Synonyms: Viral Gastroenteritis or Canine Corona Virus Gastroenteritis
Distribution
This disease is world-wide in distribution. This viral infection was first observed in 1971, both in calf and dog. The outbreak of the disease has been reported in 1972 from UK and 1978 from USA in canine population.
Pillai in 1990 reported the disease in canine from India.
The virus has been reported from calf in India. Corona virus infection has been recorded from pigs. In a survey, 26% of family owned dogs up to 87% of Kennel raised dog have been found to be infected with canine corona virus.
The disease can occur in any of dogs. This viral infection can be considered as emerging disease in canine population of India. In a recent survey in Madras 14% of faecal samples of dogs were found positive to corona virus infection. The incidence is more in winter.
Aetiology
It is caused by corona virus. The virus has affinity for gastrointestinal tract. The virus can be isolated through cell culture. This is a RNA virus, pleomorphic and 100 nm in diameter and replicates in enterocytes.
Borvine corona virus is a member of the family Coronaviridae, order Nidovirales. It posseses a single stranded enveloped, non-segmented RNA genome with positive polarity. The virus contains five structural proteins. They are:
- Nucleocapsid
- Transmembrane
- Haemaglutinin/esterase
- Spike
- Small membrane protein
The severity of the corona viral disease syndrome is influenced by various factors like stress, age, environmental conditions, breed and concurrent infections. This viral infection most often invade along with other infective agents. Neonatal diarrhoea in calf has been found to occur due to corona plus reo virus; corona plus E. coli, corona plus cryptosporidium; corona plus IBR. Concomitant infection with bacteria, other viruses, parasites etc may aggravate the condition in dogs.
Susceptible Hosts
Canine population is the main host of this viral infection. The disease is popularly known as CCV disease. Virus has been isolated from calves from their diarrhoeic faeces. Pig may also suffer. Guinea pig can be used as an experimental animal. Faeces of normal cat may contain the virus and therefore inapparent infection is prevalent in them.
Transmission
The virus is mostly transmitted through faecal contamination and vomitus. Animal to animal transmission is the main way of spread of the disease.
Faecal contaminated feed and water is the main source of infection
Pathogenesis
The virus invade the small and large intestine and damage the intestinal villi and there is villous atrophy. There is damage of the intestinal epithelium. The fluid from the intestine can not be absorbed and retained and later on profuse diarrhoea ensues. In dogs, the diarrhoea is accompanied with vomiting resulting to severe dehydration and death. In case of calf, on consuming milk it can suffer. Milk cause more and more absorption of fluid resulting to voluminous faeces and thus dehydration and death. This virus may also invade the respiratory tract causing respiratory problem.
Clinical Findings
Enteritis is the principal clinical signs of this disease. The initial signs of the disease are depression, lethargy and anorexia. There is sudden onset of vomiting and the vomitus sometimes may contain blood. Diarrhoea may persists up to 7-10 days and then subsides by itself. But, protracted or recurring diarrhoea may supervenes 2-3 weeks later. The faecal materials has yellow orange colour with occasional mucous and blood. The faeces has a marked foul odour. This viral infection has been associated with respiratory symptoms accompanied by nasal discharge and ocular signs like ocular discharge. As a consequence to diarrhoea, weight loss and dehydration takes place and severe dehydration may lead to death. Cat may show vomiting and diarrhoea accompanied by fever. Temperature reaction may or may not exist in dog. Majority may recover in 7-10 days. Death may occur in 24-36 hours.
Lesions
Lesions are mostly found in intestine. The villie of the intestine are atrophied and desquamated.
Diagnosis
It is based on history, clinical sings, history of immunization, post mortem lesions. There is drop in both WBC and lymphocytes. Serological diagnosis with various diagnostic tests are made
- Agar gel immuno diffusion test
- Counter immuno electrophoresis
- ELISA may be employed for the detection of the antigen. In a survey in Madras ELISA was found to be a superior test to detect the bovine enteric corona virus antigen in the faecal samples of bovine. Ager gel immuno diffusion test revealed 15.3% infection rate in canine from Chennai.
- PCR: In order to reduce mortality rates and economic losses caused by BCoV, it is suggested that in addition to vaccination and good management it is necessary to ensure that sub-clinical individuals are detected by RTPCR, nested PCR, quantitative real-time RTPCR.
Differential Diagnosis
This infection may be confused with similar other viral infections. In case of cattle this disease must be differentiated from reo-viral infection.
In dog, gastroenteritis is seen in number of other viral infection and therefore the differential diagnosis is to be done.
Canine distemper virus
It causes a contagious disease in dog, characterised by diphasic fever, gastrointestinal and respiratory catarrh along with neurological and pneumonic complications; Leukopenia and high mortality rate.
Canine parvo virus
It causes enteritis in dogs of all ages though dogs below 6 months of age are frequently affected. There are two form of the disease, enteric and mycardial. The enteric form is indicated by signs of depression, inappetance, diarrhoea, bloody stools, leukopenia and lymphopenia. Myocardial form is the less common form, reported in pups. Infected pups often cry and vomit with high as 50% mortality rate.
Infectious canine hepatitis
The disease is characterised by high rise of temperature, congestion, depression, leukopenia and prolonged bleeding time.
Canine adenovirus Type II
It is primarily a disease of respiratory tract characterised by pharyngitis, bronchitis, tonsilitis and pneumonia
Treatment
There is no specific treatment against this viral infection. Antibodies like tetracyclines, chloramphenicol may be administered for 5-10 days. Attempt should be made to prevent secondary bacterial invasions.
Symptomatic treatment should be done to control diarrhoea. Preparation containing kanamycin sulphate, pectin; bismuth sub carbonate may be tried.
Dehydration should be controlled with ringer lactate or dextrose with sodium chloride. In severe blood losses plasma volume expander may be used.
Control
Control as has been indicated in case of parvo virus in dogs can be followed.
In order to prevent the disease in endemic areas canine virus vaccine can be used for the vaccination of healthy dogs. This vaccine is commercially available as Duramune Cv-K, Nobivac-C, Biocan-C etc.
Dose: 1 ml subcutaneously or intramuscularly. The primary vaccine should be done at about 6 weeks of age. All dogs over 12 weeks of age should initially receive 1 dose and a second dose 2-3 weeks later. Annual revaccination with 1 dose is recommended.
In case of anaphylactic reaction adrenaline should be administered.
