The number of drug residues that occur in meat is very small — 0.003 percent of all cattle slaughtered. However, cull dairy cows are the No. 1 violator when it comes to drug residues. And, it’s an issue that the dairy industry must take care of without further delay.
Any level of drug residue is unacceptable, says Mike Apley, a veterinary clinical pharmacologist at Kansas State University. And, if we do not address the issue, the dairy industry faces serious consequences. (See “Time to take action.")
The good part is that it’s not difficult to prevent residues from occurring. But it will take commitment and due diligence on your part to prevent them.
Here is how you can prevent residues.
Establish written protocols
Work with your veterinarian to develop written protocols.
Written protocols serve as an on-farm guide for diagnosis and treatment decisions. A protocol should include signs of disease and detailed directions for treatment, including meat- and milk-withdrawal times. The University of Minnesota will soon be releasing a software program that will help veterinarians establish written protocols.
Written treatment protocols are an area where we can all improve, notes Virginia Fajt, clinical assistant professor in the College of Veterinary Medicine at Texas A&M University. A 2006 survey of 381 dairy producers in Washington showed that less than one-third had written protocols for diagnosing or treating disease. This concurs with research done in Pennsylvania in 2002, where only 21 percent of farms surveyed had written plans for treating sick animals.
Protocols should not change until you and your veterinarian have consulted with each other, notes Apley.
Once protocols have been established, train all employees who are authorized to treat animals how to identify sick animals and when to treat.
Teach employees the proper way to administer medicines to make sure that the products are used safely and effectively. Show employees the proper drug-handling procedures and educate them about responsible drug use.
Remember, the employees treating animals may or may not speak English, so the information needs to be translated into their native language if necessary.
Prevent accidental improper use by storing drugs for dry cows and heifers separate from the ones for lactating cows.
Follow route of administration
Read the label and follow the route of administration listed.
Route of administration makes a huge difference, says Fajt. If a product is to be administered intravenously, intramuscularly or subcutaneously, use it in this manner only.
Different locations on the animal absorb the drug at different rates. Therefore, a change in location can change withdrawal times — sometimes by a matter of days or even months.
For example, with penicillin, changing the route of administration from intramuscular to subcutaneous can increase the residue withdrawal time in milk from days to more than a month.
“When it comes to ceftiofur crystalline free acid, one might think moving from the ear to the neck is no big deal, but it’s a huge deal,” says Apley. “The pharmacology between locations is different and it has a huge impact on the necessary withdrawal time.” Other forms of ceftiofur are labeled for subcutaneous injection in the neck and using them in this location is appropriate. This highlights the importance of knowing exactly which formulation you are using.
Look at dosage
Be sure the animal gets the correct dose based on the animal’s body weight. The dosage per body weight appears on the label.
“This means knowing the animal’s weight and calculating the specific dose,” says Dale Moore, director of veterinary medicine extension at Washington State University.
Never give more than 10 cc’s of a product in one location. Too much in one place can cause a residue, says Fajt.
Be sure to give the drug for the number of days specified on the label. Withdrawal periods start after the last dose of the drug is given.
Be aware that different products with the same generic drug name may have different withholding times.
Account for extra-label usage
Work with your veterinarian to establish meat withdrawal times for extra-label use.
For any extra-label drug use, your veterinarian will arrange for a special label to be attached to the drug detailing extended meat and milk withdrawal times.
There is one credible source for establishing extra-label withdrawal time periods and that is the Food Animal Residue Avoidance Databank. Veterinarians have easy access to this database.
Keep good records
Avoiding drug residues comes down to good record-keeping.
Develop a systematic way of keeping track of when an animal is treated, says Fajt. A national survey of 389 farms with more than 200 cows found that 40 percent of farms don’t keep written records of treated animals. Another survey of Pennsylvania dairy producers found that only 50 percent kept treatment records.
Records should include date treated, disease indicated, animal ID, person administering the treatment, drug used, amount used, route of administration and meat- or milk-withholding times.
It does not matter if it is computerized or hand-written, as long as you keep accurate records, says Keith Sterner, veterinarian with Sterner Veterinary Clinic in Ionia, Mich. Work with your veterinarian to come up with a system that works for you.
Identify all treated animals
Be sure to identify all treated animals.
Treated animals should have some sort of identifier — either leg bands or chalk. A combination of identification methods may be best, as chalk tends to rub off, notes Moore.
It is also highly recommended that you separate treated animals from the milking herd.
Correct procedural drift
Periodically review treatment records to verify that employees are adhering to written protocols.
“It’s not uncommon to find drift in protocols,” says Apley. When working with feedlots, Apley says he would visit once or twice a month to check treatment records of animals that died to look for mistakes and variances in protocol.
“You can’t afford procedural drift because you may get an antibiotic or drug in the herd that is ineffective or harmful,” notes Apley. It also creates the potential for residue violations.
Check and recheck
Review all treatment records before culling an animal.
Every cow’s record needs to be examined before shipping, says Apley. “It’s too late to check when the animal is on the truck.”
