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Cats are experts at hiding when something is wrong, so it can be really hard to tell if your cat is ill or feeling unwell. If there is something wrong with your cat you might find the signs are very subtle. The best way to know if there is something wrong with your cat is by having regular check-ups at the vet and visiting your vet if you think there is something wrong straight away.

Different diseases and conditions will have different symptoms, but generally, the signs your cat is unwell might include:
• Hiding more.
• drinking more or less than usual
• being off their food
• sleeping more than usual
• sudden weight loss
• change in their grooming habits (for example, overgrooming or stopping altogether)

What are the most common cat illnesses?

Sadly, our cats can get all sorts of illnesses and diseases. However, there are certain illnesses and problems that vets see more often in our feline friends. See below to find out more.


Fleas are really common in cats (and other pets). They make your cat itchy and uncomfortable by biting them. If your cat has fleas, you’ll notice them scratching more, they might have flea bites on them and you might find flea bites on yourself! The best way to stop fleas is by regularly treating your cat and any other pets in your home with a flea treatment from your vet. You should also treat your home, as fleas lay their eggs in carpets and soft furnishings.


Worms are another common parasite and there are two types your cat can get. You might notice your cat has an itchy bum and may have an upset tummy. You may even see parts of the worm in your cat’s bed or their poo.
You can treat worms by making sure you get a worm treatment regularly from your vet.

Cat flu

Just like us, cats can also get a type of flu (specific to cats – humans can’t catch cat flu and cats can’t catch human flu). It can cause a runny nose, sore eyes and in very extreme cases can be fatal.
The best way to prevent your cat falling ill from cat flu is to get them vaccinated and keep on top of any regular boosters.


Cats can develop diabetes a lot like humans and will often need insulin injections to manage their condition. Overweight cats are more at risk of developing diabetes than cats who are a healthy weight, so it’s important to feed your cat a healthy, balanced diet to keep them in shape.
Signs of diabetes can include drinking more, losing weight and sleeping more than normal. If your cat has any of these symptoms you should take them to the vet for a check as soon as possible.

What is hyperthyroidism?

Your cat has two thyroid glands in their neck that control their metabolism.
Hyperthyroidism is over-activity in these thyroid glands. The vast majority of cases are caused by harmless swellings but some rare cases are caused by cancer (1-3% of cases).
Hyperthyroidism causes a high metabolism, which has many negative effects on the body. Weight loss, a high heart rate and high blood pressure are just a few of the common problems encountered by hyperthyroid cats.
Symptoms appear slowly, so you may not notice a problem at first but left untreated over a long period, hyperthyroidism can be fatal.
Hyperthyroidism is most common in middle aged to older cats.

Hyperthyroidism is over-activity in the thyroid glands.

An overactive thyroid can cause the following symptoms:
• An increased appetite
• Weight loss
• Hyperactivity, noisy and demanding behaviour
• Drinking and peeing more
• Sickness and diarrhoea
• A dry, untidy coat
• Low energy (lethargy).
You might also notice:
• One or two small lumps in the neck under the skin
• A very fast heartbeat (you may feel this when your cat is sat on you)
• Hair loss (alopecia).

When to contact your vet
Contact your vet if you notice any of the symptoms above or you suspect your cat may have hyperthyroidism.
You know your cat best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.

Hypotension (Blood Pressure)

Hypertension in animals is almost always secondary to other problems. In cats the most common link is with kidney failure, but some cats with hyperthyroidism (an overactive thyroid gland) may also develop hypertension. Any cat that has been diagnosed with one or both of these diseases should also be monitored for hypertension every 3-6 months.
Other diseases that may cause hypertension include tumours of the adrenal glands and hyperadrenocorticism (Cushing’s disease), but these diseases are very rare in cats. Diabetes mellitus (sugar diabetes) often causes hypertension in people, but although it is a common disease of cats it rarely seems to cause hypertension.

