Preventing disease caused by bacterial pathogens associated with Bovine Respiratory Disease (BRD) should be on every herd health calendar for cattle of all types and sizes. BRD complex associated with Mannheimia (Pasteurella) haemolytica for example is known for its severity and rapid onset in cattle, particularly after they experience stress.
Vaccines are a great tool to help combat any number of cattle diseases, including BRD. However, to get the most protection vaccines can offer, producers need to keep a few things in mind — especially as temperatures heat up.
Dr. John M. Davidson, professional services veterinarian with Novartis Animal Health, advises producers to be mindful of weather conditions when working and vaccinating cattle in the heat of summer.
“Heat stress can trigger a variety of health issues for cattle,” notes Davidson. “One of the challenges of heat stress is that it limits an animal’s ability to build an immune response. So administering vaccines in high heat or excessively humid conditions should be avoided whenever possible. It’s always better to work and vaccinate cattle early in the day when ambient temperatures are cooler.”
Davidson also reminds producers to monitor the number of gram-negative vaccines they are administering to cattle at the same time. “This is especially important during hot weather,” he says. “There are a quite a few gram-negative bacterial diseases we protect against with vaccines, including M. haemolytica, formerly known as Pasteurella haemolytica.”
The challenge is that the majority of vaccines licensed for protection against respiratory disease bacteria contain whole cells of the target bacteria, like M. haemolytica for instance. The cell walls of these bacteria contain lipopolysaccharide, or LPS, also known as endotoxin. And the LPS endotoxin has a negative impact on an animal’s overall system—specifically its immune system.
“The effect of LPS is cumulative,” explains Davidson. “That’s why there are recommended limits on the number of gram-negative bacterial vaccines administered to cattle. This is especially important for calves and lightweight cattle. Producers should always consult with their veterinarian for guidelines on calfhood vaccinations against respiratory disease because every operation has a unique set of circumstances or risk factors.
Heat stress can lower an animal’s natural barriers to bacteria1, increasing the potential for LPS levels to rise and adding to the cumulative effect.