When to Use Metaphylaxis

Published on: 09:53AM Nov 02, 2009

By Dan Goehl, DVM

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Metaphylactic use of antibiotics(giving the product to head off mass spread of disease in a group) in purchased calves can be an useful management tool. 

This decision is not to be taken lightly for several reasons. Antibiotics should always be used prudently to avoid overuse and cost on these products can run over $15 per head depending on the product and the size of the calf. 

There are several factors that we use to make a decision on metaphylactic use. Source, purchase pattern, size/age of calf, value of calf, management practice, availability of help, availability of time to ride pens, vaccination history (if known), weaned or unweaned are among some of the factors we look at. These items are used to determine a risk level for each pen of calves and then a decision is made rather to treat on initial processing event or pull cattle that appear ill and treat at that time. 

On pens of cattle that the determination is made to pull and treat, we still keep pen level treatment on the table. As treatments mount up in a pen, we may determine it is time to mass treat the pen to prevent the “perfect storm”. 

It is best to set trigger points to determine when that time has arrived. Some rules of thumb are 20 - 25% on one day or 10% two or more days in a row.  These also will vary from operation to operation. One reminder I give to clients that implement this strategy is when the trigger point is reached on Sunday morning or Christmas Day the antibiotics need to be given that day.  If this is not an option then the plan needs to be adjusted. Allowing 24 hours to pass can be a fatal flaw in stopping the spread of the pathogen (disease causing agent).

There are several reasons that these practices can be beneficial. One of the advantages is that it helps cover up our inability to determine which calf is ill and if ill will it benefit from antibiotics. This ability varies from person to person but as a whole the industry is not very good at identifying these animals.  This is not to discredit the talent of pen riders, there is simply no good way to visually determine the answer. Our ultimate goal of our health programs is to decrease the reproductive rate of disease to below one. That is for every animal that becomes sick less than one more animal will become sick as opposed to a disease that has a high reproductive rate where every animal that gets sick infects several more animals.

Often when we use metaphylaxis we will see the peak in sick pulls to be extended out to after day 14 but we are able to keep this reproductive rate of disease low through the initial acclimation period. At this later time the calves are on good plane of nutrition and our vaccinations have had time to begin to provide protection. 

Ultimately our goal should be to only use metaphylaxis if it will decrease the respiratory sickness and death loss. Using it to overcome shortcomings in other management practices should not be tolerated. 

Dan Goehl, DVM, and his wife own and operate Canton Veterinary Clinic in Canton, MO, where Dan works primarily with stocker and cow/calf beef operations. Dan is also partner in Professional Beef Services, LLC, which offers herd consultation and helps in data management and marketing of beef cattle.

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