Beat Calf Scours Before It Hits Your Bottom Line

Calf scours is one of those problems that instantly puts cow/calf producers on high alert—and for good reason. It’s the number one cause of financial loss in young calves, costing operations time, money, and sometimes entire calf crops if it gets out of hand. What makes calf scours in cattle especially frustrating is how quickly it can appear and spread. One day calves look fine, and the next you’re dealing with diarrhea, weak calves, and long nights in the barn. It can feel like a wildfire moving through a pasture, leaving producers scrambling to get ahead of it.

Part of the challenge is that calf scours isn’t a single disease. It’s a clinical sign associated with several causes, ranging from management issues to infectious pathogens. No matter the trigger, the result is the same—diarrhea that prevents the calf’s intestines from absorbing fluids and nutrients. That fluid loss leads quickly to dehydration, weakness, and a calf that just can’t keep up. If left untreated, scours can escalate fast, turning what looks like a minor issue into a life-threatening emergency.

Ask any experienced producer, and they’ll tell you just how serious scours can be. Calf scours is the leading cause of death in calves between 2 and 30 days of age, and dehydration is usually the real killer, not the infection itself. The good news? Calf scours is highly treatable when caught early. With quick action, proper treatment, and a solid prevention plan, most calves can recover and go on to perform well. In the sections that follow, we’ll break down what causes calf scours, how to spot it early, and the practical steps you can take to protect your herd and your bottom line.

As I mentioned above, no single disease causes scours. The known causes can be divided into two categories: non-infectious and infectious causes. The non-infectious are often referred to as contributing factors. Whatever you want to call them, there are interesting interactions between them. Preventing infectious causes is usually pointless unless you take profound control of the non-infectious causes.

Non-infectious causes of calf scours are often the result of how calves are managed and cared for rather than a specific pathogen or disease. These causes might not seem as urgent as infectious ones. Still, they play a significant role in setting the stage for the development of scours. It’s like creating the perfect storm. When calves are under stress or exposed to less-than-ideal conditions, their immune systems weaken, leaving them more vulnerable to infections. By addressing these factors, you’re not just avoiding scours but giving your calves the strongest possible start in life.

Poor nutrition, inadequate environments, and insufficient attention to newborns are among the most significant contributors to non-infectious calf scours. For example, suppose a cow doesn’t receive the proper nutrients during her last trimester. In that case, the quality and quantity of her colostrum may suffer. Without this vital first milk, calves miss out on critical antibodies that protect them from disease. Similarly, muddy, crowded calving areas and cold, wet weather can stress calves, making them less likely to nurse and more prone to illness. By focusing on these areas, you can dramatically reduce the chances of scours taking hold in your herd.

A cow’s nutrition during the last trimester of pregnancy plays a huge role in the quality and quantity of colostrum she produces at calving. If her diet is short on energy, protein, or key vitamins like vitamin A and vitamin E, the colostrum simply won’t deliver the immune protection a newborn calf needs. That puts the calf at a disadvantage from day one, increasing the risk of calf scours, sickness, and poor early growth. In short, what the cow eats late in gestation directly impacts how strong that calf starts out.

The good news is that this is one area where management really pays off. By meeting a cow’s late-gestation nutritional requirements, you can dramatically improve colostrum quality and give calves a stronger immune system right out of the gate. Balanced energy, adequate protein, and proper mineral and vitamin supplementation set the stage for healthier, more resilient calves. When you think of late-pregnancy feeding as an investment rather than a cost, it becomes one of the simplest ways to protect calf health and improve overall herd performance.

Muddy, overcrowded calving lots and mixing first-calf heifers with mature cows can create the perfect setup for calf stress and disease. These conditions increase exposure to bacteria and viruses while also placing additional pressure on newborn calves already trying to adjust to life outside the womb. Stress weakens a calf’s immune system, making it easier for infections like calf scours to take hold. Simply put, the dirtier and more crowded the environment, the harder it is for calves to get a healthy start.

Cold, wet weather only adds to the problem. Chilled or weak calves burn energy just trying to stay warm, which often delays standing and nursing. When calves don’t nurse early, they miss out on high-quality colostrum, their first and most important source of immunity. Providing clean, dry calving areas and managing cows and heifers separately can make a big difference in early nursing success. Small changes in calving management can go a long way toward reducing sickness and improving overall calf health.

Difficult births and rough weather can easily delay a calf’s first meal of colostrum, and that delay can have real consequences. After a hard pull or a long, cold night, calves are often slow to stand and nurse, especially if they’re weak or stressed. Every hour that passes reduces the calf’s ability to absorb antibodies, which raises the risk of calf scours and early sickness. When timing slips, calves start life already behind the curve.

Colostrum is the first milk a cow produces after calving, and it’s packed with antibodies that provide passive immunity to the newborn calf. Those antibodies are the calf’s only defense against disease until its own immune system matures. Getting colostrum into the calf as soon as possible—ideally within the first few hours of life—is one of the most effective ways to prevent calf scours. That’s why close observation at calving and being ready to step in with assistance can make all the difference in calf health and survival.

