Anaplasmosis in Beef Cattle

Steve S. Sachtleben, PhD. PAS, KNG Beef Research and Nutrition

What is Anaplasmosis?
Anaplasmosis is an infectious disease caused by a protozoan parasite that is spread by ticks and biting insects. Needles, dehorning, castrating and other medical-type equipment can also spread it. During the incubation period within the animal (3-8 weeks), the parasite slowly reproduces in the blood stream. Symptoms are not obvious during this time but the parasites continue to develop and reside attached to the red blood cells of the host. At some point, the animal’s own immune system senses the infection and attacks its own red blood cells. This attack destroys the red blood cells and when the host cannot replace these cells as fast as they are destroyed, anemia occurs. After the animal is exposed to the pathogen, it takes 3-6 weeks for clinical signs to be manifested.

Clinical Signs of Infection
In most pathogenic cases, animals less than one year of age are the most susceptible. However, clinical symptoms are most severe in older cows. Exposed young animals become carriers, but are immune from the disease’s ramifications. Recovered animals become carriers and generally will not get sick again. These carrier cattle are vast reservoirs to infect the biting bugs. In general, if more than five minutes elapse between when the insect bites a diseased/carrier animal and the time it bites a new animal, anaplasmosis is not transferred.
Newly infected 1- to 3-year-old cattle typically show the worst clinical signs with 30-50% mortality if not treated effectively. In herds where the outbreak has not been discovered the first signs may be dead animals. However, if the herd is closely observed, infected cattle may show weakness and be unable to keep up with healthy animals. Intakes and water consumption go down. Skin around the eyes and mouth may be pale and perhaps yellow when jaundice occurs due to lack of red blood cells. Blood samples will be anemic. Pregnant cows may abort. The first 4-9 days after onset of symptoms is most critical, as chances of survival increase if the animal survives this period.

Diagnosis may be made by the blood samples being severely anemic with low oxygen- carrying capacity. Autopsies reveal pale mucus membranes, an enlarged spleen and liver and perhaps gall bladder. Urine will not be discolored with hemoglobin (red). Blood smears may or may not show the presence of the parasite attached to the periphery of the blood cell.

Treatment is most effective when conducted early. One dose of LA-200 (9 mg/lb of body weight) given subcutaneously is usually sufficient. Animals in later stages of the disease may be so anemic that the stress of treatment will kill them. Additionally, cattle at this stage of illness may not respond to antibiotics. So treatment of older animals in the later stages of the disease should probably not be attempted, allowing them to survive on their own.

Tetracyclines can help reduce the risk of anaplasmosis. It’s the first line of defense in eliminating the carrier state in the existing cow herd. This requires injections of oxytetracycline or long-term treatment with feed antibiotics (chlortetracycline, CTC). The FDA allows the feeding of 0.5 mg of CTC per pound of body weight for cattle over 700 pounds for the control of active infection of anaplasmosis (350 mg/head/day for cattle under 700 lb bodyweight). This level of feeding CTC will typically eliminate the carrier state after 120 days of continuous feeding. There are vaccines that may be given and boosters are required. However, this method may be too laborious and ineffective to be practical.

Kent Nutrition Group Products
KNG has a line of free-choice minerals that can help control an active outbreak and/or eliminate the carrier state in the herd. Any KNG mineral product that provides 0.5 mg CTC/lb of bodyweight will control anaplasmosis. The CTC concentration on the tag determines the animal weight that the product is approved for by the FDA. So, a mineral with ANAPLAZ in the name with 5000 grams of CTC/ton is no better at controlling anaplasmosis than a mineral product with the same CTC level named FW 365 ADE CTC 5000. Both provide control of anaplasmosis in a 1250 lb cow. It’s the medication concentration and the feeding level that make the difference. FDA clearances are for generic CTC, not Aureomycin specifically.