Preventing Residues in Tissues and Milk- Craig Shultz


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Dr. Shultz presented this material on November 10, 2011 as part of DAIReXNET's webinar entitled "Appropriate Drug Use and Residue Avoidance Practices".

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  • The performance bar for residue avoidance continues to rise as new detection methods become increasingly sensitive and capable of indentifying a wider variety of compounds. Tolerances established by the Food and Drug Administration for specific animal drugs in food products are intended to ensure the safety of the product for the consumer. Public tolerance for foods adulterated with animal drug residues is low. Expansion of tissue residue surveillance to include anti-inflammatory drugs including flunixin and phenylbutazone has added to producers’ residue avoidance demandsAn proposed FDA national milk sampling plan would change surveillance of bulk milk to include a broad range of antibiotics, as well as anti-inflammatory drugs, anti-parasitic drugs and even antihistamines. Residue findings in edible tissues have driven expanded surveillance in milk and the proposed national milk sampling plan is designed to target milk producers with a history violative residues in cull animals at slaughter.
  • Market dairy cows are recognized as a slaughter class with an elevated risk for violative residues and account for a majority of violative residues in slaughter cattle. Bob veal calves, most of which are the off-spring of dairy cattle are also at high risk for violative animal drug residues at slaughter.
  • Because of their relatively advanced age at slaughter and use during their productive life spans dairy cows are prone to a variety of acute and chronic inflammatory conditions including mastitis, metritis, peritonitis, pneumonia, and cellulitis. These conditions are red flags for potential violative tissue residues during ante mortem and post mortem slaughter inspection. Managing these conditions in animal production with the careful use of a variety of approved animal drugs presents in a significant residue avoidance challenge to the dairy producer.
  • The conventional paradigm in residue avoidance has been to consider the drug being used and the minimum withhold as stated on the drug label. But in extra-label and prescription drug use the process of establishing an effective pre-slaughter or milk withhold becomes much more complex. The Animal Medicinal Drug Use Clarification Act of 1994 (AMDUCA) made extra-label drug use a regulated veterinary medical activity. AMDUCA amended the Federal Food Drug and Cosmetics Act to legalize extra-label drug use under a valid veterinarian-client patient relationship (VCPR). Within that relationship veterinarians are given certain guidelines to follow when using a drug on an extra-label basis in food animals. Those guidelines include making a careful diagnosis, determining there is no approved animal drug that is labeled for such use in the species or that contains the same active ingredient in the required dosage form and concentration, assuringthat the identity of the treated animal is maintained, and establishing an extended, scientifically supported withholding time for meat and other food products derived from that animal. The bottom line – complicated cases require accurate treatment record-keeping and input from an veterinarian engaged in a viable VCPR to establish a safe milk or meat withhold.
  • Dosage errors resulting in overdosage, altering label-indicated or prescribed duration of dosage or route of administration, and using multiple drugs in prolonged treatment of non-responding cases have significant impact s on milk and meat withholding times.
  • Recognizing the effect of chronic illness and debility on the elimination time of administered drugs is extremely important. The input of your veterinarian in making culling decisions on cattle with a complex health history is critical.
  • In on-farm tissue residue investigations by FDA a frequently identified deficiency is failure of the producer to maintain accurate treatment records. Treatment records should reflect a valid veterinarian-client-patient relationship when extra-label or prescription drug use is employed. References to treatment protocols written by your veterinarian and to consultation with your veterinarian when complex withholding decisions are made strengthen herd health record systems.
  • Understanding the residue surveillance procedures at slaughter plants is helpful in developing an effective tissue residue avoidance strategy. It is important to realize that high violation risk cattle are selected for screening based on their ante mortem condition prior to slaughter and the presence of residue-associated lesions identified on the slaughter line during post mortem inspection.
  • Under Hazard Analysis and Critical Control Point (HACCP) inspection slaughterestablishments are responsible for addressing hazards identified in a hazard analysis of their production process. Those hazards are addressed with critical control points and established critical limits at each control point. Plants are required to take action when critical limits are exceeded. In market dairy cow and bob veal slaughter plants violative residues are almost always identified as a hazard. Plants must formulate a strategy to reduce the hazard to an undetectable level.
  • Once residues are identified as a hazard, the slaughter establishment must take actions to ultimately reduce the hazard to an undetectable level. That includes tracing violations to the source producer and obtaining assurance from the producer of actions that will correct immediate problems and prevent a recurrence. Industry also must demonstrate avoidance of chronic sources of violative animals.
  • HACCP has reduced the amount of time to provide producer feedback on violative slaughter animals. Generally once a HACCP plant with a violative residue critical control point is notified of a violation, that information gets to the producer within a few days. Regulatory investigations may require months.
  • In FSIS slaughter inspection only high risk animals are flagged for residue screening. The proportion of high risk animals in dairy cow slaughter populations is high compared to fed cattle populations. Tissues from screen-positive animals are sent to a federal laboratory for analysis.
  • Laboratory analysis may reveal that the distribution of a drug residue within an animal is limited to specific tissues (liver or kidney). In such cases only those tissues are condemned and the carcass is passed for edible use. When violative residues are detected in carcass muscle, the entire carcass is condemned. Cattle with pathologic conditions resulting in condemnation are still subject to residue screening if high violation risk lesions are identified.
  • Food animal producers and veterinarians have important roles in the One Health initiative. There are differences of opinion regarding the use of veterinary drugs on food animals and possible impacts on food safety (through multidrug resistant food borne pathogens), public health (through concerns over its potential association with drug resistant human pathogens) and animal health (because of potential reductions in the number of drugs available to treat animal disease) . The fact remains that demonstrating consistently compliant on-farm drug use by effective food animal residue avoidance is critical to the long term viability of the food animal industry. Responsible use of animal drugs demonstrates the food animal industry’s commitment to safe food, healthy people and healthy animals as we strive to reach a optimum balance between animal and human well-being.
  • Preventing Residues in Tissues and Milk- Craig Shultz

