2017 ACVIM Forum Research Abstract Program

In conclusion, administration of danofloxacin and tulathromycin SC at label doses in 3-week old and 6-month old calves demonstrated differences in distribution that are affected by age. More research is needed to determine the impacts of physiological differences and disease on the distribution and efficacy of commonly used drugs in neonatal calves. The objective of this project was to describe the ecology of host-adapted Staphylococcus spp. on the teat and inguinal skin of dairy heifers. A cross-sectional study including Holstein heifers (n = 106) at the University of Missouri Foremost Dairy was conducted. Heifers were randomly selected based on housing type and age group and enrolled in the following groups; preweaned heifers (n = 22), weaned heifers age 2-6 months (n = 15), young pasture raised heifers age 6-13 months (n = 26), pasture raised heifers age 13-18 months (n = 22), and breeding age heifers ˃18 months (n = 21). Body site swabbing samples, which included a composite sample of all four teats and a second composite sample from the inguinal regions of each heifer, were collected. Swabbing samples were mixed with 10 mL of sterile saline, agitated, and plated on mannitol salt agar and incubated at 37°C for 24 h. Up to 10 staphylococcal colonies, including at least one of each morphologically distinct colony type, were saved for analysis. Staphylococcal isolates were speciated using matrix-assisted laser desorption ionization-time of flight (MALDI-ToF) mass spectrometry or PCR amplification and sequencing of the rpoB or tuf gene. The Chi square or Fisher's exact test (as applicable) was used to investigate whether the prevalence of each staphylococcal species differed between the inguinal and teat region. Logistic regression models were used to investigate the relationship between heifer's age (continuous variable) and the probability of having a given body site colonized with a certain staphylococcal species.