I'm going to post my synopsis of the pruritic dog for you. I would need to examine Herbie to be more accurate but please take your time perusing my synopsis and then return to our conversation with further question or concerns if you wish. My initial though for any dog scratching and chewing himself in those areas is a flea saliva allergy. The odor is a seborrheic one - that of smelly gym socks" and arises as a primary skin disease in certain breeds more than another but most often arises secondary to most any chronic skin disease and from the history you've provided Herbie certain has been chronically affected. I'll also post my synopsis of seborrhea for you.
I’m sorry to hear of this with Herbie . 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 indicates 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.
Herbie's vet can check a sample of Herbie's 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.
Our dermatologists tell us to apply an effective over the counter flea spot-on such as Advantage, a fipronil-containing product such as Frontline or one of the newer prescription products available from Herbie's vet 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. In severe cases, an anti-allergenic prescription glucocorticoid 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 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 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 antiinflammatory 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.
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 Herbie's 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.) 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.
We need to consider seborrhea in such a patient as well. This is skin disorder of keratinization and maturation. It's a diagnosis of exclusion of the above mentioned skin disorders and can be suggested by skin biopsy. This can be a hereditary disorder of keratinization or appear secondary to other skin conditions as I mentioned above. Clinical symptoms can initially appear during puppyhood and may be mild at first but worsen with age. Symptoms may become apparent or worsen as an adult if underlying concurrent diseases develop.
Clinical signs may include a dull, dry, lusterless hair coat, excessive scaling (dandruff), follicular casts, scaly and crusty seborrheic patches and plaques, and greasy, malodorous skin. Most of the body is involved to some degree, with interdigital areas, perineum, face, axillae, ventral neck, abdomen, and skin folds usually most severely affected. Pruritis (itchiness) is mild to intense, and ceruminous otitis externa (oily external ear canal inflammation) is common. Secondary skin and ear infections with bacteria and Malassezia (yeast) are often present. Here's how seborrhea is addressed:
1) Ensure good nutrition. A commercially balanced dog food that meets AAFCO requirements should be fed. You should find the AAFCO statement on the food label.
2) Any secondary bacterial and Malassezia skin and ear infection should be treated with appropriate topical and systemic therapies. Periodic treatments or long-term, low-dose maintenance therapy may be needed because these dogs are susceptible to recurring infection.
3) For symptomatic control of ceruminous otitis, long-term maintenance ear care is necessary. Ear treatments with a multimodal therapy (consult with *****vet) or ear cleaner should be administered to both ears every 1-7 days to control cerumen (wax) accumulation.
4) For symptomatic control of seborrhea, antiseborrheic shampoos and emollients may be used every 2-7 days until the skin condition is improved (~2-3 weeks), then, bathing frequency should be decreased to every 1-2 weeks or as needed for maintenance. Antiseborrheic shampoos contain some combination of sulfur, salicyclic acid, tar, benzoyl peroxide, and phytosphingosine.
5) Daily oral fatty acid supplementation may be helpful as an adjunct therapy (180mg EPA/10lbs). EPA is thought to be the most antiinflammatory of the essential omega-3 fatty acids. It's plentiful in fish oil supplements.
6) Vitamin A 8000-10,000 IU per 20lbs orally administered with a fatty meal every 24 hours. Improvement should be seen within 4-6 weeks.
7) For dogs with severe, greasy, malodorous, pruritic seborrhea, treatment with systemic corticosteroids may be helpful. Acitretin (a retinoid) may be helpful in some dogs. Calcitriol (vitamin D) may be helpful in some cases.
The prognosis is variable, depending on the severity of the seborrhea. This is an incurable condition that requires lifelong therapy for control.
That's a lot to take in at one time. Please take your time and then respond with further questions or concerns if you wish.
Please respond with further questions or concerns if you wish.