Parvovirus, a killer of young dogs

Learn more about the disease that is responsible for a high mortality among puppies.

By Ricardo Ribas

Canine parvovirosis is a common and highly contagious disease affecting dogs. It is caused by a virus that attacks the cells of the intestine stopping them to absorb essential nutrients and liquids, what leads to vomit and diarrhoea and subsequent weakness and dehydration. Unfortunately, many animals diagnosed with the disease will die, particularly young dogs and puppies. The good news is that it exists a vaccine to prevent the disease.

Learn more about this disease…

Image from kim_hester, pixabay.com
Image from kim_hester, pixabay.com

WHO IS TO BLAME?

This disease is caused by a virus (CPV2) that belongs to the family of the parvovirus, one of the smallest type of virus know to date. Canine parvovirosis is a relative new disease, firstly discovered in late 1970’s. It is believed to be the result of a mutation in a very similar virus responsible for feline panleukopenia, a disease that affects cats. In spite of this, CPV2 does not cause pathology in cats and only mildly affects minks as raccoons, given that is a virus that exclusively infect canines. In addition, it is very resistant to a wide range of pHs, temperatures and the majority of disinfectants, allowing it to survive in ground soil for up to a year. Commercial bleach is the only disinfectant able to kills this virus.

There are two types of parvovirus that can infect the dogs: the type 1 or non-pathogenic and type 2, responsible for this intestinal disease.

…AND WHO ARE THE VICTIMS?

This is a canine-only disease, with the dogs being the most affected species. For unknown reasons, some breeds are more predisposed to the disease, such as Doberman Pinschers, Labrador Retrievers, German Sheperds, Springer Spaniels, Rottweilers and Pit Bull. Young dogs and puppies particularly between six weeks and five months old are more vulnerable. This is because it is around the sixth week that puppies stop breastfeeding, thus losing the protection given by the mothers breast milk. In turn, the parvovirus vaccination schedule is not completed until around five months, at which time the likelihood of infection decreases.

HOW DOES THE VIRUS SPREAD?

Heavy concentration of the virus are found in the infected dog’s stool. Transmission can occur directly through contact with another dog, or indirectly, through contaminated objects such as cages, shoe soles, hands, clothing, etc. The virus can survive for up to one year outside the host, thus the man plays an important role in the indirectly transmission of the disease through the transport of contaminated faeces. The most dangerous places are those where there is a large concentration of animals, such as public parks, kennels, pet shops and dog shows.

Image from qimono, pixabay.com
Image from qimono, pixabay.com

VIRUS MULTIPLICATION

After ingestion, the virus multiplies in the tonsils before spreading through the bloodstream, to reach its favourite organs: intestines, bone marrow and lymphatic system, time which the first symptoms appear. This takes in average five to seven days. Generally, the intestinal signs, such as diarrhoea, are the most apparent. Rarely, in newborns, the virus can also lodge in the heart triggering cardiac arrest and subsequent death.

BE AWARE OF THE SYMPTOMS

After an incubation period of five to seven days, the animal starts losing the appetite and shows signs of severe vomiting and diarrhoea, sometime accompanied by blood and foul odour. If treatment is not started quickly, the animal will start losing weight, will get lethargic and dehydrated what can rapidly lead to death. In some rare cases, the virus can also reach the heart causing cardiac arrest and death, or trigger heart failure that can persist a life time, leading to exercise intolerance, coughing and difficulty breathing.

AVAILABLE TREATMENTS

Since there are no antiviral drugs to combat parvovirus, the treatment aims to target and reduce the symptoms of the disease, avoiding unnecessary discomfort to the animal and ultimately prevent its death. Most deaths of parvovirus occur between 48 to 72 hours after the appearance of the symptoms, reason why the treatment should start rapidly. This involve administration of intravenous fluid to prevent dehydration caused by the lost of liquids during vomiting and diarrhoea. The administration of antibiotics is also advised to prevent secondary bacterial infections. Furthermore, food should be withdrawn until vomiting ceases and, in more severe cases, anti-vomiting products are advised to prevent dehydration. In cases of diarrhoea with blood, blood transfusions may be required. It is very important to keep in mind that early detection of this condition is the key for the successful treatment.

The survival rate of animals treated in the hospital is about 70% and the majority of death are as a result of dehydration, secondary bacterial infections, production of toxins or severe loss of blood during diarrhoea.

SEVEN STEPS FOR PREVENTION

1. The main form of prevention is the vaccination. Thus, dogs should begin to be vaccinated at six to eight weeks of age, they are not complete resistant to the disease until they have received several boosters until the vaccination is complete. Boosters are given every three weeks until the animal reach six months of age. From that point, the dog should be revaccinated annually to strengthen its immunity.

2. Animals that are not yet fully vaccinated should avoid contact with other dogs, as well as contaminated objects and public places, especially those where other animals circulate.

3. In kennels and places where many dogs live, disinfection should be often perform using bleach to prevent the spread of the virus.

4. In the event of the death of a dog with parvovirus at home, bleach disinfection should be performed as the virus can survive for up to one year outside the host.

5. It is particularly important to be careful not to carry faeces in the shoes, specially when around animals that have not been yet vaccinated.

6. At the first suspicious of the disease, contact the veterinarian immediately since quick treatment is decisive for the animal’s survival.

7. If the animal successfully recovers from the disease, it can remain contagious for up to 3-6 weeks and the virus can survive in the ground soil for up to a year. It is therefore important that the animal remains isolated and that neighbours and family members with other dogs are informed so they make sure their animals are properly vaccinated.

By Ricardo Ribas, Veterinary Doctor, doctorate in veterinary sciences and researcher in the area of oncology in London.

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