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  • Author or Editor: Christopher D. Luby x
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Abstract

Objective—To determine whether prepartum intramammary treatment of dairy heifers with pirlimycin hydrochloride would reduce the prevalence of intramammary infection (IMI) and lower the somatic cell count (SCC) during early lactation or improve 305-day mature equivalent milk production.

Design—Prospective clinical trial.

Animals—183 Holstein-Friesian heifers (663 quarters) from 2 dairy farms.

Procedure—Heifers were assigned to treatment and control groups. Treated heifers received a single 50-mg dose of pirlimycin in each mammary quarter approximately 10 to 14 days prior to parturition. Prepartum mammary gland secretions and postpartum milk samples were collected for bacterial culture. Postpartum milk samples were also collected for determination of SCC or California mastitis testing and were tested for pirlimycin residues. Mature equivalent 305-day milk production data were recorded.

Results—Treated heifers in herd A had a higher overall cure rate, higher cure rates for IMI caused by coagulase-negative staphylococci (CNS) and Staphylococcus aureus, lower SCC, and lower prevalence of chronic IMI, compared with control heifers. Treated heifers in herd B had a higher overall cure rate and cure rate for IMI caused by CNS, compared with control heifers, but postpartum California mastitis test scores and prevalence of chronic IMI did not differ between groups. Mature equivalent 305-day milk production did not differ between herds or treatment groups. No pirlimycin residues were detected in postpartum milk samples.

Conclusions and Clinical Relevance—Results suggest that prepartum treatment of dairy heifers with pirlimycin may reduce the prevalence of early lactation IMI, particularly IMI caused by CNS, without causing pirlimycin residues in milk. (J Am Vet Med Assoc 2005;227:1969–1974)

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in Journal of the American Veterinary Medical Association
History

A 63-kg (139-lb) 1-month-old Angus bull calf was examined because of gross enlargement of the scrotum, which had been evident since birth (Figure 1). Except for the scrotal enlargement, the owners had not detected any other abnormalities and reported that the calf was suckling its dam and gaining weight. The cow and calf were housed on a pasture that contained a mixture of grasses.

Physical examination revealed a firm, freely moveable mass within the scrotum. Palpation did not elicit signs of pain. Both spermatic cords were palpable, with the left spermatic cord larger than the right. The

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in Journal of the American Veterinary Medical Association