Why Is My Dog Not Eating? A Veterinarian Explains the Reasons

There are many reasons your dog might not eat. They can range from simple explanations to serious complications. To complicate matters, just because your dog isn’t eating, doesn’t mean they don’t have an appetite. A dog with a dental or other oral issue, including injury, may not be able to eat but is still hungry.

Other conditions can cause a dog to lose their appetite because they don’t feel well. To avoid making the situation worse, work with your veterinarian for a solution instead of trying to fix it yourself.

Possible reasons your dog isn’t eating

Non-medical causes

• Picky eater: There are various reasons for a dog being truly picky, such as having access to food all day or preferring human food and treats. If your dog is being picky but is doing well otherwise and will eat human food and treats, you can try other dog food brands. Otherwise, it’s best to have an exam to rule out medical issues like a dental problem.
• Food is stale or expired: Check the date to make sure the food isn’t expired. If it’s dry food and the bag has been open for more than 6 weeks, it might be stale, especially if the bag isn’t kept sealed.
• Stress or anxiety: The stress of a new home, boarding, travel, change in humans or animals in the home, and owner schedule changes can all cause a decreased appetite.
• Summer: Some dogs may have a decreased appetite when the weather is hot.

Medical causes

• Pain: Any cause of pain, such as dental pain, pain after a surgery, or joint pain, may potentially result in your dog not wanting to eat.
• Medication side-effect: Did your dog start a new medication or supplement? If so, call your veterinarian. Some medications are best given with food and can cause digestive upset if taken on an empty stomach. Other medications may need to be given on an empty stomach but can still cause digestive issues.
• Vaccination: Did your dog just get vaccinated? If so, this could be a reason they’re feeling under the weather.
• Infection: Infections can affect any part of your dog’s body including blood and bone infections. These can range from an infected tooth to a digestive tract infection—including parvo virus or an intestinal parasite—or a respiratory infection. Some regions of the United States can have infections that are common to that area, e.g. Valley Fever in the desert southwestern U.S., Histoplasmosis in the Mississippi and Ohio River valleys, and hookworms on the east coast.
• Food intolerance or allergy: If your veterinarian suspects your dog has a food allergy or intolerance, they’ll likely recommend a dietary trial with a food for allergies or sensitive stomach.
• Swallowed objects: Some dogs like to swallow objects, like parts of toys, and sometimes they can get stuck in the digestive tract.
• Medical conditions: This could mean an underlying organ issue that may be temporary or chronic, poisoning from plants, foods, medications, or chemicals, or even cancer.
• Multiple simultaneous causes: Dogs can have multiple reasons for not eating. For example, a diabetic dog whose blood sugar isn’t regulated may not feel well due to high blood sugar, dehydration (despite increased thirst), and possible infections, such as dental and/or urinary.

What to do if your dog won't eat

What to do depends on a dog’s particular situation. For puppies, not eating is more urgent than for a healthy adult with no other health issues.

Puppies

Puppies can quickly become dehydrated and/or have low blood sugar, known as hypoglycemia. This is especially true for toy breeds and puppies who are still nursing. If your puppy’s appetite goes down even a little, or if they skip a meal, call your veterinarian that day for what to do.

Adults

If your dog is a known picky eater, you can try different dog foods or temporarily offer plain cooked, skinless, boneless chicken breast with white rice. You can also add canned food to their dry food, adding warm water to their food, and cutting back on treats. If you have multiple dogs, try feeding the dog that’s not eating well separately.

For dog’s who are seniors and are being fed from a bowl on the floor, try raising the height of the bowl to see if that’s more comfortable for them.

But if an older dog isn’t eating properly, try not to spend a lot of time trying a variety of things like switching to another senior dog food. Older pets are more likely to have medical conditions such as problems with the kidneys not working as well as they should. Some of these concerns may require special diets—so it’s best they see a veterinarian.

If your dog’s decreased appetite along with other symptoms, call your veterinarian. They can let you know if the situation is safe for you to wait for a scheduled appointment or if it’s a possible emergency. For example, you may have a dog whose breed is more prone to bloat, which is considered a medical emergency.

If you’re scheduled for an appointment that’s not on the same day, your veterinarian may also let you know what you should and shouldn’t do in the meantime and what to do if your dog’s symptoms, such as in the middle of the night.

How long can a dog go without eating?

If they’re still drinking water, a healthy adult dog can go about 3-5 days without food but that doesn’t mean you should wait that long before contacting your veterinarian. If your healthy adult dog is still not eating on day 2, call your veterinarian for advice.

A puppy shouldn’t go a whole day without eating. For some, like nursing puppies and small breed puppies, even going several hours beyond their normal meal time can be harmful. Puppies are at an increased risk for low blood sugar, which can cause seizures.

When to see a veterinarian

Generally well adult dog

If your adult dog isn’t eating their normal amount but is still in good spirits, active, drinking their usual amount of water, and doesn’t have additional symptoms, you can likely wait 48 hours before having them seen by a veterinarian. But given it can take days to get an appointment on a non-emergency basis, it doesn’t hurt to call your veterinarian for advice.

Unwell adult dog

Call your veterinarian right away if your adult dog has known medical conditions and/or has any additional symptoms such as:

• Lethargy
• Weight loss
• Drinking less (or more) water than usual
• Vomiting, diarrhea or other changes in stool (including not defecating)
• Drooling
• Trouble breathing
• Changes in urination

Let your veterinarian know what’s going on so they can decide if you need an emergency visit or if your pet can wait to be seen.

Puppies

Whether a puppy is weaned or not, if they aren’t nursing or eating their puppy food like usual, contact your veterinarian the same day, even if there aren’t additional symptoms. Though all puppies are prone to low blood sugar, toy breed puppies are particularly at risk.