A longitudinal study of risk factors for teat lesions in 67 suckler ewes in a single flock in England.

A longitudinal study of 67 suckler ewes on a commercial sheep farm near Wolverhampton, England was carried out from March to July 2010. Data on ewe teat lesions and udder and teat conformation were collected together with data on lamb health and weight at lambing and at 14-day intervals until lambs were 8-10 weeks old. Each ewe was examined on 4-5 occasions. Teat lesions were categorised as traumatic or non-traumatic based on appearance. Risk factors for the development of each type of teat lesion were investigated using mixed effect binomial regression models. The incidence of traumatic teat lesions was greatest 3-4 weeks after lambing with 27.9% new cases by udder half. There was an increased risk of traumatic teat lesions in 2 year old ewes (OR 3.5, CI 1.2, 10.5) compared with 6 year old ewes and in ewes with abnormal compared with normal teat placement, a wide or narrow udder width compared with a normal udder width, a heavy total litter weight, body condition score (BCS)<2.5, compared with BCS of 2.5 14-days previously, and in ewes with abnormal udder skin (waxy, dry or chapped) compared with normal udder skin. The incidence of non-traumatic teat lesions was greatest 7-10 weeks after lambing with 21.4% new cases. Non-traumatic lesions were more likely to occur in ewes with BCS=3 compared with BCS of 2.5. The risk factors for traumatic and non-traumatic teat lesions differ. Traumatic lesions are associated with teat and udder morphology, ewe age and BCS, and lamb growth rate, whereas non-traumatic lesions are associated with ewe BCS.