Udder Oedema

Acute udder oedema occurs in high producing dairy animals but is more severe in heifers. It starts a few weeks before calving and can continue up to 3 weeks into lactation.

Oedema is characterized by an excessive accumulation of lymphatic fluid in interstitial spaces. Visible accumulation sites include the udder, navel and brisket regions, and in exceptional cases the thighs and vulva. Udder oedema may interfere with milk production, milk letdown, and machine attachment during milking. The teats tend to strut outward so that milking can be more difficult. There can be physical damage such as cracking of the skin on teats and harm to suspensory ligaments, leading to broken down udders. Severe mammary enlargement makes walking and lying down difficult and causes discomfort to the animal.

Causes:
The exact cause of udder oedema is not known. Factors such as inheritance, circulatory disturbances, and diet are considered the possible causes. Genetic factors may play a role because some dairy

animals tend to have oedema annually regardless of feeding programmes. However, heritability of oedema is low, so selecting against it would be a slow process. A long dry period and older age at first calving may increase the incidence of oedema. Serum and urine chemical data do not differ significantly between dairy animals with and without udder oedema. There is no clear relationship between concentrate intake, dietary protein content, and the incident of udder oedema. The common belief that feeding grain causes udder oedema, may be caused by the practice of salt supplementation in the grain mixture. Supplementation of diets with either an excess of 136 g NaCl or 272g KHCO₃ resulted in significantly severe oedema in first calf heifers than in control animals. Addition of both salts resulted in less oedema than when each salt was fed separately.

Prevention:
The prevention of oedema lies in avoiding excess salt during the close-up period. Another approach consists of feeding anionic salts to prevent milk fever which may also help prevent udder oedema. However, this needs more detailed studies. Provision of moderate exercise along with good care before calving is also indicated. Diuretic treatment can reduce severity and duration of oedema. Udder supports may be helpful to protect ligaments from breaking down. In severe cases, one can start milking before calving. The colostrum thus obtained may be frozen for later use.

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