A recent case of Anaplasmosis has been confirmed by Dr. Roger Thomas, DVM of Thomas and England Veterinary Services, in southcentral Kentucky between Scottsville and Smiths Grove. Anaplasmosis is a tick-borne blood infection that impacts the cattle industry every year which can go unnoticed until it is too late. Once you are able to identify some of the clinical signs, the animal usually only has days to live.

In most cases, the disease can be in the animal’s system for 30 to 100 days before showing any symptoms and by that time, there is no treatment. However, if caught in time, there are antibiotic treatments available but “when the animal is showing clinical disease, mortality rate is near 100 percent even with treatment,” according to Dr. Thomas.

“The organism attaches to the red blood cells.The immune system cannot remove the organism from the red blood cells soinstead it attacks the entire red blood cell destroying it. Symptoms are weakness, weight loss, abortion, labored breathing,jaundiced (yellow) tissues (inside of mouth, whites of eyes), etc.,”stated Dr. Thomas is a release Monday, Aug. 31.

Ticks are the biological vectors of the disease and this is important to realize that the tick can carry and maintain the disease for up to a year. Transmission is by transfer of infect red blood cells from the infected animal to a susceptible cattle. It can also be transferred mechanically by any transfer of blood including other insects or veterinary instruments. This is another great reason to use new needles with every animal and to destroy all contaminated needles as soon as possible. In more recent studies, intrauterine transmission can cause fetal death or abortion or the calf. In the case the calf is born alive, they are “persistently infected” and never develop clinical signs of the disease yet serve as a source of infection to the entire herd.

There are four general phases of the disease. Incubation is the time between exposure and detection in the blood which can vary in length from 3-6 weeks or longer. During this time, the animal remains healthy while the infection organism continues to reproduces in the bloodstream. Soon, the animal will begin to fight against the organism by destroying parasite but in turn is also destroying red blood cells. Most of the outbreaks we see in late summer, early fall are the results of infection from June or July.

The developmental stage is where most of the clinical signs start to appear. Most of the symptoms last between 4-9 days. Symptoms start with fever and then vary from anemia or paleness around eyes, muzzle, or teats, weight loss, dehydration, weakness, or sudden death. Treat with tetracycline is essential during this stage and must be administered by a licensed veterinarian. Tetracycline will only last in the system of the animal for 6-8 days.

There is no approved antibiotic to completely treat Anaplasmosis so prevention is key. “To control active infection during the vector season, feed CTC in a free-choice feed at the higher level of the approved range (0.5-2mg/lb BW/day)for cattle over 700 pounds for 40-60 days. The individual dose will vary based on intake. Aureomycin© is the only brand of CTC approved as a free choice feed for Anaplasmosis control. Extra-label use of feed additives is illegal and strictly prohibited by producers, veterinarians or nutritionists,” says Dr. Michelle Bilderback, Ruminant Extension Veterinarian, University of Kentucky.

During the convalescent stage, the infected animals if treated will begin to reach normal blood values, yet can last 2-3 months. Cows frequently lose weight and abort calves during this time.

Though the clinical signs might be gone, the infected cattle remain carriers for the rest of their lives unless cleared with long term antibiotics, hence the carrier stage. A blood test can be done to find out if the animal is a carrier. Please consult your veterinarian for any further information and testing. 

Information in this article was taken from a release of Dr. Roger Thomas and his confirmed case the week of Aug. 28, and an informational article from Dr. Michelle Bilderback, “Strategic Management of Anaplasmosis in Kentucky,” published in the December 2010 “Off the Hoof” University of Kentucky publication.