From early March through April 2009, numerous ranches in southwest
Q: How many cows were affected in these herds?
A: Although true numbers are hard to come by, it’s estimated from veterinarian’s reports that nearly 200 cows were lost from 16 herds recorded. The numbers affected per herd range from 1 to 55. According to information compiled, the median number of cows affected from these herds was six.
Q: Much was made about ticks as the cause of these losses. What was learned about the role of ticks?
A: One of the interesting aspects of these cases was that some—but not all—of the affected herds reported that the affected cows were covered with ticks. Early on, the onset of these cases of down, weak cows coincided with an unusually early tick hatch in those areas. Other herds reported finding only a few ticks on their affected cattle.
Q: What kind of tick was found on these animals in
A: Two species have been identified in these affected herds: Dermacentor andersoni (Rocky Mountain Wood Tick) and Dermacentor albipictus (Winter Tick). The normal ranges of these ticks are generally in the
Q: What problems could ticks cause for cattle?
A: First, ticks are the source of blood loss for cattle due to their feeding activities. This could cause some borderline anemia, and would affect the animal’s ability to gain weight or produce milk. In addition, irritation from heavy infestations of ticks will likewise interfere with weight gains or production. This could be a very
important issue in cows in late gestation that are already partitioning quite a bit of their energy and protein into the developing calf inside them.
Second, ticks can carry and spread certain viral, bacterial, and protozoal diseases. Dermacentor andersoni has been implicated in transmission of Rocky Mountain spotted fever, tularemia,
Although tularemia is endemic to this area of
One of the modes of transmission of Q Fever may include ticks and wild animals; however, its characteristic signs of late term abortions were not observed in these cases.
Tick paralysis, caused by a toxic substance in the tick’s saliva, has been reported in cattle; however, it is usually observed in calves and younger cattle, rather than older cows.
"Tick fever” or “