Dogs love to eat. It's their favorite time of day, next to playing, going outside, riding in the car, and sleeping. But what if your dog suddenly doesn't want to eat?
It's actually not that uncommon. If an adult dog with a normal appetite suddenly loses interest in dog food, there could be several reasons. For example:
Your dog is ill. If there are other signs, such as vomiting, diarrhea, listlessness, coughing, or congestion, contact your veterinarian as soon as possible. If it turns out that your dog needs medical treatment, be sure to ask your vet about diet changes during medication and recovery.
Your dog has recently had a vaccination. Many vaccinations, while commonly administered, do include such side effects as loss of appetite. In time, your dog should be back to normal and eating regularly.
You have changed your dog's food. If the food change is for the better, i.e. healthier, it may take a while for him to accept the new food, even several months. "Junk food" pups sometimes need incentives and gradual change to get with the program.
Start by mixing 25% of the new food with 75% of the old for a few days, and gradually increase the proportion in favor of the new food. A healthy adult dog isn't greatly affected if he refuses to for one or more days. So if he stages a hunger strike against the healthier food, even after it's been mixed with the old, put down a tablespoon or two of the new mixture. Leave it down for 15-20 minutes and then take it up. After a day or two of this, he will give in and dive into the new food.
Picture this transition as similar to a child who is used to eating fast food and snack foods day in and out. Your dog's taste buds have been conditioned in the same manner by comparable pet foods. If you love him, you will insist that he eats something that is more nutritious and life-sustaining.
Your dog isn't used to dry food. Wet food is so much more palatable to dogs, so it can be very difficult to switch a dog over from eating canned or homemade food to eating dry food. You can ease the transition by adding some canned food, unsalted meat, poultry broth, or bits of meat to the dry food, and easing back gradually.
The food has gone bad. This is always a possibility, especially in the heat of the summer. Both canned dog food and dry dog food can turn rancid, and sometimes a batch of bad food accidentally makes it to the shelves. Most dogs aren't as picky as humans about smelly food, but even they have limits!
You should always keep wet food in a sealed container, and never leave an opened can of food out of the refrigerator all day. It is a good idea to transfer the remaining contents of a can of food into a glass container if it will not be consumed in one day. Despite its several advantages, naturally-preserved dry dog food has a much shorter shelf life than chemically-preserved dry dog food, so be sure to check the expiration date.
The food isn't warm enough. Cold food has less of an appealing aroma for dogs. Bring the food to room temperature first, or add a bit of hot water before serving.
Your dog doesn't have an appetite at dinner time. Is he snacking on dog treats in between meals? Cleaning ice cream bowls or licking plates? Are any house guests sneaking him food? Are you or any other family members sneaking him food? Is he raiding the garbage, or visiting unsuspecting neighbors? Just as with children, too much snacking between meals may be ruining his appetite for dinner. And if he doesn't appear underweight, that is probably the case. You must exert your authority, and resist the urge to spoil your dog.
Your dog is accustomed to free-feeding. Free-feeding is leaving food accessible at all times, and a common option in households where dogs are left alone for long periods. Some dogs have the discipline not to nibble all day, but even they can become finicky. Since they can eat anytime, why should they get excited when mealtime comes?
There are several reasons why free-feeding is not recommended. First of all, dogs prone to obesity will get fat and unhealthy. Also, a dogs with a tendency to bloat or stomach torsion requires controlled feedings. Most of all, with the gastric juices churning all day long, a free-feeding dog's digestive system has no time to rest and medical problems often arise.
Changing a "free-feeder" to a scheduled and/or regimented system may take some discipline on your part. Your dog may not eat his whole meal the first few times you feed him the new way because he is expecting to nibble on it all day long. However, when he sees that there are no more in-between-meal snacks, he will learn to take full advantage of mealtime. Until he has adjusted (usually within two weeks), you will have to bear with vocal protests and sad, pathetic looks. But stick to it, and you will soon get him on schedule.
Your dog's routine has changed. Dogs are creatures of habit, and they like their routines. If he always eats in the same corner of the kitchen, he might not respond if the bowl is moved to a different part of the house, or if he's fed somewhere outside the home - for example, on vacation or visiting another house. If his mealtime changes, or the time for walks is different, or even new people are in your house, this can disturb what your dog considers the norm, and he'll need to get used to it.
Your dog is stressed or anxious. Being scared will certainly cause a do to lose his appetite. If something has startled your dog - say, a loud noise like pots and pans crashing near his normal meal place - he may need to get used to a new spot to eat. This can take some time, but eventually he'll be accustomed to the new place. And again, he'll eat when he's hungry.
These are just some examples, and only apply to otherwise healthy dogs. Additional factors will apply to puppies and senior dogs, particularly dental issues in the case of the latter. But in most cases, the reason your dog won't eat is easily addressed.