Dogs' paws can become red and irritated from environmental factors, illness or allergies. Bacterial, fungal and parasite infections are common causes. Wounds, insect bites and tumors can also cause redness and irritation of paws.
Some dogs lick their paws obsessively out of anxiety or because allergies cause itchiness, and this can cause redness. It can also be a sign of exposure to a chemical or other irritant. During the winter, walking dogs on areas that have been treated with salt or de-icer can cause irritation. Some metabolic or immune-mediated illnesses can also cause red paws. Cancer can also be a cause, although paw tumors are uncommon in dogs. Dogs with persistently red and irritated paws should be seen by a veterinarian for diagnosis and treatment.