By Dr. Karen Becker

Generally speaking, healthy dogs and cats love mealtime. That’s why a change in appetite — especially a decreased interest in eating — is something pet parents and veterinarians must closely monitor. Cats, in particular, can’t go long without eating due to the risk of feline hepatic lipidosis, or fatty liver disease. There are actually three different forms your pet’s lack of appetite can take:¹

• Anorexia is a complete lack of food intake. There is no such thing as partial anorexia.
• Hyporexia is a reduction in food intake, regardless of the reason or cause.
• Dysrexia is distortion of normal appetite or eating patterns, for example, a dog who refuses to eat his regular diet but will eat cooked chicken and rice.

While it’s beneficial to keep these terms in mind, what’s most important when a pet’s appetite suddenly decreases or disappears is finding the root cause.

8 Potential Causes of Lack of Appetite in Dogs and Cats

In the vast majority of cases, when a pet loses interest in eating, it’s a symptom of an underlying medical problem. Some potential triggers include:

1. Pain — A painful condition anywhere in the body, and especially in the gastrointestinal (GI) tract, can cause your dog or cat to eat less or refuse to eat.
2. Nausea — While relatively uncommon in dogs and cats, nausea can certainly put your pet off her food. Unless there’s an underlying illness, nausea most often accompanies car travel.
3. Illness — A pet who feels sick will often show little or no interest in eating. Sometimes it’s just a passing GI disturbance; other times it’s much more serious, such as liver or kidney disease, or cancer.
4. Obtundation — This describes a lack of alertness more pronounced than lethargy, and is usually the result of an underlying medical condition such as hypercalcemia, or trauma.
5. Dental or gum disease — Sometimes a problem in your pet’s mouth can make eating unbearably uncomfortable. This can be a broken or loose tooth, severe gum disease, an oral tumor or a condition such as feline stomatitis.
6. Recent vaccination — Loss of appetite can be an immediate adverse effect of vaccination.
7. Stress — If your pet is feeling stressed for some reason, he may turn away from his food bowl. For example, some dogs don’t have much appetite when they’re in an unfamiliar place, or when their favorite human is away from home. Your cat may refuse to eat if her food bowl is in a high traffic area or there are other pets around at mealtime.
8. Food aversion or “pickiness” — Food aversion can occur if you make a sudden change to your pet’s diet. It’s almost never a good idea to do this quickly because it often causes diarrhea. If you want or need to change the diet you’re feeding your pet, do it gradually by mixing the new food in with the old food in a slow transition.

Some pets, especially kitties, refuse to eat certain foods for reasons that may or may not make sense. And some animals are simply notoriously picky eaters who often require special menus or lots of coaxing.

Loss of Appetite Always Requires a Veterinary Visit

If your dog or cat refuses to eat for longer than a day, especially if there are other symptoms, or if there’s a sudden noticeable reduction in her food intake, it’s important to see your veterinarian right away. If the decrease is gradual, it’s just as important to get her checked out, but it’s not as urgent a situation as a sudden, dramatic change.

It’s crucially important that your veterinarian searches thoroughly for the underlying cause of your pet’s loss of interest in eating, because there almost always is one, and her appetite isn’t likely to improve if the problem isn’t identified and addressed.

It’s also important to know that appetite stimulants (which were originally designed as antidepressants) prescribed by your veterinarian can be useful in the short-term, but they don’t address the underlying problem of inappetence. In other words, they may for a time successfully treat the symptom (refusal to eat), but not the cause.

When it comes to treating a pet who won’t eat, there’s no one-size-fits-all approach. Your veterinarian must do a thorough physical exam and diagnostic workup, and investigate metabolic changes such as hypertension, blood potassium levels, anemia or vomiting. He or she should also consider any medications or supplements your pet is taking to rule those out as a cause.

You’ll also want to fill your vet in on any changes that have occurred in your household or daily routine that might be causing stress for your pet. The cause of your dog’s or cat’s disinterest in eating will determine an appropriate treatment approach. If there’s an underlying disorder that can be successfully treated or managed, your pet’s appetite should pick up as the condition resolves.

Sometimes, In appetence Disappears With a Change to a Better Diet

Needless to say, the diet you feed your pet can play a big role in both maintaining his interest in food and for his health and overall vitality. As always, I recommend a nutritionally balanced, diverse, species-appropriate fresh food diet.

Over the years, I’ve known many dogs and cats on processed diets who were considered fussy eaters, or who spent as much time playing with their food as eating it. When their owners gradually transitioned them from a kibble or feed-grade canned diet to raw or gently cooked fresh food, the weird eating habits disappeared.

One client of mine adopted a tiny dog who came home with a bag of the same dry food he’d been eating at the shelter. She knew to continue the diet until he was settled in to avoid tummy troubles, but she wasn’t prepared for his odd eating behavior.

At mealtime, the little guy approached the bowl of kibble slowly and pushed it around on the floor with his nose. Eventually he’d pick a piece of food out of the bowl and drop it on the floor. Sometimes he ate it, sometimes he didn’t before pushing the bowl around some more. He seemed anxious about the whole experience.

Since he was tiny to begin with and slightly underweight, she was concerned he wasn’t getting enough calories. She noticed he seemed quite interested in her cat’s canned food, so she went out and bought a couple cans of high-quality dog food and mixed it with the kibble.

He immediately gobbled up the moist food and left the kibble in the bowl. He did have loose stools for a few days from the sudden change in diet, but since he was eating like a champ, she just kept a careful eye on him until his poop was firm again. From there, she did a gradual transition to a nutritionally balanced, commercial raw diet. He’s been a chowhound ever since, with no sign of his initial odd eating behaviors.

If your cat or dog gets a clean bill of health from your veterinarian but still isn’t eating well, review the diet you’re offering and see where it falls on my latest ranking of best-to-worst pet foods. Make upgrades as you’re able to, and see if your pet’s appetite improves.