Calf dehydration is a serious problem that often sneaks up on producers. It’s easy to overlook until it becomes critical, but by then, the damage may already be done. The most common culprits are scorching summer heat and scours, both of which can strip a calf of fluids fast. The key to saving a dehydrated calf is spotting the signs early and acting quickly.
Once dehydration sets in, time becomes a critical factor. A calf’s condition can deteriorate rapidly, from mild weakness to severe compromise, in a matter of hours. Scours, a major cause, can lead to a life-threatening situation if not addressed promptly. This underscores the importance of being prepared with the right treatment and knowing when to intervene, as it can mean the difference between life and death for the calf.
Recognizing dehydration in calves is not always straightforward. It’s not just about noticing a calf looking a little droopy—there are subtle signs that can indicate trouble. Understanding these signs and knowing how to respond can play a crucial role in maintaining your calves’ health and minimizing losses. Here are five key signs that a calf might be dehydrated, empowering you to take proactive steps.
What causes dehydration in calves?
Young calves are especially vulnerable to scours, which is essentially severe diarrhea that disrupts their fluid balance. When a calf experiences scours, its intestines struggle to absorb the fluids it desperately needs. At the same time, extra water is drawn into the gut from the body. This combination creates a perfect storm that can quickly lead to dehydration and other health problems. It’s a critical issue that every producer needs to be aware of from day one.
The problem is compounded by young calves’ almost entirely liquid diet—they’re still nursing and haven’t started on solid foods like forages yet. This liquid diet makes them more prone to scours because their digestive systems are still developing. At birth, research from Texas AgriLife Extension tells us that calves are about 70% water, which underscores just how much they depend on proper hydration and nutrition right from the start. Any disruption in their fluid intake can have serious consequences.
Given these challenges, it’s clear that preventing and quickly addressing scours is vital for maintaining calf health. Understanding that scours not only cause fluid loss but also interfere with nutrient absorption helps explain why even a short period of diarrhea can be so dangerous. By monitoring calves closely and knowing what signs to look for, producers can step in before the problem escalates. In this way, early detection and proper management can make all the difference in keeping your young calves thriving.
Unraveling the Causes of Calf Scours
Any digestive upset can cause scours, but the three major causes are bacteria, viruses, and parasites.
- Bacteria: Such as Escherichia coli and Salmonella are common in newborn calves (usually younger than two weeks old). However, Salmonella can affect cattle of any age.
- Viruses: These include Rotavirus and Coronavirus, and they commonly affect calves in their first few weeks of life, usually 1 to 3 weeks.
- Parasites: Normally, Coccidia and Cryptosporidium parvum can cause diarrhea in young calves.
Even though these are the prominent three causes, they are not the only ones. Things like inadequate nutrition can also cause scours to pop up. My previous post, “Calf scours: what to watch for, how to treat it,” goes into more detail about this problem and how to handle it.
Along with the fluid loss from scours, the body also loses the electrolytes needed to maintain all bodily functions in the calf. This loss is why the death caused by scours is typically from dehydration. The loss of electrolytes causes a condition called metabolic acidosis, which will kill the calf in less than two days if not treated quickly.
Spotting the Warning Signs of Dehydration
There are generally five signs you can look for when trying to decide if the calf is dehydrated or not:
Courtesy of Penn State Extension
- Look at the calf’s overall attitude. A calf suffering from this will be more lethargic, will not stand as quickly, and will show a reduced interest in nursing.
- Check their suckle reflex. This check is done by putting a finger into the calf’s mouth to see if it will start to suckle on it or not. A well-hydrated calf will have a strong suckle reflex, while a dehydrated one will have a very weak response.
- Look at their eyes. As a calf becomes dehydrated, the eyeballs will pull inward, forming a gap between the eyelid surface and the eyeballs.
- Check the skin tend. This test is performed by pulling the skin and then releasing it. The more dehydrated the calf is, the longer the skin will snap back into place. It is normal if the skin flattens in less than 2 seconds. If it takes 2-6 seconds, the calf is moderately or 8%, and if it takes longer than 6 seconds, it is severely or 10%.
- Check their gums. In a healthy calf, the gums are moist, but as they become dehydrated, they will become sticky and take longer to return to normal color when pressed with a finger.
Stop Scours Before They Start
Since calf dehydration is primarily the result of calf scours, it is essential to understand that this disease is preventable. Taking the proper steps can significantly reduce the risk of scours and, consequently, calf dehydration at your farm, giving you a sense of control and hope.
Ensure all the calves get colostrum within the first 6 hours from birth. If they do not nurse from the cow, then provide colostrum via a bottle or tube. I go over what to look for in this in a previous article, “6 tips for colostrum replacer.” Colostrum is a calf’s most crucial defense until its own immune system kicks in.
The best way to prevent pathogens from popping up is to provide a clean environment during birth. The calving areas should be clean and uncrowded. No amount of colostrum or treatment can make up for excessive exposure to bacteria and viruses. Change the calving areas many times during calving to minimize exposure.
Providing a balanced mineral program to the momma cows before and after calving will also go a long way. This program will ensure that she has the foundation for average electrolyte balance and milk production.
Vaccinating cows during their final trimester can prevent Salmonella, Rotavirus, and Coronavirus infections. Vaccination causes the cows to produce immunoglobulins that attack these organisms. When the calves receive their colostrum and start nursing, they will receive these nutrients.
Fast-Acting Treatments for Scours
The type of treatment you will need to use depends on the severity of the calf’s dehydration. If the calf is light to moderately dehydrated, you can use oral rehydration solutions. 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 is receiving electrolytes, it will still need milk or milk replacement to supply it with energy and protein.
photo courtesy of Cargill
Feeding a calf too many electrolytes is nearly impossible, but giving them too little is a common problem. To calculate the amount of liquid to provide them with, multiply the calf’s weight by the percentage of dehydration and divide by 2 to get quarts of fluid.
For example, if a 100-lb calf is 8% dehydrated (100 x 0.08), then you will need 8 lbs of liquid. Next, 8 lbs of liquid divided by 2 equals 4 quarts required per day in addition to the regular milk feeding.
Summer heat affects these calculations without a doubt. When the temperatures get over 90 degrees, you will need to increase the amount by 50%. If the temperature is over 100 degrees, then you will need to double the amount to give them.
