I see minorly affected skin overall. There appears to an erythema (redness) around his neck and axillae (armpits). I don't see obvious evidence of bacterial or yeast infection but, then again, he's been treated with antibiotics and most likely steroids such as prednisone. I'm going to post my entire synopsis of the itchy dog that you can send to your brother who can share with his vet...
Pruritic (itchy) dogs are suffering from an allergic dermatitis in the great majority of cases. Allergies to flea saliva, environmental allergens (atopic dermatitis) such as pollens, molds, dust and dust mites, and foods should be considered. (Paw and extremity licking indicate both atopy and a food intolerance and so it behooves vets to distinguish one from another.) In many instances, a concomitant pyoderma (bacterial skin infection), yeast infection (Malassezia), or mange mite (Demodex or Sarcoptes) might be contributory.
His vet can check a sample of his skin surface microscopically (a “cytology”) for abnormal numbers of bacteria and yeast and skin scrapings can be taken in an attempt to find mites. Pyoderma is treated with a minimum of 3-4 weeks of an antibiotic in the cephalosporin class such as cephalexin (Keflex) and yeast is addressed with ketoconazole for at least a month. Mites are addressed topically, orally, and by injection.
Our dermatologists tell us to apply an over the counter flea spot-on such as Advantage/Advocate, a fipronil-containing product such as Frontline or, preferably, one of the newer prescription products available from his vet to which fleas are less likely to have become resistant even if fleas aren’t seen. Dogs can be such effective groomers so as to eliminate all evidence of flea infestation. Dogs who remain primarily indoors can contract fleas because we walk them in on us and flea eggs and larva can remain viable in your home for months. As the weather warms or you turn on heaters at this time of year, egg hatches are common. If the area between the edge of his rib cage and tail (the “saddle” area) is particularly excoriated (it doesn't appear so), a flea saliva allergy should be the most important differential diagnosis. In severe cases, an anti-allergenic prescription glucocorticoid (steroid) such as prednisone will work wonders for dogs allergic to the saliva of the flea. If you have other pets they may have fleas too but may not be allergic to the flea’s saliva.
Environmental allergies (atopy) are usually initially addressed with prednisone as well. In some dogs an over the counter antihistamine such as clemastine (Tavist) at a dose of 0.025 - 0.75mg/lb twice daily or diphenhydramine (Benadryl) dosed at 1-2mg/lb twice daily (maximum dose of 50 mg at any one time) may be effective. Antihistamines, however, aren’t reliably effective. Adding fish oil to the diet at a dose of 20mg/lb daily of the EPA in the fish oil might synergize with antihistamines to provide better anti-pruritic action. The omega-3 fatty acids in fish oil are anti-inflammatory but may take 8-12 weeks to kick in. The new cytokine antagonist oclacitinib (Apoquel) is likely to revolutionize how we address atopic dogs and should be discussed with his vet. Oclacitinib works as well as a steroid without a steroid's adverse effects. The new injectable immunomodulary drug IL-31 (Cytopoint) should also be considered. Please note that atopy, at least initially, should have a seasonality to it while a food intolerance should cause pruritis regardless of the season. Chronically atopic dogs may be pruritic year round.
Food intolerance/allergy is addressed with prescription hypoallergenic diets. These special foods contain just one novel (rabbit, duck, e.g.) animal protein or proteins that have been chemically altered (hydrolyzed) to the point that his immune system doesn't "see" anything to be allergic to. The over the counter hypoallergenic foods too often contain proteins not listed on the label - soy is a common one - and these proteins would confound our evaluation of the efficacy of the hypoallergenic diet. The prescription foods are available from his vet. There are many novel protein foods and a prototypical hydrolyzed protein food is Hill’s Prescription Diet z/d ultra. (I prefer the hydrolyzed protein diets because it avoids the possibility of my patient being intolerant to even a novel protein.) A positive response is usually seen within a few weeks if we’ve eliminated the offending food allergen. Food intolerance can arise at any age and even after our patient has been eating the same food for quite some time.
Please respond with further questions or concerns if you wish.