Tips on Giving Fluid to Scouring Calves.

 By Heather Smith Thomas.

 Neonatal diarrhea, or “calf scours”, is frequently seen in young calves, and dehydration is the most common cause of death in scouring calves.  The major causes of scours are viruses, bacteria, or protozoa, and these can also occur in combination.

Two common causes of viral diarrhea are rotavirus and coronavirus but they vary greatly in severity, with coronavirus being much more serious.  Both viruses damage the intestinal lining.  The intestines are lined with microscopic, fingerlike structures called villi, which greatly increase the surface area of the gut, allowing more absorption of fluid and nutrients.  Rotavirus causes the villi to shrink, reducing the surface area; fluid moves through the gut without being absorbed, resulting in diarrhea.  This diarrhea usually does not last more than a few days; the calf generally recovers relatively quickly, especially if given oral fluids to replace what is lost.  Rotavirus diarrhea usually occurs at two or three days of age, and is often a mild disease that responds to fluid and supportive care.

Coronavirus often occurs at seven to ten days of age, and affected calves do not respond to fluid therapy. They quickly become depressed, with severe signs of weakness and dehydration.  Coronavirus infection destroys the villi, so the intestine is unable to absorb water or nutrients.  Oral fluids are often ineffective; the calf has very little ability to utilize them until the intestinal lining can regenerate, which often takes up to a week.  Unlike rotavirus that mainly affects just the small intestine, coronavirus affects both the small and large intestines, with more severe effects.  Coronavirus is especially deadly during cold weather because the calf needs more energy to maintain body heat.  Death often results from starvation; the calf cannot absorb sufficient nutrients to meet its needs.

Bacterial scours can affect calves at almost any age.  Most common in newborn calves is E. coli, though many other bacteria can cause disease including Salmonella, Enterobacter, and Clostridium perfringens (several different types).  Protozoal diseases that can cause scours include cryptosporidiosis and coccidiosis (which affects calves that are older than 3 weeks, due to a longer incubation period).

It is important to detect early signs of sickness and begin supportive treatment with fluids before the calf becomes severely ill.  This increases your chances of saving the calf, but can also halt contamination of the area where the calf is housed.  A calf with scours will multiply the pathogen by millions, and shed them in diarrhea.  If calves are in individual hutches, care should be taken to clean up thoroughly after the sick calf and not inadvertently carry the pathogens to other calves (on your hands, clothes, feet, etc.)  If calves are housed together in pairs or groups, they will all be vulnerable if one gets sick; even calves with good antibody levels cannot fight off the vast number of pathogens shed by the infected calf, and a chain reaction of disease can occur in a group.

Young calves with diarrhea dehydrate rapidly.  If the sick calf is still strong and able to absorb fluids orally, provide 1 to 2 quarts of warm water (with electrolytes mixed in) by stomach tube or esophageal feeder every 6 to 8 hours, or more often for a young calf with serious diarrhea.  Calves less than a week of age with severe diarrhea may need fluids every 4 hours.

Giving fluids is important, no matter what the cause of scours may be.  Dehydration and acid/base imbalance is generally what kills a calf that dies from scours, so the crucial thing is to give enough fluids to prevent or reverse dehydration.  Then the calf can stay stronger, and more able to fight off the infection—whether it’s bacterial, viral or protozoa.  

Some people still have the misconception that a scouring calf should be taken off milk until diarrhea resolves.  This was the advice veterinarians used to give, many years ago, since milk can keep the damaged gut irritated.  This is true, but the calf needs the fluid and nutrients; the benefits of milk far outweigh the drawbacks.  Current advice is to alternate milk feedings with oral electrolyte fluids. 

Don’t give electrolytes at the same time as the milk—especially an electrolyte product that contains bicarbonate, since this will interfere with proper digestion of the milk.

