One of the germs that contributes to calf scours cases is cryptosporidia, or “crypto”. Crypto is a one-celled protozoa that is normally present in small numbers in the digestive tract of cows and calves. As such, it’s not an organism you can eliminate from a farm. Calves pick this bug up from manure on their mother or in their pen. It’s a very hardy germ; in cool temperatures it can survive for weeks or months. Illness results when calves get exposed to enough of the organism, or if their immune system is weakened by factors like poor colostrum intake or cold wet weather stress.
Crypto in Calves
Baby calves usually get their first exposure to crypto soon after they’re born, but the effects of the germ don’t show up until about 7 days of age. Once a calf gets to be about a month old, they’re pretty resistant to the effects of crypto.
The crypto organism invades the tips of the cells lining the intestines and significantly impairs digestion. There is an impaired ability to absorb fluids from milk, and the increased load of intestinal content further sucks water into the gut. Diarrhea is the result, sometimes mild and sometimes very watery. Often the manure from a calf with crypto has a pudding-like consistency, sometimes with a spot of blood in it. The resulting dehydration and metabolic derangements like low blood pH give rise to a calf that is slow, droopy, and uncoordinated. Many times crypto works in conjunction with other viruses or bacteria to cause calf scours.
There are no approved vaccines or specific treatments for crypto. Veterinarians have tried different medications with varying degrees of success. Supportive treatments like oral or intravenous fluids are pretty much all we have. When it comes to prevention, producers work on managing the calves’ exposure to large quantities of crypto by calving in clean lots or pens and managing weather and nutritional stresses.
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