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Preventing calf scours starts at conception with good management

by Wyoming Livestock Roundup

“My new favorite slogan is nutrition matters,” says Dave Rethorst, veterinarian and owner of Beef Health Solutions. 

According to Rethorst, diseases like calf scours are often a secondary issue to poor nutrition and overall herd management. 


“Scours in calves can be caused by a whole list of bacteria and viruses,” Rethorst says. “Nailing down the cause will help ranchers begin a proper treatment plan and better prevent the issue in the future.” 

He notes bacteria such as E. coli can present in calves as young as 24 hours old and extend on for weeks. While viruses show up later, they can wreak havoc on the calf’s gut health and ability to retain fluid. 

“It is nearly impossible for a vet to accurately diagnose any sort of issue over the phone,” he says. “Especially with scours, there is a lot that goes into it, and we need to see the conditions and know the history of the herd to get a full grasp on the causes.”

“We understand not everyone is close enough to bring an entire calf for testing,” he says. “But, taking the right samples to send is critical in diagnostics. Isolated gut loops, swabs, tissues and lymph nodes are all helpful samples for vets to make an accurate diagnosis.” 

“Once in the lab, the samples will do a culture and sensitivity test to determine what virus or bug is causing the scours,” says Rethorst. “If bacteria are present, a sensitivity test is run to determine which antibiotic will be most effective.” 


“Our first and foremost concern with scour calves should be rehydration,” says Rethorst. “More often than not, the bug causing the scours doesn’t kill the calf, butdehydration does.” 

He explains dehydration occurs because the bacteria or virus prevents the calf from properly absorbing fluid. Dehydration can be determined by a skin-snap test. When we pull a calf’s skin, it should snap back. If it doesn’t, the calf is dehydrated. 

“I really like oral fluids to help with dehydration,” Rethorst says. “There are many effective brands.” 

He notes with oral fluids, ranchers should be careful of the dextrose levels. Too much dextrose in the mixture can prolong the scours. 

“I recommend two quarts of fluid, two to three times per day,” Rethorst suggests. “We also want to have our calves in a warm, dry environment.” 

“In the case the scours were caused by bacteria, be sure to consult the local veterinarian to ensure the correct antibiotic is being used,” says Rethorst. “I personally prefer injectable antibiotics as opposed to oral because injectables can treat a systemic infection more effectively and won’t disturb the gut any more than it already is.” 

Prevention is key

“Prevention is something I’m very passionate about,” Rethorst explains. “Diseases like scours are preventable through sound management practices in the herd.”

“When we think about calf scours, we have to think about the calf’s immunity,” he says. “Immunity begins at conception and in utero.” 

He explains the diet the cow consumes during her pregnancy can play a huge factor in the calf’s ability to fight off infections such as scours. 

“Once the calf is born, we want them to get maximum colostrum intake,” Rethorst says. “Calves without adequate colostrum are three times as likely to get sick in the first 24 hours and six times as likely to get sick prior to weaning.” 

“I really like the Sandhills method of calving,” he says. “This method prescribes after 10 days of calving, remaining pregnant heifers are moved to a new pasture so they can give birth on clean ground.” 

Rethorst notes his pet peeve is bringing orphan calves in from off the ranch to prevent drying up in cows that lost a calf. 

“All it takes is one calf bringing in salmonella and getting the rest of the babies sick to make a producer never do it again,” he says. “We never want to run the risk of introducing bacteria to the herd, especially with calves.”

Rethorst was featured on Merck® Animal Health’s weekly Doc Talk segment, hosted by Dan Thomson.  

Callie Hanson is the assistant editor of the Wyoming Livestock Roundup. Send comments on this article to

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