Anaplasmosis is thought of as a southern disease, but an astute veterinarian in New York investigated an unusual illness in a dairy cow and it was found to be positive for anaplasmosis. New York State Department of Agriculture and Markets veterinarian Pepi F. Leids, DVM, says a 7-year old home raised cow presented to the herd veterinarian with a history of having been treated for two days previously with an antibiotic since she was “breathing hard”, had a temperature of 104°F, and was presumed to have pneumonia, but did not respond to the treatment.

The herd veterinarian noticed that the cow’s muzzle and vulva were pale, and it was presumed to be anemic. Her temperature was 102.4°F with increased respiratory rate, but no abnormal lung sounds. The cow was given antibiotics, magnesium oxide boluses and removed from fermented feeds. Blood was taken and hematocrit was 9.2. The next day the cow seemed to be improving but had not passed any bloody manure. Four days after initial presentation, the cow was improved, eating better and had a temperature of 101.8°F. There was still some labored breathing and the Hct was up to 11.5. 

“When there was no response to treatment, no bloody or dark manure and the PCV remained low, the veterinarian thought it was possible that the cause of the severe anemia was anaplasmosis,” Leids explains. “He said he looked at the cow from afar and what was most striking was the very pale muzzle.”

A younger cow (3 years of age) was also showing signs of depression and lethargy for about a week. Her
vulva was pale also; her Hct was 12.5. Both cows were tested for anaplasmosis using the cELISA test. Both cows were test positive and had exhibited signs of acute infection. These cows presented with clinical cases of anaplasmosis in an area of the country where this disease has historically not occurred. An additional 14 cows were found positive, but none with clinical signs. All of the heifers tested negative as well as the calves that have been born and tested. Heifers and dry cows housed at a brother’s farm were also negative.

She adds that the only consistent finding with the positive animals is that all were given oxytocin at milking and common needles were used. “The clinically affected animals had to have been acutely infected. The history indicates that these two animals just started on oxytocin and were infected via the common-use needles resulting in a clinical presentation.”

Leids notes that recently another cow in the herd showed clinical signs of anaplasmosis; she was negative on the previous herd testing. “These cows are out to pasture and the flies have been really bad this summer; perhaps a biting fly served as the vector in this instance.” She says the owner has switched to single-use needles and has employed best management practices to prevent the transfer of blood, and the latest clinical cow was not on oxytocin.

Using separate needles between cows should be a given, Leids says. “It is encouraged to decrease any spread of blood borne pathogens such as bovine leukosis virus and anaplasmosis.”

Where did it come from?

It is unknown when the organism first entered the herd. Leids is convinced that the original infected animal came from an endemic area since this herd was open and bought/sold registered cattle.

Leids believes there is probably more anaplasmosis spread across the U.S. due to the ease of cattle movement. Many states do not require an anaplasmosis test for cows imported to their state, even from endemic areas. “For instance, the ‘original’ cow could have come from a southern state to Pennsylvania,” she says. Pennsylvania does not require anaplasmosis testing for cattle, even from endemic areas (states). New York doesn’t require any testing for cows coming from Pennsylvania into New York, just a health certificate and identification. “So cattle can conceivably move through states without any testing and end up in a place where you would not expect to find them.”

Sometimes it’s wise to “look for zebras”, especially when you don’t readily see the “horses,” Leids adds. “The herd veterinarian did indeed diagnose a disease most of us would never have even considered in our differential; this case illustrates the importance of a complete physical exam and an outstanding understanding of the nature of infectious disease.”