Problems with dry food consumption may originate in three parts of your dog’s body. Your dog’s refusal to eat dry food can stem from a general systemic failure, in which the need for hydration drives your dog to seek moist food. Your dog may have difficulty digesting dry food. There can also be various problems within your dog’s mouth that make it painful for him to process hard food.
Dehydration
A dog’s lack of hydration affects his entire body. A dehydrated dog may have a dry nose, mouth, and gums, with sticky mucous membranes; he may be tired, dull, and weak, he may pant more than normal and have a fast rapid-fire breathing pattern, and will be generally operating at a low capacity. Dehydration simply means that your dog’s body is losing more water than it takes in, through panting, vomiting, or simply drinking less, possibly because of a deeper condition. This is more likely to occur in young, old, and nursing dogs, as well as small breeds.
Nausea
If your dog is nauseous, he has an upset stomach. This can occur as a reaction to illnesses, such as Parvovirus and gastroenteritis, or environmental causes, such as motion sickness, blockage of the intestines, or toxic exposure. Nausea is an equal-opportunity condition; dogs of any age, breed, or sex can experience nausea.
Oral Conditions
Oral conditions can include tongue cancer, tooth root abscess, periodontal disease and various other oral injuries, such as lacerations, puncture wounds, and broken teeth. Tongue cancer, the most common one being squamous cell carcinoma, is most likely to occur in dogs between 6 and 10 years old, and in the breeds: Keeshond, Standard Schnauzer, Basset Hound, and Collie (Boxers actually suffer from tongue cancer less than most other breeds). While there may be a genetic cause to tongue cancer, this is not certain, and there are no other clear causes. Tooth root abscess, also known as apical abscess, is a pus formation under or around your dog’s tooth or teeth. It develops from an oral infection, which can result from periodontal disease, bacterial skin infections and puncture wounds caused by bites, splinters, and wood. Any dog can receive an oral injury from a foreign object that he takes into his mouth. Dogs like to chew many different things, and some of those things, like sticks, rocks, and other hard objects, can injure your dog’s soft oral tissues, sometimes even breaking a tooth. As teething puppies chew more often than adult dogs, this may make them more vulnerable to oral injuries.