In a Dec. 19 "Dear Veterinarian" letter, the Food & Drug Administration clarified the Center for Veterinary Medicine’s (CVM) position on complying with the conditions of use of the drug tylosin phosphate in beef cattle.

According to the letter, tylosin phosphate, marketed as Tylan 40 or Tylan 100 Type A medicated article, is approved for use in beef cattle to reduce the incidence of liver abscesses caused by Fusobacterium necrophorum and Arcanobacterium (Actinomyces) pyogenes. As a Veterinary Feed Directive (VFD) drug, feeding a medicated feed containing this new animal drug is permitted only under the professional supervision of a licensed veterinarian and in accordance with a valid VFD.

The approved labeling for the product indicates that medicated feeds should be prepared to provide a final concentration of tylosin phosphate of 8-10 g per ton of feed and that such feed should provide between 60 mg and 90 mg of tylosin phosphate per head per day, FDA said. However, due to higher consumption rates associated with cattle in the U.S. that are generally larger today than at the time this product was originally approved, veterinarians have raised concerns to FDA that it is practically difficult to comply with both the approved feed concentration level and drug intake rate.

FDA said CVM is currently working with the drug sponsor, Elanco US Inc., to revise the product labeling to address the issue. In the interim, CVM recommends that veterinarians authorizing the use of tylosin phosphate to reduce the incidence of liver abscesses in cattle focus on ensuring that feed containing tylosin provides the approved intake level of 60-90 mg per head per day, the letter says.

FDA acknowledged that maintaining an intake of 60-90 mg per head per day may require the feed to be prepared at concentrations that are below 8 g per ton. If the veterinarian anticipates that the level of VFD drug in the VFD feed will need to be less than 8 g per ton of tylosin phosphate, the veterinarian should note in the “Special Instructions” section of the VFD order: “The level of tylosin in this VFD feed should contain x g/ton tylosin phosphate (e.g., 7 g/ton) to ensure that the intake of tylosin phosphate will be within the 60-90 mg/h/day daily intake range.” The veterinarian may also include a reference to this Dear Veterinarian letter in the special instructions, the agency said.

During this interim period, a feed mill may manufacture the tylosin phosphate feed as indicated by the veterinarian’s special instructions on the VFD to achieve an approved intake level of 60-90 mg per head per day, FDA said, reiterating that this represents interim recommendations until the product labeling is revised.

FDA also recommended that this approach be followed as new VFDs are issued. The agency said it recognizes that valid VFDs for the use of tylosin are currently in place and does not expect those VFDs to be reissued with these instructions; however, a feed mill may prepare feed to fulfill those VFDs as outlined in this recommendation.

Those with additional questions should contact [email protected].