According to Dr. Tom Hairgrove, Texas
AgriLife Extension veterinarian, some of the problems we see in cattle are like the tip of the iceberg; we are only seeing a small part of the picture. “We may see a few subtle signs of a problem and then suddenly have a big hit in conception rate or, depending on the disease, an outbreak of disease in young calves, or in weaning age calves,” he says. “Most of those serious herd health situ-
ations are subclinical in most of the animals, and by the time we see obvious signs of a problem the disease may be already well es- tablished in the herd,” he explains. “The diseases we’ve been looking at lately
Sneaky
Diseases You May Not Be Able to See
here in Texas include anaplasmosis, and we are still in the middle of that project,” says Hairgrove. This is a sneaky disease because it can enter the herd without the producer know- ing it. “When purchasing replacements, just look-
ing at those cattle you’d never be able to tell if they are anaplasmosis carriers. If a producer doesn’t understand the dynamics of this dis- ease and how it is spread, he may expose his cattle to infection.” If he comingles new cattle with the herd
and then decides to dehorn, castrate, ear tag or vaccinate them as a group, he could inad- vertently spread anaplasmosis from the new cattle to the others — via the needles or tools he uses — unless the tools are disinfected between animals or a new needle is used for each animal. Otherwise the pathogens in the blood from a carrier animal may be introduced into healthy animals. “These sneaky diseases are frustrating to
many ranchers. We might routinely see things like calf scours, a few cases of pneumonia, etc. but we don’t really see the things that are costing us a lot of money until it’s too late,” he says. Some of these subtle problems include
92 The Cattleman September 2013
parasites and certain nutritional problems that may be subclinical until a certain point is reached — causing poor health or reproduc- tive issues. “Most of our problems in the cow-calf sec-
tor relate to reproduction. There will be some pneumonia cases, scours and other diseases, and most of them relate back to management, as when cattle are too confi ned or in a con- taminated area,” he says. For instance, calving heifers in the same place every year (where they can be easily watched) can lead to more disease problems in calves. But the diseases that cost the most are usually the ones that hinder reproduction, resulting in fewer cows bred or bred on time. “The frustrating thing is that when we re-
alize there is a problem we are always working backward trying to fi gure some of these things out. I recently attended a meeting where we discussed orbiviruses such as bluetongue and epizootic hemorrhagic disease (EHD). These diseases may be potentiated by other immu- nosuppressive diseases such as BVD,” says Hairgrove. “We want to think in terms of simple
things and simple ways to prevent or treat them, but most reproductive problems are caused by multiple factors. It’s like respiratory disease; we want to just look at one bug. If we fi nd that bug we quit looking any farther and think we have it solved, but those bugs tend to work together,” he says. “Another issue is trying to fi gure out the
cause of an abortion. Finding an aborted fetus and sending it to a lab for testing increases the odds of determining the cause — but may not be that helpful. The lab tests may be looking for a virus or bacteria or protozoa, but many times the organism that caused the problem was an earlier infection (killing the fetus) and is no longer present,” he explains.
thecattlemanmagazine.com
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