The most common illness in young calves is scours. Dr. George Barrington of Washington State University says diarrhea causes the greatest economic loss in this age group—costs for treatment as well as death losses. In beef calves, one study showed 5.5 percent of calves die from diarrhea in the first three weeks of life.
Some years are worse than others. Intestinal infection and diarrhea can be caused by bacteria, viruses or protozoa. Whether calves get sick depends on multiple factors including “dose” of pathogens, level of calf immunity, and stress. Good weather, clean environment, and stress reduction help reduce incidence of scours.
Reducing exposure to pathogens is important—calving on clean ground (not where cows spent the winter being fed) and not having newborn calves in the same group with calves that are several weeks old. The Sand Hills calving method, in which the cows that have not yet calved are moved to new, clean pasture every two weeks, is one way to help prevent scours in young calves.
“The goal is to keep pathogens away from the youngest calves,” said Barrington.
If young calves are exposed to high levels of pathogens, they usually get scours. “Then they become ‘super shedders’ of those pathogens in their feces, and contaminate the environment quickly. This puts other calves at a much higher risk for disease,” he explained. Younger calves are most at risk.
Boosting calf immunity is another important strategy, giving cows pre-calving vaccines to ensure they have a high level of antibodies in their colostrum, then making sure each calf nurses soon after birth—to absorb those antibodies.
Treating the scouring calf
Barrington says supportive treatment with fluid and electrolytes is crucial. Regardless of the cause of scours, dehydration and resultant acid-base imbalance is often what kills the calf. A calf that becomes acidotic may go into shock and die. Dehydration and acid imbalances must be reversed.
Determine how dehydrated the scouring calf might be, to know if you can turn it around with oral fluids or whether he needs IVs. “When a calf is 5 percent dehydrated, we see clinical signs,” Barrington said. The calf is dull—not strong and perky.
“By about 12 percent dehydration you could lose the calf. There’s a small window between 5 percent (where you wonder if he’s dehydrated), to 10 or 12 percent when he’s on death’s doorstep,” said Barrington.
If a calf is scouring, losing more fluid than he’s taking in, and isn’t suckling the cow, you need to reverse this while he is still strong.
Ideally, we want to give fluids orally—while he still has a functional gut that can absorb fluid. When he gets severely dehydrated, oral fluids won’t do any good because there’s no gut motility; the gastrointestinal tract has shut down. Most cow-calf producers are good at giving oral fluids but some don’t feel comfortable giving IVs and might take the calf to the vet instead of doing it themselves.
“The goal is to keep pathogens away from the youngest calves.”
If the calf is still able to stand and walk, even if he’s weak and wobbly, he may not need IV fluids. “If he’s down and can’t get up without assistance, he may be past the point for oral fluids. Muscles are weak, ears are cold, body temperature is low, and the mouth is dry. If a calf gets so dehydrated that he’s going into shock, he needs intravenous fluids as soon as possible,” said Barrington.
“With shock, the body shuts down circulation to non-essential body systems like the gut (shunting blood to heart, lungs, brain, etc.), and oral fluids won’t help. Our goal is to try to treat calves with oral fluids before they get to this point. If we match the proper electrolytes with the calf’s needs, we can usually reverse dehydration,” he explained.
Determine the volume of fluid needed, by weight of the calf. “Based on his weight, we consider three issues. First is what he needs for normal maintenance (how much he would drink in a day). Second is the degree of deficit due to dehydration. Third is how much he’s continuing to lose, via diarrhea.”
If he’s been off feed, not nursing mom, and scouring, he may be quite dehydrated. “For example, a 150-pound calf would typically drink about 4 quarts per day, just for maintenance, and likely drink nearly twice that much milk. If he’s dehydrated just 5 percent, he’s down that much already and will need about twice that much in a 24-hour period just to get back to a good level. A 150-pound calf that’s 5 percent dehydrated is already about 4 quarts short of fluid to begin with,” Barrington said.
During a 24-hour period this calf would need about 8 quarts of fluid to satisfy his deficit and maintenance, plus what he’s continuing to lose via diarrhea. “He might need 10 or more quarts of fluid per day, split into three feedings. One feeding of fluid/electrolytes might help, but it’s not enough,” said Barrington,
The younger the calf, the more quickly he can dehydrate with scours. He has no body reserves and it’s urgent to administer fluids often. “These calves need adequate volume and also need the electrolytes they are losing through diarrhea,” he said.
To reverse the imbalances, the electrolyte mix must contain salt (sodium and chloride), potassium, an energy source like glucose, and amino acids like glycine or alanine. “The glucose and amino acids aid absorption of electrolytes (especially the sodium, which in turn helps the gut absorb fluids) and provide some energy for the weak calf,” he said.
“By about 12 percent dehydration you could lose the calf.”
“Since most calves are acidotic because of the dehydration causing electrolyte imbalance, commercial electrolyte solutions may also contain bicarbonate, acetate, or citrate. All of these have advantages, depending on the calf’s situation.” Ask your vet which products might be best for certain cases. In some instances acetate is better than bicarbonate, if the calf is still consuming milk. Bicarbonate interferes with digestion of milk.
Ranchers who are proactive on supportive care save more calves. Most producers know how to use an esophageal feeder probe for giving fluids and some use a nasogastric tube. These are quick and easy ways to get electrolyte fluids into the calf and a safe way to do it if you know how to use these tools.
Often the diarrhea on a certain ranch is caused by certain pathogens. Work with your vet to determine the cause. If it’s bacterial the calf needs antibiotics. “Often, we guess at the cause (viral or bacterial, or protozoal like cryptosporidiosis or coccidiosis) based on age of the calf and clinical signs. There may be some merit in putting certain calves on systemic antibiotics (in addition to supportive care with fluids and electrolytes) to combat secondary bacterial infections that may cause septicemia.
“If you can’t turn scours around quickly with oral fluids the calf probably needs an IV, and your veterinarian can show you how to do it,” said Barrington. — Heather Smith Thomas, WLJ correspondent
