice is not only to prevent the clinical signs in the dog, but also to demonstrate reduction of mortality and the prevention of excretion of the bacteria though the dog’s urine. Few long lasting immunity vaccines exist against these pathogenic strains, even fewer are able to avoid the asymptomatic excretion of the bacteria.

Rabies

Rabies is a zoonotic viral disease which occurs in humans, domestic and wild mammals. When it occurs, the virus induces neurological troubles with changes in behavior. Often, a usually quiet dog becomes furious and extremely aggressive, and tries to bite any other animal, or human close to him. Every time rabies induces various behavior changes from furious behavior to paralysis. Once symptoms of the disease develop, rabies is fatal for both animals and humans.

The virus is transmitted to other animals and humans through close contact with saliva from infected animal (i.e. bites, scratches, licks on broken skin and mucous membranes). In Europe, foxes play a key role in rabies transmission to dogs and every year humans (mostly children) die after being bitten by a contaminated dog with rabies. Bats are also responsible for rabies transmission and may contaminates dogs even if they use to stay at home.

Rabies vaccination is the most effective way to prevent from rabies. The recommended vaccinal protocol can differ depending of the country legislation, but will start with 1 injection at the age of 3 months.

Kennel Cough

Kennel Cough is bronchitis characterized by a harsh, hacking cough which most people describe as sounding like “something stuck in my dog’s throat.” It is analogous to a chest cold for humans and it can become a serious condition in special circumstances (see below); in general, it resolves on its own.

Kennel Cough occurs when the respiratory mucosae have been weakened:

Environmental conditions may weaken these mucosae: shipping stress, cigarette smoke exposure, crowding stress, cold temperature, heavy dust exposure, poor ventilation.

When the dog is in contact with contaminated dogs, some contagious viruses can easily be transmitted then attack these mucosae:

• These viruses are the distemper virus, the Infectious laryngotracheitis virus and the Canine parainfluenza virus. Some others less frequent can be also involved. (canine herpes virus for example)
• Sometimes a bacteria such as Bordetella Bronchiseptica can worsen the infection.

The first line of prevention is to avoid exposure to aggressive environmental conditions. Then vaccination against the most important viruses involved build a strong barrier against Kennel Cough. Such vaccination should be done for all dogs.

Piroplasmosis

Canine piroplasmosis (also called canine babesiosis) is caused by a blood parasite called Babesia. It is transmitted by ticks a few days after the tick has attached the skin of the dog. This disease is widely spread over Europe and has been progressing north for a few years maybe due to the global warming.

Generally, incubation lasts 3 to 5 days, then, acute fever, general weakness and anorexia are the first signs that are observed, afterwards, dogs emit dark brown urine. The disease induces a liver and kidney failure that can evolve fatally within a few days. Sometimes the parasite wakes up after several months incubation and the disease may occur even if no tick were noticed during the previous weeks.

Vaccinating and controlling ticks’ infestation are the way to prevent canine piroplasmosis.

Lyme Disease

Lyme disease is also called Borreliosis. This disease affects both dogs and humans and is caused by a bacteria called Borrelia. This bacteria is transmitted by Ixodes ticks that live in forests. Even if diagnostic is uneasy, cases are frequently reported all over Europe. The first symptoms are not characteristic, mild fever, loss of appetite, lameness. Afterwards, more severe symptoms can occur like arthritis, cardiac failure or neurological troubles.

Treatment is based on long range antibiotic treatment. Prevention is possible by annual vaccination and Ixodes control by parasiticide treatment.

Canine Herpesvirosis

Canine herpesvirosis is caused by a virus specific to the dog. It is transmitted through genital or oronasal contact between dogs. In case of outbreak during pregnancy, it affects the embryo or the foetus and induces abortion. If the virus is transmitted to new-born pups, it causes mortality during the first 2 weeks of age. This disease is often asymptomatic in adults, sometimes canine herpesvirus is involved in kennel cough syndrome.

Vaccination of the mother can be proposed to induce passive protection in puppies.

Feline Panleucopenia

Thyphus is a highly contagious viral disease often lethal. Kittens are particularly vulnerable. When sick, the cat initially has a high fever, then diarrhea and immunosuppression result. Sometimes it can induce neurological damages. The virus responsible for typhus which is a parvovirus that is highly resistant in the environment. Therefore it is perfectly conceivable that an owner can carry the virus home on his shoes after walking in a contaminated area (places with unvaccinated cats).

Upper Respiratory Tract Infectious Syndrome

This is a syndrome caused by several viruses and bacteria that act alone or interact together. The most important viruses involved are the feline herpesvirus and the feline caliciviruses. The feline herpesvirus induces a high fever and a severe oculo-nasal infection with local inflammation and discharge which can lead to secondary infections. The cat never completely recovers from it and when the clinical signs disappear, the virus remains latent in the nervous system. The recovered cat becomes a latent carrier and relapses are likely to occur in case of a stressful event.

This is the reason why it is recommended to maintain regular vaccination of any cat throughout his life in order to minimize the risk of herpes recurrence even if the cat does not have contact with other cats. Regarding feline calicivirus, one should speak of feline caliciviruses because there are many variants of this virus capable of infecting several organs including the upper aero-digestive tract. Some calicivirus strains are considered as “hypervirulent” and may generate lethal infection within a few days.

Vaccination against feline calicivirus is highly recommended, however there are some calicivirus mutants that may escape the vaccine protection.

Chlamydia is also part of the agents involved in the upper respiratory tract syndrome. Chlamydia (or Chlamydophila) is a bacterium that is responsible for severe conjunctivitis especially in young cats and in catteries. Infected cats can be treated with antibiotics applied locally and given orally, daily during several weeks. Such option is fastidious and doesn’t exclude residual bacteria carriage.

Feline Leukemia

This disease should not be confused with FIV or “feline AIDS” although it is caused by a retrovirus closely related to FIV. The infection can induce the development of tumors and immunosuppression. The cat may be infected by direct contact with a carrier cat likely to shed the virus. After being infected, he might remain seropositive during several months or years without clinical signs before the first symptoms appear (weight loss, fever, lymph nodes swelling...). There is no treatment available.

Vaccination against leukemia provides a good level of protection on FeLV-negative cats and must be recommended for any cat that may come into contact with other cats of unknown FeLV status.