If cattle with respiratory problems aren't responding to antibiotic treatment, and some cattle later develop swollen joints, take a closer look.

The herd could be infected with Mycoplasma bovis.

Bill Safley, DVM, Sioux Nation Veterinary Clinic, Spencer, IA, says when large feedlots under his care experienced respiratory problems, he sent samples to a lab for diagnostics and the finding was M bovis.

"Despite treatment, the respiratory problem wouldn't go away, and that was a strong indication that another organism was involved," Dr. Safley says.

In addition to being difficult to identify as a disease, the M bovis organism is difficult to detect in the laboratory, as a standard bacteriology culture will not detect its presence. To confirm a Mycoplasma diagnosis, a Mycoplasma culture must be specifically requested when samples are submitted to the laboratory.

M bovis can be difficult to identify, because the disease is often present with other infections," explains Dan Keil, DVM, PhD, DACVM, senior research scientist for Novartis Animal Vaccines, Inc., Bucyrus, KS.

Dr. Keil adds that M bovis infections are commonly found in conjunction with, or followed by, infections such as Bovine Viral Diarrhea (BVD) or Bovine Respiratory Disease Complex (BRDC).

Signs to look for that indicate M bovis might be the causitive organism include rapid breathing, shortness of breath, fever, eye and nasal discharge, depression, decreased appetite, arched stance and swollen joints.

Dr. Keil advises producers to have their veterinarian obtain cultures when animals with multiple swollen joints have been unresponsive to pneumonia or respiratory treatment.

Adding to the frustration of having M bovis in a herd is the fact that no commercial vaccine on today's market contains this bacteria to help prevent or control M bovis. Thus, the only management route is a custom (autogenous) vaccine.

Dr. Keil says custom vaccines are quite common and can often be purchased in the same price range as commercial vaccines.

"The key expense for a commercial vaccine is the efficacy testing required for a license," Dr. Keil explains. "The government doesn't require efficacy testing of custom vaccines because of the immediate need for a vaccine solution. Thus, custom vaccines may have the perception of being expensive because they are herd-specific, but custom vaccines are usually not any more expensive than commercial vaccines."

The primary difference between a commercial and a custom vaccine is that a custom vaccine is specific to one producer's herd and can only be used in that herd or feedyard. Additionally, a custom vaccine can only be sent to the veterinarian who obtained the culture and requested the vaccine for his client.

"We tried autogenous (custom vaccine) at one feedlot and saw an incredible response," Dr. Safley states. "Producers want something that works, and I have confidence in custom products."

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