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Udder Diseases in Sheep

UDDER DISEASES OF SHEEP

Clell V. Bagley, DVM. Extension Veterinarian Utah State University

There are two major udder disease problems of ewes, hardbag and bluebag. They both tend to occur sporadically and are frustrating for producers to treat or prevent.

Hardbag
Hard bag results from an accumulation of fibrous tissue in the udder which replaces the milk producing tissues and results in lamb starvation from lack of milk. It may be caused by a virus, the same one which causes ovine progressive pneumonia, (OPP) ("lungers"). Or, it may also result after the ewe is affected with a mild or moderate case of bluebag and one or both halves of the udder fills with scar tissue.

Hardbag tends to be seen by producers mostly at lambing and at weaning. When seen at lambing, the udder appears full and usually well shaped but has little or no milk for the lambs. Some ewes may develop more milk with time but usually by then the lamb has been removed or died. Hardbag is also seen at weaning or in the fall if the ewes are worked and "bagged" or crutched (shorn).

If both halves of the udder are involved in most affected ewes, then the cause is likely the OPP virus. It is common in most sheep flocks, especially range ewes. Be sure to keep poor doing, "lunger" type of ewes away from replacements as infected ewes spread the virus. It takes a year or two before the infection becomes apparent by affecting their lungs or udders. A blood test for OPP is also available for those who want to eradicate the virus from their flock.

If only one half of the udder is affected, the hardbag is probably due to the after affects of a bluebag type of infection. The ewe may be able to feed one lamb okay but should usually be culled from the flock.

Bluebag
Bluebag is a severe form of mastitis and is caused by bacteria which enter through the teat canal and cause an infection in the udder. It often becomes so severe as to interfere with the blood supply to the udder. This reduced blood supply causes a blue discoloration and if there is a complete loss of blood supply, gangrene, with sloughing of that half of the udder. If seen and treated early with antibiotics, there is often a good response. But, the problem is finding and getting them treated soon enough. Bluebag usually occurs within a couple months of lambing or shortly after weaning. To prevent cases at lambing time focus efforts on:

1. Bedding in the corrals and in the jugs, especially directed to keeping the ewes udders dry. Provide better drainage, clean out and/or add bedding more often.

2. Don't put the ewes on lush feed too quickly. The production or too much milk, before the lambs are big enough to remove it, greatly increases the incidence of bluebag.

3. Continue to provide adequate feed for the ewes so the lamb's needs are met. If the ewes go onto poor feed and decrease their milk production, the lambs become very aggressive in nursing and the resulting udder injury contributes to more cases of bluebag.

4. Control respiratory infections in the lambs, mostly by improving the ventilation in the lambing sheds. One of the agents most often involved in lamb respiratory disease (pasteurella) is also a major cause of ewe mastitis. A lamb with a mouthful of infectious bacteria is more likely to spread it to the teats of their dam.

5. Try to prevent lambs "bumming" milk from ewes besides their own dam. Lambs doing this tend to spread infection to many ewes.

6. Prevent soremouth, if it is a problem in the flock. The mouth lesions, caused by a virus, also allow the growth of a variety of bacteria which may infect the udder of ewes nursed by affected lambs.

The major concern at weaning is the continued production of large amounts of milk and over distention of the udder. At weaning, restrict the water and feed intake of the ewes for 24 to 36 hours to rapidly decrease their milk production.

If either hardbag or bluebag has been a special problem with your flock, seek some extra information and help in dealing with it. It may be helpful for you to collect milk samples from ewes affected with bluebag in order to determine the main bacteria involved. For collection, restrain the ewe in shearing position, clean off the end of the teat of the affected udder half with several pieces of cotton soaked in alcohol or iodine. Milk out 1-2 squirts, then direct the next 2-3 squirts of milk into a sterile test tube. Keep dust out of the tube while getting the milk into the tube. Don't touch the top of the tube or the inside of the cap or stopper. These samples can be frozen until it is convenient to deliver them to the Diagnostic Lab or they can be refrigerated and shipped immediately, with an ice pack and insulation.

Utah State University Extension

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