The oral fluids you give a calf should contain electrolytes—the important salts that the calf is losing through diarrhea.  You can use commercial one-dose packets, or a measured amount from a tub of electrolyte mix, or a homemade mix.  An inexpensive electrolyte solution can be created using 1/2 teaspoon table salt (sodium chloride) and 1/4 teaspoon Lite Salt (a mix of sodium chloride and potassium chloride) in two quarts of warm water.  If the calf is severely ill, you also need an alkalizing agent to reverse acidosis, and you can add 1/4 teaspoon baking soda to the mix.  Most calves won’t suckle a bottle of electrolyte solution; the fluid must be administered by tube—with an esophageal feeder probe or nasogastric tube.

A weak, dehydrated calf that’s unable to suckle also needs some form of energy added to the mix, and an alkalizing agent like sodium bicarbonate (baking soda).  Chemical changes have occurred in his body when he’s dehydrated, causing acidosis.  Normal pH of body fluids is slightly alkaline.  Diarrhea can drop the pH drastically and the resulting acidosis can lead to coma and death.  If a calf is weak and severely dehydrated, use a product containing an alkalizing agent, or add baking soda to your home mix.  But after the first couple days leave out the baking soda if the calf is improving, or change to a product that doesn’t contain bicarbonate.  You don’t want to overbalance the body pH.

Oral fluid for a calf that is weak and dehydrated should supply four  things.  First, enough sodium to replace what’s being lost through diarrhea.  Second, an agent to facilitate absorption of sodium and water from the intestine (and this can be glucose, acetate, propionate or glycine).  Third, an alkalizing agent like acetate or bicarbonate to correct metabolic acidosis.  Fourth is energy.  Most commercial products contain these four things.

Depending on the cause of scours, your veterinarian may recommend antibiotics.  Viral infections do not respond to antibiotics, and in these instances, fluid therapy is the most beneficial treatment.  Your vet may be able to determine whether the calf is fighting viral or bacterial scours, or a protozoal infection (coccidiosis or cryptosporidiosis) and prescribe appropriate treatment.  Even with viral scours, however, an antibiotic might be necessary to combat secondary bacterial infection.

If a scouring calf is still mobile, make sure he has access to clean water.  Sick calves will often drink water even if they don’t feel like suckling.  If given a opportunity, these calves will often drink water.

Salt is also important; a calf that’s been scouring will eat salt to help replace what he lost through diarrhea.  Loose salt is easier for calves to eat than block salt.  You can mix one-third potassium chloride with regular loose salt (one-third is better than half and half, since the mix won’t be so bitter).  This makes a self-feeding electrolyte mix that calves will readily eat if they need it.

Some calves may also be helped by anti-inflammatory medication.  Diarrhea is painful and irritating.  If calves are uncomfortable and off feed and we want to keep them willing to suckle (obtaining energy and fluids from milk or milk replacer), a non-steroidal anti-inflammatory drug may help.  It only takes a very small dose for a young calf and can pay off if it helps the calf feel well enough to suckle and not become weak and dehydrated.  The calf may recover faster, with fewer treatments.  Your veterinarian can prescribe an appropriate anti-inflammatory medication.

Giving Iv Fluids
You need to know when it’s appropriate to use oral fluids and when you should give IVs.  Some scouring calves are dull and depressed, but still strong, and they can benefit from oral fluids.  You are wasting time and money, however, to give fluids and medications orally if the calf needs IVs.  If he is very dehydrated, the blood supply to body tissues is decreased, acid-base balance in his body is out of whack, and he starts to go into shock.  Whatever fluid is still circulating in his bloodstream gets shunted to the most critical organs such as heart and brain, and all other organs are shortchanged--including the gut and kidneys.  If he’s so dehydrated there’s not much blood supply to the gut, he can’t absorb oral fluids.

You can usually tell if the calf needs an IV.  If the blood supply is not servicing the gut it is also not servicing the skeletal muscles.  His legs are cold and he can’t walk.  If he is still strong enough to walk he can still absorb oral fluids.

