Hello, I'm Dr. Deb and will do my best to help you today.
I'm sorry that Dexter is having this issue with his skin. I have several thoughts as to what might be causing him to chew his feet:
1. Inhalant or pollen allergies are a very common for dogs to itch, lick and scratch. Pollens, grasses, weeds, trees, dust mites, mold....any or all of these things can cause a dog's skin to become itchy. Sometimes mild itch, sometimes intense itch to the point of losing fur. Since you moved about a year ago and he never had this problem in the past, it's possible that there's something new in his environment which is triggering this reaction.
It would take skin testing by a dermatologist to confirm this problem but sometimes response to steroids can confirm it. Anti-histamines can sometime help if the itch level is not too high. You might try Benadryl 1mg per pound of body weight twice daily to see if it helps. Sedation is the most common side effect although it can cause excitement in some dogs. If this is not strong enough, steroids are often needed. Anti-itch sprays are not terribly effective, in my opinion, although there's no harm in using them. Oatmeal shampoos can sometimes help soothe the skin and can be given once/week without drying out the fur if other parts of his body are affected...not just his feet.
2. If this is entirely new behavior (there have never been skin issues before) or the itch level is worse than it's ever been (if there have been skin problems in the past), then Sarcoptes Mange mites should be included on the list although these patients are usually itchy on other parts of their body.
These are very itchy mites which burrow under the skin and are thus difficult to find on a skin scraping done by your vet. However, we do have a blood test available now which can help with the diagnosis.
(If you have chickens, then Dermanyssus gallinae which is a mite that affects both dogs, people and chickens is a possibility but if you don't have chickens, then this isn't likely.
There are a number of different treatment options but I prefer oral Ivermectin given once weekly for four weeks.
4. Dogs can also become allergic to the food that they have been eating for a period of time; this is often a difficult to diagnose to make without a hypoallergenic food trial which is basically reading the label of the current food and feeding something entirely different (usually the protein and/orcarbohydrate source should be changed). It can take several months on the new food to know if this is the problem or not although it's a relatively simple thing to do.
Antihistamines might help a little with the itch level; same for steroids.
5. If only his feet are itchy and no other part of his body is affected, I suppose some sort of contact allergic reaction may be to blame. Think about any new toys (especially if they are plastic and are dyed) or new carpets, etc. to which he might have had recent contact.
6. Dogs who are anxious or bored can lick or chew their feet but not typically to the point where they're red or inflamed.
Additional treatment options:
1. Soaking his feet in a warm Epsom salt bath once or twice a day may help sooth the skin.
2. Fish oil supplements such as Welactin (which is a liquid drizzled on the food once daily) may also help isn't necessarily a short term solution since it can take several weeks to build up in the system.
If none of the above appears to be effective, then a vet visit may be prudent.
I hope this helps. Deb