Dogs have a lower third eyelid, which has a gland on the back contributing to tear production. Sometimes this gland becomes enlarged and everts over the top of the third eyelid. The resulting red mass looks like a small cherry hence the name. Some breeds seem more prone to this happening and there is thought to be a genetic weakness of the structures holding the gland and third eyelid in tight against the eye. Beagles can be prone to this condition it usually occurs in puppies as young as a few weeks.
The tear gland rarely can be replaced manually and usually needs treatment. There are two surgical options available:
The first involves tacking it back. This involves replacing the gland in a pocket created in the back of the third eyelid. This is a fiddley operation and sometimes suture reaction can result in a swollen eyelid, which is unsightly.
The second method is just to remove the gland. This will reduce tear production but most dogs actually cope with this although a few may need extra lubrication given as eye drops. It was thought that reducing the tear production was a detrimental thing but now some of the UK eye specialists are advising removal as it is thought the dogs who develop Dry Eye through reduced tear production would have anyway.