When I last talked with Dr. Bruce Nosky, it was mid-summer and we discussed a too common fall problem – the onslaught of Pneumonia and the costly problems it can create in an otherwise healthy herd.
Dr. Nosky, manager of Merial Veterinary Services, pointed out that there are two causes of the disease – viral and bacterial – and you need a plan in place that attacks both.
“Mannheimia haemolyticaandPasteurella multocida are two of the main bacterial pathogens associated with bacterial pneumonia, he said. “They’re commonly found in the nasal cavity of healthy cattle and usually don’t cause a problem.”
He explained a defense mechanism as a combination of mucus and cilia lining the trachea. “The lungs are sterile, the nasal passages are not. The trachea is the windpipe connecting the two. If the bacteria drift downwards toward the lungs, they’re trapped on the mucus and the cilia (small hairs) move them up toward the mouth. Cattle swallow the mucus and the bacteria are destroyed by acid in the gut.”
Simple enough, but maybe more than I wanted to know.
It’s a natural process, though, that helps keep a calf healthy. Add some stress, though, and things can go awry quickly. Stress, Dr. Nosky pointed out, usually peaks in the fall and makes a calf more susceptible to disease.
Stressors that can peak in the fall include weaning, introduction to new environments, commingling with other animals, feed changes, overcrowding, transportation and changes in weather. And remember, the negative impacts of stressors are additive.
Dr Nosky was particularly cautious about fall weather patterns. “The consistent heat of the summer is OK,” he said, “and cold weather is only a problem because the animal might need some additional energy. Dramatic fluctuations in temperature, though, can really add stress”.
“A healthy, unstressed animal can fight off a small amount of bacteria reaching its lungs. White blood cells can usually take care of that,” he said. “Stress can weaken its defenses, though.”
“Producers should try to eliminate or minimize stress.” He said. “Stress, plus viral and bacterial infections are almost always involved in pneumonia. If you’re just vaccinating against viral agents, you’re overlooking bacterial causes. Calves should be prepared to defend against both.”
The effects of Pasteurella pneumonia can be as mild as slight depression and lack of interest in eating or as bad as high fever and labored breathing. In worst cases, irreversible lung damage can put the animal way behind in its growth, or they can die. Most vets consider bovine respiratory diseases (BRD) as the leading cause of cattle industry losses.
Cattle producers should follow a preconditioning program such as Merial’s SureHealth. Dr. Nosky suggests vaccinating calves prior to the stress of weaning. A first shot that includes the Pasteurella vaccine administered three to four weeks before weaning is best,” he said. “If that’s not possible, definitely make it part of the weaning process.
“Not all Pasteurella vaccines protect calves against Mannheimia haemolytica and Pasteurella multocida, (some only contain Mannheimia)” he warned. “Merial’s RESPISHIELD HM is effective against both bacterial agents, which is important because producers should use one that is effective against both major causes of bacterial pneumonia.”
“Fall and winter are unavoidable stressors that contribute to pneumonia,” said Nosky. “That’s why producers need to protect their cattle now against factors that contribute to pneumonia, starting with a vaccination program that includes RESPISHIELD HM.”
Source: http://www.cattlenetwork.com