AMDUCA and drug issues in sheep and goats (Proceedings)

Since 2005, the American Veterinary Medical Association and several species specialty groups have published their policy statements regarding judicious use of antimicrobials online at www.avma.org/issues/policy/jtua.asp. The policy statement for the American Association of Small Ruminant Practitioners concerning prudent drug use guidelines is available at www.aasrp.org. Veterinarians and producers are reminded that FDA revises its policies frequently and the information in this paper is based on data available in August 2009.

All sheep and goats are food animals

Both USDA and FDA classify all sheep and goats as food animals regardless of the reason that the producer chooses to maintain them. The cute pet pygmy and the horse companion are only one owner away from the slaughterhouse, and veterinarians should remember this when choosing drugs for treating any sheep or goat. FDA currently maintains a list of approved animal drugs searchable by species or product at http://www.accessdata.fda.gov/scripts/AnimalDrugsAtFDA/. While this website indicates that 154 drugs are licensed and labeled for use in sheep and 35 are legally available for use in goats, most of these are actually different formulations of a small number of drugs. For example, the 35 drugs licensed for use in goats include only the 7 products ceftiofur, decoquinate, fenbendazole, morantel tartrate, neomycin, rumensin, and thiabendazole. Very few of the drugs that veterinarians use or prescribe for goats on a daily basis are on this list.

Animal medicinal drug use clarification act - AMDUCA

After much debate and comment, the Food and Drug Administration published the final rule for the Animal Medicinal Drug Use Clarification Act of 1994, effective December 9, 1996. AMDUCA allows veterinarians to use approved animal drugs for indications and species that are not on the drug label when labeled products are not available. In order for the AMDUCA regulations to apply, a drug must have a new animal drug application on file; not all drugs that are commonly used have NADA's. An example of a commonly used drug that does not have an NADA is aspirin which is marketed and labeled for use in cattle but cannot legally be used in sheep or goats. The AMDUCA regulations have differing impact for food and non-food animal veterinarians. Extra-label use of drugs for non-food animals is now acceptable in most situations if it will not pose a threat to animal health. These rules allow equine and companion animal veterinarians access to most human drugs as well as all approved animal drugs. Companion animals are rarely consumed for food in this country, so the rules recognize that there is little concern for drug residues. Because the problem of drug residues is of great concern in those species consumed for food, AMDUCA regulations for food animals are restrictive and specific.

Extra label drug use - ELDU

AMDUCA outlines what classes of drugs can be used in a manner different than what appears on the label and under what circumstances they can be used. Small ruminant practitioners are frequently asked to prescribe drugs to manipulate reproduction in goats, yet AMDUCA allows extra-label use only when licensed drugs are not available and then only to save the life of an animal. ELDU refers to extra-label drug use or the privilege granted to veterinarians to prescribe the use of a legal drug in a manner than is different from what appears on its label. ELDU might mean a different dosage, duration of therapy, method of administration or specie. An important concept is that producers cannot legally use drugs in an extra-label manner, but a veterinarian can prescribe drugs for producers to use in an extra-label manner.

Veterinary client patient relationship – VCPR

VCPR refers to the establishment of a Veterinary-Client-Patient-Relationship which is a necessary requirement for extra-label use of pharmaceuticals. Veterinarians and clients who wish to use medications in an extra-label manner must meet three requirements to establish a formal VCPR. The veterinarian must assume the responsibility for making clinical judgments regarding the health of the animals and the need for medical treatment, and the client must agree to follow the veterinarian's recommendations. The veterinarian must have sufficient knowledge of the animals in question and this requires that the veterinarian must have visited the premise, examined the animals on the premise, and must be aware of the management practices and health status of the animals. Lastly, the veterinarian must be available for follow-up evaluation, or has arranged for emergency care in the event of adverse reaction or treatment failure. Once these requirements have been met, veterinarians can, with some exceptions, prescribe drugs in a manner different from the label.

ELDU and medicated feeds in minor species

Under AMDUCA, medicated feeds and topical anthelmintics may not be used in an extra-label manner. However, in May 2007, FDA published a list of conditions for the Compliance Policy Guide that would allow the extra-label use of medicated feeds in minor species such as sheep or goats. Any extra-label use of medicated feed in a minor species requires the involvement of a licensed veterinarian within the confines of a valid VCPR. The veterinarian is expected to make a written recommendation for the extra-label use of medicated feed based on a recent diagnosis of an active disease for which no other drug treatment is approved. The medicated feed may be considered for treatment only when the health of the animals is threatened and suffering or death would result from failure to treat the affected animals. Extra-label use of medicated feed is not allowed for production purposes. Once manufactured and labeled as approved for use in a major species, the feed cannot be either reformulated to meet the nutritional needs of the intended minor species or relabeled as such.

