Metaphylaxis is a traditional method used in cattle to help decrease the incidence of bovine respiratory disease (BRD). Historically, it has meant administering an antibiotic on arrival to groups of calves at high risk of developing BRD. While our industry continues to make strides in antibiotic stewardship, the concept of metaphylaxis may need to be reevaluated. 

In recent years, the concept of “targeted metaphylaxis” has become more popular, relying on evidence-based medicine to make successful treatment decisions. This concept “targets” individual high-risk calves, instead of blanket-treating whole groups of cattle.  

For a targeted metaphylactic approach to be successful, it’s important to develop a plan with your veterinarian on how to select animals for treatment, as well as a logical means to evaluate results. 

A plan to identify individual high-risk calves 

Historically, metaphylaxis has been a standard method used to decrease illness and death loss in high-risk calves vulnerable to BRD. Calves considered high risk will often have unknown health histories, and will have experienced recent stressful events like commingling or transportation. 

When managing a group of high-risk calves, a conservative approach is often taken to ensure all calves are protected from respiratory disease whenever possible. However, it’s valuable to recognize that some calves treated with metaphylaxis may not have developed BRD. It’s important to work with your veterinarian to identify which calves truly require metaphylaxis, so treatments can be applied effectively and responsibly. 

Selection criteria for metaphylaxis may involve several factors, including the age and weight of the cattle, the length of time they were in transport, the weather conditions during transport and arrival, the origin of the cattle, as well as their perceived nutritional status. One way to reduce the amount of antibiotics used for metaphylaxis is to precondition or purchase preconditioned calves. Studies show that preconditioned cattle are at a lower risk for developing BRD.¹  

The growing importance of chute-side diagnostics 

Chute-side diagnostics can be an important tool for targeting calves for metaphylaxis. With that being said, it’s important to remember that added processing and handling time amounts to added stress on the cattle. Therefore, any chute-side diagnostics we utilize need to be done quickly, while not compromising the integrity of the test itself.  

Currently, there are technologies being explored and developed that monitor animal movement, temperature, behavior and feed intake, and that could potentially change the game with respect to early identification of sick animals. These technologies may offer the benefit of capturing subtle signs of illness before we, as humans, are able to.  

While many of these diagnostics are in the infancy stages of development and use, going forward, we could see these being very valuable assets when it comes to making decisions about targeted metaphylaxis. At this time, the most valuable asset we have to spot sick cattle as early as possible is still the properly trained human eye.  

The D.A.R.T. assessment is used by many operations to evaluate the health status of a calf or calves. It focuses on four key areas: Depression, Appetite, Respiratory rate and Temperature. These criteria are straightforward to implement, and should be used consistently on a daily basis. 

Choose the right antibiotic 

When you are selecting an antibiotic for metaphylaxis, your veterinarian will be invaluable in making the right choice. Efficacy studies, the spectrum of activity and the length of time the antibiotic is at therapeutic levels in the bloodstream (post-metaphylactic interval) are all factors they will consider when matching an antibiotic best suited for your operation.  

In addition, it’s important to choose an antibiotic that gets to the spot of infection quickly and provides broad-spectrum coverage. Doing this gives you the best chance of offsetting disease. While it may be tempting to go with a cheaper, less-proven antibiotic, the cost of respiratory disease later in the feeding period may be much higher than the cost of using the right product up front. 

Measure success and determine return on investment 

For each operation, there must be a consistent method to evaluate the current protocol. Data such as morbidity, total death loss and case fatality rate are all factors you and a herd veterinarian can analyze together to evaluate the effectiveness of metaphylaxis. Average daily gain and feed efficiency can also be analyzed on operations that feed cattle to finish. 

Recordkeeping can help determine the return on the investment from metaphylaxis. More importantly, as data accumulate over several groups of cattle, the analysis of that data can be used to improve the success of metaphylactic protocol. 

Metaphylaxis will have the most success in an operation when it is used with a holistic approach in mind. This includes good animal husbandry, strategic parasite control, optimum nutrition and minimizing stress in the cattle. 

Reference: 

¹ Shelley C, Matney C.Fact Sheet #8.023: Bovine respiratory disease: preconditioning calves. Colorado State University Extension. 2016. Available at: https://extension.colostate.edu/docs/pubs/livestk/08023.pdf. Accessed February 5, 2020. 

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