Month: August 2018

Acromegaly in cats

Acromegaly is a relatively rare condition, caused by excessive hormone production in the brain or in mammary gland (breast) tissue. It is more common in cats than dogs. Affected cats can develop gradual changes in their appearance but because the disease develops over a long period of time owners may not notice any problems. Some cats become extremely hungry or start drinking and needing to use the litter tray more frequently. Often it is the vet who notices the change in a cat’s appearance, when cats are presented because of the changes in appetite or increased drinking and may recommend further investigation. It is important to get a diagnosis as early as possible if treatment is to be effective.

Acromegaly is caused by the production of too much ‘growth hormone’, which, as its name suggests, stimulates body tissues to grow. If too much growth hormone is produced it causes many tissues in the body to grow bigger, causing problems for the cat. Growth hormone also interferes with the way insulin works and so cats with acromegaly often have diabetes that may be very difficult to control and they may need a higher dose of insulin than expected in ‘normal’ diabetic cats.

Growth hormone is made in a specialised part of the brain (the pituitary gland). The amount of growth hormone in the body is normally carefully controlled. When there is enough growth hormone, signals are released that tell the pituitary gland to stop producing any more. Acromegaly is usually caused by a small cancer in the pituitary gland that continues to produce growth hormone despite the signals telling it to stop.

Acromegaly usually affects middle-aged or older cats (8-14 years) and males more often than females. The physical signs of acromegaly can be difficult to see and the changes come on very slowly, so an owner, seeing their cat every day, may not notice alterations in its appearance. Sometimes you can only see how much your cat has changed by looking back at photos of your cat taken some years ago. Acromegaly often causes widening of the face – which is sometimes easiest to appreciate by looking at the teeth (which move apart as the bone grows, widening the space in between the teeth).

In many cases owners first notice there is something wrong with their cat when it develops the signs of diabetes (excessive drinking and urination and increased appetite). Your vet may first diagnose your cat as having simple diabetes and prescribe insulin injections. If, after a period of time, your cat does not seem to be responding as expected to the injections your vet will want to do further tests. If it is discovered that your cat is resistant to the effects of insulin then a diagnosis of acromegaly may be suspected.

Your own vet may make the diagnosis of acromegaly or they might refer your cat to see a specialist for investigation of one of the problems caused by acromegaly.

Your cat’s appearance may make a vet suspicious of acromegaly. It is likely that your cat may already have been diagnosed as having diabetes, but if not blood tests may show abnormally high levels of sugar (glucose) in the blood and sugar in the urine. Serial blood tests may also show that your cat is not responding to insulin injections as well as expected.

X-rays and ultrasound may show that your cat has an enlarged heart (or, if changes have been present for a long time, even heart failure), or changes to the kidneys bones and joints. Blood tests can measure the levels of hormones in the blood but these often have to be sent to specialist laboratories and it can take some time to get a result back.

A scan of the brain (CAT scan or MRI) can be used to try to visualise the growth in the pituitary gland, and this scan will be necessary if you are considering having treatment for your cat.

Removal of the cancer in the brain is difficult – it would be unusual in the UK for surgery to be performed. Some centres can use radiotherapy to direct a beam of radiation into the cancerous growth in the brain. In cats, so far, no obvious side effects have been noted and the treatment seems to be tolerated extremely well.

Radiotherapy can only be performed at specialist centres and requires a general anaesthetic. If you decide to have this treatment you would have to take your cat along to the centre for a number of treatments over several weeks (or your cat may be able to board in the hospital for the duration of treatment).

Drugs that inhibit growth hormone production can be given as tablets – unfortunately these are not usually very effective.

If the cancer can be destroyed then the high level of hormones will drop and the signs of acromegaly hopefully resolve slowly. However some organs may have already been too damaged at the time of diagnosis to recover fully, and some changes may persist even after treatment. Often insulin requirements will go down a lot in diabetic cats, but your cat may still require insulin injections daily. In a significant number of cats the diabetes resolves completely or the signs relating to the growth in the brain improve due to the shrinkage of the growth.

If the disease is not treated more serious problems like kidney disease, high blood pressure, permanent diabetes, joint problems, seizures and heart problems can develop. On average cats with acromegaly live around 18 months from diagnosis if they receive no treatment. They will almost certainly suffer from diabetes and this may be very difficult to control with insulin injections. However it is important to persevere with insulin treatment as without this the signs of diabetes would be even more severe. Most cats eventually die as a result of other complications of the disease such as heart or kidney failure.

Cardiomyopathy

Cardiomyopathy is a disease affecting the heart muscle. There are two main forms of the disease – hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). HCM commonly affects middle-aged cats and is more common in male cats than females. Cardiomyopathy is commonly associated with signs of heart failure and abnormal heart rhythms.

The cat’s heart, like that of humans, is a muscular pump with four separate chambers. The right side of the heart sends blood to the lungs where it picks up oxygen. The left side receives blood from the lungs and pumps it around the rest of the body.

Cardiomyopathy literally means disease of the heart muscle (cardio = heart and myopathy = muscle disease). There are 2 basic forms of the disease (although lots of variations of these are also recognised).

The most common form of cardiomyopathy is HCM, in which the heart muscle becomes abnormally thick which prevents the heart from working properly and reduces the amount of blood flowing through it.

Another form of cardiomyopathy is DCM that is caused by stretching of the heart muscle. This is often seen in cats whose diet contains insufficient amounts of a chemical called taurine. However, DCM is much less common now because pet food manufacturers add extra taurine to their cat foods.

When any muscle has to work harder it becomes bigger (why else do we work out at the gym?) and the heart muscle is no exception. This expansion is called hypertrophy.

