Anyone who works with calves knows they can become sick and dehydrated very quickly. Andrea Lear, D.V.M, an assistant professor in the Department of Large Animal Clinical Sciences at the University of Tennessee, discussed fluid therapy options during a presentation at the virtual Association of Bovine Practitioners (AABP) annual meeting.
Lear began by explaining that young calves, especially during the first few weeks of life, have more body water compartments than older animals. Their capillary filtration rate and interstitial compartments are much more spongy and likely to hold water. She said this is important to know because it means calves are much more likely to be over fluid resuscitated — or more bluntly, our well-intended fluid therapy can drown them if not done properly.
Lear shared three methods for delivering fluids to calves: oral, subcutaneous, and intravenous.
Calves that are still standing and have a suckle reflex are good candidates for oral therapy. Lear pointed out that this is not a replacement for milk feeding. “We do not want to remove milk feeding from our calves if possible, and for no more than 12 hours,” she said. “The gut needs to heal, and they need that energy source. We need to supplement with some energy source if they are not taking in milk.” She suggested alternating oral fluids with milk feedings or adding an extra meal.
When selecting an oral electrolyte, Lear said to choose one that has sodium, potassium, and chloride. She said to supplement enough sodium to offset what is typically lost in diuretic calves by using an alkalizing solution. Bicarbonate does a great job, but she said that acetate and propionate are also good alkalizing agents, and a strength they have over bicarb is that they help with sodium absorption without affecting the abomasum’s pH.
Lear said that subcutaneous fluid delivery is a producer friendly method to give resuscitation to calves. It takes one to two hours to absorb, so it is not a great option for severely ill calves. Lear explained that subcutaneous fluids are inferior to intravenous therapy but may be useful in some situations.
Intravenous (IV) fluids can be lifesaving in calves that are very depressed, recumbent, severely dehydrated, or in shock. With IV delivery, Lear said the administrator has a lot more control of what is given, how fast, and how much. She did recognize that IV therapy is more costly and takes more time, particularly when placing and maintaining the catheter.
When using IV fluids, calves are typically treated for two to six hours, and then can be switched back to oral fluids as the calf responds. Lear said there are many commercial products available, or there are recipes for homemade fluids. Lear reminded that not all solutions are created equally, and she said that bicarbonate is the best for improving blood pH, followed by acetated ringers, and then lactated ringers.
“The use of combination therapy is critical,” Lear said. Due to the cost, time, and challenge of maintaining IV therapy, use IVs to resuscitate a calf, and then switch to oral electrolytes to save money and time.
Lear again emphasized that milk should not be withheld for more than 12 hours. “Those calves need energy stores to heal, not only their gut, but to grow and maintain their immune system to recover,” She said. If for some reason a calf can’t or won’t drink milk, Lear said to provide an IV dextrose solution or dextrose bolus to provide energy.