2024 Winter Cattle Journal | Overview of Prevalent Diseases
There are many diseases that can affect beef cattle, but some are more common in certain regions. In the intermountain West, some ranchers must contend with brucellosis (spread to cattle from elk and wild bison leaving Yellowstone Park), and trichomoniasis, along with common problems like BRD (bovine respiratory disease).
Dr. Rose Digianantonio, Wyoming Assistant State Veterinarian, says the biggest disease issue seen in cattle across the country is pneumonia, especially in fall and winter. “We had a long fall, then suddenly plunged into winter weather in late October. With sudden temperature change, we see more cases of pneumonia.” Wind and wet weather, freezing rain and snow can be stressful for cattle and stress can suppress the immune system, making animals more prone to disease.
In Wyoming, Montana and Idaho a regional disease risk for cattle is brucellosis. “These states have surveillance areas for this bacterial disease that in cattle causes abortions or weak calves, and can lead to fewer pregnant cows. The surveillance areas are based on elk populations that have the disease, since currently the disease is most commonly spread to cattle from wildlife,” she says. The surveillance areas have been set according to elk migration patterns.
Prevention measures for brucellosis include managing wildlife/cattle interactions and ensuring cattle are “bangs” vaccinated. “Take note of any cows that are open and watch for abortions, or newborn weak calves—and keep a record of those cows. Follow general health rules; ask your veterinarian about vaccination and any other management practices,” Dr. Digianantonio says.
Create a herd health program in consultation with your own veterinarian who knows your herd. “We have guidelines in the state for diseases like brucellosis, but the best advice will come from your own veterinarian who can help with individual situations.” Good nutrition and appropriate mineral status are also important to cattle health and overall immunity.
Vaccination can help prevent some of the major causes of respiratory disease and give the herd a higher level of immunity. In the fall, calves are vaccinated and weaned. This is when most people have their heifers vaccinated for brucellosis, which must be done by a veterinarian. Cows are generally vaccinated and preg-checked. It pays to preg-check and determine which cows to cull or keep. A higher-than-usual open rate may indicate a possible disease issue.
“Another regulatory disease is trichomoniasis, which can lead to open cows,” Rose says. This reproductive disease is caused by tiny protozoa within the bull’s sheath and cow’s reproductive tract and spread by breeding. Ranchers using shared summer range pastures should stay aware as situations where cows may be bred by other producers’ bulls can be an issue. Bulls should be trich tested before they go out with cows. Some people trich test in fall or winter after breeding season to determine which bulls to sell or keep, since they might have been exposed to this disease during the summer.
MORE REPORTABLE DISEASES – Some diseases like brucellosis must be reported by any veterinarian who diagnoses them. Dr. Beth Thompson, South Dakota State Veterinarian, says her state agency is most concerned about foreign animal diseases that are reportable. “Foreign animal diseases are the ones we don’t have in this country (and want to make sure we don’t have). Other reportable diseases are the ones that cause economic concern to the cattle industry. Many endemic diseases that cattle producers frequently deal with, on an ongoing basis, we don’t get involved with; producers work with their own herd veterinarian rather than with our office,” she says.
One of the reportable diseases is bovine tuberculosis. Many people think this is mainly a problem in dairy cattle, but since it is spread by wildlife it is also a concern for beef cattle. “Here in South Dakota, that’s where we’ve found most cases—in beef herds. These have all been TB strains that trace back to Mexico,” she says.
Bovine tuberculosis is a slow-growing disease. “Cattle sometimes don’t show signs. They might lose weight or look like they aren’t doing well, but it’s not a disease where a rancher goes out and finds several sick animals.” It’s a subtle disease that can sneak into a herd and you wouldn’t know it.
“Most of the South Dakota TB cases in the past have been found at slaughter; the producer didn’t know the animal was affected. Trained meat inspectors check carcasses at slaughter facilities and we then trace it back to the herd the animal came from. We haven’t had an established problem here in this state, in contrast to Michigan where it’s a serious challenge. In Michigan this disease became established in whitetail deer.”
