Why is my senior cat losing weight? Weight loss in an older cat is never normal on its own — it is a sign that something has changed, and it needs a vet check, not just more food. A senior cat can lose weight for many reasons: dental pain that makes eating hurt, kidney disease, thyroid problems, diabetes, cancer, or simply the loss of muscle that comes with old age. This guide covers the causes, the warning signs, what the vet will do, and how to feed a senior cat that is losing weight. A senior cat is one from about 11 years, and geriatric from 15, and from that age vet checks should move to twice a year.
The short version is: see a vet promptly if a senior cat is losing weight, especially if it is losing weight without a change in food, if it is off its food, if it is lethargic, or if it is drinking or urinating more than usual. Bring the weight record: a list of weights with dates is far more useful than a single number, because it shows how fast the weight is falling. Do not just feed more: a senior cat that is losing weight needs a vet to find the cause, and feeding more without finding it can hide the problem. The senior cat diet guide covers feeding older cats, and the when is a cat considered a senior guide gives the senior thresholds by size.
Why do senior cats lose weight?
Senior cats lose weight for two broad reasons: they eat less, or they burn more than they take in. They eat less because of dental pain, because their sense of smell has dulled and food is less appealing, because they are nauseous from kidney disease or another illness, or because they are in pain from arthritis and cannot get to the bowl comfortably. They burn more than they take in because of illness: an overactive thyroid in cats, diabetes, kidney disease, and cancer all increase the body's energy use or waste nutrients, so the cat loses weight even when it is eating normally.
Muscle loss is the other cause, and it is a normal part of ageing — but it is not harmless. An older cat loses muscle every year, and a cat that loses muscle loses strength, balance, and the ability to move well. Muscle loss is slowed by good protein and by gentle, regular exercise, but it is not stopped by food alone. A senior cat that is losing weight fast, or that has lost a lot of weight in a short time, needs a vet check promptly, because fast weight loss is more likely to be illness than ageing. The arthritis in cats guide covers the joint problems that make eating and moving hard, and the kidney disease in cats guide covers the most common cause of weight loss in older cats.
Warning signs to watch for
See a vet promptly if a senior cat is losing weight, and the same day if it is losing weight fast, if it has stopped eating, if it is vomiting or has diarrhoea, if it is drinking or urinating much more than usual, if it is lethargic or weak, or if it has a lump, a sore that does not heal, or a change in behaviour. Those are signs that need a vet, not waiting and not more food. Bring a note of what the cat eats, how much, and any treats, and whether it has been drinking more — that information helps the vet far more than a guess about the food.
At home, watch for the small signs as well as the big ones: a cat that leaves food in the bowl, that eats slowly, that drops food, or that paws at its mouth may have dental pain. A cat that is drinking more and urinating more may have kidney disease or diabetes. A cat that is restless at night, confused, or house-training badly may have cognitive decline. A cat that is stiff, slow to get up, or reluctant to jump may have arthritis. Each of those signs is worth mentioning to the vet, because each one points to a different cause, and each one is easier to treat when it is caught early.
What the vet will do
At the vet, expect a weigh-in, a body condition score, a check of the teeth and mouth, and questions about food, water, urination, and behaviour — and usually a blood test and a urine test, because those are the usual first steps when a senior cat is losing weight, and they show whether the kidneys, the thyroid, the blood sugar, and the liver are normal. The vet may also check for lumps, listen to the heart and lungs, and feel the belly. Those checks are not overkill: weight loss in a senior cat has many possible causes, and the blood and urine tests narrow them down fast.
Depending on what the tests show, the vet may recommend a change in food, a medicine, dental treatment, or further tests. A cat with kidney disease may need a food with controlled protein and phosphorus, and more water. A cat with an overactive thyroid needs medicine. A cat with dental pain needs its teeth treated, not just softer food. A cat with diabetes needs insulin and a feeding routine. Each cause has its own treatment, which is why finding the cause matters more than feeding more. The diabetes in cats guide and the thyroid disease in cats guide explain the conditions that most often cause weight loss in older cats.
