Viral infections are very dangerous in all living beings and may leads to death because they compromise immunity badly. Like humans viruses are also leathal in animals and are high both in morbidity and mortality due to this reason every year large number of animals either large or small died due to viruses.
By Dr. Muhammad Rahman,Dr. Muhammad Sohail Sajid
Overview:
Viral infections are very dangerous in all living beings and may leads to death because they compromise immunity badly. Like humans viruses are also leathal in animals and are high both in morbidity and mortality due to this reason every year large number of animals either large or small died due to viruses.
Like other viruses Parvovirus is one of the deadly virus, it is non enveloped, single stranded DNA virus in case of feline this virus is known as feline Panleukopenia virus(FPV), and this maybe the origin of virus in dogs known as canine parvovirus(CPV) as real cause is still unknown which cause acute gastroenteritis and dysentery(bloodydiarrhea). It also compromises the canines other than dogs as foxes, wolves, Coyotes, minks, bobcats, and raccoons are among the wildlife animals that can become affected by parvovirus.
There are two strains of Parvovirus in dogs as CPV1 and CPV2, CPV2 is more life threatening contageous disease which affects about all breeds of dogs. Canine parvovirus mainly attack on unvaccinated puppies of age under 6 months but some cases reported upto the age of 10 months.
Transmission:
Transmission of virus takes place by feco-oral route as infected animal shed virus in feces(through diarrhea) which can be ingested by healthy animal. Virus can also transfer by body fluids as by saliva, nasal discharge, blood, urine etc. Fomites also play important role in viral transmission as contaminated floor, water and feeding bowls, collars, leashes, clothes, waste material of veterinary clinics like used syringes etc.
Direct contact with infected dog, owner hands, clothes, shoes and other utensils and pollution in environment can also be a risk factor.
Pathogenesis:
In first few weeks puppies get immunity from mother through antibodies in clostrum if she was vaccinated but if she was not vaccinated prior to whelping(delivery) then puppies are more prone to get infection due to lack of antibodies. As virus effects more quickly on immunocompromised puppies i.e if newborne do not feed on clostrum due to any maternal issue then they would have very low immunity and they will get infection at early stage.
So when those immunocompromised puppies come in contact with any infected animal or ingest any contaminated food with feces of infected dog then, according to estimate in one gramme of clinically affected dog faeces, there is enough viral content to contaminate almost ten million exposed dogs through oral ingestion, according to current scientific thinking. The virus is assumed to reproduce primarily in oropharyngeal lymphoid tissue before spreading to other tissues through blood. It is common for the gastrointestinal crypt epithelium to become affected by the fourth day following infection. Antibodies begin to form roughly 5 days after infection and reach maximum levels by the 7th to 10th day after exposure.
The virus gets into interaction with the dog’s body when it cleans itself or eats food that has fallen down on floor from mouth. Following the introduction of the virus into a dog, it takes three to seven days for the infection to express itself in clinical manifestations. Inside the lymph node, it then multiplies in an enormous number of copies. Approximately a week later, large masses of viruses in the circulation are expelled, and the pathogen infiltrates the bone marrow approximately 3-4 days later (fast dividing cell). The virus then weaken the intestinal cells, causing them to form sloughing as a result of the virus’s replication. Following that, the infectious agent targets the bone marrow and destroys the newly formed cells of the immune system to complete its destruction. Along with that, it begins to dismantle the body’s most effective system, defence system. Following that, the pathogen has the most devastating effects on the digestive system (GIT), and as a result of the inflammation of bone marrow, Canine parvo virus infection is indicated by a decrease in the white blood cells (WBCs). Villi are little finger-like projections that protrude from the surface of the intestine. These small fingers have been massively reinforced on the surface areas where fluids and nutrients absorption in the gastrointestinal tract is most difficult in access. These transitional cells are compact and easily replaced by new cells because of their compact nature. The Crypts, a rapidly dividable section of the villi at the root of the villi that serves as a source of new cells that contribute to the overall number of cells in the villi, is located at the base of the villi. The parvovirus invaded the crypt and rebuilt the villi into dulled shapes, rendering them incapable of engrossing nutrients. As a result, diarrhoea occurs as a result of a lowering in new cells from the crypt and as a result of the easy entry of bacteria resulting in widespread infection, which is addressed as secondary infection.
Symptoms and Complications:
Symptoms arises as due to the severity of disease in puppies as common symptoms which owner can see or observe like dullness, depression, loss of epitite, fever, off feed, lethargy, vomiting, diarrhea, dysentry (bloody diarrhea) etc.
Clinical signs:
Clinical signs of CPV infection may develop with in 5-7 days and may range upto 2-14 days clinical signs include:
- Temperature (104-106˚F)
- Dehydration
- Increase Capillary refill time(CRT)
- Sunken eyes
- Foul smelly diarrhea
- Dysentry(Bloody diarrhea)
- Vomiting
- Lacrimation and nasal discharge
Laboratory Test/Diagnosis:
Diagnosis based upon the history and clinical signs of disease and further to confirm diagnosis laboratory tests are required and for that purpose different tests can be performed to confirm the cases i.e
- ELISA
- PCR
- Fecal parvoviral antigen test
- Viral kit test
Kit is available now a days which is quick, cheap and efficient way to diagnose or detect infection in fews minutes. It is qualitative way to detect virus by the use of chromatography test so called as immunochromatography test to detect antigens in dog feces.
Treatment:
As it is viral disease so there is no specific treatment of disease but the only way is to increase the immunity of animal so he/she can resist against virus so for that purpose line of treatment to be used as supportive therapy so, intravenous route is best for quick recovery treatment can be;
- Use of Antipyretic and Antiinflamatory drugs
- Use of Fluids to compensate body fluid loss for that purpose crystalloide isotonic solution should be prefer
- Use of multivitamins to enhance immunity and for electrolyte balance
- Use of antibiotics like cephlosporin
- Use of metronidazole
- Use of Vit k or transamin to reduce blood loss.
- Use os antiemetics, metoclopramide
- Use of hyperimmune serum
Prevention and control:
To prevent disease quarantine is best method as separate infected animal from healthy ones and avoid all types of contacts either direct or indirect, so strict isolation is necessary. Proper disinfection is necessary to eleminate virus, as parvovirus is resistant to many detergents and disinfectants so use of formaldehyde and Chlorine is good solution.
Vaccinate puppies in time to minimize infection so to prevent virus it is necessary to strictly follow the vaccination protocol.
Different vaccines are available in market now a days, administer first shot of vaccine at age of 6 weeks and second shot after 21 days of previous shot. For proper vaccination 4 shots are required and then annually boster is necessary every year.
Authors
Dr. Muhammad Rahman
DVM, M.Phil Parasitology
University of Agriculture, Faisalabad
Dr. Muhammad Sohail Sajid
Associate Professor, Department of Parasitology
University of Agriculture, Faisalabad