Dave Barz, DVM

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October 7, 2011
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Vet's Voice: Be wary of dry, dusty conditions

What a harvest season! It is so dry the fields seem to spontaneously combust as they are harvested. The fire departments can hardly keep up. First 15 miles one direction to fight a fire; then another call 10 miles in the other direction. The dry conditions have really produced a dust problem. The feedlots seem to be a hazy, with animals breathing dust and dirt. One major potential health problem is mycoplasma due to injury to the lungs.

Mycoplasma is hard to detect and often impossible to treat, but can spread rapidly and result in big losses in feedlots and cow-calf operations. Here in the Northern Plains we used to believe mycoplasma was a southern problem; and we did not need to worry about it. Until a few years ago, the SDSU Diagnostic Lab would not test for mycoplasma unless a producer asked specifically for the testing. Now we are able to isolate mycoplasma in more than one-third of respiratory tissues submitted.

Many producers that have fed Holstein cattle remember the chronic hacking cough and lameness as a result of swollen joints. We were able to culture mycoplasma bovis from both nasal swabs and joint fluid from these animals. The only means of control was perpetually feeding chloro tetracycline. In our area black and whites were blamed for future problems.

The organism that causes this complex disease is a bacteria, but one that doesn't operate like most others. The mycoplasma organism does not have a cell wall. Most bacteria react to antibiotic treatment by interfering with cell wall proliferations. The cellular membrane of mycoplasma responds to very few antibiotics and must be repeated for longer than normal intervals to initiate actions. A lot of our purebred cow-calf herds are having mycoplasma problems. We have been able to grow the organism from the milk of mastitic cows; joint fluid from lame bulls, cows and calves; and of course nasal swabs and lung tissue. We have been able to isolate mycoplasma from ear swabs collected from calves with a chronic hanging ear.

Mycoplasma is spread very easily from animal to animal. It does not live for long periods of time outside the body. Any calf drinking contaminated colostrum or milk is exposed. Once the organism enters the lungs the disease is spread by coughing and nasal discharge just like the common cold or flu. If you have one carrier and it enters the herd or feedlot, it can spread it very rapidly.

Because of the problems in treatment, the best means of controlling the problem in the feedlot is to empty the lot. Several clients have had problems and had 10 percent "poor doers." They kept these animals and allowed them access to new animals purchased the next year. The problems continued until all the animals in the lot were finally sold.

Mycoplasma was thought to be eradicated, but has recently become a major problem in our area. Antibiotics are not as effective against mycoplasma as they are against other bacteria. We used to use prolonged antibiotics believing if we controlled all other respiratory disease, the calf could live with mycoplasma. Vaccines have been utilized and appear to be moderately successful.

Visit with your veterinarian and devise a program which works in your herd. If your strategy is to keep mycoplasma out, set up testing and isolation protocols for your herd. If you have the problem, develop vaccination and antibiotic protocols to minimize the problems of this chronic debilitating disease. Minimizing mycoplasma losses will increase the profitability of your herd.

What a harvest season! It is so dry the fields seem to spontaneously combust as they are harvested. The fire departments can hardly keep up. First 15 miles one direction to fight a fire; then another call 10 miles in the other direction. The dry conditions have really produced a dust problem. The feedlots seem to be a hazy, with animals breathing dust and dirt. One major potential health problem is mycoplasma due to injury to the lungs.

Mycoplasma is hard to detect and often impossible to treat, but can spread rapidly and result in big losses in feedlots and cow-calf operations. Here in the Northern Plains we used to believe mycoplasma was a southern problem; and we did not need to worry about it. Until a few years ago, the SDSU Diagnostic Lab would not test for mycoplasma unless a producer asked specifically for the testing. Now we are able to isolate mycoplasma in more than one-third of respiratory tissues submitted.

Many producers that have fed Holstein cattle remember the chronic hacking cough and lameness as a result of swollen joints. We were able to culture mycoplasma bovis from both nasal swabs and joint fluid from these animals. The only means of control was perpetually feeding chloro tetracycline. In our area black and whites were blamed for future problems.

The organism that causes this complex disease is a bacteria, but one that doesn't operate like most others. The mycoplasma organism does not have a cell wall. Most bacteria react to antibiotic treatment by interfering with cell wall proliferations. The cellular membrane of mycoplasma responds to very few antibiotics and must be repeated for longer than normal intervals to initiate actions. A lot of our purebred cow-calf herds are having mycoplasma problems. We have been able to grow the organism from the milk of mastitic cows; joint fluid from lame bulls, cows and calves; and of course nasal swabs and lung tissue. We have been able to isolate mycoplasma from ear swabs collected from calves with a chronic hanging ear.

Mycoplasma is spread very easily from animal to animal. It does not live for long periods of time outside the body. Any calf drinking contaminated colostrum or milk is exposed. Once the organism enters the lungs the disease is spread by coughing and nasal discharge just like the common cold or flu. If you have one carrier and it enters the herd or feedlot, it can spread it very rapidly.

Because of the problems in treatment, the best means of controlling the problem in the feedlot is to empty the lot. Several clients have had problems and had 10 percent "poor doers." They kept these animals and allowed them access to new animals purchased the next year. The problems continued until all the animals in the lot were finally sold.

Mycoplasma was thought to be eradicated, but has recently become a major problem in our area. Antibiotics are not as effective against mycoplasma as they are against other bacteria. We used to use prolonged antibiotics believing if we controlled all other respiratory disease, the calf could live with mycoplasma. Vaccines have been utilized and appear to be moderately successful.

Visit with your veterinarian and devise a program which works in your herd. If your strategy is to keep mycoplasma out, set up testing and isolation protocols for your herd. If you have the problem, develop vaccination and antibiotic protocols to minimize the problems of this chronic debilitating disease. Minimizing mycoplasma losses will increase the profitability of your herd.


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Tri-State Livestock News Updated Aug 14, 2012 04:05PM Published Oct 7, 2011 10:40AM Copyright 2011 Tri-State Livestock News. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.