Gangrenous Mastitis - Sheep
Introduction
Gangrenous mastitis occurs sporadically during the first three months of lactation often associated with poor milk supply related to ewe underfeeding and over-vigorous sucking by the lambs.
The condition is more common in ewes nursing triplets than twins, and very rare in ewes rearing singletons.
It is usually caused by organisms such as Mannheimia haemolytica and Staphylococcus aureus.
Gangrenous mastitis is a major welfare concern and is a sporadic cause of ewe death and loss of lambs.
Clinical Signs
Gangrenous mastitis is often preceded by lesions on the udder and teats caused by the lambs' incisor teeth.
Ewes are often dull and depressed, separated from the rest of the flock, and sometimes drag their hind leg on the side of the affected quarter.
The udder gland is usually markedly swollen with purple/black discolouration of the skin extending to the ventral abdominal wall.
Affected ewes will show a marked loss of condition due to the toxaemia, and the gangrenous udder tissue eventually sloughs leaving a large granulating lesion with superficial bacterial infection. Granulation tissue can continue to proliferate over the following months.
Diagnosis
Diagnosis is made on the basis of the clinical signs and culture of a swab of the area might reveal the organism involved.
Treatment
Prompt antibiotic and supportive therapy should be instituted, such as procain penicillin injections and anti-inflammatories. Lambs from the affected ewes should be housed and given supplementary feeding.
Topical antibiotics can also be applied to any udder or teat lesions to prevent progression of the disease.
Ewes with a severe form which have lost part of their udder are unsuitable as breeding stock and they should be culled during the acute phase of the disease.
Prevention
Ewes should not be expected to rear triplets under commercial farming conditions in the UK.
Appropriate levels of nutrition should be maintained during pregnancy and early lactation to prevent teat abrasions. Supplementary feeding can be considered to restore the body condition of thin ewes, prevent gangrenous mastitis and improve lactation and lamb growth rate.
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References
Kahn, C. (2005) Merck Veterinary Manual Merck and Co
Scott, P. (2008) NADIS Health Bulletin - Mastitis in Ewes Nadis Publishing
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