Skin pH is a critical factor when picking a bathing product for your dog. Dogs have neutral skin (neither alkaline nor acidic), making them susceptible to products that aren't specifically designed for them. You should buy a mild moisturizing dog shampoo. However, be careful as dogs can still react negatively. You should stop using mild moisturizing shampoos that cause side effects like itchy skin, red skin and/or hives. The shampoo should also be harmless when ingested. Some negative effects of ingested shampoo include drooling, vomiting, and decreased appetite. Visit a vet immediately to get appropriate remedies and alternative products if the shampoo or grooming products have resulted in negative side effects. Your vet can give you recommendations if you don't know which shampoo to buy. He/she is the best placed professional to recommend a good cleaning product based on your dog's medical history.