Hello, my name is***** and I have over 20 years of experience as a veterinarian. I'm sorry to hear that your pup has chewed the top layer of skin off her upper metacarpal pad on her right front foot.
Most of the time excessive licking, chewing or scratching an area and breaking the skin barrier is due to an allergic reaction of some type. This allows bacteria that normally live on the skin to get in the skin and thrive, and this only further irritates them and increase the urge to lick and chew. It can also be due to a puncture would or piece of foreign material (splinter, plant awn) getting under the skin.
Getting her to stop licking and chewing to allow the skin to heal is essential. This likely involves placing an elizabethan collar so she cannot reach the area and treating the underlying allergy/cause.
Allergens can be inhaled (like grass pollen, dust mites or molds) and you can use a combination of antihistamines and high doses of omega-3 fatty acids to help with those (they also help with the symptoms of flea allergy). In combination fatty acids and antihistamines work synergistically, much better than either one alone.
You can try:
1) Benadryl (diphenhydramine only don't use the combo products as they can be toxic) at 1mg to 2mg per pound or one 25mg capsule per 15-25 pounds of body weight orally every 8 hours. Dogs take a much higher dose per pound of body weight compared to people so don't let the size of the dose he would need concern you.
OR 2)Claritin (loratidine) at 5mg per 25 pound dog once or twice daily.
OR 3)Hydroxyzine at 1mg per pound orally every 8 hours.
OR 4) Chlorpheniramine at 4mg to 8mg per dog once or twice daily.
OR 5) Zyrtec (Cetirizine hydrochloride) at 1/2 mg per pound of body weight orally every 24 hours. That would be one 10mg tablet per 20 pounds of body weight. Make sure it is NOT the formulation with a decongestant (such as Zyrtec-D) because dogs cannot tolerate decongestants.
Some dogs do better on one antihistamine rather than another. Give the one you pick a week trial and if it isn't working try another. Be aware antihistamines can cause sleepiness or hyperactivity in some dogs. These side effects do wear off with repeated use.
Omega-3 fatty acids are fish oil products. 3V by DVM or Derm Caps ES are good brand name products. Use the high end of the dosing schedule for your pup's weight, which means if he is between doses go with the higher one. I recommend a dose based upon the EPA portion (eicosapentanoic acid) of the supplement as if we do that the rest of the supplement will be properly balanced. Give her 20mg of EPA per pound of body weight per day. For example an 18 pound dog could take 360mg of EPA per day.
If the hair around the pad is wet and the skin is red there too then clip the hair around the pad very short and use a solution mix of Betadine solution (povidine iodine solution) and warm water, made to look like weak tea. Clean the affected pad area twice daily. Make sure you get the solution, not the scrub. This is an antibacterial and will dry the lesion out to allow them to heal. No need to rinse this, let it dry on her skin. It does stain horribly though so you probably want to do this outside. Clipping the hair stops bacteria from wicking into the site and allows the skin to breathe and dry.
In cases where the infection gets deeper than the surface of the skin oral antibiotics may be needed to treat deeper infection. If she isn't significantly better in 3-4 days she should see her family veterinarian.
Please let me know if you have any further questions.