McOrist S, Morgan J, Veenhuizen MF, Lawrence K & Kroger HW
Oral administration of tylosin phosphate for treatment and prevention of proliferative enteropathy in pigs.

Am J Vet Res, 58(2): 136-139, 1997
ISSN: 0002-9645 American Journal of Veterinary Research (PubMed)

Abstract
OBJECTIVE: To evaluate the efficacy of orally administered tylosin phosphate for prevention and treatment proliferative enteropathy (PE) in pigs. ANIMALS: Crossbred pigs weaned at 24 days of age. PROCEDURE: Pigs were challenge exposed with an inoculum of Lawsonia intracellularis strain LR189/5/83. Seven control pigs received buffer solution. Of 33 challenge-exposed pigs, 8 were untreated. Two groups of challenge-exposed pigs were dosed orally with tylosin phosphate via a 2% stabilized premix, starting with 100 or 40 ppm 4 days before challenge exposure and continuing for 16 days, when the dose was reduced to 40 or 20 ppm, respectively, which was continued for 12 more days. Another group of challenge-exposed pigs was dosed orally with 100 ppm of tylosin phosphate commencing 7 days after challenge exposure and continuing for 21 days. Pigs were euthanatized and necropsied 4 weeks after challenge exposure. RESULTS: The 8 untreated pigs had reduced weight gain, 3 of them had moderate diarrhea 3 weeks after challenge exposure. Five pigs had gross lesions of PE at necropsy. Seven pigs had histologic lesions of PE with numerous L intracellularis organisms. None of the pigs in the control, nonchallenge-exposed, or the 3 groups given tylosin phosphate before or after challenge exposure had clinical signs or lesions of PE. CONCLUSION AND CLINICAL IMPLICATIONS: Tylosin phosphate can be effective for prevention and for treatment of PE, using reported dosing schedules. We can experimentally induce PE, using the pure culture challenge-exposure model, for use in testing of treatments.