Scours pathogens are viruses, bacteria, and microscopic parasites. The damage that these pathogens cause will be in the intestinal tract. They cause the intestinal lining cells to malfunction and die. When the linings are damaged, it becomes difficult to absorb ingested milk.

E. coli is the single most important cause of bacterial scours in calves. The K99 strain causes diarrhea by impairing the intestines’ ability to digest and absorb milk nutrients. Most newborn calves will pick this up from the environment if sanitation is marginal. This particular strain, however, is only capable of causing scours when the calf is under a week old.

Rota virus, coronavirus, and a protozoan parasite called Cryptosporidia can damage intestinal walls. Healthy cows and heifers shed these parasites through their manure, releasing them into the environment. The scours they cause tend to be yellow and watery. Because they are not susceptible to antibiotics, the only treatment is to replace the fluids lost in the calf until the intestinal wall is repaired.

As is well known, diarrhea is one of the main symptoms of scours. A pathogen damages the intestine, preventing it from absorbing water and nutrients. As a result, the calf loses a significant portion of its nutrients. Because of this, treating diarrhea is the main focus. Signs of dehydration, such as sunken eyes, weakness, and dry mouth, are signs to look out for. Other symptoms include a loss of appetite, lethargy, and decreased body weight.

Acidosis is another sign that your calf might have scoured. The loss of salts disrupts the calf’s normal pH balance, leading to acidosis. In simpler terms, the calf’s body becomes more acidic than normal, which can lead to a range of symptoms. Calves with acidosis are weak and uncoordinated. They will show a drunken kind of wobbly gait when they walk. When you make them nurse, their suckle response is just a weak chewing motion. The calf cannot stand as it worsens and will become lethargic and sleepy.

Another common problem with calf scours in colder weather is hypoglycemia. Having scours prevents them from absorbing milk’s nutrients, so they won’t be able to replenish their body’s sugar reserves. If a calf has low blood sugar, it will generally develop subnormal temperatures as it loses its ability to maintain body heat. Low blood sugar also contributes to weakness and lethargy-induced acidosis.

When treating calf scours, the primary goal is to replace fluid losses from diarrhea. The intestinal wall will often repair itself, so you need to provide fluids to keep the calf healthy. Young calves are more prone to scours because of their liquid diet. They are still nursing off their mommas and have yet to begin eating more solid foods, such as forages and feed. Another factor to consider is that, according to Texas AgriLife Extension research, a calf is approximately 70% water at birth.

The treatment you need depends on the severity of the calf’s dehydration. You can use oral rehydration solutions if the calf is light to moderately dehydrated. Severe dehydration will require an IV solution to get the calf back to where it needs to be. One thing to note is that even though the calf receives electrolytes, it will still need milk or a milk replacer to provide it with energy and protein.

Feeding a calf too many electrolytes is nearly impossible, but giving them too little is a common problem. To calculate how much liquid they need, multiply the calf’s weight by the percentage of dehydration and divide by 2 to get quarts.

The ability to use antibiotics will depend on the cause of the scours. If rotavirus and the like are causing it, then it will be basically useless to use them.

The economic benefits of prevention far outweigh those of treatment. Prevention is the most essential and cost-effective way to invest your time. There are three main areas to consider when it comes to prevention.

Good hygiene will minimize exposure and help prevent the disease. When it comes to improving sanitation, you can take many approaches. The options include:

One essential step in preventing the spread of calf scours is isolating affected calves. Scouring calves can spread pathogens through their manure, contaminating the environment and exposing healthy calves to infection. By separating sick calves from the rest of the herd, you can minimize the risk of an outbreak spreading like wildfire. Isolation also allows you to focus on treating the sick calves without putting the rest of your herd at unnecessary risk. Think of it as creating a safe zone for your healthy calves while you work to get the others back on their feet.

Another critical prevention measure is ensuring that newborn calves receive enough high-quality colostrum. Colostrum is their first line of defense, providing essential antibodies that build up their immune systems. Without it, their risk of illness skyrockets, sometimes as much as three to ten times higher. This golden first milk is so important that it’s worth taking extra time to ensure each calf gets what it needs. If you’re curious to learn more about the power of colostrum, check out my previous post, “5 Astonishing Truths About Colostrum to Start Calves Right.“

Finally, vaccinating your cows before calving is a proactive way to protect your calves. Vaccines for diseases like E. coli, rotavirus, and coronavirus help boost the antibodies that the cow passes to her calf through colostrum. This boost gives calves a much-needed head start in their early days when they are most vulnerable. Vaccination is a straightforward step with significant benefits, helping protect your herd from the potentially devastating effects of calf scours. By taking these preventative measures, you’re not just avoiding problems—you’re setting your herd up for long-term health and success.