Anaplasmosis Season

Sudden Deaths in Cow Herds

Victoria G Myers
By  Victoria G. Myers , Progressive Farmer Senior Editor
Antibiotics and vaccines offer some protection for cow herds in areas where anaplasmosis is a concern. (DTN/Progressive Farmer file photo by Becky Mills)

Cow herds in some areas are always hit hard by the blood-borne disease anaplasmosis. Severe anemia caused by anaplasmosis can lead to sudden death, with mature cows especially at risk. These losses have been a big concern as cow-calf producers move into restocking phases across their operations.

The impact of anaplasmosis is heightened as new adult cattle are brought into existing herds. The new animals may be anaplasmosis carriers, or they may be clean but lack herd immunity the home herd (which may carry anaplasmosis) has developed. Either way, losses can be devastating.

Initial infection periods are especially dangerous and are most often when sudden death results. Once animals are infected, if they survive, they carry the illness and can pass it on for the rest of their lives.

Texas has historically been a prime area for anaplasmosis, due to environmental conditions that a common carrier, ticks, thrive in. Thomas Hairgrove, Extension veterinarian and professor at Texas A&M, has researched and written on the topic of anaplasmosis for many years. He explained in an earlier interview with DTN that the blood-borne disease is most often spread by ticks, biting flies, and use of contaminated instruments used to work cattle, including needles and ear taggers.

Hairgrove noted carrier cattle rarely show symptoms but are persistently infected and generally live with the disease.

"In carriers, we can't find anything to support the idea that there are more abortions or lower conception rates," he said in that earlier interview. He added that bulls may also be infected, and research continues to look at whether this could impact their fertility.


Bob Weaber, an Extension cattle specialist for Kansas State University's (KSU), reported that clinical signs of anaplasmosis appear as red blood cell counts fall and animals become anemic. Producers should watch for weight loss, abortions, respiratory distress, yellow mucus membranes (gum tissue, around eyes, vulvar), dark yellow urine, and constipation with hard, dry, shaded green feces. Behavior may become aggressive, or animals may act in a stupor, as oxygen levels decline.

Weaber urged producers to handle animals they suspect might be infected with anaplasmosis very carefully, trying not to excite or agitate them.

"If you think you're dealing with an anaplasmosis situation, be very gentle in animal movement. You don't want them running. Keep them as quiet as you can as you move them," he said.

Treatment options should always be dictated by the herd veterinarian, but Weaber noted there are antibiotics to help infected animals get past critical time periods. Some producers will feed antibiotics in a daily supplement, and he said some antibiotics are approved for use in a mineral mix. These are only available with a Veterinarian Feed Directive (VFD).

"Self-feeding is an issue," Weaber added. "Not all of the animals will eat minerals at a dose we want them to every day. So, there are challenges when it comes to controlling the disease."


In some cases, veterinarians in endemic areas have recommended an anaplasmosis vaccine as a type of control program. This is traditionally a multi-vaccine approach, which some producers have limited by first testing for anaplasmosis and then only treating animals with positive test reactions.

Developed by Louisiana veterinarian Gene Luther in 2000, the University Products LLC (UP) vaccine has FDA approval for experimental use. Based on literature from UP, the vaccine is a 1cc dose, administered subcutaneously in the neck. The first year, two doses are required (four weeks apart), with annual boosters each year thereafter. Protective immunity, according to UP, occurs "in a week to 10 days after the second injection of vaccine". This is a killed vaccine, and stable at environmental temperatures. The vaccine is reported safe in pregnancy.

There may be other options on the horizon when it comes to vaccinations. A one-dose implant vaccine has been under development by researchers at KSU and Iowa State University. The objective was reported by KSU to be an implant to provide "long-term immunity against anaplasmosis infections by releasing vaccine contents over an extended period." It is administered in the back of the ear. Based on reported research results, the implant protected against clinical anaplasmosis up to two years.

Producers should work with their herd veterinarian to determine the best treatment protocol for their situation.

Victoria Myers can be reached at

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Victoria Myers