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Home >  Blog >  Symptoms & Causes of Weight Loss in Cats

Symptoms & Causes of Weight Loss in Cats

Posted on 16 July 2022
Symptoms & Causes of Weight Loss in Cats

What weight should my cat be?

Every cat’s weight expectations will differ depending on several variables such as age, breed, sex and health conditions.

For example a healthy weight of  a Singapura, the smallest cat breed, is significantly less than the Maine Coon, the largest cat breed. The Domestic Shorthair will normally weigh 4-5kg, but can still vary.

And a change in weight over time is to be expected with changes in diet, exercise, and other lifestyle factors. 

But sudden, unintentional weight changes can indicate underlying health issues.


Reasons your cat may be losing weight

They aren’t eating enough

If your cat is leaving more leftover food in the bowl, this change in calorie intake can affect their weight. And if their bowl is still empty, they may still be eating less than you think. 

If you have other pets in the home, they may be eating their food or obstructing access.

Intestinal parasites

Intestinal parasites such as worms can cause sudden unexpected weight loss when left untreated. A cat with worms may:

  • Have an increased appetite

  • Show a change in coat condition (dull)

  • Have irregular bowel movements or diarrhoea

  • Have a swollen stomach

  • Be lethargic

  • Have worm segments in droppings

Feline diabetes

Diabetes is a common and serious illness in cats that requires veterinary care and ongoing treatment.  Cats may initially be overweight and then experience quick or unusual weight loss. A cat may also exhibit the following symptoms:

  • Increased, ongoing thirst

  • Excessive urination

  • Increased appetite initially 

Thyroid issues (hypothyroidism)

More common in older cats, hyperthyroidism affects the thyroid gland, which helps regulate the body’s metabolism. 

A cat affected by hyperthyroidism may exhibit the following symptoms:

  • A rapid change in weight

  • Substantial increase in appetite

  • High heart rate

  • Change in personality and behaviour

  • Trouble sleeping at night

  • Increase in water intake and urination

Feline Viral Disease

Feline aids, feline leukamia and feline infectious peritonitis are all severe viral illnesses in cats that can present with slow or rapid weight loss in both young and older cats. 

Feline Kidney Disease

Feline kidney disease can cause sudden or chronic weight loss in cats. It can be accompanied by symptoms including:

  • Increased thirst

  • Increased urination, inappropriate urination

  • Weakness

  • Lack of appetite

  • Bad breath

  • Vomiting (occasionally with blood)

Feline Cancer

Like in humans, cancer comes in many forms in cats and symptoms vary widely depending on the areas affected. One symptom of many feline cancers is a fast or drastic change in weight. Other symptoms may include:

  • Visible or feelable lumps which change in shape or size

  • Sores or wounds that don’t heal

  • Unusual changes to bowel and bladder habits

  • Vomiting

  • Diarrhoea

  • Loss of appetite


My cat is losing weight, what should I do?

As with any unexpected changes to your cat’s body, unintentional weight loss can be a concern. And, as symptoms are shared across many illnesses, you should always consult us before beginning any treatments or dietary modifications. 

Your cat’s weight loss could be caused by something as simple as a change of diet or exercise plan, but it’s always safest to check.

Contact us or call the team at (03) 9596 4804 to make an appointment.

The clinic is open 7 days a week, Monday to Friday 8 am to 7:30 pm, Saturdays 8:30 am to 4 pm, and Sundays 9:30 am to 4 pm.

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