The Science

Bumble foot (Ulcerative Pododermatitis) is a bacterial infection most commonly caused by caused by Staphylococcus Aureus. Lesions occur on the pads and soles of the feet and consist of granulomatous cellulitis or chronic, fibrous granulomas with or without an crusty discharge, of the feet.

Wire floored cages are normally one of the major causes of Bumblefoot. When a rat walks on this wire it can cause cuts and abrasions on their paws which allow the Staphylococcus Aureus to enter and infect the paws. Rough bedding and excess weight can also be factors. There are other causes, although they generally aren't as common as the wire floor. Basically any cut or abrasion will allow bacteria in, which may lead to infection.

If left untreated, the infection may spread to the bones or blood stream, at which time the infection changes from a bit of a nuisance to something perhaps more deadly.

Symptoms

Large lumps, often red and hard, on the underside of the paws. If really badly infected, the lumps may bleed off and on over a period of time.

Treatment

Surgery is unlikely as the rat may bleed too much and die. Steroids will not help and most anti-fungal treatments appear to have little affect. The most affective treatment would probably be to put the animal on antibiotics and flush the wounds daily with an anti-septic. Change any bedding daily and wipe the cage clean at the same time.

There is a topical antiseptic called Blu-Kote (USA) or Purple Spray (UK) that a few people say they have had success with. Apply to the wounded areas on the feet once or twice a day.

You may also be able to get antibiotics from the Vet:

Herbals remedies you could also try are:

Prevention

Use a softer bedding on the floor of the cage. Cover any wire floors (vinyl or plexiglas are good ideas). Clean any wounds as soon as you see them. Keep cages hygienic by cleaning regularly.