If he’s weak and down, you can usually get him back on his feet again with IV fluid containing bicarbonate or some other alkalizing agent to combat acidosis.  If he’s too weak to raise his head, the only way you’ll save him is with IVs.  Most dairy farms have their veterinarian teach someone on staff how to give IV fluids.

If you don’t have commercial IV fluid packets on hand, you can make you own, using distilled water.  To supply the bicarbonate needed by the calf, add baking soda to a gallon of distilled water.  Fill a plastic syringe cover (the casing for a 20 cc disposable syringe) to the top with soda, and put that in the water.  This amount is very close to what your veterinarian would weigh with a scale.  For a weak, down calf, the recommendation is to give at least a gallon of this fluid.    

It should be warmed to body temperature.  A calf that is down and dehydrated will have subnormal temperature and should be in a warm place or under a heat lamp, hot air blower or heating pad.

To attach IV tubing to the gallon jug of distilled water you can use a regular rubber IV bottle top.  If you stretch it, this will slip over the gallon jug top.  Or, you can simply insert the IV tube (the sharp tip that’s designed to penetrate an IV bag) into the bottom of a plastic gallon jug of distilled water (warmed to body temperature).  Once you get a needle into the jugular vein of the calf, let the IV tubing fill with water, to get all the air out of it, then attach it to the inserted needle.  

You can control the speed of flow with needle size; a 20-gauge needle in the vein will keep the flow down to a safe speed.  But for a calf that’s flat out, you can usually run the fluid in faster without problems; these calves have low blood pressure and can take additional fluid pretty fast.

Most calves will be able to get up after a gallon of this fluid is given by IV.  They may go down again if they are actively scouring, but you can repeat the fluid--another gallon--if they do go down again.  If they don’t get up after a gallon, or don’t look like they have improved, their problem is usually more complex (perhaps septicemia) and not just scours, and they may need more extensive emergency treatment with help from your veterinarian.

How To Tell If A Calf Is Dehydrated
You can generally tell if a calf is dehydrated by using the pinch test.  Pull a pinch of loose skin out from the thin skin over the shoulder, or the eyelid, to see how quickly it goes back into place.  In a normal calf, the skin will spring right back into place as soon as you let go of it.  If he is dehydrated, he has lost some of the fluid in and around the body cells and the skin is less elastic; it will stay pinched up for a second or more after you let go.

If it takes two or three seconds for the skin pinch to sink back into place, the calf is mildly dehydrated and may have lost 6% of his body weight.  If the pinch of skin stays elevated for six to 10 seconds or longer, the calf is severely dehydrated.  He has probably lost 10% of his body weight and is in serious trouble.

Mucous membranes in the mouth become dry and sticky rather than moist, and dark red/purple instead of pink.  The eyes seem to sink back into the head; eyelids and tissues around the eyes appear wrinkled and sunken, due to loss of fluid.  Another sign of dehydration is poor capillary refill time.  If you press your finger into the calf’s gum, the blood does not rush right back afterward; when you remove your finger, that spot stays white and pale a few seconds.

A calf that is 6% dehydrated can stand and walk and look fairly normal, but in a pinch test the skin will stand up for several seconds.  A calf that’s 8% dehydrated is weak and has an unsteady gait and the eyes appear sunken.  A calf 10% dehydrated will have cold legs, mouth and ears, and generally doesn’t want to get up.  If he is more dehydrated than that, he can’t get up.  The calf that is 12% dehydrated will be in a coma and flat out, and if he becomes as much as 14% dehydrated he will die.

[Note – some of the information in this article was provided by Derek Foster DVM, PhD (Assistant Professor of Ruminant Medicine, North Carolina State College of Veterinary Medicine), George Barrington, DVM, PhD, Dipl. ACVIM (Professor, Large Animal Medicine, Veterinary Clinical Sciences, College of Veterinary Medicine, Washington State University) and Dr. Robert Cope (veterinarian, Salmon, Idaho).]