Rotavirus causes calf scour symptoms in calves between 3 days and 3 weeks old. Poor hygiene is the main cause of transmission in which can often be prevented through isolation.
There are two major viruses that are responsible for the prevalence of calf scour symptoms in dairy calves: rotavirus and coronavirus. These two viruses are highly infectious and can take a heavy toll on a calf’s body.
Bovine rotavirus is responsible for more incidences of calf scour or neonatal diarrhea in newborn calves than bovine coronavirus.
With calf scour (neonatal diarrhea) in newborn calves likely to cause a serious case of dehydration due to rapid loss of fluids, it’s essential to learn more about bovine rotavirus and what you can do to prevent it, and if need be, treat it.
What Is Rotavirus?
Rotavirus is an aggressive virus that causes calf scour symptoms in calves, affecting young calves between 3 days and 3 weeks of age. It is highly contagious and is the leading cause of neonatal calf diarrhea worldwide.
Unlike the human rotavirus that spreads by direct contact, rotavirus infection affects calves through the fecal-oral route before attacking the enterocytes (the intestinal absorptive cells), which leads to hemorrhagic calf diarrhea and eventually, dehydration.
Outbreaks usually have high mortality rates, and calves that manage to recover have less absorptive surface area of the small intestine, decreasing nutrient absorption and reducing their growth rates. Rapid loss of body fluids along with diarrhea often results in dehydration, essential nutrients, as well as electrolytes that are required.
Dehydration is particularly dangerous for calves due to their smaller body weights. In case of severe dehydration, rehydration therapy using enough liquid and electrolytes may be necessary. Severe dehydration can lead to death if not properly treated on time.
Newborn calves can be affected by bovine-specific coronavirus strain. This bovine coronavirus is also a major cause of calf scours (neonatal diarrhea). Calf experts have been dealing with it for many years before SARS-CoV-2, the novel virus that causes Coronavirus disease 2019 (COVID-19) appeared on the world scene.
Common Causes and Symptoms
Poor hygiene is the main cause of rotavirus transmission in dairy herds. Asymptomatic dairy herds can shed the rotavirus via their feces, making their calves susceptible to the infection.
Unfortunately, the virus can also be transmitted through exposure to rabbit and pig feces, so it’s best to keep these animals separated until cows are at least 6 months old.
Rotaviruses infect cells necessary for nutrient absorption in the small intestines. This causes nutrient deficiencies in a calf’s body and hinders water absorption in other parts of the digestive tract. The outcome is calf diarrhea, which makes the calf undernourished and unlikely to effectively combat infections like calf scours.
Common symptoms include:
- Watery or pale yellow diarrhea
- Dehydration
- Drooling
- Illness from secondary bacterial infections
- Straining when passing manure
- Reluctance to eat and drink
- Weakness and weight loss
Sometimes rotavirus infection can cause severe dehydration, heat stress, and electrolyte imbalance, which could be fatal. These symptoms last for 2 to 4 days, with fecal viral shedding persisting for 5 to 7 days.
Even if the calves manage to survive, they might be unable to attain their full growth potential.
Treatment and Prevention
- Animal rotaviruses spread via the fecal-oral route, and hence, it’s important to keep the calves in a clean and dry environment, particularly during the first few weeks of their life as this is when they are most vulnerable.
- Infected calves must be isolated in a dry and warm environment.
- Proper shelter or housing should be provided to protect the calves from weather elements to minimize stress.
- High hygiene standards should be maintained by cleaning and sterilizing all calving and feeding equipment.
- Infected calves must be hydrated with enough liquid and electrolytes to help replace those lost due to dehydration and electrolyte imbalance.
- While rotavirus vaccines are available for bovine rotavirus, they are often administered to adult cows before calving. This helps to increase the level of antibodies to potential rotavirus, coronavirus, Escherichia coli (e. coli), and other pathogens in the colostrum.
- Calves should receive enough colostrum within the first few hours after birth to boost resistance to rotavirus infection. However, you need to ensure that the said colostrum comes from vaccinated and infection-free cattle herds.
- Your vet can administer antibiotics to lower the chances of secondary bacterial infections.
- In case of severe dehydration, a drip can be administered.