Think anaplasmosis can’t affect your herd? Think again. While the highest prevalence has generally been in the Southern states, anaplasmosis has been identified in all 50 states, and with increased cattle movement over the last decade the footprint has spread.
It’s something cattle producers should be watching out for now through the fall.
“Since the insect vectors are more active during this time of year, we will see the disease when they are active,” said Douglas Hilbig, DVM, Beef Technical Services, Zoetis. “The symptoms of the disease will start to show up 60 to 120 days after infection, more often in the older and weaker animals first.”
An organism primarily spread by vectors, such as ticks, biting flies, and needles, anaplasmosis invades red blood cells and causes severe anemia. The cattle disease tends to occur most commonly in mature cows and bulls during the summer and early fall.
Hilbig said symptoms usually show up in the old, stressed, and weak first, and can include abortions, weak cows, weight loss, unthrifty cows, and cows that go down and can’t get up. Sometimes the animals may appear as aggressive due to anemia causing lack of oxygen transport to the brain. Findings on the animals will be pale mucous membranes, icteric appearance of eyes and mucous membranes, and blood that is drawn will be thin and reduced in red blood cell counts (RBCs) – anemia.
Cattle that are infected with anaplasmosis may recover, but they remain chronically infected carriers and a source of infection to the rest of the herd. Cattle infected early in life may never show signs of disease, but they serve as a source of infection for herdmates.
In fall-calving herds, heavy bred cows and recently calved cows seem to be at greatest risk of death or abortion. Anaplasmosis causes a rapid onset of profound anemia, and those cows experiencing the extra metabolic requirement of advanced pregnancy, or the stress of early lactation are less capable of managing that anemia. In spring-calving herds, cows are getting bred during the peak of vector season, so bull health and fertility are of particular concern. Cows nursing calves at this time are also at risk.
Since VFD came into place, Hilbig said he has seen cattle producers trying several different strategies to keep the disease at bay.
“Some producers have worked with their veterinarians to continue to include Aureomycin in their feed/mineral for protection of their herds. Others have tried to include a vaccine to help with protection in their herd or done nothing at all and hoped to have positive results by doing nothing,” Hilbig said. “The risk of the last two is their cows may have no prior immunity and won’t have idea of disease presence until it is in an advanced state in the herd.”
Hilbig recommends working very closely with your veterinarian on the best choice for your operation. If not working with any veterinarian, find one that can help develop a program to control the disease.
“Many times a control program will include Aureomycin fed to cattle via a hand fed feed/mineral of an approved free choice mineral,” Hilbig said. “The ideal level and form to use can be done with your veterinarian, who can then write you a VFD that meets your individual needs.”
Finally Hilbig advises producers to be proactive in their approach to anaplasmosis.
“Anaplasmosis is a subtle, chronic, progressive disease that when a threshold of damage to RBCs has occurred, the animal will appear to have an acute onset of disease. In other words, the onset of disease occurs months after infection happened,” Hilbig said. “Be sure to work with your veterinarian to establish a plan to control anaplasmosis. Also monitor your cattle for changes in your herd or individual animals that display any negative attitude or conditions that may indicate the presence of anaplasmosis. Your veterinarian can diagnosis the disease by examination of the animals and/or use of blood tests.”