Scouring Calves – Factsheet
Once a cow has calved the next big challenge is to get the calf through the first few weeks without scouring. Scours are the main cause of death in calves between 2 and 30 days of age. Of scour samples submitted by Dalehead Veterinary Group for laboratory examination in 2006-7, the following infectious agents were found.
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Calves under 2 weeks old
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80% Cryptosporidia
50% Rotavirus
10% Coronavirus
10% K99 Ecoli
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Calves over 2 weeks old
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35% Cryptosporidia
30% Rotavirus
12% Salmonella
5 % Coccidiosis
40% No diagnosis
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The fact that the percentages add up to over 100 shows that mixed infections, for example with Rotavirus and Cryptosporidia, are common.
ROTAVIRUS AND CORONAVIRUS
Sources of infection – adult cows (symptom-less carriers) or scouring calves. Hygiene in the calving boxes is important, if there is faecal contamination on the cow’s teats the calf may get a mouthful of Rotavirus as well as colostrum when it suckles!
Colostrum contains antibodies to Rotavirus and Coronavirus. During the first few hours of life the calf can absorb significant amounts of antibodies from colostrum through the gut wall. After 6 hours of age only a small proportion of antibodies are absorbed although colostrum still has a local protective effect on the gut wall. It is therefore vitally important for a calf to receive as much colostrum as possible from its mother in the first few hours of life (at least 2 litres in the first 3-4 hours of life).
Infection with Rotavirus and Coronavirus targets the cells lining the small intestines resulting in a failure of digestion and absorption of nutrients, causing a yellow loose scour in calves 4 days to 3 weeks old.
Approximately 70% of the birth weight of a newborn calf is made up of water. A scouring calf loses fluids through the diarrhoea and rapidly dehydrates. The loss of body fluids also results in the loss of essential electrolytes (sodium and potassium) and the build up of acid.
Treatment consists of re-hydrating the calf and replenishing electrolytes with solutions such as Life Aid Extra. Antibiotics may be used to combat secondary bacterial infections. As a rule of thumb when a bucket fed calf starts scouring it should be taken off milk and receive at least 3 feeds (2 litres each feed) of electrolyte in a 24 hour period. As there is not enough energy in the electrolyte solutions to satisfy the demands of the calf and because the ability of the gut wall to digest milk is impaired if milk is not fed for significant periods of time I would recommend that for day 2 of treatment the calf should receive alternate feeds of milk and electrolyte, even if it is still scouring. I would not feed watered down milk because milk is digested by forming a clot in the abomasum and that watering down milk may inhibit clot formation. For the scouring suckler calf I would often recommend to leave the calf on the cow but to stomach tube the calf twice daily with 2 litres of electrolyte to limit the amount of milk that it takes from the cow. If any calf is unable to stand or appears very dehydrated I would recommend that it should be placed on an intravenous drip.
Prevention of Rotavirus infection in calves is by attention to hygiene in the calving boxes and calf pens and ensuring adequate update of colostrum by the newborn calf. In addition, vaccination of cows with Rotavec Corona between 3 months and 3 weeks before calving is an important part of any control programme and provides triple protection to the calf against Rotavirus, Coronavirus and K99 Ecoli and is far more effective than Rotavirus antibody pastes given to calves at birth.
CRYPTOSPORIDIA
Cryptosporidia is a protozoal organism (related to coccidiosis). It is not a bacteria, therefore is not controlled by antibiotics.
Cryptosporidia is not species specific – the same organism can also infect lambs and humans.
Oocysts (eggs) passed in the faeces of infected animals will survive for months in the environment.
Once ingested by a calf the organism multiplies rapidly causing the calf to scour after 2-5 days. Most frequently affected calves are 5-14 days old with a profuse watery yellow diarrhoea that is unresponsive to all the usual therapies.
A sick calf will pass millions of oocysts per gram of faeces.
There are no protective antibodies specifically for Cryptosporidia in a cow’s colostrum
Mixed infections with Rotavirus are the most common cause of severe scours in young calves between 5 days and 3 weeks of age.
Prevention involves paying particular attention to hygiene and stocking density in calving boxes and calf pens. Ensuring adequate intakes of colostrum will provide protection against other causes of scours and therefore help the calf to combat cryptosporidial infections. Halocur (a drug licensed specifically to combat Cryptosporidia) can be given daily to calves for 7 days as a prevention starting at 24 hours of age.
Treatment involves re-hydration of scouring calves and Halocur treatment daily by mouth for 7 days to suppress multiplication of the cryptosporidial organisms.
DIAGNOSIS OF SCOUR PROBLEMS
We are able to offer free “in house” testing of scour samples in the surgery for Cryptosporidia and are currently able to arrange free testing at Biobest Laboratories for Rotavirus, Coronavirus and K99 Ecoli examination. Although treatment of all calf scours involves re-hydration it is important to determine the cause before embarking on preventive treatments for Cryptosporidia.