Anaplasmosis is a common disease in cattle with worldwide distribution. Anaplasmosis will occur every year with some variation in its intensity, usually based on the strain of Anaplasma marginale, which is a bacteria that infects red blood cells. Once an animal becomes infected, they are infected for life.
Anaplasmosis is transmitted through the bites of ticks and flies, as well as blood-contaminated instruments like needles, tattoo tools, castration equipment and dehorning instruments. This bacteria does not harm red blood cells directly, but the cow’s immune response recognizes it when it reaches certain levels and kills the infected red blood cells, causing anemia.
This will limit the amount of oxygen that is transported throughout the animal’s blood, which can then lead to aggressive behaviors exhibited by normally docile cows or bulls. Other clinical signs that animals are infected with the bacteria are extreme lethargy, yellowing of the mucous membranes, abortions, weight loss and difficulty breathing.
Most producers will not know they have an anaplasmosis problem until they see dead cows or bulls that are older than 2 years of age. This disease can be devastating, with death losses in some herds approaching 50 percent.
Treatment and prevention
First, consult with your veterinarian so that they can develop a comprehensive plan to limit the impact of anaplasmosis. This relationship is important because the most commonly utilized control plan is to administer tetracycline antibiotics through mineral supplements or feed, and the only way to access this preventative treatment is to obtain a veterinary feed directive.
Clinical signs of infections can be treated with injectable antibiotics via an intramuscular injection of oxytetracycline administered over multiple days, and it should be given under a veterinarian’s directions. Successful antibiotic therapy that cures the clinical signs of infection results in a carrier animal.
Carrier cattle will be immune to further disease from anaplasmosis, but they will remain a source from which needles, flies and ticks can spread the disease. A vaccine is available in some states, and Oklahoma is approved for this vaccine. This vaccine does not prevent infection, but anecdotal evidence demonstrates a reduction in clinical signs.
In Oklahoma, it is not a matter of “if,” but rather a matter of “when” anaplasmosis will impact your cattle herd. Best management practices to prevent and control the transmission of this disease include:
• Feeding tetracycline antibiotics during the fly and tick seasons (essential).
• Rotating pastures (when possible) to avoid pastures with a history of tick issues during tick season.
• Burning pastures in the spring to control ticks.
• Controlling fly and tick populations to the extent possible.
• Changing needles and disinfecting any instruments that may result in transmitting blood from animal to animal when working with cattle. — Mark Z. Johnson, Oklahoma State University Extension beef cattle breeding specialist