    1. 1. Ensuring the Wholesomeness of Food Animal Products
    2. 2.  Tissue Residues in Dairy Beef – (circa. 2005) • Surveillance to include non-antibiotic drugs  Flunixin – 2010 Proposed FDA Bulk Milk Sampling Milk Plan - • 26 animal drug residues • Not limited to antibiotics Tissue findings at slaughter drive expanded surveillance in milk
    3. 3.  7.7% of cattle slaughtered in the US are dairy cows – account for 67% of violative residues detected by FSIS in all slaughter cattle.
    4. 4.  Age at slaughter - inflammatory conditions Use – multiple lactations and parturitions Individualvalue – greater incentive to These factors increase the treat complexity of on-farm residue avoidance strategies.
    5. 5.  Complicated in the dairy cow Notsimply a matter of knowing the drug used and its minimum pre-slaughter withhold
    6. 6.  Other equally important factors: • Dosage • Duration of dosage • Route of administration • Use of multiple drugs over time in treating a chronic condition
    7. 7.  Compromised and debilitated animals do not metabolize and eliminate drugs as efficiently as those with normal bodily functions – a VCPR in the culling decision process is critical.
    8. 8.  Accurate treatment record-keeping Veterinarian-Client-Patient Relationship Over-the-counter drugs • Must follow label directions exactly • If you change anything it is extra-label use and you must have a VCPR  Dosage  Duration of dosage  Route of administration VCPR is required for all prescription drugs
    10. 10.  HACCP Final Rule for large plants (1998) Inspected establishment must : • identify hazards in its process • set critical control points with critical limits to control hazards If violative residues are an identified hazard • they must be addressed in HACCP Plan Goal – to reduce hazard to an undetectable level
    11. 11.  Under HACCP, Industry is responsible for • Addressing violations, • Reducing risks • Ensuring the safety of its product Industrymust trace violations, obtain corrective actions and prevent recurrence Industry is required to avoid high risk sources of animals
    12. 12. Feedback Loop ProducerAvoidance HACCP Violations Notification (Days) Slaughter Plant FDA Investigation (Months)
    13. 13.  Onlyhigh risk animals based on ante and post mortem presentation are screened • High quality dairy cows: 5-8% • Lower quality lean dairy cows : up to 15% Tissuesamples from screen-positive animals are submitted to a Federal laboratory for analysis • Identify specific residue in tissue • Amount of residue in tissue
    14. 14.  Violativeresidue levels may be restricted to a tissue (e.g. Kidney) or may involve entire carcass resulting in condemnation Cattle with high violation-risk conditions are screened even if they are condemned on post mortem inspection
    15. 15. Use of Food Animal Drugs and “One Health” Food Safety •Multi-drug resistant food borne pathogens •Public expectation of safe food •Pathogen free raw products •Farm to fork surveillance •Food product liability •Food Product traceability •Food borne illness data Animal Health Public Health •Preventive & disease control •Human Antimicrobial Use antimicrobial use •Immune compromise (HIV, chemo) •Antimicrobial drug availability •Animal drug use and resistance of •Animal traceability human pathogens •Disease data •Disease data Animal Well Being Human Well Being• Perception of animal well being - Companion •Perception of human well beinganimal vs. production animal •Food preferences•Food production practices – different conditions •Food affordability and qualityfor animal vs. human antimicrobial therapy •Antibiotic effectiveness and human•NSAIDS use vs. abuse well-being•Environmental sustainability – carbon •Environmental sustainability – carbonfootprint of intensive animal production footprint of non-intensive animal production