Bovine Respiratory Disease. Preventive measures save time and money.

Managing environmental factors, plus immunization, can help prevent respiratory disease in young dairy calves.

Bovine respiratory disease (BRD) is an extremely virulent disease, and on today’s dairy operations, requires greater attention than ever before. Caused primarily by two different organisms, Mannheimia haemolytica (formerly called Pasteurella haemolytica) and Pasteurella multocida, this pneumonia
condition not only creates a management challenge but can significantly reduce your bottom line if it’s allowed to develop.

Some species of bacteria are commonly found in the environment, and even in the animal, but do not create problems unless other factors such as stress or another disease  are present. Mannheimia haemolytica and Pasturella multocida are two such  species. Normally found in the upper respiratory tract, these infections are spread through direct nose-to-nose contact, or through feed and water contaminated by other infected cattle. The bacteria spread quickly, especially if calves are crowded or closely confined such as when they are grouped and penned at weaning, or upon arrival at a heifer grower facility.

Disease from M. haemolytica, often called shipping fever, is characterized by severe lung lesions that can develop very rapidly. When the bacteria infect a calf or heifer they produce a substance called
leukotoxin, which destroys white blood cells at the site of infection. Destruction of white blood cells leads to release of highly toxic substances that cells normally use to kill bacteria. In this case, however, these substances cause permanent damage to the lung tissue, making the disease far worse than it would be from infection alone.

P. multocida is less likely to cause the classic lung lesions found with shipping fever. But, it is still a disease that has a significant economic impact on dairy performance. Occurring often in housed dairy calves, environmental factors such as air ventilation and the nutritional and immune status of the calf play a critical role in the spread of this disease.

Some studies estimate that P. multocida affects an average of 10% of all dairy calves in some herds and as many as 30% in many operations. As a result, its economic impact could constitute up to one-third of all losses in dairy calves. Calves affected by pasteurellosis typically don’t grow as well, subsequently mature more slowly and often don’t calve at an appropriate age.

Specific situations on individual farms can also increase the risk of BRD. For example, many of today’s larger, expanding dairy herds often have large groups of dairy heifers arriving at the farm from various
locations for calving. The combination of increased co-mingling and stress during this stage of the dairy animal’s productive life puts her, and her herd mates, at heightened risk. Proper management practices, including immunization in certain cases, will go a long way toward preventing the disease.

The Role of Stress

The typical pathogenesis of cattle pneumonia involves stress and most often, an initial respiratory viral infection followed by a secondary bacterial infection of the lower respiratory tract.

When calves are in situations where they are stressed, such as shipping/movement, overcrowding and/or improper nutrition, immunity is compromised. With the immune system depressed, pathogenic bacteria P. multocida and M. haemolytica are able to set up shop and replicate. Once an outbreak occurs it is difficult, if not impossible to treat, and animals may never fully recover.

Once a calf has BRD, its chance of dying is significantly increased. Once lactating and in the herd, the resulting performance deficiencies put those animals at greater risk of being culled. So even if the
animal recovers as a calf, there will likely be long-term consequences that will affect future performance.

Prevention through management

Viral challenge, age of the calf, immune status, environmental conditions and presence of bacteria can all have a significant impact on the disease. M. haemolytica and P. multocida are frequently isolated pathogenic organisms. If Bovine Viral Diarrhea Virus (BVDV) infections are present, the risk of BRD is increased.

Environmental and management factors that can promote the spread of bacteria and compromise the immunity of young calves include ambient temperature, humidity, lack of adequate fresh air and air movement, overcrowding and direct contact with older calves.

Overcrowding can be one of the most significant contributors to the stress and circumstances that allow this disease to manifest. Poor ventilation is another factor for which particular attention is required.
Experts recommend paying close attention to the nose-to-nose route of transmission as you study your housing arrangements. Air flow patterns from older to younger calves should be avoided to prevent the
transmission of disease.

It’s important to keep birthing areas clean, move calves into calf hutches quickly, and implement a proper vaccination protocol for your specific situation. These steps coupled with proper age separation will help minimize the risk of respiratory disease.

Managing stressful situations and following some basic calf health protocols will help keep respiratory disease at bay. It’s important to work closely with your herd veterinarian to determine the specific protocols that will be most effective in your dairy operation.

Respiratory Bacteria are Big Component of Dairy Calf Respiratory Disease

Dr. Gary Rotenberger, DVM, consults with dairy producers in Northeast Iowa, and deals regularly with trying to prevent and control bovine respiratory disease (BRD) in calves.

“The big thing is seasonal Bovine Respiratory Syncytial Virus (BRSV) as the weather gets cooler during the fall,” says Dr. Rotenberger, who is with the South Winn Veterinary Clinic in Ossian, Iowa. “We find a lot of groups of calves weighing 200 to 500 pounds that get a hacky cough and nasal discharge.”

In addition to the BRSV component of BRD, Pasteurella multocida and Manheimia haemolytica (formerly called Pasteurella haemolytica) are also big factors in BRD cases in dairy calves, says Dr. Rotenberger.

It doesn’t matter how big or how small a dairy is because BRD can affect all sizes of dairies. Dr. Rotenberger says, “The more confined and concentrated the calves are, the better the set-up for having respiratory problems. We see it in calves housed in big open pens and in calves that are in buildings. Some farms are more prone to it if they have had trouble in past years.”

Because the pasteurellosis component can be responsible for as much as 75 percent of the dairy calf respiratory problems he sees, Dr. Rotenberger pays particular attention to controlling it. “Pasteurellosis is more likely to be what will destroy your calf. That’s the one that’s going to give you the most economic loss.”

Dr. Rotenberger believes in vaccinating calves against pasteurellosis. “If I could get everybody to  vaccinate sometime in September, and then again three weeks later before nights start getting too cool, I could control a lot of the problem,” he says. “Without pasteurellosis stressing the calves, they are much healthier, and they grow a lot better.”

He says he has had good success using products from the Pulmo- Guard family of pasteurellosis cattle vaccines, including Pulmo-Guard PH-M and the combination Express5-PHM.

Dr. Rotenberger believes these vaccines have been good tools to help fight respiratory disease in dairy calves. “They have worked for my clients and I am very happy with them.”

Solid management helps to minimize respiratory disease

• Prevention begins with a good cowvaccination program against specific respiratory viruses (such as a 5-way viral vaccine) used at prebreeding and considered again at dry-off to improve the quality of colostral antibodies. Calves should receive 4 quarts (12-15% of body weight) of
  high quality colostrum as soon as possible after birth.
• Newborn dairy calves should be housed individually in hutches and fed a high-quality milk replacer or pasteurized non-saleable milk. The use of super hutches or segregated pens in a pole shed prior to moving calves into groups helps prevent the spread of disease.
• If calves are to be vaccinated against bacteria and respiratory viruses, that should be accomplished before the first grouping. Calf vaccinations should be determined by you and
  your veterinarian based on housing situations and management practices.
• Calves should be of similar age when assembled into post-weaning groups. The group should
  be provided adequate pen and bunk space.
• As calves mature, groups can become larger as facilities and labor dictate. An “all-in/all-out”
  management style should be practiced when establishing and terminating a group.
• Newly purchased calves should be isolated before introduction into an existing group.
• When symptoms of disease are detected, antibiotic treatments should be administered.