“Cattle are dependent on their immune system as a primary defense against invading organisms, viral or bacterial. The immune system generally functions quite well but is subject to compromise during stressful situations.” David McClary, DVM, MS and Elanco technical consultant, describes how the immune system works and the factors that can sometimes compromise an animal’s ability to fight infection. 

Q: When are cattle most susceptible to respiratory disease?

A: For cattle, periods of stress are when their physiological state changes, such as weaning or severe changes in weather. Generally, the greatest stress to a beef animal is at the time of movement from farm of origin to some type of feeding facility, such as a stocker operation, backgrounding facility or a feedlot. For dairy calves, in most cases, the time of greatest stress is as we transition them from individual housing to group housing. A stressed animal releases a number of agents, particularly corticosteroids, that reduce the ability of the immune system to fight infection.

Q: How does an animal naturally react to fight infection?

A: When a bacterial infection occurs in the lungs, alveolar macrophages are some of the first responders. They eliminate bacteria by a process called phagocytosis. Another primary defense cell that responds to infection is the neutrophil. Neutrophils are like the cavalry in that once they recognize the presence of infection, they migrate in large numbers to the site of infection, in this case the lungs. Like macrophages, neutrophils also kill bacteria by engulfing and digesting them.

Q: How does Micotil® (tilmicosin injection) work with the immune system?

A:Micotil is a macrolide antibiotic approved for the treatment and control of BRD which has characteristics that allow it to concentrate in the immune cells, specifically alveolar macrophages and neutrophils. We know these cells are migrating to fight infection in the lungs. As they are delivered to the site of infection, they bring high concentrations of tilmicosin (Micotil) directly to that site as well.*

Q: How quickly does Micotil respond and what is its duration when treating respiratory disease?

A: Micotil is fast-acting*1 and long-lasting.*2,3,4 Data shows that Micotil concentrates in diseased lungs within one hour1 following a subcutaneous injection of 1.5 mL/100 lbs body weight. Even in consolidated or severely diseased lungs, Micotil concentrates within two hours.*1 Micotil does not depend on circulation for delivery to the lungs; it concentrates in the first cells that migrate to the infection site, enabling its fast-acting response.

Important Safety Information

See label for complete use information, including boxed human warnings and non-target species safety information. Micotil is to be used by, or on the order of, a licensed veterinarian. For cattle or sheep, inject subcutaneously. Intravenous use in cattle or sheep will be fatal. Do not use in female dairy cattle 20 months of age or older. Use in lactating dairy cattle or sheep may cause milk residues. The following adverse reactions have been reported: in cattle: injection site swelling and inflammation, lameness, collapse, anaphylaxis/anaphylactoid reactions, decreased food and water consumption, and death; in sheep: dyspnea and death. Always use proper drug handling procedures to avoid accidental self-injection. Do not use in automatically powered syringes. Consult your veterinarian on the safe handling and use of all injectable products prior to administration. Micotil has a pre-slaughter withdrawal time of 42 days.

1Thompson, TD, SB Laudert, S Chamberland & K Lawrence. 1994. Micotil: pharmacokinetics of tilmicosin, a semi-synthetic macrolide antibiotic, in acutely pneumonic cattle and primary bovine alveolar macrophages. 6th European Assoc Vet Pharmacology and Therapeutics Congress, Aug., pp 31-32.

2Thompson, TD & K Lawrence. 1994. Micotil: pharmacokinetics of tilmicosin, a semi-synthetic macrolide antibiotic, in cattle. 6th European Assoc Vet Pharmacology and Therapeutics Congress, Aug., pp 55-56.

3Fossler, SC, JW Moran & TD Thomson. 1998. Pharmacologic mechanism for tilmicosin in the control of cattle pneumonia. Proceedings of the 79th Annual Meeting of Conf of Research Workers in Animal Diseases, p 82.

4Fossler, SC, JW Moran, MA Martinez & TD Thomson. 2000. Distribution of Tilmicosin into Bovine Peripheral Neutrophils Following Micotil Treatment. Proceedings of the 81st Annual Meeting of the Conference of Research Workers in Animal Diseases. p 101.

5Carter, BL, DG McClary, GD Mechor, RA Christmas, MJ Corbin & CA Guthrie. 2006. Comparison of 3-, 5- and 7-day post-treatment evaluation periods for measuring therapeutic response to tilmicosin treatment of bovine respiratory disease. Bov Pract 40:97-101.

6 McClary DG, MJ Corbin, BL Carter, J Homm, G Vogel, W Platter & CA Guthrie. 2008. A Comparison of 3-, 5-, 7- and 10-day Post-metaphylaxis Evaluation Periods on Health and Performance Following On-arrival Treatment with Tilmicosin in Feeder Cattle – A Summary of Two Studies. Bov Pract 42:117-127.

Micotil® is a trademark for Elanco’s brand of tilmicosin injection.
© 2011 Elanco Animal Health.
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