Originally Posted by 4theluvofpetz
Given the age and breed (pit mix) I would be highly suspicious this is Demodex you are dealing with. I know you said he was tested for it but "testing" I am sure was taking some plucks of hair, and some skin scrape samples which is appropriate but it is not very common to actually find Demodex on a sample. I am sure he improved with the antibiotics because they almost always get a SECONDARY skin infection with it and that would of taken care of it but not the primary issue. Before you invest in the $1000 allergy testing you may want to consider treating for Demodex and go from there. Just a thought, hope things resolve soon.
Demodex is frequently and usually easily diagnosed by skin scraping, you may be thinking of sarcoptic mange/scabies, which is much less commonly found on a skin scrape and usually ruled out by treating empirically since it's easily treated with antiparasitic meds (usually revolution or ivermectin). The vets would have been sure to rule out demodectic mange before prescribing steroids, as an immunosuppressant drug will likely make demodex worse (also the OP would likely have seen worsening of symptoms, rather than improvement on steroids if it were demodex). Dogs with sarcoptic mange are usually intensely itchy, have scabby lesions/crusts, and lesions may be concentrated on the ears/head.
OP, has your vet ruled out possible fungal causes? I had a dog who had seasonal (environmental) allergies, and one time she developed those moth eaten areas all over her body, in addition to the "usual" pustules/areas she dug raw by scratching. After trying a bunch of other stuff ( my dog was diabetic, so steroids were not feasible) antihistamines, antibiotics, etc, we did a trial with an antifungal drug, and it cleared up. She was negative on a fungal culture and woods light exam, but did frequently have a "yeast" smell to her belly and ears, so I don't know if that may have been a factor. My grandmom's dog also developed a bunch of little raw/hairless patches in response to some sort of allergy, though hers were typically preceded by bumps/pustules which would rupture and heal over leaving hairless areas. Your dog's spots look pretty red/inflammed, are the hairless areas "scars" from previous lesions? My grandmom's dog's skin issues have been decreased with a change to a better food, but she still gets some lesions seasonally- probably an environmental component. She's got a bunch of little spots right now that are red/hairless- they were hives last week, scabs a few days ago, but seem to be on the mend. If he had scabs/sores, you may just be seeing areas where the hair has yet to grow back?
If it is environmental allergies, shampooing with a benzoyl peroxide shampoo may help to flush allergens out of his follicles and reduce his reaction, but my experience has been that too much shampooing can dry them out and cause problems as well. It's worth asking your vet if there's anything in particular you should be washing him with. My current favorite shampoo for allergic dogs is Phytovet PSS, which has both benzoyl peroxide and salicylic acid, as well as an additional component which helps to restore the skin's protective moisture. It's helped quite a bit with my grandmom's dog's gross skin, I used it once a week or so, letting it soak for a while before rinsing- always with tepid/cool water for dogs with skin issues.
It sounds like your vets suspect an allergy, which is why they wanted to do the food trial (the only way to rule out a food allergy is to feed a completely novel diet for 6-8 weeks, or a hydrolyzed protein diet for the same, and see if symptoms abate), and the intradermal testing, which is the gold standard for testing for environmental allergens. If it's a food allergy, you would manage by avoiding allergens in his diet, and if it's an environmental allergy, you can either avoid allergens, OR try immunotherapy injections to see if you can desensitize him to them. Either way, you will likely still have at least occasional breakouts which will require treatment.
I guess your vet is thinking that it may be cheaper for you in the long run to try to get a definitive diagnosis at the dermatologist rather than continue trying to treat the symptoms with intermittent success.
If you aren't able to do the testing at the derm right now, you might ask your vet about trying one of the newer allergy meds (atopica or apoquel), though over the course of one year, they'll probably cost as much if not more than a derm visit. Alternatively, maybe see if you can use steroids to "put out the fire" so to speak, then maintain on antihistamines and maybe a low dose of steroids if needed over a longer period of time. I'm having a similar situation with one of my cats right now, where she is maintained on an antihistamine 2x daily, plus pred every 3rd day with decent results most of the time. When she has itching even with that, I bump the pred up for a few days, then taper it back down. The goal is to eventually hopefully wean her off the pred completely, but it's possible that may never happen. I have one dog who is sporadically itchy (seasonal? it seems), and he gets antihistamines mostly, and rarely steroids if he's still itchy with that. I try to use steroids minimally with my animals, but I know of some dogs who have been on higher doses of steroids long term and been fine despite the odds/risks, their owners can't or won't do further diagnostics or try other meds, or have and still find that the steroids are the most effective treatment, so they accept the risks.
It can't hurt to try a diet change even if you decide not to do a true food allergy trial, and isn't a bad idea to rule out a thyroid problem, even though he's on the young side of the typical age range for diagnosis. It's possible though that you might do both those and still come out at the same place you currently are, and since you have limited funds (no offense, I'm in the same boat, and I've seen people spend thousands of dollars and still have itchy dogs with patchy coats), I would weigh where you will get the most out of your money. Maybe continue to treat symptomatically for now and put aside money for a derm consultation at least, even if you decide not to do the intradermal testing, they may still have some novel ideas for treatment that your vet hasn't considered.