Symptom · Cats
Cat losing weight: what it means and when to call the vet
Unintended weight loss is one of the most important early signs of illness in cats, especially older cats. A cat losing weight while eating well or more than usual needs checking for thyroid disease or diabetes.
By Maya HartCommon causes
- Hyperthyroidism — often with a big appetite
- Diabetes — often with thirst and weight loss
- Chronic kidney disease
- Dental disease making eating painful
- Inflammatory bowel disease or intestinal lymphoma
- Competition for food in multi-cat homes
- Parasites
What you can do at home
- Weigh your cat monthly on kitchen or baby scales
- Check whether another cat is eating their food
- Offer food in a quiet place
- Note changes in appetite, thirst and litter tray habits
What the vet may do
- Full examination including teeth
- Blood tests for thyroid, kidney function and diabetes
- Urine tests
- Ultrasound or other imaging if needed
Prevention
- Twice-yearly check-ups for cats over 10
- Regular weigh-ins at home
- Early dental care
The details
Cats are small, so weight loss that sounds tiny is significant. Half a kilo lost by a 4 kg cat is more than 10% of their body weight — like a 70 kg person losing 8 kg without trying. Because it happens slowly and is hidden by fur, owners often don’t notice until it is well advanced.
Many causes of weight loss in older cats, such as hyperthyroidism and diabetes, are very treatable, especially when caught early.
Questions owners ask
Is cat losing weight an emergency?
Usually it is not an emergency, but your pet should see a vet within 24 hours. Go now if you see: not eating for more than a day; weight loss with vomiting, diarrhoea or weakness; yellow gums or eyes (jaundice); breathing difficulty.
What causes cat losing weight?
Hyperthyroidism — often with a big appetite; Diabetes — often with thirst and weight loss; Chronic kidney disease; Dental disease making eating painful; Inflammatory bowel disease or intestinal lymphoma; Competition for food in multi-cat homes; Parasites.
What can I do at home?
Weigh your cat monthly on kitchen or baby scales. Check whether another cat is eating their food. Offer food in a quiet place. Note changes in appetite, thirst and litter tray habits.
Sources
Tailwise is for general information and is reviewed by veterinary professionals, but it is not a substitute for advice from your own vet, who knows your pet. How we check facts