To make this easier, Fajt suggests using sell-after dates in your record-keeping system to make reviewing the records easier. “Instead of counting out 28 days from the last day of treatment, the person reviewing the records just has to check the date.”
If treatments are adequately recorded and checked prior to shipping, the chances of having a residue violation on the day the withdrawal period is completed is one out of 1,000, notes Apley.
At the end of the day, residues are caused by people. And it’s up to you to prevent residues from happening. “If you aren’t taking steps to prevent residues from happening, you’re jeopardizing your own operation and the entire industry,” notes Sterner.
It’s not just antibiotics
In 2008, the USDA reported that there were 1,086 adulterated carcasses that contained drug residues. Of those 879 were cattle and 791 originated as dairy animals. Residues were found for both antibiotics and anti-inflammatory drugs.
Residue violations in five Western states show that penicillin was the most common drug found in dairy cows, followed by sulfa drugs, flunixin meglumine, and the metabolite of ceftiofur. Tetracycline residues were also found, as well as gentamicin, neomycin and tilmicosin. For tilmicosin, the label says specifically “Do not use in female dairy cattle 20 months of age or older. Use in lactating dairy cattle or sheep may cause milk residues.” For gentamicin, the FDA has not approved gentamicin for use in cattle or scientifically established a withdrawal time for cattle. While the Food Animal Residue Avoidance Databank recommends a minimum withdrawal period of 18 months or more for this drug, the American Veterinary Medical Association and American Association of Bovine Practitioners have called on veterinarians to avoid extra-label use of aminoglycosides, including gentamicin, in cattle because of the likelihood for these drugs to be retained in kidney tissue for long periods of time.
Dale Moore, director of veterinary medicine extension at Washington State University, offers insight on why these residues might occur.
Flunixin. The most common reason for a residue from this anti-inflammatory drug is the improper route of administration, says Moore. The label directs us to administer the injection intravenously, but many people may give the drug incorrectly in the muscle. When this happens, a much longer withdrawal time is needed before the tissues will no longer have a residue.
Flunixin is labeled for use in dairy cattle to control fever associated with bovine respiratory disease and endotoxemia. Too often, it is used without regard to the need for it, says Moore.
Desfurloylceftiofur (a metabolite of ceftiofur). The most likely reasons for a meat residue with ceftiofur include improper dose, duration or route of administration or an inappropriate withdrawal period, notes Moore.
Sulfadimethoxine. Different formulations of this drug are available, and the ones specifically focused on the correct class of animal (dairy) need to be used.
Penicillin. A possible reason for a residue is an extra-label dose without an extended withdrawal time. This drug is sometimes used as an intra-uterine infusion and withdrawal times might not be followed, adds Moore.
Tetracycline. Most formulations of oxytetracycline are not to be used in dairy cattle 20 months of age or over. There are also specific requirements for the dose by weight of the animal and not exceeding a specific duration of treatment. Going off-label with this drug with regards to route of administration, dose or duration of treatment could result in a residue.
Ivermectin. An example of how an error could occur is a bull might be dewormed with this drug, along with the rest of the cattle, and then marketed without following the label withdrawal time, says Moore.
How well do you manage the use of antibiotics on your farm?
The Washington State Agricultural Antibiotics Project, in association with Washington State Dairy Federation and Washington State University, has developed an antibiotic stewardship self-assessment tool kit for dairy producers.
There are three levels to the self-assessment. If you are doing everything listed in level one, you are practicing a basic level of antibiotic stewardship. If you meet the criteria listed in assessment level two, that means you are practicing an intermediate level of antibiotic stewardship. Meeting the level three assessment means you are practicing an advanced level of antibiotic stewardship. All three assessment levels include best-management practices that can help you improve the handling and use of antibiotics.
What is a VCPR and do I have one?
A valid veterinarian-client-patient relationship is required for the use of any prescription drug or use of any extra-label drug on the farm.
It is defined as follows: A veterinarian agrees to be responsible for making decisions about diagnosing and treating animals on the farm and the client (owner or caretaker of the animal) agrees to follow the veterinarian’s instructions.
The veterinarian is familiar enough with the farm to be able to make a diagnosis of medical conditions of the animals on that farm. The practicing veterinarian is available for follow-up in case of a drug reaction or if the therapy does not work.
Routine visits and discussions with your veterinarian are key elements to maintain this relationship.
Just because you buy a pharmaceutical product at the feed store doesn’t mean can use it any way you want, says Keith Sterner, veterinarian with Sterner Veterinary Clinic in Ionia, Mich.
Using over-the-counter (OTC) drugs in a manner that differs from the label is illegal unless it is done by or under the direction of a licensed veterinarian with whom you have a valid veterinarian-client-patient relationship. Only the uses listed on the label are legal for use without veterinary involvement.
Using an OTC drug in an off-label manner also changes the withdrawal time, notes Sterner. “If there is no withdrawal time listed, that does not mean that there is no withdrawal time if you use the product off-label.”
A proper withdrawal period cannot be established without consulting a veterinarian.