Use of oxytocin to improve diagnosis of subclinical mastitis caused by Staphylococcus aureus
Mastitis, inflammation in the udder tissue, caused by S. aureus is a big problem in dairy cattle production. It causes suffering for the cow and curing or replacing the infected cow is costly for the farmer. It is known that beef cattle also suffer from mastitis caused by S. aureus. The aseptical methods commonly used to diagnose mastitis in most cases require several milk samples from the same udder quarter. A method where only one sample is necessary would be useful, especially in beef cattle production where handling and milking the animal is difficult. Research has shown that S. aureus can change shape into microabscesses, entering the inside of the secretory cell. In this shape it is hidden from the immune system. A high dose of oxytocin could break the secretory cell wall, were the microabscesses are hidden, to shed them in to the milk. The objective of this study was to evaluate if the milk ejecting hormone oxytocin could be used to detect subclinical mastitis caused by Staphylococcus aureus (S. aureus).
In this trial 14 cows of the breed Swedish red and white were used. Ten produced milk with a somatic cell count (SCC) higher than 250 000 cells per ml milk (HSCC). A control group of four cows producing milk with a SCC lower than 50 000 cells per ml milk (LSCC) were also included. During the trial milkings samples were taken aseptically for bacteriological examination of premilk and postmilk. Premilk samples were taken for SCC analysis. Also composite milk samples for analysis of SCC and composition of fat, protein and lactose were taken during the milking. During the trial the cows were each given a single intramuscular injection with 100 international units of oxytocin.
It was found that the oxytocin injection (OI) resulted in a higher (p