By Heather Smith Thomas
Sometimes calves develop bacterial infection in the gut that proliferates rapidly and produces gas and toxins. If this condition is not treated quickly and reversed, toxins may get into the bloodstream and the calf goes into shock and dies within a few hours. In other instances, the calf may just be dull and bloated (usually with the abomasum distended with gas, rather than the rumen), and might not die as quickly.
A common type of toxic gut infection in calves is caused by Clostridium perfringens, one of the Clostridia species normally found in the GI tract of livestock and passed in the feces. These bacteria rarely cause gut infections in adult animals, but can cause fatal disease in calves when conditions are just right within the gut to enable them to proliferate rapidly. There are several types of C. perfringens, however, and these different types can affect calves of different ages, and may also affect calves in different ways.
There are also other kinds of bacteria that may be involved in causing bloat in young calves. Dr. Geof Smith, DVM, PhD (College of Veterinary Medicine, North Carolina State University), says he often sees abomasal bloat in dairy calves. "It also occurs in beef calves and may have a similar cause. It generally affects calves one to three weeks of age. We don't always know exactly what causes it."
It is possibly due to excess fermentation of high-energy contents in the GI tract, allowing gas-producing bacteria to proliferate. C. perfringens, Sarcina ventriculi or Lactobacillus species may play a role. According to Smith, large amounts of fermentable carbohydrates present in the abomasum (from milk, milk replacer or high energy oral electrolyte solutions) along with the presence of fermentable enzymes produced by the bacteria could likely lead to the gas production and bloat. This process could be exacerbated by anything that slowed the movement of ingesta through the tract.
These calves may or may not have diarrhea. "Many of them have a big belly on both sides—rather than the typical rumen bloat you find in older animals. The whole abdomen looks full, rather than just the left side," says Smith. At necropsy most of these calves have a distended abomasums and forestomach. There is abomasal edema, hemorrhage, and mucosal necrosis.
"We often find that clostridial bacteria are involved, but if you just put these bacteria into a calf you can't produce the disease. There have to be other factors involved as well. Some of the things we see in the dairy industry that seem to cause this include very high osmoality milk replacers or electrolyte solutions. Normally, milk is isotonic, but some milk replacers or some of the electrolytes you might give to a beef calf have a lot more sugar or dextrose in them. These have been shown to slow down the rate of abomasal emptying. This causes a back-up of the GI tract contents," he explains.
"Anything that slows abomasal emptying may be a risk factor. The bacteria are probably always there, already present in the stomach, so if you give them more time to grow and proliferate, you could end up with bloat," says Smith. Risk factors include products with high sugar levels, sudden changes in the type of milk you are feeding a calf, etc.
Beef producers often call this condition sloshy gut, rather than bloat. When the calf moves around you can hear fluid sloshing in the calf. "You may see this occur after a siege of bad weather when the cattle were standing bunched up under a tree for shelter and the calves didn't nurse for awhile. Then they are really hungry and they load up on milk. They get a big, full belly that empties more slowly, which gives the bacteria more time to grow. An erratic feeding schedule, which we see in dairies sometime, is similar to what we sometimes find in beef cattle," he says.
Anything that interrupts the calf's normal nursing can be a risk factor. The calf might have been off feed for some reason and then when he feels better he loads up. If the cow was bulling and being chased around by the bull or fighting/riding other cows, the calf may not have gotten a chance to nurse until she went out of heat. In other instances a cow might not have much milk and her calf has to steal milk from other cows when it can, with very erratic nursing. Many different situations may be factors.
"When a certain farm has a problem with this condition in calves, we don't know whether it's the bacteria on the farm or if there are management issues that contribute to this," says Smith.
"As soon as these bacteria proliferate, the calf goes off feed and might kick at his belly. It can be very painful." Some calves don't become bloated; they just suddenly develop gut pain and may run wildly to try to get away from the pain, and then throw themselves to the ground, thrashing and kicking.
"There was one study a few years back, in which the researchers were able to reproduce the disease, but in order to do this they had to give calves milk replacer with corn starch and extra glucose, mixed with water—a very rich energy product. It probably provides nutrients for the bacteria to grow, and then slows down the turnover of milk in the stomach," he explains.
Vaccination can sometimes reduce the incidence of disease, if the problem is caused by C. perfringens type C or D. There is also a vaccine for type A, and some producers use it because type A has often been implicated in abomasal infections and ulcers. "But vaccine alone won't halt a problem if the farm management is inadequate. It's like putting lipstick on a pig. It doesn't address the underlying problem. Outbreaks are often due to some kind of management reason. In a dairy for instance, the neighbor down the road may be using the same milk replacer and he's not having a problem," says Smith.
"In the beef industry, it's a different situation because you can't do as much to control the environment for those calves. If there is a vaccine that would help with some of these other types of infections (like C. perfringens type A), producers might want to try it," he suggests. Some labs will create an autogenous vaccine from a culture, to target a specific pathogen on your place, if there is no vaccine for that particular bacteria or strain.
TREATMENT – Some of these calves will need veterinary attention. "The way I treat a calf with abomasal bloat is to roll the calf on its back, clip and scrub the appropriate area of the belly and stick a long needle (with plastic catheter over it) into the abdomen. I have someone squeeze on the calf's belly while I stick the needle in. The catheter I use is similar to an IV catheter that is put into humans. I can pull the sharp needle back out, as soon as I get the catheter into place, so the needle won't puncture something it shouldn't. While the catheter is in place I have someone squeeze the belly, and I try to get as much gas out of that stomach as possible," says Smith.
"It's important to put the calf on its back. Some people try to stick the needle in with the animal standing, like we would in an adult cow that's bloated. But this isn't the rumen that's full. If the calf is standing, as soon as you get a little bit of gas out of the abomasum it drops off the needle and everything shifts." You wind up getting some leakage of that fluid into the abdomen, which puts the animal at risk for peritonitis. The rumen is always easier to access because it sticks up against the skin, whereas the abomasum is lower in the belly.
It also doesn't work to try to relieve the bloat by passing a stomach tube, because the tube only goes into the rumen. "You can't get the tube through the rumen into the abomasum. A tube works great for cows or even a big calf that has bloat in the rumen, but a baby calf's rumen is not developed yet, and in this instance the stomach that's full of gas is the abomasum instead of the rumen. The calf needs to be on its back when the catheter is inserted to drain off the gas," he says.
Smith also gives the calf penicillin, assuming the infection has a clostridial component. "Penicillin is an excellent antibiotic for any type of clostridial disease," he explains.
"After I've gone to a farm to do relieve abomasal bloat 3 or 4 times, I may train the farmer or farm manager how to do this." It's a technique that is best learned by having your veterinarian show you how, and not something that can just be explained to people over the phone.
Smith also likes to know if a herd is having on-going problems with this. "If they are having a bunch of cases I don't want them to just try to handle it. I want them to tell me, because I really need to go out there and try to figure out what's going on and what the cause might be. If you have 3 or 4 cases in a beef herd right after bad weather, you can figure that was a major factor. But on some of the dairies when they are losing 3 or 4 calves per week or month from this condition, we need to do more diagnostics and figure out what's happening, and how we might prevent it," he says.