thurl

Either of the rear hip joints where the hip connects to the upper leg in certain animals, particularly cattle; often used as a reference point for measurement.

1918, G. C. Humphrey, The Rural Efficiency Guide, Volume 4: Stock Book, page 22, Deficiencies which are common to the hind quarters of the cow, include shortness and narrowness of rump, a drooping rump, narrowness between the thurls and pin bones and thickly fleshed thighs.

Also I would call attention to the fact that the heifers were wider through the thurls at five months of age than through the hips, but after they had become mature cows they were wider through (or across) their hips, than across their thurls.

Alternative form of thirl.

Alternative form of thirl.