Appropriate drug use in sheep and goats (Proceedings)

Extralabel use of drugs in small ruminants can be a confusing issue, highlighted by complicated regulations, an openness for interpretation, and in individual animal's intended use. In this session, I will attempt to give an overview of the regulations regarding extralabel drug use in small ruminants, some guidance in decision-making, and resources I have found useful. This will only focus on sheep and goats. It is very important to note that the information provided is time-sensitive, subject to change at any time, and is based on my own interpretation of the regulations and should not be used as the final word in extralabel drug use decision-making.

There are a variety of agencies, acts, and research groups involved in the guidance of extralabel drug use in food animals, including FDA, USDA (biologics), EPA (pesticides), National Research Support Project #7 (NSRP-7), Animal Medicinal Drug Use Clarification Act (AMDUCA) of 1994, Minor Use and Minor Species (MUMS) Animal Health Act of 2004.

Some definitions per the FDA:

     • Extralabel : use of any approved drug (prescription or over the counter) in a manner that is not in accordance with the approved label or the package insert. [This may include use in a different species, route of administration, dosage or dosing frequency.]

     • Minor species: species other than cattle, horses, swine, chickens, turkeys, dogs and cats (sheep were a major species until 2000)

     • Drug: any compound for which the diagnosis, cure, treatment, mitigation, or prevention of a disease is claimed

     • Withdrawal time: the time at which 99% of animals would be expected to reach the tolerance level for drug residue

The FDA maintains a list of prohibited drugs for use in food animals. For these drugs, extralabel use in food animals is not allowed under any circumstances. The list currently includes: chloramphenicol, nitroimidazoles (including dimetridazole, metronidazole and ipronidazole), sulfonamides in adult dairy cattle (>20 months of age, except for on-label use of sulfadimethoxine), clenbuterol, dipyrone, fluoroquinolones, glycopeptides (vancomycin), nitrofurans (topical included in prohibition), phenylbutazone in adult dairy cattle, genetian violet.

The real challenge in drug therapy in small ruminants is the lack of labeled drugs. Extralabel use is permitted for therapeutic purposes only. Use of extralabel drugs for production purposes, manipulation of reproduction or grown promotion is not allowed. In order to use a drug in an extralabel manner, the following conditions must be met:

     1. Animal health is threatened or suffering or death may result from failure to treat

     2. There is a written or oral order of a licensed veterinarian in the context of a valid VCPR

          a. The veterinarian has assumed responsibility for making clinical judgements regarding the health of the animal(s) and the need for medical treatment, and the client has agreed to follow the veterinarian's instructions.

          b. The veterinarian has sufficient knowledge of the animal(s) to initiate at least a general or preliminary diagnosis of the medical condition of the animal(s). This means that the veterinarian has recently seen and is personally acquainted with the keeping and care of the animal(s) by virtue of an examination of the animal(s), or by medically appropriate and timely visits to the premises where the animal(s) are kept.

          c. The veterinarian is readily available, or has arranged for emergency coverage, for follow-up evaluation in the event of adverse reactions or the failure of the treatment regimen.

     3. There is no approved product or the approved product is clinically ineffective as determined within a valid VCPR

     4. After establishing a careful medical diagnosis and an extended withdrawal time, assuring the identity of treated animals is maintained, and assuring that the withdrawal time is observed and that no illegal residues occur

Record keeping is an exceptionally important component of extralabel drug use. When drugs are used appropriately on-label, the liability for problems associated with that use lies with the manufacturer. With extra-label use, however, that liability shifts to the veterinarian. Maintaining records which can substantiate veterinarian instructions regarding drug use can be protective to the practitioner. Records must be kept by the veterinarian for 2 years, and should contain: The established name of the drug and its active ingredient, the condition treated, the species of the treated animal(s), the dosage administered, the duration of treatment, the number of animals treated, the specified withdrawal or discard time for each food product. Establishment of extended withdrawal times should be based on published data (Webb, et al 2004) or direct contact with FARAD (www.farad.org).

