Milk and other dairy products have long enjoyed a positive consumer image. Most producers take great pride in believing that they produce wholesome and nutritious foods for human consumption. Along with that image, however, comes the responsibility for ensuring that dairy food products are both wholesome and safe, through prevention and treatment of diseases that can adversely affect milk quality.

Currently there are two primary mechanisms for achieving these goals: the carrot (industry) approach and the stick (regulatory) approach. These dual methods of regulation have worked quite well for many years. Most farms operate very well with the current carrot and stick approach to ensure that they do not produce milk for sale that contains violative pharmaceutical residues.

From a producer’s perspective, a cow that is sick enough to require treatment intervention represents a lost profit opportunity, not just because of the drug and labor costs, but because something has possibly gone wrong with the farm’s management protocols that are supposed to ensure things run smoothly and without incident.

There are many conditions and circumstances on today’s dairies that necessitate the use of pharmaceutical products. Mastitis is but one disease of many that occur in dairy cattle that may respond to therapeutic intervention. The first goal of any dairy farming operation is to have management and husbandry procedures implemented, so that the livestock on the dairy can achieve their genetic potential for productivity.

Responsible drug use on a dairy embraces many factors. First, there needs to be a means of examining animals for abnormal physical conditions and overt disease. It is both desirable and important to have a facility that allows for prompt and proper identification of abnormal animals. Personnel charged with the observation and examination of cattle need to have adequate training and equipment to properly recognize and treat animals with disease issues that require medical intervention. This includes the authority to summon and involve a veterinarian in these activities to ensure that a diagnosis and a plan for mitigation can be developed and implemented.


Economic pressures for labor efficiency create a trend to ever- increasing numbers of animals per employee. This reduces the employee’s ability to accurately identify and treat disease issues, as well as to evaluate the effectiveness of those treatments.

In the late 1980’s, the U.S. dairy industry found itself dealing with a public relations dilemma regarding antibiotic residues in supermarket-shelf milk. The public outcry over this incident resulted in an industry wide program to promote responsible and proper drug usage, through a variety of initiatives that depended on a combination of federal and state regulatory oversight, industry education and professional drug prudent use guidelines.

In the aggregate, these interventions have been very successful at decreasing the incidence of violative drug residues in milk and dairy products. Each dairy is aware of the testing programs that involve screening of every tanker load of milk shipped, and of the consequent penalties that are assessed should a violative residue be attributed to their dairy.

As a result of these efforts, many procedures were implemented on the farm to ensure that milk from treated animals was segregated and kept from being put into the dairy’s bulk tank. These procedures involve everything from segregation of the cow from the milking herd in a separate treated cow facility, to screening tests run on each treated cow’s milk before she is allowed back into the milking herd.

Unfortunately, over time, there seems to have developed a disconnect between the ‘comfort’ that dairies are producing very few violative milk residues, and the ‘discomfort’ of drug use practices that are well outside prudent drug use guidelines. Recent news reports have dealt with human illness attributed to food-borne bacteria and antimicrobial resistance resulting from antibiotic use on farms. While there has been much debate over the scientific validity of these associations, one thing is certain – the livestock industry will be blamed for this antimicrobial resistance, regardless of the science.

This article’s primary focus is to address prudent drug use as it applies to milk and dairy products. It is beyond the scope of this article to address the issue of violative drug residues found in the tissues of cull dairy animals, which is a significant and ongoing concern for the industry.

The regulatory effort developed in response to the violative residues found in supermarket-shelf milk, primarily dealt with residues of Beta-lactam antibiotic products, and in large part, it has been very successful at reducing these residues. The Center for Veterinary Medicine (CVM), a branch of the Food and Drug Administration, has approved a number of pharmaceutical products with either a zero or very short milk and tissue withdrawal when used according to the label instructions.

This has been a complicated issue for many dairy farm personnel to grasp. It has led to the false assumption by some farm personnel that a zero or short withdrawal period means that there is little or no risk of producing a violative residue, even when the product is used in an extra-label manner.

Extra-label drug use can be a very confusing concept for dairy producers and veterinarians alike. Simply put, extra-label applies to any use of a drug not consistent with its labeling. Some of the most common extra-label uses are via a route or in a dosage not listed on the label, such as an antibiotic given via the intramammary infusion route versus intramuscular administration, when the drug label specifically calls for intramuscular administration only.

This is complicated by the fact that several drugs labeled for different routes of administration have the same active ingredient, but are in different concentrations or formulation bases. Treatment personnel often fail to differentiate this important difference, and consequently, the potential for producing a violative residue from extra-label usage due to changed absorption and elimination times is great.

Most caregivers are entirely focused on a “cure” rather than on the potential for violative residues. This is especially true when the emphasis is on return to the milking herd, with little thought given to the potential for creating violative milk or tissue residues if the animal’s milk is put into the tank or she is sold for slaughter.

State and federal programs developed from the late 1980s are primarily focused on Beta-lactam residues in milk; therefore, there are very few milk testing programs in place for other classes of antimicrobials and pharmaceuticals. As a result, some dairies have been able to avoid citations and penalties for violative residues because the current testing system for classes of pharmaceutical compounds other than Beta-lactam, do not occur with the same testing frequency. This can lead to a false sense of confidence by dairy personnel regarding the avoidance of residue detection.

