Yes apple cider vinegar is good for dogs.
You can add a cup of apple cider vinegar to a dogs water bowl and then they can drink the apple cider vinegar that way.
Giving your dog some apple cider vinegar can help prevent and treat bladder issues, Urinary Tract infections etc.
You can give the dog some apple cider vinegar everyday or just whenever you want too.
If your dog has a bladder issue or Urinary Tract Infection then the apple cider vinegar is a good way to naturally treat the dog.
It's still a good idea to take the dog to the vet for treatment of bladder issues or Urinary Tract Infections but the apple cider vinegar can help.