Signs of Hypotension

In the early stages of disease there are few, if any, signs of hypertension itself, but because hypertension is commonly associated with an underlying disease you may notice signs of that disease in your pet. Appetite may be decreased in kidney failure, or may be increased in hyperthyroidism, and both conditions can cause weight loss, excessive drinking and vomiting.
Signs related to secondary damage to blood vessels will depend upon the organ affected. Damage to the blood vessels in the eye may cause sudden onset blindness, and this is often the first recognisable indication of hypertension in cats. Damage to blood vessels in the brain can cause “strokes” and other neurological disorders, and increased blood pressure in the blood vessels that supply the kidney can cause further deterioration in kidney function.

Diagnosing Hypotension

The signs and symptoms that your cat develops may be highly suggestive of the presence of hypertension, especially if there is also evidence of kidney failure or hyperthyroidism. If your vet suspects hypertension they will want to examine your cat’s eyes for areas of haemorrhage (bleeding) or detachment of the retina (at the back of the eye). Examination of the eyes can be a very useful way to identify the disease but the best way to confirm the diagnosis, and to monitor the response to any treatment, is by measurement of blood pressure.
Hypertension must always be considered in cats that have been diagnosed with kidney disease or hyperthyroidism and blood pressure should be checked regularly in these cases.

What is Chronic Kidney Disease (CKD)?

There are two types of kidney disease, ‘chronic’ and ‘acute’. This article focuses on chronic kidney disease.
Chronic kidney disease (CKD) is when the kidneys slowly stop working, often due to ageing but occasionally because something has harmed them in the past.
Acute kidney disease is when the kidneys stop working very suddenly, usually because they have been damaged by something such as a toxic substance (e.g. antifreeze), a drug or an infection.

Symptoms of CKD

Symptoms to look out for include:
• Drinking more than normal
• Peeing more than normal
• Weight loss
• Eating less, or nothing at all
• Vomiting (which can come and go)
• Low energy (lethargy)
• Bad breath with a “urine” smell
• Mouth ulcers
• Messy or matted coat
• Sudden blindness.
Chronic kidney disease develops slowly until the body is unable to hide the symptoms anymore. Unfortunately, this means that when we see symptoms, the kidney disease is usually quite advanced.

When to contact your vet
If you notice any of the symptoms above, contact your vet. The earlier kidney disease is detected, the better the chance of slowing further damage and the longer your cat is likely to live.
Kidney disease is much more common in older cats. Have your cat checked by your vet regularly especially once they are in their senior years (8+).
You know your cat best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.

Feline leukaemia virus (FeLV)

FeLV is a fatal disease. It is passed between cats through infected saliva by sharing water bowls, mating or fighting. Early symptoms include respiratory infections that keep coming back and tummy problems.
FeLV can be prevented in cats by getting them vaccinated and keeping infected cats away from other cats.

Feline parvovirus/feline infectious enteritis (FIE)

The feline parvovirus can cause serious illness in cats, particularly kittens, and is sadly often fatal. Signs include vomiting, being hungry and thirsty but not able to eat or drink, and watery diarrhoea. If you think your cat has feline parvovirus it’s important to get treatment from your vet urgently.
You can prevent your cat from getting this disease by making sure they are vaccinated.

Chlamydia felis

Chlamydia felis infection is fairly common in cats and causes conjunctivitis and a thick yellow discharge from their eyes. Vets can usually treat the illness with eye drops, or antibiotics if the infection has spread.
If your cat has chlamydia it’s important that you wash your hands after touching them. They can also be vaccinated to reduce the effects of recurring infections.

How can I stop my cat from getting ill?

Sometimes we can’t do anything to stop our cats from getting poorly, but the good news is there are a lot of illnesses we can prevent.

A lot of cat diseases can easily be prevented by vaccinating your cat and getting regular booster jabs. Cat flu, feline parvovirus and FeLV can all be kept at bay through regular vaccinations.
Keeping your cat healthy and feeding them the right diet can go a long way to ward off certain illnesses. Diseases like diabetes and arthritis are more likely if your cat is overweight, so keeping them slim and active can help to prevent these from developing.

Getting regular flea and worming treatments from your vet will help fend off unwanted parasites. It’s important to get good treatment. Those you can get ‘off the shelf’ are often not very effective and it’s important to be aware that some treatments meant for dogs can be harmful to cats. It’s best to get a treatment from your vet as these will be the most effective product for your individual circumstances.