Programs for surveying other classes of compounds as violative residues exist, but they need to be routinely implemented if they are to be effective. As regulatory emphasis and efforts change, these loopholes will undoubtedly be closed. Tissue testing programs are conducted in slaughter plants for all classes of antimicrobials and pharmaceuticals.

There are many CVM-approved pharmaceuticals that are legally available, usually through prescription in the U.S. A properly written prescription is supposed to mean that a dairy using these products does so within the context of a valid Veterinarian Client-Patient Relationship (VCPR). Unfortunately, the reality is that prescription drugs are quite readily available through many sources, and it only takes a very few unscrupulous veterinarians looking for profits through drug sales to subvert the entire system of oversight for prescription drug distribution and usage.

This is an area that has been a long-standing problem, and for which there are yet to be effective controls developed. When the supermarket-shelf milk residue issue was in the news, the industry developed programs aimed at education and voluntary compliance. These regulatory programs made great strides toward increasing producer and veterinary awareness of responsible drug usage.

Federal and state efforts at compliance developed from that incident were directed towards proper drug labeling and storage through the National Conference on Interstate Milk Shipments (NCIMS) and their enforcement document, the Pasteurized Milk Ordinance (PMO). Their efforts allowed for inspection of drug storage areas on the dairy. Properly labeled drugs served as evidence that the dairy was using drugs in the appropriate manner and that the prescription drugs had been obtained within the context of a VCPR.

Once initiated, on-site farm inspections revealed a number of troubling concerns. First, there appeared to be efforts to hide drugs from inspection that did not comply with labeling requirements. Second, inspections revealed that there was a good deal of drug compounding by veterinarians that did not meet federal standards for good manufacturing practices, and whose sale was primarily aimed at enhancing the profitability of the individual or practice that was making and selling such products.

As a result of these findings, each of the animal species specialty groups developed and published prudent drug use guidelines for veterinarians under the umbrella of the American Veterinary Medical Association. Vigorous efforts at publicizing the guidelines helped to bring about the collective awareness of responsible use and valid prescribing to a better standard. It appeared that compounding of products for use on farms by veterinarians was on the wane. It was a practice no longer in vogue. State and federal inspection programs resulted in better labeling and storage compliance over time.

Recently, however, it would appear that the industry has forgotten some of the lessons of past history, and indeed, history appears to be repeating itself. There are anecdotal reports of compounding by rogue veterinarians and lay persons resurfacing. Producers that previously had been compliant with responsible drug use have been noted to be using drugs more frequently in an extra- label manner and without the input or knowledge of a veterinarian. Such practices, while seemingly innocuous to an animal caregiver on the individual dairy, can have tremendous negative ramifications for the industry as a whole.

It is undoubtedly time for the industry to begin a reeducation effort for itself, before the issues of compounding and compliance reach the headline column of the popular press. The non-compliant behavior of only a few individuals has the potential to produce huge negative effects for the entire industry.

Dairies that adhere to a policy of responsible drug usage make sure that certain procedures are in place. First, they employ management, nutrition and husbandry practices that are designed to reduce or eliminate diseases on their dairy. Second, they involve the input of a competent veterinary professional to ensure that their drug usage, treatment plans and record-keeping procedures are effective and compliant. This includes, but is not limited to, timely and appropriate diagnostic workup (including laboratory sample submission), training of farm personnel, establishment of effective protocols, monitoring the effectiveness of procedures and willingness to make revisions when necessary.

There is, however, a certain irony as the dairy industry evolves to fewer and larger operations. Often the management decision tree is understood and implemented in dramatically different ways by the animal caregiver, the herdsperson and the owner/manager of the dairy. Surveys of these three different personnel groups reveal dramatically different perceptions as to how troubleshooting and treating disease is actually accomplished on the dairy.

It still comes down to making sure that dairy personnel are properly trained for their job, and that they have the tools, materials and time necessary to accomplish their job. In addition, there needs to be in place an agreed-upon means of monitoring and measuring job performance. All too often, the devil is in the details, and this is particularly true when it comes to drug usage.

Procedural ‘drift’ away from compliance comes about as the dairy expands numbers, without corresponding increases in labor and training. This problem is exacerbated as employees change jobs on the dairy or leave, and untrained or inadequately trained replacement employees assume care and treatment duties.

The industry continues to deal with many of the same issues that it always has. Whether it is heat detection or responsible drug use, it always involves people knowing and doing the right thing. There will always be changing technology; indeed, the only certainty is that the dairy industry will continue to face change.

From the perspective of a veterinarian, it is readily apparent that the application of current knowledge and technology to the daily dairying routine yields a wide range of interpretations. The guidelines for responsible drug use have already been developed and written, so there is little need to reinvent the wheel. It is up to the industry to decide how to best reintegrate that body of knowledge into effective and practical procedures for today’s dairies. How we deal with prudent drug use now, and how the consuming public perceives our efforts, will go a long way to preserve the positive image that milk and dairy products deserve in our society. PD

References omitted but are available upon request at

—Excerpts from National Mastitis Council 47th Annual Meeting Proceedings

Keith E. Sterner, Sterner Veterinary Clinic