PARVO

Parvo is a highly contagious viral disease that can be potentially fatal, especially in unvaccinated puppies.
The responsible virus is classified as Canine Parvovirus Type 2 (CPV 2), to distinguish it from another Parvovirus (CPV 1) found in dog feces, without pathological significance. It is a very resistant virus in the environment (it can also withstand up to 1 year) and to the action of detergents and disinfectants.
The virus is excreted in the faeces and multiplies in the digestive tract and bone marrow. Penetrated into the body orally, after an incubation period of 3-8 days, the virus initially replicates in the oropharyngeal lymphatic tissues, from which it spreads haematogenously to all tissues. Subsequently, the virus localizes to the lymphohematous tissues of the bone marrow and to the lymphoid tissues of the jejunum and ileum, where it causes respectively neutropenia, lymphopenia, destruction of the intestinal villi with necrosis of the epithelium and hemorrhagic diarrhoea. As a result of immunosuppression, infected animals have frequent secondary bacterial infections (from Escherichia coli, Salmonella, Campylobacter and clostridia) which aggravate the pathogenetic picture. From the 3rd day post-infection the animal becomes a virus eliminator.
Infection can occur by direct contact with the faeces of infected dogs or indirectly through exposure to the environment or to contaminated objects, such as litter boxes or bowls.
Parvoviral infection can affect dogs of any age, although most cases occur in young puppies between the ages of 6 weeks and 6 months. Unvaccinated or partially vaccinated animals have a considerably higher risk of developing parvo.
Some breeds are described as predisposed to canine parvovirus infection, such as Dobermann Pinscher, Rottweiler, English Springer Spaniel, German Shepherd, American Pit Bull Terrier and Dachshund. These breeds, once infected, also tend to develop more severe symptoms.
Toy Poodles and Cocker Spaniels appear to have a reduced risk of canine parvovirus infection. Puppies whose mothers have been regularly vaccinated are also affected less frequently and less severely by parvo. This is because vaccination from the mother increases the levels of circulating maternal antibodies in young puppies. The spread of canine parvo is worldwide. The first episodes of canine parvovirus sustained by CPV were observed in 1978 in America, the disease spread rapidly throughout the world, affecting wild canids and domestic dogs, soon becoming an endemic disease.

CORONAVIRUS

The incubation period is short, from 1 to 4 days.
After 3-4 months of infection CCoV can usually be present in the faeces of infected dogs.
After infection, the virus migrates to the mature epithelial cells of the small intestine villi, in which attacks and damages them, and where it reproduces rapidly.
During infection, the virus and its viral antigens are then transported to the underlying lymphoid tissue. Absorption into intestinal lymphoid tissue suggests that CCoV may persist and become latent in some dogs.