Bovine Respiratory Disease Complex: VIRUSES

Diseases of the respiratory tract amount to substantial economic loss in the cattle industry every year. Often referred to as Bovine Respiratory Disease Complex (BRDC) because of the many factors involved in creating this disease. These factors can be divided into Stress, Virus Agents, and Bacterial Agents. This website will focus on the 4 main viruses involved in BRD in North America. These viral agents often produce mild clinical signs by themselves, but when combined with bacterial or other viral agents in association with stress, they can lead to severe clinical signs and death.

Signs of BRD may involve nasal discharge, coughing, fever, lack of appetite, depressed look, rapid and/or noisy breathing, droopy ears, stiff gait, and death. Signs will vary from mild to sever depending on the disease agents, immune status, environment, and individual genetic differences.

Although several species of bacteria can be involved in BRD, the most common bacterial agents isolated from BRD animals are Mannheimia haemolytica, Pastuerella multocida and Mycoplasma bovis.

Treatment is often difficult with varying results, but some steps that increase the probability of survival include: 1) early detection based on clinical signs and separation to a sick pen; 2) treatment on a daily basis following a veterinary program; 3) change in treatment and continuation if no improvement in 24-48 hours; 4) continued nursing and monitoring as in many cases sever lung damage can occur quickly and relapses and poor gains are inevitable.

Prevention of BRD is the most important aspect in minimizing economic loss. Although the disease cannot be eliminated, economic loss can be minimized dramatically. The two most important areas are management and vaccination. Management involves minimizing stress on animals particularly during weaning, shipping, and placing in feedlots. Although stress can not be eliminated, many practices have been researched that minimize stress without reducing profits. Other management decisions can include reducing co-mingling among unrelated cattle, dust, and mud.

Several vaccines are available today from a wide variety of companies. Talking to your veterinarian and researching the different vaccines can help producers decide which vaccine will be most effective for their herd. Vaccination of young calves should be evaluated as their maternal antibodies will often prevent full protection from the vaccine.


Produced by Chase Wendorff, Tim Ritson-Bennett, Adam Schierman, Troy Gowan, Justin Rosing for WCVM class project