Scours Treatment - Dealing with Dehydration

Published on Fri, 08/06/2021 - 1:00pm

Scours Treatment - Dealing with Dehydration.

 By Heather Smith Thomas.

 Diarrhea in calves can be a challenge, and a common killer of young calves.  It’s generally not the gut infection that kills the calf, however, but dehydration.  Early treatment and rehydrating the calf can make a big difference in the outcome.

Geof Smith, DVM, North Carolina State University says dehydration is one of the major things we need to deal with when calves have diarrhea.  “Dehydration, the loss of electrolytes and decrease in pH in the blood (metabolic acidosis) are the three biggest problems.  Rehydrating those calves is critical,” he says.

Regardless of the cause of scours (whether bacterial, viral, protozoal or something else), dehydration and the resultant acid-base imbalance is often what kills the calf.  A calf that becomes acidotic may eventually go into shock and die.  The dehydration and imbalances in the body need to be reversed before shock is severe and internal organs shut down.

“We typically combat dehydration with oral fluid and electrolytes, but use IV fluids if we need to.  Getting fluids into the calf is crucial, in terms of rehydration,” Smith says.  Generally, if treatment is started early, before the calf is severely dehydrated and going into shock, oral fluids are sufficient, if given often enough.    

George Barrington, DVM, PhD, Veterinary Clinical Sciences, Washington State University) says the first thing is to determine how dehydrated the calf might be, to know if you can turn this around with oral fluids or whether the calf needs IV fluids.  “When a calf is about 5% dehydrated, we start to notice signs,” he says.  The calf will be dull and not quite as strong and perky.

Getting a calf to drink oral electrolytes is challenging and time consuming since most sick calves don’t want to suckle (and especially don’t want to suckle something that’s not milk), so most people administer fluid via esophageal feeder/probe.  

You need to start reversing the problem before he’s severely dehydrated.  “By about 12% dehydration you could lose the calf.  There’s a small window between 5% (where you might be wondering if he’s actually dehydrated), to 10 or 12% when he’s on death’s doorstep,” says Barrington.  You want to intervene well ahead of that situation.

If the calf is scouring but doesn’t appear dehydrated yet, you should still address the fluid loss because he’s losing more fluid than he’s taking in, especially if he doesn’t feel good and doesn’t want to suckle.  If you can reverse this while he is still strong, you can turn it around a lot quicker.

It’s important to use a good oral electrolyte solution.  “Many folks think that one product is as good as another, but this is not the case,” says Smith.  When comparing electrolyte products in terms of rehydration potential, sodium content is very important.  Water by itself will not rehydrate the body; it must contain electrolytes and sodium.  This is why athletes don’t just drink plain water; they drink Gatorade.  We need to make sure the sodium concentration of the oral electrolytes we choose is adequate,” he explains.

 “It must contain salt (sodium and chloride), potassium, an energy source like glucose, and amino acids like glycine or alanine,” says Barrington.  “The glucose and amino acids aid in absorption of electrolytes (especially the sodium, which in turn helps the gut absorb the fluids).  Oral electrolyte solutions typically have sodium, chloride and potassium (the actual electrolytes) plus an energy source like glucose to aid sodium absorption, as well as provide a little energy for the weak calf.  It’s also ideal to have the proper amino acids,” he explains.

“Since most of these calves are acidotic because dehydration causes electrolyte imbalance, commercial electrolyte solutions may also contain some kind of buffer.  There are a number of different ones, including bicarbonate, acetate, citrate, etc.  All of them have their advantages, depending on the calf’s situation.”  Producers can ask their veterinarians which products might be best for certain cases.

When treating the calf, it’s important to keep administering the electrolyte fluid until the calf is no longer scouring.  “These calves often have diarrhea for several days, and should be given fluid and electrolytes during that time.  As long as they still have loose feces (even if they start to have good appetite and are also back on milk or milk replacer again), they need to be kept on the fluid and electrolytes to make sure they don’t relapse,” he says.

“We’ve found that oral electrolytes are very effective, as long as you are using a good product that is getting the calf rehydrated.  It is important, however, to recognize diarrhea early.  By the time the calf is weak or down and unresponsive, you have a much harder road in terms of treatment,” says Smith.  Some of these calves can get sick very quickly and if you are only seeing them twice a day at feeding time they may develop severe diarrhea between one feeding and the next.  Often the first sign of a sick calf is one that is a little off feed—not as eager for the bottle.  If calves are on a self-feeding system you might not notice that one is sick until it has severe diarrhea.

If you catch the problem early and put the calf on oral electrolytes, most of them will bounce back.  “Once they are down, and have no suckle reflex, they probably don’t have much gut motility and have lost the ability to absorb oral electrolytes.  If we tube them with fluid, it will just pool in the stomach and they can’t absorb it,” says Smith.  This is when a calf needs IV fluid and electrolytes.

