Udder edema of Jersey cattle affected with rectovaginal constriction

Abstract

Ten Jersey cows affected with rectovaginal constriction (RVC), which developed udder oedema near calving, were studied. One normal Jersey and 3 normal Holsteins served as controls. Before euthanasia the animals underwent daily clinical examination, with special emphasis on the size of the foramen in the rectus abdominis muscle (milk wells). The permeability of the mammary blood vessels was studied by giving one gram of 1% solution Evans blue i/v and examining changes in the colour of the milk and also of interstitial fluid collected by stab incisions. After euthanasia, the entire udder, milk veins, milk wells, subcutaneous tissues and muscles covering the abdomen were removed intact, except in two cows where udder vascular systems were studied by latex infusion. Fifteen minutes after Evans blue injection, the colour of the milk and interstitial fluid were whitish blue and yellowish blue respectively. Oedema involved the entire udder but was more pronounced ventrally. Microscopically there was excessive fluid infiltration between the muscle fibres of the subcutaneous tissues, in the interlobular and interalveolar interstitial spaces of the udder parenchyma, and in the supramammary lymph nodes. The latex studies showed that both milk veins were demarcated by ring-shaped depression of constrictions at the entrance of the milk wells. The studies with Evans blue demonstrated an increase in udder vascular filtration of fluid and protein, possibly due to enlargement or stretching of capillary pores. The latex studies suggested that the milk wells may be a restrictive point for venous blood flow from the udder. Udder oedema may be associated with RVC in Jersey cows.