By a licensed veterinarian with over a decade in small-animal practice
I’ve been practicing veterinary medicine for more than ten years, and if there’s one pattern I’ve learned to take seriously, it’s unexplained weight loss in older cats. A 10-year-old cat isn’t ancient, but they’re no longer young either. At this age, gradual changes are expected. Steady weight loss is not.
I still remember a gray domestic shorthair I examined a couple of winters ago. The owner brought him in because he “felt lighter” when she picked him up. She hadn’t changed his food; he was still begging at the kitchen counter, and his behavior seemed normal. On the scale, he’d lost close to a pound since his last visit. That might not sound dramatic, but on a cat, that kind of loss is meaningful. It turned out to be early hyperthyroidism, caught before things spiraled.
That situation isn’t unusual. In my experience, weight loss is often the first visible sign that something deeper is happening in a middle-aged or senior cat.
Aging alone rarely causes weight loss.
One of the most common assumptions I hear is, “He’s just getting older.” I understand why people think that. Older humans often lose muscle mass, so it makes sense that cats would, too. But healthy aging cats typically maintain a stable weight if they’re eating properly and absorbing nutrients.
When a 10-year-old cat is losing weight, I don’t chalk it up to age. I start asking questions. Is the cat eating more, less, or the same? Has the litter box output changed? Is there vomiting that’s being dismissed as hairballs? These details matter, and owners often don’t realize how much until we talk it through in the exam room.
The patterns I see most often in practice
Over the years, specific causes have come up again and again. Hyperthyroidism is high on that list. I’ve diagnosed it countless times, often in cats that are ravenous yet steadily shrinking. Owners are sometimes surprised because the cat seems energetic, even restless. Weight loss with a big appetite is a classic red flag.
Kidney disease is another frequent culprit at this age. I think of a tabby I saw last spring who had been “picky” with food for months. His owner kept rotating flavors, thinking boredom was the issue. Bloodwork told a different story. Early kidney changes were already affecting how his body handled nutrients, even though outward signs were subtle.
Dental disease is underestimated, too. I can’t count how many times I’ve found painful mouths in cats that were still eating, just not efficiently. Cats are incredibly good at hiding oral pain. They’ll approach the bowl, take a few bites, walk away, and repeat that cycle all day. From a distance, it looks like normal eating. On the scale, it doesn’t.
What owners often miss at home
One mistake I see repeatedly is relying on the food bowl as proof that everything is fine. “He eats every meal” doesn’t always mean he’s eating enough, or that his body is using what he eats properly.
Another common issue is multi-cat households. I’ve had owners swear a cat is eating well, only to discover another cat is finishing the leftovers. Weight loss can sneak up quietly in those situations, especially if no one is regularly feeling along the ribs or spine.
I also see people wait too long because the cat seems otherwise okay. Cats don’t slow down the way dogs do when they’re unwell. Many continue jumping, grooming, and interacting right up until a disease is relatively advanced.
How I approach a 10-year-old cat losing weight
In my clinic, I start with history and hands-on exam before jumping to conclusions. I palpate the abdomen carefully, assess muscle condition, check hydration, and examine the mouth thoroughly. From there, I usually recommend baseline bloodwork and a urine test. At this age, those tests often reveal things we can’t detect any other way.
I’m opinionated about this part: guessing and changing foods without diagnostics often delays proper treatment. I’ve seen well-meaning owners spend months experimenting with diets while an underlying condition quietly progresses. Early answers usually mean simpler, more effective management.
Treatment isn’t one-size-fits-all.
What happens next depends entirely on the cause. Some cats respond to medication. Others need targeted dietary changes, not generic “senior” labels. Occasionally, dental treatment alone leads to weight stabilization, which always feels like a small victory.
I once treated a cat whose weight rebounded after a much-needed dental cleaning and extractions. The owner was shocked by how quickly her cat’s appetite and body condition improved. The problem hadn’t been the food at all; it was the pain.
My professional advice, plainly stated
If your 10-year-old cat is losing weight without an apparent reason, don’t wait for more signs to appear. Weight loss is already a sign. In my experience, earlier evaluation leads to better outcomes and fewer regrets.
I don’t recommend assuming age, switching foods repeatedly, or waiting until appetite disappears. I do recommend paying attention to subtle changes and acting on them while your cat still feels mostly normal.
Cats age quietly. Weight loss is one of the few ways they tell us something isn’t right.