A 15-year-old dog that suddenly seems ravenous all the time is telling you something, and it’s rarely just greediness. Constant hunger in a senior dog, known clinically as polyphagia, usually points to a medical condition, a medication side effect, or age-related changes in the brain. Some causes are straightforward to manage, while others need prompt veterinary attention, especially when the hunger comes with weight loss.
Medical Conditions That Drive Constant Hunger
Several diseases common in older dogs create a disconnect between how much your dog eats and how much nutrition actually reaches their cells. The result is a dog that feels genuinely starving no matter how full their bowl was an hour ago.
Diabetes mellitus is one of the most common culprits. When a dog’s body can’t produce or respond to insulin properly, glucose stays in the bloodstream instead of entering cells. The cells are essentially energy-starved even though there’s plenty of sugar circulating. The body starts breaking down fat and muscle tissue to compensate, which is why diabetic dogs often lose weight despite eating more than usual. If your dog is drinking and urinating a lot on top of the hunger, diabetes moves near the top of the list.
Cushing’s disease (excess cortisol production from overactive adrenal glands) is another frequent cause in senior dogs. Cortisol drives appetite aggressively. Dogs with Cushing’s typically develop a pot-bellied appearance, thinning hair or bald patches on their body, increased thirst and urination, and restlessness or panting. The hunger from Cushing’s can be intense, with dogs counter-surfing, raiding trash, or begging relentlessly when they never did before.
Exocrine pancreatic insufficiency (EPI) means the pancreas isn’t producing enough digestive enzymes to break down food properly. Your dog eats a full meal, but the nutrients pass right through without being absorbed. These dogs are often ravenous and losing weight at the same time, sometimes with greasy or unusually large stools.
Inflammatory bowel disease and certain cancers can produce similar patterns. IBD interferes with nutrient absorption in the intestinal tract, while cancer increases the body’s caloric demand. In both cases, the dog’s body sends persistent hunger signals because it isn’t getting what it needs from food.
Medications That Increase Appetite
If your 15-year-old is on any steroid-based medication for arthritis, allergies, or an immune condition, that alone could explain the constant hunger. Glucocorticoids like prednisone and prednisolone are among the most commonly prescribed drugs in veterinary medicine, and increased appetite is their most predictable side effect. In one study of dogs receiving prednisone for joint inflammation, 100% developed increased hunger and thirst. Every single dog.
The effect is dose-dependent, meaning higher doses cause more dramatic appetite changes. If your dog recently started a new medication or had a dose increase, mention this to your vet. Sometimes adjusting the dose or switching to a different drug can reduce the food obsession without sacrificing the treatment benefit.
Cognitive Dysfunction and “Forgetting” Meals
At 15, your dog is in the age range where cognitive dysfunction syndrome becomes a real possibility. This is the canine equivalent of dementia, and one of its recognized signs is changes in appetite and food-seeking behavior. Some dogs with cognitive decline genuinely seem to forget they’ve just eaten. They finish a meal, walk away, and 10 minutes later act as though they haven’t been fed at all.
Other signs that suggest cognitive dysfunction rather than a metabolic problem include pacing or wandering aimlessly, getting “stuck” in corners or behind furniture, not recognizing familiar people, loss of house training, disrupted sleep cycles (awake and restless at night, sleeping more during the day), and reduced interest in interaction or play. If the hunger appears alongside several of these behaviors, cognitive decline is worth discussing with your vet. It won’t show up on blood work, which makes it a diagnosis based on behavioral patterns.
When Weight Loss Accompanies the Hunger
The single most important detail to track is whether your dog is gaining weight, maintaining weight, or losing weight despite eating more. A dog that’s hungry and gaining weight may simply be getting too many calories or treats, or may be dealing with Cushing’s disease or a medication side effect. A dog that’s hungry and losing weight is a more urgent concern. That combination points toward diabetes, EPI, cancer, or another condition where the body can’t use or absorb the calories it’s taking in.
Weigh your dog before the vet visit if you can. Even a rough number helps. If you don’t have a scale large enough, step on your own scale holding the dog, then weigh yourself alone and subtract.
What Your Vet Will Look For
A vet evaluating increased appetite in a senior dog will typically start with bloodwork and a urinalysis. A basic blood chemistry panel checks glucose levels (high glucose suggests diabetes, very low glucose can indicate a rare pancreatic tumor called an insulinoma), liver enzyme levels (often elevated with Cushing’s disease or diabetes), and kidney function markers. The urinalysis checks for glucose spilling into the urine, which happens when blood sugar exceeds roughly 180 mg/dL in dogs, a hallmark of diabetes.
If Cushing’s disease is suspected based on the overall picture, specific hormone tests are needed since it won’t show up definitively on a standard blood panel. These involve measuring cortisol responses to stimulation or suppression. Your vet will guide the sequence of testing based on your dog’s symptoms.
Dietary Adjustments That Help
While you’re sorting out the underlying cause, or if the cause turns out to be cognitive or medication-related, there are practical ways to help your dog feel more satisfied between meals.
Adding fiber to your dog’s diet increases the feeling of fullness without adding significant calories. Senior dog foods formulated for weight management tend to have higher crude fiber content for exactly this reason. A balanced mix of soluble fiber sources (like beet pulp or psyllium husk) and insoluble fiber (like pea fiber or rice bran) supports digestion while slowing the rate food moves through the stomach. Splitting your dog’s daily food into three or four smaller meals instead of one or two larger ones can also reduce the intensity of hunger between feedings.
Puzzle feeders and slow-feed bowls extend mealtime, which gives your dog’s brain more time to register that food has arrived. For a cognitively declining dog that forgets meals, keeping a simple log on the fridge of feeding times can help everyone in the household avoid accidentally double-feeding, which is easy to do when the dog is acting like they haven’t eaten.
One thing to avoid is simply increasing portions without knowing why your dog is hungrier. If the cause is diabetes or EPI, more food won’t solve the problem because the issue is what happens after the food is swallowed. And if the cause is Cushing’s or steroids, extra food just leads to rapid weight gain that strains already-aging joints.