Posted by Dr. Steve Dudley on June 16 2005 10:12
Dairy Calf Newsletter 2nd Quarter 2005
Mycoplasma bovis is a significant emerging pathogen in cattle. There are several strains of Mycoplasma but the most common species that causes disease in cattle is Mycoplasma bovis. When we refer to Mycoplasma in this article we are referring to Mycoplasma bovis. Mycoplasma is a small organism that commonly causes pneumonia, mastitis, ear infections and/or joint problems in cattle. You may have a problem with Mycoplasma in your calves if you see head tilts, droopy ears, swollen joints, fevers, or pneumonia that does not respond to antibiotic treatment.
Mycoplasma is commonly found in the respiratory and reproductive tracts of healthy cattle. It is contagious and is spread through the air and by nose-to-nose contact. It is also spread orally by nipples, colostrum, waste milk, and buckets. Cattle can carry Mycoplasma for a long time and shed it at times of stress.
Mycoplasma infection is commonly seen as respiratory disease that does not respond to antibiotic treatment protocols. Generally the animals with pneumonia are more bright and alert than we see with bacterial or viral pneumonias. There can also be a thin, clear nasal discharge or crusting around the eyes. Mycoplasma also causes ear infections. Signs of an ear infection include droopy ears, head tilt and ear drainage. Calves may also have fevers and swollen joints that do not improve with antibiotic treatment.
The biggest concern with Mycoplasma, is that once the calves are infected, it is very difficult to treat. This is because Mycoplasma is a very small organism that lacks a cell wall. These characteristics limit our ability to treat it with antibiotics, because many antibiotics kill bacteria by destroying the cell wall. Mycoplasma is often a secondary problem and can cause abscessing that also makes it difficult to treat. Some antibiotics that may have some affect on Mycoplasma include Oxytetracycline and Spectinomyocin.
If you are concerned you have Mycoplasma in your herd, prevention is the best solution. This is because Mycoplasma is so difficult to treat and even when animals recover, they usually have fallen behind the rest of the group. One way to prevent Mycoplasma is to use farm specific vaccines. These farm specific vaccines are very effective at controlling Mycoplasma. The first step is to isolate the Mycoplasma organism from your herd. Mycoplasma may be isolated from ear swabs, joint swabs or lung tissue. There are many different strains of Mycoplasma bovis. This is why sometimes the only symptom on one farm is pneumonia where on the next farm the major problem may be ear infections. This bacteria changes rapidly within the animal. A very useful diagnostic tool is comparing the DNA of Mycoplasma bovis isolates to determine how similar they are. It appears that there is poor cross protection.