Advice on anaplasmosis

It is difficult to quantify the risk of anaplasmosis in any given herd in any given time of year, but when an outbreak occurs, it can result in devastating consequences for a cow/calf herd.

Anaplasmosis is most commonly caused by Anaplasma marginale, a microorganism that invades red blood cells and causes severe anemia. Transmitted through the blood, the main culprits in spreading the disease include biting flies or ticks or infected blood transferred on contaminated needles or other equipment. The disease can result in death, aborted calves, bull infertility, weight loss and diminished milk production as well as additional treatment expenses. The risk for disease increases when mixing noninfected cattle with those that carry the disease or when environmental conditions favor increased activity of biting flies or ticks.

"Anaplasmosis is sporadic, not all factors that cause outbreaks in a herd are known but when they occur, consequences can be significant," said Daniel Scruggs, DVM, managing veterinarian with Zoetis.

Anaplasmosis causes special concern for cow/calf producers since mature animals have higher susceptibility to the disease than younger animals. Cows in the late stage of pregnancy and those nursing calves have particularly high death loss.

Signs of anaplasmosis can include:


Orange-yellow coloration of the mucous membranes


Thin, watery blood


Slow, reluctant to move or short of breath cattle


Aggressive behavior shortly before death


Sudden, unexplained death of adult cattle



One of the most commonly used and predictable methods of controlling anaplasmosis includes incorporating a feed-grade chlortetracycline (CTC), such as Aureomycin, in the animal's feed or mineral supplements. In endemic regions where ticks and flies remain active all year, CTC administration can occur year-round in feed or minerals. In other areas, producers often focus on late spring through fall, the time of highest transmission.

"It's really a factor of diligence in making sure cattle are protected," Dr. Scruggs said. "With spring-calving herds, the bulls are out during the spring and summer vector season. When bulls are experiencing an acute infection of anaplasmosis, and they become anemic or dead, they're not good at settling cows. Whether a producer is running a spring-calving or fall-calving herd, there's never a good time to go to sleep on anaplasmosis control."

Producers should consult with their feed or mineral supplier to ensure their mineral mix containing CTC delivers adequate levels for their herds' needs.

Adding CTC offers one of several measures producers can take. Preventive measures include:


Implementing fly and tick control to help reduce transmission.


Changing needles and disinfecting instruments between cattle when working cows and bulls.


Consulting your veterinarian early for diagnostics on unexplained death seen in adult cows or bulls.

"If you believe you can control anaplasmosis by just controlling flies, ticks and horseflies, you probably believe in the Easter Bunny, too," Dr. Scruggs said. "It's important to keep anaplasmosis control top of mind to help avoid unnecessary surprises and run a healthy, profitable cattle operation."

For more information on controlling anaplasmosis, contact your veterinarian, feed company nutritionist or Zoetis representative. To learn more about AUREOMYCIN, visit

Do not use AUREOMYCIN in calves to be processed for veal.