Ultrasonographic appearance of exogenous isobutane gas in the mammary glands of dairy cows

Objective - To determine whether exogenous isobutane gas infused into the udders of dairy cattle could be detected ultrasonographically, and if so, what effects volume of gas infused and infusion pressure had on how long after infusion exogenous isobutane gas could be detected. Design - Randomized block design. Animals - 8 Holstein cows 28 to 32 days after parturition. Procedure - In each cow, 1 mammary gland was not treated and the other 3 received 1 of 3 treatments by means of intramammary infusion: low volume-high pressure, low volume-low pressure, and high volume-high pressure infusion of isobutane gas. Mammary glands were examined ultrasonographically 1 hour before and 1, 3, 12, 24, 36, 48, 72, and 96 hours after treatment. Results - After intramammary infusion of isobutane gas, bright echoes and associated acoustic shadows were seen ultrasonographically; echoes were no longer seen 72 hours after gas infusion. Percentages of mammary glands in which bright echoes were detected were not significantly different among the 3 treatment groups at any time during the study. Conclusions and Clinical Relevance - Results suggest that exogenous isobutane gas infused into the mammary glands to enhance the appearance of the udder of show dairy cattle can be readily detected by ultrasonography.