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- Bovine coronavirus is one of the pathogens frequently associated with calf diarrhoea.
- Calf diarrhoea has several potentially fatal outcomes, such as dehydration, an electrolyte imbalance and acidosis. The cause of infection is multifactorial.
- The mechanisms of action and clinical appearance of corona- and rotaviruses in calves are very similar.
- While there is no specific treatment, calves will require oral or intravenous fluids. The disease is best prevented though good hygiene and farming practices, with lots of emphasis on adequate, timely colostrum intake.
- Although the test is extremely sensitive and targets specific antigens, it is important to investigate diagnostic results and confirm the outcome by way of further laboratory tests.
Bovine coronavirus is one of the pathogens frequently associated with calf diarrhoea. Like a few other viruses, including rotavirus, it is part of a group of organisms known to cause diarrhoea in calves in the first three weeks of life.
In an article published in VetNews, Dr Chantelle Erwee, technical manager of ruminants at Zoetis South Africa, says calf diarrhoea is a serious problem worldwide, especially because of the sizable impact it has on the welfare of infected animals.
Cause and effect
Calf diarrhoea has several potentially fatal outcomes, such as dehydration, an electrolyte imbalance and acidosis. The cause of infection is multifactorial; however, it can be broadly classified as contagious, non-contagious or a combination of both. In terms of infectious causes, multiple pathogens such as viruses, bacteria and protozoa play a role.
While calf diarrhoea often has a primary cause, multiple factors and pathogens, which can exacerbate the disease and number of fatalities, are involved. Depending on the situation, such as the country in question, the pathogens most associated with calf diarrhoea are bovine corona- and rotaviruses, Escherichia coli (E. coli) and Cryptosporidium parvum.
Dr Erwee says the mechanisms of action and clinical appearance of corona- and rotaviruses in calves are very similar. Both viruses have a short incubation period of around 24 and 48 hours, and affect mainly calves up to three weeks old – disease incidence is often highest at one week of age.
Read more about infectious bovine rhinotracheitis here.
Disease prevalence
In the article, “An overview of calf diarrhoea – infectious etiology, diagnosis and intervention”, authors Y Cho and KJ Yoon explain that coronavirus infection can present as three distinct clinical syndromes in cattle: diarrhoea in calves at one to two weeks of age; haemorrhagic diarrhoea in mature animals; and respiratory diseases, including bovine respiratory disease complex, in both young and mature cattle.
According to Scotland’s Rural College’s Premium Cattle Health Scheme News and Animal Disease Surveillance News, a diverse number of species are susceptible to coronavirus diseases. These pathogens have a severe impact on livestock, especially because they are highly contagious. Infected calves become depressed and present with persistent milky diarrhoea. The accompanying dehydration can be so severe that calves may die.
While there is no specific treatment, calves will require oral or intravenous fluids. The disease is best prevented though good hygiene and farming practices, with lots of emphasis on adequate, timely colostrum intake. On farms with confirmed cases and a history of disease, it is best to vaccinate in-calf cows against coronavirus. This will ensure that their calves enjoy greater protection via the colostrum they ingest.
Diarrhoea outbreaks may also occur in mature herds and are characterised by watery, dark, and sometimes bloody diarrhoea which is highly contagious. Some animals may also present with mild respiratory problems, and a slight drop in milk production may occur. Although supportive care is required in some instances, cattle are fully capable of recovering on their own.
Timely, accurate diagnosis
Dr Erwee emphasises the importance of quick, accurate diagnosis. Calf diarrhoea progresses rapidly and requires urgent treatment. It is also essential to plan future interventions to protect unaffected animals and prevent further outbreaks.
Veterinarians can make use of Zoetis’ WITNESS® BoviD-5 test kit for quick, reliable diagnosis. The test can detect rota- and coronavirus, E. coli K99, Cryptosporidium and giardia antigens in calf manure. It can also serve as a screening test, and it only takes ten minutes to interpret the test results.
Although the test is extremely sensitive and targets specific antigens, it is important to investigate diagnostic results and confirm the outcome by way of further laboratory tests. These results must be correctly interpreted by including clinical signs, a detailed history of the farm, and knowledge of the management practices and procedures employed on the farm.
Prevention through vaccination
Disease prevention, says Dr Erwee, is always the first line of defence and producers can use a product such as Scourguard® 4KC to vaccinate healthy, in-calf cows and heifers – it is also an excellent option for preventing diarrhoea in calves infected with bovine corona- or rotavirus (serotypes G6 and G10), enterotoxigenic strains of E. coli with the K99 pili adhesion factor, and Clostridium perfringens type C.
However, while the mother can be vaccinated, she warns, good colostrum management remains the key to preventing diarrhoea. Sound biosecurity protocols are therefore essential and include, among other things, good hygiene practices and the timely quarantining of infected calves. – Christal-Lize Muller, Stockfarm
For more information, send an email to Chantelle.Erwee@zoetis.com.
