Ultrasonographic distribution and duration of udder edema in post-partum and over-bagged dairy cows

Abstract

The objective of this study was to determine the ultrasonographic distribution and duration of edema in the mammary gland of dairy cattle due to recent parturition or prolonged duration of not milking ("over-bagging"). Mammary glands of 74 post-partum cows were imaged ultrasonographically within 24 hours of parturition and every 48 hours until ultrasonographically negative for mammary gland edema for 96 hours. All post-partum cows were imaged 10-11 hours after last milking. Distribution of edema on ultrasonographic examination of the mammary gland was also mapped on 26 over-bagged cows at exhibitions. Sixty-eight of 74 (91.8%) post-partum dairy cattle had ultrasonographically detectable udder edema. Post-partum edema was centered at the ventral midline region at the junction of the udder and body wall between the subcutaneous abdominal veins. Edema persisted for an average of 14.7 days in the fore and 14.8 days in the rear quarters. No edema was detected after 22 days post-partum in any cow. In the fore udder of over-bagged cows, edema was centered on the peripheral vein mid-height on the lateral surface of the fore quarters. In the rear quarter, edema was centered in the mid to ventral aspect of the median crease. Average time since last milking in the "over-bagged group" was 19 hours, and average days-in-milk was 104 days. These two patterns of distributions are important for differentiation from injection-induced edema in show cows, and ultrasonographic differences between physiological and artificially induced edema are discussed.