Scours can be caused by certain kinds of bacteria, viruses or protozoa, but other factors come into play as well.
“It’s often the interaction between the immune system, the environment and the pathogen load. The old saying is that the solution to pollution is dilution (or) minimizing the pathogen load,” says Dr. Paul Hardes, a veterinarian who practices at Turtleford, in northwestern Saskatchewan.
It’s important for producers to talk with their local veterinarians to know what the common problems are in the area and the treatments that seem to work for specific strains of various pathogens.
“The best way to prevent scours is to have a relatively clean environment and a good vaccination program for the cows. If the cows have good immunity they provide good quality colostrum to their newborn calves. If those calves can get colostrum within the first four hours, they have good protection.”
Colostrum from the dam is ideal, and the next best is stored colostrum from your own herd, Hardes adds. The third option is commercially produced, good-quality colostrum products, he adds.
“Some of these are created from actual colostrum and others from blood or plasma that’s spun down and dried,” he says.
Reducing stress can also help reduce scours. That includes protecting calves from bad weather, along with not confining the animals too much during calving season.
Pinpointing the cause of scours
When a young calf breaks with diarrhea, the producer often tries to determine whether it’s due to bacteria, a virus or protozoan. It’s hard to tell without isolating the actual pathogen from a fecal sample, but the age of the calf can be a clue.
“If the calf is very young — less than five days old — we often suspect E. coli as the cause,” says Hardes. A scouring calf that’s a bit older, such as between 10 days to three weeks, is likely suffering from a virus such as rotavirus and/or coronavirus.
If the sick calf is older than three weeks, vets suspect coccidiosis, a protozoa disease, as the cause. It takes at least three weeks for the coccidia to go through their life cycle within the intestinal tract and cause the damage that results in diarrhea.
“If a producer gets in a wreck with multiple calves getting scours, my first move is to take a fecal sample, to see what we are dealing with. Then we’ll know how to treat subsequent cases more effectively,” says Hardes.
Try to keep the younger calves from getting scours, if at all possible.
“If you have more than five to 10 per cent of calves in the herd affected, this becomes a significant problem. When you see the damage done to the intestine, you realize why it sets these calves back so much. The calves that were sick just don’t go on to perform as well — either on the cow, or later in the feedlot.”
Hardes points out that a lot of nutrients required for feed efficiency and growth are absorbed through that gut, which is now permanently damaged.
With coccidiosis there is usually some blood in the feces, but not always. There will usually be some oocysts in the feces, however, which might be seen when checking a fecal sample.
Crypto can be harder to diagnose. Calves often pick up protozoa pathogens from feed and water contaminated with feces. If calves are drinking out of puddles they may be at risk, so you might want to fence off contaminated water sources and provide clean water that the calves can access. Calves with scours caused by protozoa (crypto or coccidiosis) can benefit from antimicrobial products.
“If there is a really high coccidiosis load in the cows, a coccidiostat in their mineral mix prior to calving will help, so cows won’t be shedding so many coccidia in their feces,” says Hardes.
The newborn calves will have a cleaner environment and won’t pick up so many coccidia. There are also some coccidiostats that can be added to a creep feed for young calves. Your local veterinarian can help you figure out how to deal with this in your particular situation and facilities, with a customized prevention or treatment program.
Treating sick calves
When dealing with scours it is important for the producer to determine whether this is a calf that can be treated on-farm or needs to be hospitalized. On the farm, producers can effectively treat scours if these cases are caught early and if they have the time to intensively treat multiple calves. Scours rarely occurs as one isolated case.
Hardes says identifying cases that can be treated on-farm can be done by following certain guidelines.
“If a calf is strong enough to get up and move around, you can treat him at home. If the calf is too weak to get up but is still lying sternal (on the breastbone, with head up) and still has a suckle reflex… you can still treat at home — even if you have to give the fluids and milk, if the calf is unable to nurse, via tube. But if a calf is lying flat out and doesn’t attempt to get up and has a very weak or absent suckle reflex, he needs IV fluid,” says Hardes.
The IV fluids are crucial at this point due to lack of blood circulation in the gut and limited absorption of oral fluids. If that calf is not treated with IV fluids, it becomes weaker and unable to suckle.
“Acidosis and dehydration is what kills these calves,” he says.
In general, good supportive care with lots of fluid/electrolytes and keeping these calves warm and dry is always a good place to start, even if a specific cause for scours has not been determined.
“When treating any kind of scours, I also recommend to producers that they use commercial electrolytes — with the proper mix and balance of electrolytes — versus homemade mixes that may have an imbalance and might do more harm than good,” says Hardes.
For example, if oral electrolyte solutions used on-farm are not mixed with enough water, the extra salts pull more water out of the body and into the gut to try to dilute and balance the salt. This further dehydrates the calf.
“Some producers simply give water to their scouring calves, but this is not going to work either. Those calves have lost a lot of crucial electrolytes via the diarrhea that need to be replaced,” he explains.
Biosecurity is also important. Any sick calves should be brought in from the field with the cow and isolated, so they don’t keep spreading pathogen-loaded feces around to infect other calves.
Another general management practice includes providing the calf with adequate nutrients/energy fairly often so it doesn’t weaken. Calves have relatively small stomachs and can handle only about two litres of fluid at a time. Producers realize that a scouring calf needs a lot of oral fluids to make up for the losses, especially if the calf isn’t sucking the cow, but this has to be given over 24 hours in smaller feedings. Hardes recommends that producers alternate milk or milk replacer with the oral electrolytes and fluid, feeding one or the other every six hours.
Hardes doesn’t recommend giving oral electrolytes at the same time as the milk because the electrolytes usually contain bicarbonate, which interferes with proper milk digestion. Plus, the overall volume will be too much for the calf to handle at one time.
Dehydration is the number one cause of mortality in calves with scours and should be addressed aggressively. Calves need to be individually assessed to decide on the best treatment protocol.
When supportive care and fluids aren’t enough, your local veterinarian may suggest adding antibiotics as well as non-steroidal anti-inflammatory medications to a scour treatment protocol.
“When calves are brought in to our hospital, I usually add on a broad-spectrum antibiotic, not necessarily to treat the primary infection if we’re dealing with viral scours since antibiotics won’t be effective against a virus, but to prevent a secondary bacterial infection,” says Hardes.
Check young calves regularly
Hardes recommends frequent checks, no matter which season you calve, as sickness in calves can progress and change quickly regardless of weather conditions.
“Heat stress has become more of an issue now, as calving season has been pushed later in the spring in hopes of avoiding the -50 degree temperature we may see in February or March in Saskatchewan.”
If the daytime temperature breaches 24 C, a sick calf lying in the sun can become severely dehydrated, he adds.
The best way to safeguard your herd is to get cows and calves out on clean ground whenever possible and have a good vaccination protocol in place. Herd health investigations done by your veterinarian in the face of a scours outbreak can better control and decrease disease spread, while also helping to prevent more cases the next year.
Biosecurity vital to manage scours
It pays to isolate any sick calves from the main herd until they recover so they don’t spread the infection to other calves.
It’s also wise to not bring other animals onto your place during calving season, especially from a dairy. Producers who buy dairy calves to graft onto cows that lose their calves may inadvertently bring home a new bug such as crypto or salmonella.
“Producers who bring in a dairy cow to raise extra calves such as twins may also end up with something they don’t want,” says Hardes.
A dairy cow may also be shedding something such as Johne’s disease. A person should not get colostrum from a dairy for the same reasons.