The two major areas to emphasize for prevention are management and vaccination. Of the two, management is usually much more important.
1. Management
Evaluate all the possible causes for stress on the cattle and determine which ones can reasonably be eliminated or at least reduced. Look carefully at alternative methods of operation and at specific timing of processing, vaccinating, etc. Recognize the critical period for disease detection during the three weeks immediately following weaning, placing on feed, or shipping of cattle. Avoid mixing (co-mingling) cattle from different sources during this highly critical three week period. Preconditioning does reduce the rate of illness and death but must be evaluated in terms of economic costs and benefits for the specific producer involved. Arrange the pens and feeders to keep new cattle close to the feed and water supplies. Don’t overcrowd, especially early in the feeding period. Control the dust and mud.
2. Vaccines
Vaccines are available for several infectious diseases of cattle. However, with the various brand names as well as different combinations available, the choice of vaccines can become very complicated. The six respiratory disease agents for which vaccines are available are categorized and briefly described below.
Calves vaccinated under 6 months of age should generally be re-vaccinated after that age to provide a longer lasting immunity. It is important to follow the specific directions provided with a vaccine. If two doses are recommended initially, don’t count on very much protection until 7–14 days after the second dose has been given.
A) IBR (Infectious Bovine Rhinotracheitis—Rednose): A viral infection of the upper respiratory tract. It is present in almost all herds, but causes illness in unexposed animals or those with lowered levels of immunity. Many cattle carry the virus and begin shedding it to others during times of stress. This agent is commonly implicated with bacterial agents in causing shipping fever and other severe cases of pneumonia.
Both MLV (modified live virus) vaccines and killed (or attenuated) products are available. Some are designed for IM (intramuscular) use while others are given IN (intranasally). The killed and intranasal products may be used for, or around, pregnant cows but some other vaccines may cause abortions. The IN vaccines will cause some antibody response within 3 days and may be useful even in the face of an outbreak. Two doses of a killed product must be used to confer protective immunity.
B) PI3 (Parainfluenza-3): Another viral respiratory agent that causes a relatively mild disease by itself, but a severe problem when combined with a bacterial agent. It is often included with IBR vaccines and can be used on the same schedule.
C) BVD (Bovine Virus Diarrhea): A common viral agent, present in almost all herds. It may cause respiratory, digestive tract or reproductive problems. It has a profound detrimental affect on the immune system.
A number of MLV vaccines have been available for BVD. Killed vaccines are now available which stimulate good immunity, but two doses of these are required initially.
D) BRSV (Bovine Respiratory Syncytial Virus): A relatively recently recognized disease agent, but now identified all across the country in respiratory infections. It is mainly a problem in weaner and feedlot animals (also young dairy stock). Killed virus vaccines are available with two initial doses required. Modified live virus vaccines are also available.
E) Pasteurella: A bacteria carried by many normal cattle. It becomes a major cause of severe “shipping fever” pneumonia when combined with stress and a viral agent. Two species are common: P. hemolytica and P. multocida. Vaccines available in the past were poor, and use of a single dose caused more problems than if none were used.
Great improvements have been made in recent years and several products are available, with more to come. Some of the killed products require two doses to stimulate protective immunity, but others are available for which one dose is sufficient. Attenuated (modified live) vaccines are also available. Follow directions carefully for these products to be beneficial. They must usually be given prior to weaning in order to help hold down the occurrence of disease at this critical time.
F) Haemophilus somnus: This agent is the other major bacterial agent involved in shipping fever. It also causes “brain fever” in feedlot cattle (also known as TEME: thromboembolic meningioencephalitis). The killed vaccine must be given in two doses initially and should be used prior to weaning for the greatest benefit.
Source: Clell V. Bagley, DVM, Extension Veterinarian, UtahStateUniversity