Ask a vet online-‘my cat has suddenly lost weight, she was fine a few weeks ago’

Question from Gemma Loopylou Moorey:

I has my cat suddenly lost weight I can even fill her ribs now she was fine a few weeks ago. Even her mood is changed she meows loudly when I talk to her in a bad mood way

Answer from Shanika Winters online vet:

Hi Gemma and thank you for your question regarding your cats sudden weight loss and change of temperament.  I will discuss in my answer some possible cause for the changes you have noticed in your pet.  I would advise that you take your cat to see your vet as soon as possible.

A sudden loss of a significant amount of weight can be very dangerous for your cat, regardless of the cause of the weight loss in the first place such changes can lead to organs failing and your cat being in need of emergency veterinary care.

An average cat weighs between 4 and 6 kg so even a change of a few 100g of weight is significant on such a small animal.  Ideally your vet will weigh your cat each time they are seen; it is easy to keep track of your cat’s weight at home too, weigh your cat carrier empty and then with your cat inside and the difference is your cat’s weight.  This should be easier than trying to convince your cat to stand on weighing scales.  Some owners may be able to weigh themselves and then again when holding their cat if the cat carrier causes stress.

The fact that you have described that you can feel your cats ribs and you could not before suggest a lot of weight has been lost.

You have mentioned that your cat seems to meow as if in a bad mood, this is what we would call a change of temperament.  Changes to a cat’s temperament can be due to many stresses or changes to their home, environments, routine, companion animals or due to pain/illness.

What will happen when I take my cat to the vet?

Your vet will ask you lots of questions about your cat’s general state, what time scale the changes have happened over and if you can think of anything that may have led to the weight loss and temperament change such as moving home, new pet/family member and or exposure to chemicals such as rat/mouse poisons.

Your vet will then perform a full clinical examination of your pet including recording its weight.  If the physical examination and the details you have given your vet are not enough to confirm a diagnosis then your vet may advise further test most likely blood tests and or x-rays to work out what is happening with your cat.

What will the blood tests and x-rays tell us?

Blood tests usually consist of routine haematology, biochemistry, and or specific disease test.

Haematology looks at your cat’s red blood cells, white blood cells and platelets.  These give an indication of whether your pet is fighting an infection, anaemic (low in iron) or has abnormal cells or parasites present.

Biochemistry looks at the chemicals in your cat’s blood and gives an indication of how the major body organs are functioning.  Significant changes can suggest for example liver or kidney disease.

Specific disease tests include looking for viruses such as FeLV (feline leukaemia virus), FIV (feline immunodeficiency virus) and increased levels of thyroid hormone (Hyperthyroidism).

X-rays are often done of the chest and abdomen( tummy) two views of each at 90 degrees in order to look for any obvious abnormalities such as enlarged or shrunken organs or unexpected tissues ( infection or tumours).

Some practices may also offer ultrasound scans and or MRI (magnetic resonance imaging) scans to help make a diagnosis.

Biopsies may need to be taken, this is when small or large pieces of tissue are removed from your cat (under anaesthetic if appropriate) and sent to a laboratory for analysis.

What happens next?

Hopefully all the information your vet has found out will lead to a diagnosis and then treatment plan for your pet.  From the information you have given in your question some of the possible disease that come to mind are Kidney failure, hyperthyroidism and or a severe infection.

Kidney disease can be treated by increasing your cat’s fluid intake, reduced protein diets, anabolic steroids( body building) and various medications to reduce the components in your pet’s that are difficult for the kidneys to deal with .

Hyperthyroidism can be treated medically with tablets to reduce thyroid hormone production, surgically by removal of thyroid gland tumours or by radiation therapy to destroy the thyroid gland tumour tissue.

Severe infections can be treated by use of appropriate and in some cases several antibiotics at the same time, and supportive intravenous fluid therapy.

I hope that this answer has helped you to understand some possible causes for your cat’s condition and why a full examination from your vet with or without further tests is most likely to help lead to a diagnosis and treatment plan for your cat.

Shanika Winters MRCVS (online vet)

If you have any worries about your pet, please make an appointment with your vet, or try our Symptom Guide.

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