Fur Loss/Scaling/Black Spots one side only

Hello, I have a 12 yr old female spayed Lab on thyroid tabs daily. For past four weeks, she has had thinning, breaking hair, flaking, scaling and sporadic fur loss areas on left side only. Vet asked me to change food to improve skin and coat. I did; no change yet. She has always been on high quality food. All bloodwork, thyroid and Urinalysis are normal. There is a slight odor to her left side. Dermabend shampoo was ordered, created a reaction to skin so I have used baking soda and apple cider vinegar on coat prior to using anti-itch shampoo. She is fine for 2 days before flakes are back. There are small black splotches on her skin. Vet was not concerned. Vet will not prescribe any antibiotics, says it is a wait and see approach. Meanwhile my girl’s normally luxurious coat is thinning terribly on her life side and clearly she is uncomfortable. Please, I’ll do whatever it takes for her. Thank you for any help.

Hello   I wonder why this is only happening on one side?  This being an elderly labrador, I wonder if she has a preferred side for lying on e.g. due to underlying arthritis or pain in the abdomen, which means that one side is either in contact with a particular surface (or not exposed to the air) more often, or hurting a lot?  Sometimes, for example, pain relief for arthritis or pancreatitis can make a huge difference to skin disease. What you are describing sounds as though there may be a yeasty skin infection (these are usually secondary to scratching:  the scratching cuts the skin very lightly and then the yeast that live normally on the surface of the skin, move into the skin and cause a slightly smelly infection).  I am disappointed that the shampoo has not helped;  does your vet know that you are not using it?  There may be alternative anti-yeast / bacterial shampoos that you can try (prescription ones have been shown to work and therefore vets prefer them;  so many shampoo 'products' look very similar but are in fact never going to help fight a yeast infection).  Often, anti-yeast shampoos have to be left in contact with the skin for a certain length of time before being rinsed off.  Furthermore, a flea treatment may be advisable - not that your dog necessarily has a flea infestation.  More specifically, most dogs that are prone to allergy tend to overreact to random fleas, so even a single flea of someone else's that they meet while out for a walk, can be enough to set a horrid reaction off - and a good quality flea treatment for 3 months can help to rule this possibility out. in summary, there are lots of possibilities - and as always, when there are multiple possibilities, you vet might not reach the answer immediately.  This case definitely merits a revisit or two.  Questions such as:  'What might be causing the scratching?  What will this rule out?  What will you do if this doesn't work?'  Might help you to extract a logical plan, so that you can understand your vets' course of approach.  Best of luck and please do let us know how you get on.

Of course, another possibility that I haven't mentioned, is that your dogs' required thyroid dose might have changed.  Thyroid disease causes skin changes and it could be that a different dose is now needed.  This is something else to ask your vet about, as Thyroid Medication comes on prescription.  https://vethelpdirect.com/vetblog/2018/11/05/dry-skin-dog-common-causes/

Thank you, Dr. Buchanan, you have given me some good points to question. I will follow your advice with my vet. Many thanks.