It is good for yeasty ears, skin, and itching. This has been discussed at length on another forum and I have been adding it to my Gab's food with good results in a two week period. She is prone to yeasty ears. You can find it under the brand name Braggs or look for organic unpasturized apple cider vinegar. "The Mother" is the cloudy residue that is the "starter" if you will. Trader Joe's has it. Start with one tablespoon per feeding then up it to two. I mixed honey in the bottle and shook it up good. The stuff is strong and your Labbie will probably notice it.
I have heard that mixing equal parts apple cider vinegar and honey(over a low flame) is good for lameness and joint aches and pains in both humans and dogs.
I buy the Bragg brand of ACV. It is a great pick me up tonic for humans - mix honey and ACV with a little warm water, and drink up. The honey has B Vitamins, among other, and really helps if you are worn down, mid-day.
Remember that ACV is alkaline, not acidic, and too much of it can result in a high Ph in the urine. Struvite crystals like an alkaline environment.