Urethral Prolapse:

Urethral prolapse is the prolapse or protrusion of the urethral
mucosal lining at the tip of the penis. It most commonly presents as
a red or purple colored "doughnut" on the end of the penis. It may
attract an owners attention as an accidental finding or may be
discovered if bleeding from the sensitive mucosal tissue occurs.
Bleeding may be very mild to heavy.
Surgery has long been the treatment of choice for prolapse but
many practitioners have begun manage it medically if bleeding is
mild and/or easily controlled using topical atibiotic/steroid
medications applied topically and within the distal end of the
urethra. Many cases are asymptomatic and anecdotally appear to
resolve with time with little or no treatment. The condition is most
often seen in brachycephalics and some toy breeds. The mode of
inheritance is unknown. While it may seem logical that neutering
might be curative by preventing sexual excitement and erection, it
does not always alleviate bleeding in animals where significant
episodes of hemorrhage has already occurred.
Owners of animals which are experiencing bleeding or other issues
related to prolapse should discuss all medical and surgical options
with their veterinarian.