Labeling requirements exist for extra label drug use and labels must include: the name and address of the prescribing veterinarian or the name of the veterinarian and name and address of dispensing pharmacy, the established name of the drug and ingredient(s), directions for use as specified by the veterinarian, including the class/species or ID of the animal or herd, flock, pen, lot, or other group of animals being treated, the dosage, dosing frequency, route of administration and duration of therapy, cautionary statements, veterinarian's specified withdrawal or discard times for each food product.

The purpose of the MUMS Act was to make more medications legally available to veterinarians and animal owners to treat minor animal species and minor diseases in major species. The following active ingredients are currently approved by MUMS (as of April 2011):

     • All caprine/all goats/goats: albendazole, ceftiofur sodium, crufomate, decoquinate, fenbendazole, lead arsenate, monensin sodium, morantel tartrate, neomycin sulfate, oxytocin, phenothiazine, proparacaine hydrochloride, thiabendazole

     • All sheep/lambs: albendazole, ammonium chloride, ceftiofur sodium, chlortetracycline calcium, chlortetracycline hydrochloride, crufomate, decoquinate, dihydrostreptomycin sulfate, erythromycin, flurogestone acetate, FSH, gelatin, gonadorelin, ivermectin, lasalocid sodium, lead arsenate, levamisole hydrochloride, methoxyflurane, moxidection, neomycin sulfate, neostigmine methylsulfate, oxytetracycline, oxytetracycline dehydrate, oxytetracycline hydrochloride, oxytocin, oxytocin acetate, penicillin g (procaine), phenothiazine, polymyxin b sulfate, progesterone, proparacaine hydrochloride, selenite sodium, sulfadimethoxine, sulfamerazine, sulfaquinoxaline, tetracycline, tetracycline hydrochloride, thiabendazole, thialbarbital, tilmicosin phosphate, vitamin E, zeranol

     • Milk goats: ceftiofur sodium

     • Nonlactating goats: albendazole, decoquinate

     • Sheep: albendazole, ammonium chloride, ceftiofur sodium, chlortetracycline calcium, chlortetracycline hydrochloride, crufomate, dihydrostreptomycin sulfate, erythromycin, flurogestone acetate, FSH, gelatin, gonadorelin, ivermectin, lasalocid sodium, lead arsenate, levamisole hydrochloride, methoxyflurane, moxidection, neomycin sulfate, neostigmine methylsulfate, oxytetracycline, oxytetracycline dehydrate, oxytetracycline hydrochloride, oxytocin, oxytocin acetate, penicillin g (procaine), phenothiazine, polymyxin b sulfate, progesterone, proparacaine hydrochloride, selenite sodium, sulfadimethoxine, sulfamerazine, sulfaquinoxaline, tetracycline, tetracycline hydrochloride, thiabendazole, thialbarbital, tilmicosin phosphate, vitamin E

Resources

Fajt VR. Label and extralabel drug use in small ruminants. In : Veterinary Clinics of North America : Food Animal Practice 2001 ;17(2) :403-420.

Webb AI, Baynes RE, Craigmill AL, et al. Drugs approved for small ruminants. J Am Vet Med Assoc 2004; 224(4):520-523.

http://www.farad.org – provides extended withdrawal times for extralabel drug use ; access to FARAD digests, which are articles with guidance on specific topics, drug classes, etc.

          Particularly useful digests for the small ruminant practitioner :

                    # 3 – Oxytetracycline

                    #4 – Tranquilizers and general anesthetics

                    #5 – NSAIDs

                    #9 – Extralabel ivermectin and moxidectin

                    #10 – Update

                    #13 – Approved drugs for small ruminants

                    #14 – Antidotes

                    #16 – Aminoglycosides

                    #18 - Penicillin

http://www.nrsp-7.org/welcome.htm - explains purpose and services of NRSP-7

http://www.nrsp-7.org/mumsrx/ - reference for MUMS approved drugs; can search by drug name, active ingredient, species

http://www.avma.org/reference/amduca/amduca2.asp - extralabel drug use algorithm