Determine the degree of dehydration and whether you can get by with oral fluids.  If the calf is still able to stand and walk, even if he’s slightly weak and wobbly, he may not need IV fluids.  

“If the calf is down, however, and can’t get up without assistance, he may be too far past the point for oral fluids,” says Barrington.  Muscles become flaccid and weak; the ears are cold, body temperature low, and the mouth dry.  If a calf gets so dehydrated that he becomes shocky, he needs intravenous fluids as soon as possible.

“What happens with shock is that the body shuts down circulation to non-essential body systems like the gut (shunting it to heart, lungs, brain, etc.), so oral fluids won’t be of any benefit.  Our goal is to try to treat calves with oral fluids before they get to this point.  If we can match the proper electrolytes with the calf’s needs, we can usually do very well to reverse the dehydration,” Barrington explains.

“If the calf won’t take the electrolytes from a bottle, but still has a suckle reflex (able to suck on your finger) we can use the esophageal feeder,” says Smith.  “A person just needs to be careful and slow when putting the probe down the throat, making sure it goes down the esophagus and not into the trachea (windpipe),” he says.  

Most problems occur when the probe is rammed down quickly.  Because of the ball on the end, the probe is not supposed to be able to go into the trachea, but you always want to check by palpating the calf’s neck.  “Make sure you can feel the two tubes; you should be able to feel the plastic tube separate from the trachea.  Once you get the probe safely down the esophagus you can administer the electrolyte fluid,” Smith says.

Assessing Dehydration
To determine if a calf is dehydrated, check the eyes.  “The more sunken the eyes look, the more dehydrated the calf is.  If the eye is right under the eyelid, hydration is fairly normal.  If you roll down the lower eyelid and see a big space or gap, this indicates dehydration.  The more sunken the eye, the more dehydrated the calf is,” says Smith.

The pinch test is another way to assess dehydration.  “If you grab a pinch of skin on the side of the neck and tent it, twist it and then let it go, it should snap back into place immediately, in a normal calf.  The slower the skin return is, the more dehydrated the calf is,” he says.

Barrington says you can do the pinch test on any part of the body where skin is thin and relatively loose.  “If you pinch the top of the upper eyelid (skin tenting) or the neck or wherever the skin can be pinched, and watch to see how fast it sinks back into place, this gives a clue.  If the calf is less than 5% dehydrated, it goes back into place quickly.  At 5% or more, the skin stays tented a few seconds.  The more dehydrated the calf, the longer the skin stays tented,” he says.

Another clue is dryness of the mouth.  The inside of the mouth should be very moist.  “If that moisture becomes tacky/sticky the calf is about 6 to 8% dehydrated.  If it feels really dry the calf is severely dehydrated.  In the dehydrated calf the eyeball looks like it’s sinking back into the head,” says Barrington.   Tissues around the eye are dehydrated.

The calf will also be depressed and dull.  “If you’ve ever been dehydrated, you know you don’t feel good.  A person can be less than 5% dehydrated and before you actually have clinical signs of dehydration you feel like you got hit by a truck.  If a calf starts to feel off and you check for signs of dehydration, he may not show much sign yet if he’s only 3 or 4% dehydrated.”

Dehydration and cold extremities (poor blood circulation to the legs and feet) means the calf is in shock.  If the calf has a bacterial infection and sepsis, with bacteria or their toxins getting into the bloodstream, resultant damage may also put the calf into shock.  Blood circulation is compromised and shunted to the internal organs and the blood is not being sent to the extremities or peripheral tissues (skin and legs will be cold).  “Shock may accompany dehydration, but not always,” says Smith.

How Much Fluid To Give
There are several important considerations when giving electrolytes.  “One is the volume of fluid needed, depending on weight of the calf,” says Barrington.  “Based on his weight, we want to consider three issues.  First is what does the calf need for normal maintenance (how much he would normally drink in a day).  The second is the degree of deficit he has, due to dehydration.  Third is how much is he continuing to lose, via diarrhea?”

If he’s been off feed and not consuming milk or milk replacer, and is scouring, he may be quite dehydrated.  “For example, a 150-pound calf would typically drink about 4 quarts of fluid per day, just for maintenance, and will likely drink nearly twice that much milk.  If he is dehydrated just 5%, he’s down about 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% dehydrated is already about 4 quarts of fluid in the hole to begin with,” says Barrington.

“So, during a 24-hour period this calf would need about 8 quarts of fluid to satisfy his deficit and maintenance, plus an estimate of what he’s continuing to lose via diarrhea.  The calf might need 8 to 10 or more quarts of fluid in a day, ideally split into 3 feedings.  One feeding of fluid/electrolytes might help, but it’s not enough,” says Barrington,

Also, the younger the calf, the more quickly he can dehydrate with scours.  The small young calf has no body reserves and it’s more urgent to administer fluids often.  “They lose fluid quickly.  These calves need adequate volume and they also need the electrolytes they are losing through diarrhea,” he says.  A very young calf may need oral fluids every 4 or 5 hours.