Pododermatitis
Inflammation of the skin of the foot is when the web of the foot in the affected areas is reddened and usually moist from fluid leakage and licking. It may be swollen and the dog may be limping.
Home treatment:
First make sure the dog does not have a foreign body in it's foot. If you find a foreign body remove it and the pododermatitis may improve quickly.
If it doesn't improve wash the foot with a gentle antiseptic soap (example: chlorhexidine, povidone-iodine) followed by thorough drying and soaking it in warm water for 15 minutes twice a day.
Try to prevent your dog from licking the area.
The application of a soothing hydrocortisone ointment usually helps clear up the condition rapidly. You can get a product of this type over the counter at your local drugstore.
If the inflammation and/or soreness persists longer than 48 hours you should take your dog to a veterinarian.
Be aware that prolonged use of corticosteriod ointments in any but the most simple conditions confounds diagnosis, aggravates certain conditions, and interferes with healing.