Mycoplasmas in Bovine Respiratory Disease
Apr. 09, 2021
The role of mycoplasmas in bovine respiratory disease has been the subject of controversy. Because nine pathogenic species of mycoplasmas have been reported to be recovered from pneumonic infections, discrimination between these species is of importance. For North America, two species have been reported as common and significant agents to consider. In young dairy calves, pneumonia is often seen shortly after grouping dairy calves that have been raised individually in hutches. Mycoplasma dispar is a prevalent agent implicated in these infections, often with limited mortality.Nevertheless, it should be noted that this mycoplasma can occasionally produce lobar bronchopneumonia with severe peribronchial cuffing, primarily in highly stressed young calves.
Indications and clinical uses
In cattle, gamithromycin is used for treatment of bovine respiratory disease (BRD) caused by M. haemolytica, P. multocida, and Histophilus somni (formerly Haemophilus somnus). It is also effective for treating infections caused by Mycoplasma. It also may be used for control of respiratory disease in beef and nonlactating dairy cattle at high risk of developing BRD (metaphylaxis) associated with M. haemolytica and P. multocida. In horses, clinical studies are not available, but experimental studies indicate that it may have efficacy for treating infections caused by Streptococcus equi and Rhodococcus equi.
Reasonable BRD Treatment Protocol Response Expectations
The BRD treatment response can be difficult to predict. Most of the focus is on BRD that occurs during the first 30 to 60 days following feedlot arrival. A good rule of thumb is to obtain a 90% to 95% first BRD event recovery for cases that occur during this time period. If the observed recovery rate for this time period is above 95%, many feedlot veterinarians feel the cattle health checkers and hospital crew are treating more cattle for BRD than should be required. If the observed recovery rate is below 90%, many feedlot veterinarians feel the cattle health checkers may be having difficulty identifying BRD cases during the early stages of the disease process or that they need to adjust their BRD treatment protocol.
Too frequently, management is quick to lay blame on either the veterinarian or the cattle health checkers. However, preexisting BRD in cattle at the time of arrival at the feedyard is the most likely cause for not identifying sick cattle in the early stages. Certainly the veterinarian should continuously monitor BRD prevention and treatment protocols. Everyone involved with the cattle health program should regularly review the steps needed to find BRD cattle early. Emphasis must be placed on evaluating the process by which cattle are acquired. Evaluate source, source, and source.
Did the source of the cattle provide proper immune management before entering the marketing channel? Did the source commingle immunologically ill-prepared cattle from different sources for more than 24 hours while traveling in the marketing channel? Did the source potentially mishandle or add unacceptable stress that could weaken them metabolically or immunologically? If the answer is “yes” to any one of these three source questions, it is not the cattle health checker's or hospital crew's fault, and it is not likely the BRD treatment protocol.
The above information is provided by the Gamithromycin injection supplier.