There is a public health concern with tuberculosis, primarily on the dairy side, with more human contact; dairy workers who handle the animals can be at risk. The main way to prevent this disease is to never import cattle that are not tested; don’t bring roping steers from Mexico and put them with your cow herd.
“It’s important to know the health of any animals coming into your herd, if you don’t have a closed herd. Even if you do, there might be some risk if your neighbor’s cattle are across the fence from yours. Traceability is important. You don’t always know when you might need to trace an animal to see where it came from. It’s important to have animals individually identified, and keep records,” says Thompson.
Anthrax is another reportable disease because it can also affect humans. Certain conditions like flooding—that bring buried dormant spores to the surface and move them around—or dry dusty conditions when spores can be carried on dust and blown to other areas—can spread this ancient disease. This past summer North Dakota had many cases. This is a disease that kills cattle quickly. A rancher may find several dead animals that were healthy the day before.
“This is a zoonotic disease, so we tell people to contact their veterinarian if they find an animal that died suddenly and unexpectedly. Other things might cause sudden death, but unless you know for sure what killed the animal, don’t become exposed by handling the carcass. If it might be anthrax, call your veterinarian and/or call us, so an accurate diagnosis can be made,” she says. The carcass must be disposed of properly so there won’t be any spread of the disease.
“There is an effective vaccine for anthrax. If your area has had cases of anthrax in the past, it pays to vaccinate. If an animal dies of anthrax, others in the herd are at risk because they’ve probably been exposed. Treatment to save the rest is to immediately vaccinate and give them antibiotics. If other animals have been exposed already, it may be too late and they will die, but vaccination and antibiotics can protect the rest.”
Vesicular stomatitis (VS) is another reportable disease, because the ulcerations it causes on feet and mucous membranes of the mouth are similar to those of foot and mouth disease. VS sometimes moves into the U.S. from Mexico during summer and fall, spread by insect vectors. “It doesn’t always get very far north, but occasionally we get a call about the disease. If you see a blister on an animal, consult a veterinarian. We need to differentiate VS from foot and mouth disease (which was eradicated from the U.S. many decades ago). You don’t want to be the person who misses a case of foot and mouth disease and it becomes the start of an epidemic. We want to keep that disease out of this country,” says Thompson.
Johne’s is a reportable disease that can be carried silently for many years before animals show signs (weight loss and diarrhea). “We haven’t had as many cases in recent years as we did in the past. We may only have one or two herds with it in South Dakota, but people still test for it,” she says. Johne’s can be devastating once it gets into a herd and middle-aged cows start breaking with diarrhea.
“A new problem is the Asian Longhorn Tick which is moving west from the East Coast and has made its way into northwestern Missouri. The female doesn’t need a male to reproduce, and can lay an incredibly high number of eggs. These ticks can carry many serious diseases, including anaplasmosis, Texas fever, etc. We used to think our winters here are cold enough that these ticks won’t survive, but they do,” says Thompson.
BIOSECURITY IS THE BEST PREVENTION – Monitor cattle closely so you know what’s going on, and know what you are buying and bringing into your herd. If at all possible, segregate and quarantine new animals for 2 or 3 weeks before adding them to your herd, to make sure they are healthy and not about to break with disease. People often inadvertently bring in something like BVD or IBR into their herd with a purchased animal. Many diseases will show up within a quarantine period, but a slowly incubating disease like Johne’s will not. Make sure you buy from disease-free herds.
“If your herd is naïve, meaning your cattle haven’t been exposed to or vaccinated against a certain disease, they are at risk,” says Thompson. The animal you bring in may look fine because it has some resistance, but can still spread the pathogens it carries.
Many diseases can be readily spread around the country with movement of cattle and wildlife. There may also be new diseases on the horizon that ranchers are unfamiliar with. “Keep good records, know your herd, and your neighbors, and stay in touch with your veterinarian,” she says.
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