Feeding a senior cat that is losing weight
Once the vet has found the cause, the feeding plan follows it. A senior cat that is losing weight because it is not eating enough needs more calories, fed little and often — two or three smaller meals a day, rather than one large meal, because a senior cat often has a small appetite. A food made for seniors, or a food with good protein to hold muscle, can help — but only with your vet's agreement, and only if the cat does not have kidney disease, where protein is controlled. Warm the food a little, or add a little water, to make it smell stronger and easier to eat — a senior cat whose sense of smell has dulled may eat more if the food smells stronger.
Feed in a quiet place, at the same times every day, and make the bowl easy to reach — a senior cat with stiff joints may struggle to reach a bowl on the floor or up a step, so a raised bowl or a bowl on the same floor as the cat's bed can help. If there are other pets in the house, feed the senior cat separately, so it is not pushed away from its bowl. Weigh monthly, and write the number down: the line over months is what matters, and a cat whose weight has steadied is a cat whose plan is working. The senior cat diet guide covers the full feeding plan for older cats, and the how much food should a senior cat eat guide gives the calorie tables.
Muscle loss and keeping a senior cat moving
Muscle loss is a normal part of ageing, but it can be slowed: good protein in the food, and gentle, regular exercise every day. A senior cat that stops moving loses muscle fast and finds it hard to get it back, so keep the cat moving every day, at a level that suits its body — shorter, more frequent walks or play sessions rather than one long session, and play that does not strain stiff joints. Ramps or steps can help a senior cat get onto a bed or into a car without jumping, and a warm, supportive bed helps stiff joints rest.
Do not try to put weight on a senior cat with a sudden large increase in food: a cat that is fed a lot more all at once can get an upset stomach, and a senior cat with an upset stomach eats less, not more. Add about 10% at a time, wait a month, and then decide — and only with your vet's agreement, once the cause has been found. The cognitive decline in senior cats guide covers the changes in behaviour that come with old age, and the senior cat lifespan guide explains what the senior years mean for the whole of a cat's remaining life.
For related reading, see the senior cat diet guide, the when is a cat considered a senior guide, the kidney disease in cats guide, the diabetes in cats guide, the thyroid disease in cats guide, the how to weigh your cat at home guide.
Frequently asked questions
Why is my senior cat losing weight?
Weight loss in an older cat is never normal on its own. It can be caused by dental pain, kidney disease, thyroid problems, diabetes, cancer, or muscle loss with age. A senior cat can lose weight because it eats less, or because illness makes it burn more than it takes in. See a vet promptly — a senior cat that is losing weight needs a vet to find the cause, not just more food.
When is a cat considered a senior?
A cat is usually considered a senior from about 11 years old, and geriatric from 15. From that age, vet checks should move to twice a year, and food, weight, teeth, and kidneys should be checked each time.
What will the vet do for a senior cat losing weight?
Expect a weigh-in, a body condition score, a check of the teeth and mouth, and usually a blood test and a urine test — those show whether the kidneys, the thyroid, the blood sugar, and the liver are normal. Depending on the results, the vet may recommend a change in food, a medicine, dental treatment, or further tests.
Should I feed my senior cat more food?
Only with your vet's agreement, once the cause has been found. A senior cat that is losing weight because it is not eating enough needs more calories, fed little and often — but a senior cat that is losing weight because of illness needs the illness treated, not just more food. Add about 10% at a time, and weigh monthly.
How can I help my senior cat keep muscle?
Good protein in the food, and gentle, regular exercise every day. A senior cat that stops moving loses muscle fast and finds it hard to get it back, so keep it moving every day at a level that suits its body — shorter, more frequent walks or play sessions, and play that does not strain stiff joints.
When should a senior cat losing weight see a vet?
Promptly — and the same day if it is losing weight fast, if it has stopped eating, if it is vomiting or has diarrhoea, if it is drinking or urinating much more than usual, or if it is lethargic or weak. Bring the weight record: a list of weights with dates is far more useful than a single number.
Results on this page are estimates for general information only and are not veterinary advice. If your pet is ill, underweight, overweight, pregnant, or has a health condition, consult your veterinarian before changing diet or care.