Weight loss in cats is a common and non-specific sign, as it can be caused by a large number of symptoms and conditions. Causes of weight loss can range from mild, easy-to-treat conditions to more serious, life-threatening diseases. Any age of cat can develop weight loss due to medical reasons.

Many conditions causing weight loss are treatable, especially with early diagnosis. Cachexia is the name used for an extreme stage of weight loss. Weight loss of over 2% a week in cats can lead to severe liver disease.

What to do if your cat is losing weight

Both sudden and gradual weight loss in cats can indicate they have an underlying disease. It’s best to get a full check-up with your local vet if your cat is losing weight.

• Keep a regular diary of your cat's weight to let your vet know how quickly it’s changing.

• Monitor for any other symptoms, such as drinking more than normal, vomiting, changes to their stools, lethargy, or appetite changes.

• Allow your cat to rest to reduce the amount of energy they are using.

• Try to monitor and keep a record of how much they are eating, including the brand and type of food and any treats.

• Be aware if your cat is losing weight and/or muscle. Muscle loss can indicate different problems than just weight loss alone.

If your cat is losing weight, it’s best to speak to a vet as soon as possible. Our Joii vets are available 24 hours a day for advice; call us now.

The most common causes of weight loss in cats

There are many causes of weight loss in cats. Some conditions are more common at different ages. Read more about the most common causes of weight loss by following the links:

Kittens

• Parasites: worms, giardia

• Incorrect diet or malnutrition

• Heart problems

Adult cats

• Dental problems

• Worms (outdoor cats who hunt)

• Diabetes

• Heart problems

• Hyperthyroidism

• Poor-quality diet

• Pancreatic problems

Senior cats

• Cancer

• Dental problems

• Heart problems

• Hyperthyroidism

• Kidney disease

• Liver disease

• Poor-quality diet

• Arthritis

The following symptoms can also lead to weight loss:

• Vomiting and diarrhoea, both short-term or chronic

• Pain

• Stress

• Reduced appetite

When you should be worried about weight loss in cats

Seek help from a vet if:

• Your cat suddenly loses a lot of weight

• Your cat is losing weight and has other symptoms such as lethargy, vomiting or drinking more than normal.

• Stops eating for over 24 hours

Call us and speak to one of our Joii Vets if:

• You want help assessing your cats body condition score

• You have any questions about what to feed your cat

Tips on how to prevent your cat from losing weight

• Keep your cat up-to-date with vaccinations and parasite preventatives. Kittens and cats who hunt need to be wormed more frequently than other cats.

• Make sure your cat is on a complete diet, especially for their age and lifestyle. And that they are actually eating the correct amounts of this food. The WSAVA website has a toolkit to help pet owner’s know what to look for when selecting cat food.

• Maintain a good oral hygiene routine for your cat from as early as possible. Brushing their teeth is the best way to do this.

• Get regular check-ups with your vet - at least once a year. Checking their teeth, weight, heart, and rest of the body can pick up any problems early on. Regular blood tests help with early detection of kidney, liver, and other organ diseases.

• Cats need a safe space to eat, somewhere that is quiet and comfortable for them. Competition with other pets can lead to a reduced intake of food.

• Follow our guide on how to prevent and reduce stress in cats.

• Speak to a vet as soon as possible if your cat starts to show signs of being unwell. Vomiting, diarrhoea, and reduced appetite can all quickly lead to weight loss in cats.

• Keep your cat in a healthy body condition to help reduce symptoms of diseases such as arthritis and heart disease.

Our Joii vets are available 24 hours a day for advice. Call us now if you have any concerns about your cat.

Diagnosis of weight loss in cats

A full physical exam with your vet is always an important step when investigating weight loss in cats. It’s important to let your vet know of any other symptoms or changes that you’ve noticed at home. In most cases, your vet will run some tests to help them come to a diagnosis:

• Blood tests

• Urine tests

• Stool tests

• Imaging, such as x-rays, ultrasound or MRI

• Biopsy of the tummy, intestines or other organs

How to help a cat with weight loss at home

It’s always best to start with a physical exam with your local vet to look for any medical problems.

• Special diets may be recommended if your cat is diagnosed with medical issues such as dental problems, cancer, or kidney disease. Otherwise, an energy dense food such as Hills Prescription Diet a/d may be recommended. Always speak to a vet before using specific foods, as they are not suitable for every cat.

• Make sure they have a quiet, safe space to eat, drink and rest

• Give any medication at the dose and frequency recommended by your vet

• Weigh your cat regularly to make sure their weight is improving

• Find out more in our blog about how much to feed your cat

Vet treatment for weight loss in cats

Treatment for weight loss depends on what the cause is. Your vet may start by advising a higher calorie diet and monitoring at home while waiting for test results. If your cat is extremely ill, your vet will likely keep them in for close observation and, if needed, feeding via a special tube.

Your vet can help you calculate your cat's RER (resting energy requirement) and MER (maintenance energy requirement). These are important measurements to work out how much your cat should be eating on a daily basis, and they change throughout your cat’s life.

Are some cats at more risk of weight loss than others?

• Kittens lose weight quickly, especially if they are not digesting enough nutrients. Diets for growing cats should contain higher amounts of energy, protein, calcium, and phosphorus.

• Senior or immunocompromised cats may become ill more quickly if they lose weight

• Thin / underweight cats are more at risk of having a weaker immune system, reduced mobility, and problems with wound healing.

Cats that have higher energy requirements:

• Kittens have higher energy requirements throughout growth and development.

• Pregnant and lactating: Feeding a high-quality kitten food is recommended to support pregnant and lactating cats as it provides more energy and is easily digestible.

• Non-neutered cats have a higher energy requirement. Neutering reduces calorie requirements by up to 30%.

Other causes of weight loss in cats

Follow the links to read more about other causes of weight loss in cats:

• Arthritis

• Old age

• Megaoesophagus

• Inflammatory bowel disease

• Stomach ulcers

• Pyometra

• Exocrine pancreatic insufficiency

• Vestibular disease

• Allergies: food and environmental

• Infections: Cat flu, FIV, FeLV, FIP