Drugs banned by FDA from use in food animals

FDA has determined that there are ten drugs that may not be used in food animals under any circumstances. This list includes chloramphenicol, clenbuterol, diethylstilbestrol, dimetridazole, dipyrone, fluoroquinolones, glycopeptide antibiotics, ipronidazole, nitroimadiazoles, and nitrofurans. Phenylbutazone and sulfadimethoxine are also restricted from use in dairy cattle over 20 months of age. Baytril may not be used in dairy cattle over 20 months of age, and FDA has prohibited extra-label use of this drug in food animals. The AVMA and the American Association of Bovine Practitioners recommend that aminoglycoside antibiotics including gentamycin should not be used in cattle, and the American Association of Small Ruminant Practitioners supports the voluntary ban on use of this class of drugs in small ruminants. This voluntary ban was instated because there are no known effective drug withdrawals for this class of antibiotics that would yield food products without detectable drug residue.

Use antimicrobial drugs wisely

The production of safe and wholesome animal products for human consumption is a primary goal of food animal practitioners. Herd veterinarians should work with producers to develop effective management programs combined with use of vaccines, parasiticides, stress reduction and sound nutrition to reduce the incidence of disease. Prudent use of antimicrobial drugs is a necessary tool to treat livestock, reduce suffering, and decrease shedding of zoonotic bacteria into the environment and food chain. Antibiotics should only be used within the parameters of the VCPR, and specific attention should be made to establishing adequate withdrawal times.

Veterinarians should carefully select and use antimicrobial drugs. Before choosing a drug, there should be strong evidence to identify the cause of the disease based on clinical signs, history, examination, laboratory data and past experience. The antibiotic selected should be appropriate for the suspected pathogen and it should be administered in adequate dosage and duration to effectively treat the identified pathogen. If a labeled product is available for that problem, that product should be chosen unless there is reason to believe that it would be ineffective. Antibiotics should be used with a specific clinical outcome in mind such as fever reduction, return to function, decreased recurrence of disease, or decreased environmental contamination. When possible, antibiotics with a narrow spectrum of activity should be chosen over broad spectrum drugs. Antibiotics should be administered for as short a period of time as is reasonable to achieve the desired result. Antibiotics that are of lesser importance in human therapy should be chosen whenever possible. Compounding of medications and use of prophylactic antibiotics should be avoided whenever possible. Producers should be educated in the proper administration, handling and storage of antibiotics. Prolonged treatment of chronically ill animals should be discouraged and consideration should be given to their removal from the herd. The selection of adequate withdrawal times cannot be over-stressed to ensure that only wholesome products would enter the food chain from treated animals. The veterinarian should stay in contact with the client to monitor whether the elected treatment has been effective.

Maintain adequate records

Under AMDUCA, food animal veterinarians face a tremendous increase in record keeping chores. Every time a drug is used in an extra-label manner, the veterinarian must keep records to indicate the established name and active ingredients of the drug used, the specific health problem treated, species of treated animal or animals, dosage administered, duration of therapy, identity of animals treated, and specific withdrawal, withholding or discard times of any food animal or food animal product produced. These records must be kept for a minimum of two years and must be made available to FDA if they perceive a risk to public health. In addition, the veterinarian must determine that no approved animal drug is available to treat the diagnosed condition, or that any available labeled products are ineffective for this disease. A sufficiently long withdrawal time must be established to insure that drug residues do not occur in any food used for human consumption. Veterinarians may obtain assistance in establishing drug withdrawals for extra-label use pharmaceuticals at www.farad.org. If no information is available to establish a withdrawal time, then the treated animal or animals are permanently barred from the human food chain. Veterinarians may not use human drugs in food animals if an approved animal drug can be used in an extra-label manner for that disease, and a less expensive drug cannot be used in an extra-label manner if there is a labeled drug approved for that disease.

Dispensing and labeling drugs

AMDUCA also specifies what information must be put on the label when dispensing a drug for extra-label use. Each drug must list the name and address of the prescribing veterinarian, the established name of the drug, specific instructions for use of the drug including identification of the animals to be treated, the dose, frequency, route of administration and length of treatment, any cautionary statements, and the withdrawal, withholding or discard times. An additional warning should state that if the producer uses this product at a higher dosage, or for a longer period of time, then the withdrawal time must be increased to prevent drug residues. If the selected drug may be harmful to other species, then this must also be listed on the label.

Use of drugs to alter reproduction

Drugs used for estrous synchronization and embryo transfer are not allowed for extra-label use in food animals under AMDUCA. FDA has determined that extra-label use applies only for the relief of pain and suffering and alteration of reproduction does not fit their definition. While FSH and LH are both licensed and labeled for use in sheep, there are no licensed or labeled drugs that alter reproduction for use in goats at this time.