Why Is My Dog Not Eating? When to Worry and When to Wait

Q: What are the most common medical reasons a dog stops eating?

Dental pain is probably the most underdiagnosed reason — dogs don't stop chewing entirely but will eat more slowly, drop food, or show obvious discomfort. Nausea from GI upset, pancreatitis, or a foreign object in the stomach is another top cause. Kidney disease, liver disease, and Addison's disease all suppress appetite significantly. In older dogs, cancer is a more serious possibility. Pain anywhere in the body — not just the mouth — commonly causes appetite loss because animals in pain conserve energy.

Q: My dog is not eating and throwing up — should I come in?

When not eating comes packaged with vomiting, treat it as a GI problem rather than an appetite one. A dog who refuses food and vomits more than once or twice in a day should be seen the same day, because that combination is what we see with a swallowed object, pancreatitis, or GI irritation that will not settle on its own. Do not wait it out overnight.

Q: My dog is eating grass and not eating their food — what does that mean?

Grass eating in dogs who are otherwise healthy is mostly normal and the cause isn't fully understood — some dogs just do it. When it's paired with loss of appetite and the dog seems nauseous, restless, or repeatedly tries to vomit without bringing anything up, it suggests GI discomfort. A dog actively trying to eat grass while refusing food and appearing distressed warrants a call to the vet.

"My dog won't eat" is one of the calls we get most often — and also one where the right answer varies more than almost anything else. We've had that call be a dog who just didn't feel like breakfast because it was 98°F in Alhambra and his food bowl was in the sunny corner of the kitchen. We've had it be something that needed to be addressed that day. The difference usually isn't in the not-eating itself. It's in everything else going on alongside it.

When you call us, we're going to ask two things right away: how long has this been going on, and is anything else different. Those two answers point us in the right direction more than anything.

One skipped meal from a dog who is otherwise acting completely like themselves — same energy, still drinking water, no vomiting, no obvious discomfort — is worth watching through the next meal before doing much. Dogs miss meals all the time for reasons that have nothing to do with illness. The heat, a stressful houseguest, a new food, a treat too close to mealtime, a bowl that moved to a new spot. If the next meal goes normally and the dog seems fine, there's often nothing to it.

Two meals in a row is a different story. So is any missed meal that comes packaged with something else — lethargy, vomiting, weight loss you can feel when you run your hands down the ribs. Those combinations move faster. A dog who hasn't touched food in 48 hours deserves a call regardless of how normal they otherwise seem — by that point you're past the "just not hungry" explanation. And younger and older dogs get shorter windows: puppies under six months who skip a meal and seem off are worth a call within 12 to 24 hours, and dogs in their senior years who stop eating should be seen within 24 — what's behind appetite loss in an older dog tends to need attention sooner.

One thing we've noticed over and over: owners consistently underestimate the mouth. Dental pain may be the most commonly missed reason a dog's appetite changes, and the reason it gets missed is that dogs don't stop eating entirely when a tooth hurts. They adapt. They start chewing on one side, swallow kibble without really chewing, drop food from their mouth, shift toward wet over dry. A dog who's still technically eating but doing it differently isn't necessarily fine. By the time a dog won't approach the bowl at all, the dental issue has usually been building for a while. If your dog has been getting gradually pickier over weeks or months, a dental check is worth scheduling. See our pricing page for dental cleaning costs.

Beyond the mouth, nausea is one of the most effective appetite suppressants there is — and it can come from a lot of different directions. GI upset is one of the more common things we see behind appetite loss in dogs. Sometimes it settles; sometimes it doesn't. A dog who's gotten into something, swallowed something that's sitting where it shouldn't be, or is dealing with irritation in the digestive system can all look like "won't eat" on the surface — but those situations don't resolve the same way or on the same timeline. We'd genuinely rather you call and let us help you figure out which bucket you're in than have you try to read it alone.

Appetite can also be an early signal of things that show up on bloodwork rather than in the stomach. A dog who's been eating noticeably less than usual for more than two weeks — even if still eating something — is worth bringing in for a check. Not urgently, but not something to keep putting off either. And pain anywhere in the body, not just the digestive system, can suppress appetite. A dog who's also moving stiffly, hesitating on stairs, or reacting when certain spots are touched should be evaluated as a whole picture. Mention that when you call — it helps us know where to start.

How long is too long to go without eating?

Owners ask us this one constantly — how long can he go without food before it's actually dangerous? The honest answer leans more on the dog in front of us than on any clean number. A healthy adult with some reserve can technically go a couple of days on water alone without organ damage, but "can survive it" and "should be seen" are two very different lines, and we care about the second one. The rule we actually use at the front desk is simpler than a chart: a healthy adult who's past roughly 48 hours needs a call, a senior or any dog with a known condition gets that call at 24, and a puppy under six months gets one within 12. The younger and smaller the dog, the faster the clock runs. Toy breeds and young puppies can drop their blood sugar dangerously low after barely a day without food — that's not a wait-and-see situation, that's a same-day one.

