Thank you for your patience. As you can imagine, there are a number of things that could be causing Taz's skin issue and the itchy spot and we need to consider everything from external parasites, to infection, to an allergy of some sort. Firstly - you need to make sure that Taz is definitely up to date with flea control. Make sure you are using a flea product appropriate for his weight. Even if you may not see any fleas on him doesn't mean there are one or two lurking and oftentimes this is all it takes for a dog with flea allergy dermatitis. In Taz's case it does sounds like he may have an underlying allergy of some sort with secondary infection, however this could also be caused by parasites or fungi (ringworm or yeast). The black bits are unlikely to be external parasites, but we need to consider that here as well. These are more likely to be plugs from the pores in his skin.
Basically dogs are allergic to four main things - food, fleas, grasses/plants (contact allergy) or environmental allergens (canine atopy - the dog version of ezcema). Flea allergies are avoided by strict flea control - every 4 weeks with Advantage or Advantage multi, or every 5 - 6 weeks with Frontline. You must also ensure any other cats or dogs in the household are treated at the same time. I would recommend a product like Advantage Multi to cover off the chance of mites and lice here. A food allergy is a little harder to diagnose and would require a special food for Taz to eat (and nothing else) for 8 - 12 weeks to see if this improved his condition. This is less likely given Taz only seems to be irritated in one specific area. Contact allergies are best treated by avoidance of the plants that are to blame, but identifying the exact cause of a contact allergy can be very hard. A referral to a canine skin specialist may be the way to go in Taz's case for either a skin patch test or a blood allergen test.
While it is very unlikely, we do have to consider whether Taz could be affected by external parasites from the wild turkeys or other wildlife in your area. There are a range of parasites that affect your boy. In terms of canine mites, the most common type are either Demodex (less itchy) or Sarcoptes mites (VERY itchy) and you should ensure a full Veterinary check up so that he or she can carry out a physical examination and possibly a skin scrape to check for mites and lice, as well as signs of fleas.
The next step would be to double check for fungal disease (such as ringworm) and there are several tests for this including a UV light and a fungal culture. Again a full Vet check will be able to confirm or deny this. You should also purchase a medicated shampoo that will deal with both yeast and bacteria, and the product Malaseb is the most ideally suited for this. This requires you to make a lather and leave this lather on for 10 minutes before washing off! For many clients this is easier said that done, but it is SO important.
All the best with Taz, and do definitely follow up on this skin issue with your local vet when you get a chance. I hope all of the above makes sense? If you have more questions or if I can help in any other way, please do not hesitate to ask! If you would like to accept my answer, please press RATE OUR CONVERSATION (I am not compensated in any other way). Bonuses are always welcome. Thanks! I hope to work with you again soon!
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