Problem #5: Tail Rubbing
The characteristic tail rubbing associated with worms is generally due to pinworms. The female pinworm partially exteriorizes itself and lays her eggs around the rectal ring. The eggs stick to the skin with a substance similar to egg whites. This substance causes an itchy sensation causing the horse to rub its tail on feed tubs, posts and other objects causing self-inflicted superficial skin irritation sometimes almost appearing as an ulcerated area.