Evaluation of udder health and mastitis in llamas

Objective - To investigate intramammary infections in llamas, identify the pathogens responsible, and determine whether effects of intramammary infection could be detected by use of mastitis indicator tests commonly used for cows. Design - Observational study. Animals - 100 llamas on 10 farms. Procedure - Milk samples were evaluated by bacterial culturing and by determination of somatic cell count (SCC), using direct microscopic and automated counting methods, California Mastitis Test score, pH, and N-acetyl-β-d-glucosaminidase activity. Correlation coefficients were determined among the various mastitis indicator tests, and test results were determined for milk from infected and uninfected glands. Results - Evidence of intramammary infection was evident in 76 of 369 (21%) milk samples, with 54 of 94 (57%) llamas having at least 1 infected gland. Staphylococcus sp other than Staphylococcus aureus were the predominant pathogens. None of the llamas had clinical signs of mastitis, and significant differences were not detected in SCC, California Mastitis Test score, pH, or N-acetyl-β-d-glucosaminidase activity between infected and uninfected samples. California Mastitis Test scores were negative or trace for 307 of 313 (98%) samples, and SCC were low. In contrast, pH and N-acetyl-β-d-glucosaminidase activity of milk from uninfected glands were higher than values reported for milk from uninfected cows, and neither variable was significantly correlated with the number of somatic cells in samples of llama milk. Clinical Implications - Although intramammary infections develop in llamas, inflammation (mastitis) appears to be rare. Values for mastitis indicator tests used for cows cannot be directly extrapolated to llamas. Subclinical mastitis is apparently not an important problem in llamas in the United States.