A screwtail is a curled or sharply kinked tail. These are not uncommon in Bulldogs. Often, an X-ray will reveal that the kinked tail is made up of adnormally shaped veterbrae called hemivertebrae.
A screwtail can cause several problems. First, the curve of the tail to one particular side can cause the anal gland duct on that side to become impacted. Also, a screwtail may extend down over the anus, causing the Bulldog to not be able to defecate properly. Having the screwtail surgically altered may be a solution that your vet can discuss with you. The last, and not so serious condition, is pyometra. This common bacterial skin infection can develop easily, and is easily prevented by regular cleaning of the skin folds under the screwtail with a cleaner containing a drying agent.