Dairy Pipeline: February 2006
John F. Currin
Extension Dairy Veterinarian
(540) 231-5838 email: email@example.com
Before 2000 Mycoplasma was almost non-existent in Virginia. Since then the dairy and beef industries have seen a steady rise in illness associated with Mycoplasma. In dairy calves Mycoplasma causes pneumonia, head tilt, droopy ears, and swollen joints. Respiratory problems with Mycoplasma can start showing up as early as 2 weeks of age. Unlike Pasturella that tends to causes severe toxemia and calves to look sick very quickly, Mycoplasma can be much more subtle and calves may go unnoticed until they have lost 50% or more of their lungs. These calves are called chronics in the beef industry and although they may live the odds of them becoming a milking dairy cow are slim. The earliest clinical sign of Mycoplasma is typically a single drooped ear when the calf is at rest.
Mycoplasma is very difficult to treat. Some commonly used antibiotics do not work for Mycoplasma. Penicillin, Polyflex®, Naxcel®, Excenel®, and Excede® all kill bacteria by destroying the cell wall. Mycoplasma does not have a normal cell wall so therefore they are ineffective in treating Mycoplasma. Micotil® shows little or no activity against Mycoplasma as well. Oxytetracycline has produced mixed results in treating Mycoplasma with some people reporting good results while others have seen poor responses. The drugs available to treat diary calves that show the best results are Nuflor and Draxxin. Two important factors in the treatment of Mycoplasma are early recognition and prolonged treatment. Calves that are treated early in the course of the disease respond fairly well, but unless these calves are treated for longer than we typically treat other causes of pneumonia, 50-70% of the calves will relapse and get sick again. Every time the calf relapses it will have more lung damage and be harder to heal. Current recommendations are to provide continuous levels of antibiotics to these calves for 10-14 days. If you suspect problems with Mycoplasma work with your veterinarian to come up with a treatment protocol that will fit these guidelines. In older weaned calves chlortetracycline can be added to the feed as part the extended therapy protocol.
Baby calves are most likely exposed to Mycoplasma by drinking colostrum or waste milk from cows with Mycoplasma mastitis. However once Mycoplasma gets into a calf rearing facility it is very easily spread from calf to calf through the air. This sets up a never ending chain of infection as older calves infect the new calves moving into the facility. This route becomes more important the closer confined the calves are. On farms that are experiencing Mycoplasma problems most all calves will become infected with Mycoplasma. However, not all of these calves should get sick. If you are experiencing a high percentage of sick calves, you need to look at your calf rearing operation and see what aspects need improving. The list to look at includes colostrum management, feeding waste milk, ventilation, and overcrowding.
If you suspect Mycoplasma on your farm work with your veterinarian to find out and then set up protocols to not only treat the problems, but prevent it.