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Correll: Exploring anaplasmosis in cattle

dfox • Oct 28, 2015 at 7:00 PM

Acute anaplasmosis is most common and usually occurs in summer and fall during the peak season of biting flies and ticks. Common symptoms include fever, loss of appetite, rapid loss of body condition, a decrease in milk production, pale and yellow mucous membranes, increased heart and respiratory rates, muscle weakness and depression. Aggression is also common, especially in beef cattle. Abortions may occur in females and temporary infertility may occur in males. Anaplasmosis can cause rapid illness and death but the acute form is more common. 

In addition to being passed by biting insects it can be passed from a sick or carrier animal via a contaminated needle or equipment contaminated with blood from a carrier or sick animal. It can also be transferred via tattooing, dehorning or castration equipment. 

Ticks are more likely to spread the disease from one herd to another, while horse flies usually require closer proximity of infected and susceptible animals. Stable flies can also transmit the disease, but probably not as effective as horse flies. 

The incubation period (time from infection to clinical disease) can be from 1 to 8 weeks depending on the infective dose. In natural infections it is usually 3 to 5 weeks. The organism replicates in red blood cells, which are then removed from circulation, resulting in a progressive anemia. Animals that survive the anemia usually become chronic carriers of A. marginale. It can be transmitted from cow to calf through the placenta. Calves that are infected in utero rarely show clinical signs but become carriers.

The severity of the disease is age and possibly breed related. Calves less than one year of age usually only show mild signs or remain asymptomatic. Cattle up to two years of age have acute but rarely fatal disease, and cattle greater than two years of age are most likely to have severe and potentially fatal disease. Bos taurus cattle appear to be more likely to develop severe disease than Bos indicus cattle. 

Acute cases of anaplasmosis can be diagnosed microscopically. However, once the acute stage is advanced, it may be difficult to find the organism. Therefore, late clinical disease or the chronic carrier state has to be diagnosed with serologic tests. A new competitive ELISA (cELISA) appears to have improved sensitivity for detection. However, the sensitivity of the serologic tests depends on the stage of infection, and during the early incubation phase these tests may be negative. 

Methods of prevention include the proper use of fly control and back rubs. Effective use of fly tags, back rubs and pour-on’s can help with reducing the incidence. It is a good idea to have a veterinarian screen any purchased animals before introducing them into your herd. Any instrument that can share blood between animals has potential for spreading the disease, so single use needles, and disinfecting of equipment between animals is highly recommended to prevent spread of the disease. 

Acute cases can be treated and cattle can recover. Work with your local veterinarian for a thorough investigation and advice regarding treatment/elimination and future prevention. An effective veterinarian/client/patient relationship is very important in preventing and treating this cattle health problem. 

Agricultural Market Summary

Cattle Market Trends

The positive price swing continued but to a lesser magnitude. More calf marketing during the next few weeks may pressure the market downward. Feeder steers $2 to $6 higher, $150-$250; Feeder heifers $2 to $5 higher, $125-$225; Slaughter cows $2 to $4 higher, $64-$81; Slaughter bulls steady to $2 higher, $94-$116.

Grain Market Trends

Corn was mixed; soybeans and wheat were down for the week. Corn – Cash prices, $3.33-$3.98. December futures closed at $3.79 a bushel, up 3 cents. Soybeans - Cash prices, $8.63-$9.26. November futures closed at $8.95 a bushel, down 3 cents. Wheat – No cash market reported. December futures closed at $4.90 a bushel, down 2 cents.

For additional information on these and other topics, contact the UT Extension Office, 925 East Baddour Parkway, Lebanon, TN 37087, 615-444-9584 or [email protected].  UT Extension provides equal opportunities in all programs.  Visit the UT/TSU Extension webpage at http://utextension.tennessee.edu... or look for UT & TSU Extension, Wilson County on Facebook.

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