When not eating shows up alongside vomiting, we stop treating it as an appetite question at all. A dog who's both refusing food and throwing up — especially more than once or twice — is telling us something is actively wrong in the gut, not just that he's a little off his food. That pairing climbs our list fast, because it's the combination behind the things that don't sort themselves out: a swallowed toy or sock sitting where it shouldn't, pancreatitis after a fatty table-scrap weekend, GI irritation that keeps feeding on itself. If your dog hasn't eaten and has vomited more than once in a day, treat that as a same-day call rather than something to sleep on.

If your dog skipped one meal and seems genuinely fine, a few things are worth trying before calling. Warm the food briefly — it makes dry food smell more interesting to a fussy dog, just check the temperature before serving. Try a different spot in the house; some dogs won't eat if their bowl moved or their usual feeding spot suddenly feels off. Make sure the bowl is clean. Skip the human medications — things people reach for when their own stomach is upset are often not safe for dogs and some are genuinely dangerous even in small amounts. If 48 hours pass without eating, call us rather than trying more at home.

A few combinations we want to hear about today, not tomorrow: a dog who isn't eating and has a distended, hard, or visibly uncomfortable abdomen — especially a large or deep-chested breed — needs to be seen the same day. Pale, white, or gray gums alongside not eating is always a same-day call. Vomiting blood, or repeated retching that produces nothing, paired with not eating — call us. Any known ingestion of something they shouldn't have, followed by not eating — don't wait to see how it unfolds.

We're at 3116 W Main St in Alhambra, seeing dogs from South Pasadena, Pasadena, San Gabriel, and across the SGV. Contact us or book online — our team can usually tell you over the phone, based on what you describe, whether it needs to be today or whether we schedule it out.

Questions we hear often

My dog skipped one meal but seems fine — should I worry?

Probably not, if this is a one-time thing and your dog is acting completely normal otherwise — same energy, drinking water, no vomiting, no lethargy. Watch for a second skipped meal or any change in behavior. If everything else is normal after 24 hours, most adult dogs are fine.

What are the most common medical reasons a dog stops eating?

Dental pain is probably the most underdiagnosed — dogs don't stop chewing entirely but will eat more slowly, drop food, or show obvious discomfort. Nausea from GI upset, pancreatitis, or a foreign object in the stomach is another top cause. Kidney disease, liver disease, and Addison's disease all suppress appetite significantly. In older dogs, cancer is on the list. Pain anywhere in the body — not just the mouth — commonly causes appetite loss because animals in pain conserve energy.

How long can a dog safely go without eating?

A healthy adult dog with normal body condition can usually go a couple of days on water alone without organ harm — but that's the outer edge, not a target. We tell clients to call once a healthy adult passes about 48 hours, once a senior or a dog with any known condition passes 24, and once a puppy under six months passes 12. Small breeds and young puppies run the fastest clock because they can drop their blood sugar dangerously low after barely a day without food.

My dog is not eating and throwing up — should I come in?

When not eating comes packaged with vomiting, we stop treating it as an appetite question and start treating it as a GI one. A dog who refuses food and vomits more than once or twice in a day should be seen the same day — that combination is what we see with a swallowed object, pancreatitis, or GI irritation that won't settle on its own. Don't wait it out overnight.

Can I tempt my dog to eat with human food?

A small amount of plain boiled chicken or low-sodium broth can help a mildly off dog eat, and that's generally fine for a day. The risk is teaching a dog that refusing regular food produces better options — some dogs will hold out deliberately once they learn this works. If your dog won't eat even something they'd normally love, that's more concerning than pickiness.

My dog is eating grass and not eating their food — what does that mean?

Grass eating in otherwise healthy dogs is mostly normal. When it's paired with loss of appetite and the dog seems nauseous, restless, or repeatedly tries to vomit without success, it suggests GI discomfort. A dog actively trying to eat grass while refusing food and appearing distressed warrants a call.

How do vets figure out why a dog isn't eating?

It starts with a thorough physical exam — checking the mouth for dental disease, feeling the abdomen for pain or masses, assessing overall body condition. Bloodwork is usually next if the physical exam doesn't point to an obvious cause — it checks kidney and liver function, blood sugar, electrolytes, and red and white cell counts. X-rays or ultrasound follow if obstruction or organ changes are suspected. Most of the time we have a working diagnosis by the end of the exam. Book an appointment here.