Your dog's lack of appetite may be your first clue that he is ill, or it may be a new symptom of an ongoing illness. As long as you keep your pet properly hydrated, a day or two without food will not cause any harm. However, any abstinence from eating longer than this must be addressed. Ensure that your dog gets the nutrition he needs to recover from his illness by encouraging him to eat.
Seek advice from your veterinarian, who may have specific recommendations for you to follow depending on the nature of your dog's illness. Examples of this include prescription diet food, appetite stimulating medications, syringe feeding instructions or even the insertion of a feeding tube. Learn the cause of your dog's appetite loss to help you overcome it; for example, if your dog needs dental work and has tooth pain, softer food may be an interim solution to get him eating again.
Gently clean away any nasal discharge that your dog may have. Use a soft, moist cloth or cotton ball. Rhinitis and sinusitis, which are infections or inflammations of the nose and sinuses, can cause excessive nasal discharge. If your dog is sneezing and has thick mucus coming from his nose, his appetite will likely be reduced because he can't smell his food as well. Clearing away this discharge may improve his interest in eating.
Entice your ill pet with more appealing types of food. Switch from dry kibbles to wet canned food. Purchase several brands, textures and flavors for your pet to sample; for instance, some pets prefer chunks in gravy while others prefer pate. Try real meat items such as small pieces of cooked chicken or beef. Avoid raw meat to guard against potential infections such as toxoplasmosis.
Hand feed your dog. Sit with him either in your lap or right next to you. Take a small portion of food in your hand or on a spoon and allow him to sniff it. Stroke his fur gently and speak in a soothing voice as you encourage him to lick the food and then eat it. Work at his pace: Continue to feed him piece by piece if he needs you to, or pass him the dish if he shows enough interest and strength to eat on his own.