lasalocid and Mastitis--Bovine

Topics: Animals; Anti-Bacterial Agents; Biofilms; Cattle; Female; Gram-Positive Bacteria; Ionophores; Lasalocid; Mastitis, Bovine; Microbial Sensitivity Tests; Monensin; Pyrans; Staphylococcal Infections; Staphylococcus; Streptococcal Infections; Streptococcus

Mastitis is a major disease of dairy cattle. Given the recent emergence of methicillin-resistant Staphylococcus aureus as a cause of bovine mastitis, new intramammary (IMA) treatments are urgently required. Lasalocid, a member of the polyether ionophore class of antimicrobial agents, has not been previously administered to cows by the IMA route and has favorable characteristics for development as a mastitis treatment. This study aimed to develop an IMA drug delivery system (IMDS) of lasalocid for the treatment of bovine mastitis.. Minimum inhibitory concentrations (MICs) were determined applying the procedures recommended by the Clinical and Laboratory Standards Institute. Solid dispersions (SDs) of lasalocid were prepared and characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy. IMDSs containing lasalocid of micronized, nano-sized, or as SD form were tested for their IMA safety in cows. Therapeutic efficacy of lasalocid IMDSs was tested in a bovine model involving experimental IMA challenge with the mastitis pathogen Streptococcus uberis.. Lasalocid demonstrated antimicrobial activity against the major Gram-positive mastitis pathogens including S. aureus (MIC range 0.5-8 μg/mL). The solubility test confirmed limited, ion-strength-dependent water solubility of lasalocid. A kinetic solubility study showed that SDs effectively enhanced water solubility of lasalocid (21-35-fold). Polyvinylpyrrolidone (PVP)-lasalocid SD caused minimum mammary irritation in treated cows and exhibited faster distribution in milk than either nano or microsized lasalocid. IMDSs with PVP-lasalocid SD provided effective treatment with a higher mastitis clinical and microbiological cure rate (66.7%) compared to cloxacillin (62.5%).. Lasalocid SD IMDS provided high cure rates and effectiveness in treating bovine mastitis with acceptable safety in treated cows.

Topics: Animals; Anti-Bacterial Agents; Calorimetry, Differential Scanning; Cattle; Chemistry, Pharmaceutical; Dairying; Drug Administration Routes; Female; Kinetics; Lasalocid; Mammary Glands, Animal; Mastitis, Bovine; Microbial Sensitivity Tests; Milk; Nanoparticles; Povidone; Solubility; Spectroscopy, Fourier Transform Infrared; Streptococcal Infections

The aim of the study was to evaluate the effect of feeding the ionophore lasalocid on the productivity and health of seasonally calving, pasture-fed dairy cows. Dairy cows (n = 1020) from 4 herds were enrolled in a split-herd, prospective intervention study. Cows were blocked by breed and age, ranked on previous production, and then assigned to 2 treatment groups. Treatment cows were each exposed to 300 to 350 mg of lasalocid/d commencing 3 wk before and ending 18 wk after the start of the seasonal calving period. Milk production was determined on 3 occasions for each cow at approximately monthly intervals (herd tests 1 to 3), body condition score was determined fortnightly, and all disease occurrences were recorded. Lasalocid treatment increased milk volume milk protein and milk fat production by approximately 2%, without altering milk composition. Fewer lasalocid-treated cows than control cows (7.3 vs. 11.6%, respectively) were diagnosed with clinical mastitis. Lasalocid treatment of pasture-fed dairy cows resulted in reduced mastitis incidence and increased milk production without changes in body condition or negative effects on metabolic processes as monitored by metabolite concentrations.

Topics: 3-Hydroxybutyric Acid; Animals; Blood Glucose; Body Composition; Cattle; Diet; Estrus Detection; Fatty Acids, Nonesterified; Female; Health Status; Ionophores; Lactation; Lasalocid; Lipids; Mastitis, Bovine; Milk; Milk Proteins; Pregnancy; Prospective Studies; Seasons