Quick answer: Excessive paw licking is most commonly caused by environmental allergies, a wound or irritant between the toes, or anxiety — each requiring a different approach.
Environmental allergies are the most common cause. Dogs absorb allergens through the skin and lick where exposure is highest — the paws, belly, and face. Reddish-brown staining between the toes from porphyrin in saliva is a telltale sign of chronic paw licking related to allergies.
Check between the toes carefully for cuts, foreign objects (splinters, grass seeds), swelling, or redness. Paw contact dermatitis from walking on treated grass or harsh surfaces is also common. Rinsing paws after every outdoor walk significantly reduces irritant exposure.
Some dogs develop compulsive paw licking as self-soothing, especially when left alone or in stressful situations. If licking only happens in specific contexts — before vet visits, when you leave — anxiety is the likely driver. Behavioral enrichment and structured exercise reduce anxiety-based licking.
Check the paws for physical causes first. Persistent licking with staining between the toes needs vet evaluation — identifying whether it's allergies, infection, or anxiety determines the right treatment.