Some relatively common diseases of cats force the heart muscle to work harder. Older cats with diseases of the thyroid gland or kidneys may develop HCM because of high blood pressure. The disease is much more common in some breeds, e.g. Persians, which suggests that it may be inherited in some cases. It is inherited in Maine Coons, and American shorthair cats.

If there is an underlying cause the condition is called secondary HCM. However, HCM can also occur in otherwise healthy cats and where there is no apparent cause and this is termed idiopathic or primary HCM.

As the heart muscle becomes thicker the chambers within the heart get smaller and so can hold a smaller volume of blood. Although the heart contracts quite strongly it can only pump a small volume of blood into the circulation. The thickened heart muscle cannot relax properly and so between contractions the chambers do not expand and fill with blood.

HCM usually affects the whole heart, but in some cases one part of the wall is affected more severely than the rest. The thickened heart muscle requires a lot of energy and oxygen but often its blood supply is poor. If the heart muscle is starved of oxygen some of the cells may die and form a small scarred area. This scar may cause irritation and the development of abnormal heartbeats.

In this disease the heart muscle becomes stretched causing the heart to swell (like a balloon filled with water). The contractions of the heart muscle become very weak so blood is not pumped around the body effectively.

DCM was once more common in cats and research showed that many cases were due to a dietary deficiency of taurine. Taurine is an essential amino acid only found in meat protein. Since this discovery cat foods have been supplemented with taurine and the disease has virtually disappeared in cats.

The truth is – you may not know your cat has heart problems until it is too late! Cats are usually good at concealing ill health and there may be no evidence of any problems until the condition is very advanced.

There are lots of signs that can be associated with heart disease. If the heart starts to fail fluid may build up in the lungs or in the chest making it difficult for your cat to breathe. Collapse and reluctance to exercise (poor blood supply to the brain and muscles) can be caused by the heart not working properly or fluid build up in the chest.

Often the first signs noticed by an owner do not appear to be related to heart disease, e.g. blindness or problems with the back legs.

Because of the abnormal blood flow within the heart the blood may start to clot within the heart chambers. Pieces of these clots may break off at any time and pass out into the circulation (emboli). These emboli are carried in the blood until they reach the smaller blood vessels where they become lodged, causing an obstruction – often in the blood vessels supplying the back legs (causing paralysis); or in the brain (causing neurological signs).

Heart disease can be associated with increased blood pressure (hypertension) that may cause blood vessels to burst. If the blood vessels in the eye are affected your cat may go blind.

A thorough examination of your cat will often be enough to tell your vet that it has heart disease. When listening with a stethoscope your vet might hear changes in the heart sounds (a ‘heart murmur’) or an abnormal heart rhythm. Your vet may be able to see other changes in your cat’s appearance that suggest that heart disease is present.

X-rays will usually be needed to see if the heart is enlarged or abnormally shaped. However, since most of the enlargement of the muscle walls occurs inside the heart in HCM, the external appearance of the heart shadow may not change much. Secondary changes associated with heart failure may also be present, e.g. fluid in the chest or belly.

The best way to diagnose cardiomyopathy is with ultrasound. Ultrasound scans allow your vet to measure the heart muscle to see if it is too thick or has become stretched. An electrocardiogram (ECG) records the electrical activity when the heart beats, and in cardiomyopathy the heart may have an abnormal or irregular beat which can be seen on the ECG.

Diagnosis of cardiomyopathy should be followed by investigation to search for underlying causes. If your cat has HCM its blood pressure should be measured (to detect hypertension) and routine screening tests performed. Thyroid hormone assays are essential to screen for an overactive thyroid gland.

If your vet is able to identify an underlying cause of the problem and this can be treated then your cat may make a full recovery.

Cats with an overactive thyroid often have HCM but this will resolve if the thyroid problem is treated. If your cat had DCM caused by taurine deficiency then taurine supplements will allow the heart muscle to recover. In these cases your cat will need to be treated for heart disease initially but can eventually come off medication as the heart recovers.

Sadly, in most cases, no underlying disease is discovered (or if it is, there is no treatment). If the heart disease is recognised early enough long-term medication and other measures can slow the disease down but they will not stop it completely. It may help to change your cat’s lifestyle to eliminate stress (although most cats lead pretty stress-free lives already). Long-term treatment for heart failure includes controlling exercise and administering oral diuretics and ACE inhibitors to reduce fluid build up in the lungs.

In HCM the heart rate is usually very fast and slowing the heart rate allows the heart muscle more time to relax and fill with blood (and reduces oxygen requirement). The drugs most often used to slow the heart are beta-blockers (propanolol or atenolol). Calcium channel blockers (diltiazem) are also sometimes used although the extent of their benefits has been questioned.

In DCM the main problem is that the heart muscle is not contracting properly so drugs can be given to increase the strength of contractions. If abnormal heart rhythms are present drugs can be given to correct these.

There is much debate on the best way of preventing blood clots and emboli in cats with cardiomyopathy. Most vets treat all animals with cardiomyopathy with a low daily dose of aspirin. Aspirin reduces the risk of blood clots forming but if the clot is already present aspirin treatment will not do much to dissolve it. Cats do not tolerate human medications very well and often need much lower doses than your would expect. Never give medication to your cat unless specifically instructed to do so by your vet.

Kidney function, and other blood tests should be performed regularly in patients receiving treatment.

It is difficult to predict how long your cat will live if it has heart disease or how good its quality of life will be. A lot depends on how far the disease has progressed. On average it is likely that your cat will survive for about six months after diagnosis but the time may vary between a few weeks and several years. Some animals with HCM die suddenly (probably as a result of developing severe cardiac rhythm disturbances or significant emboli).

Prognosis in cats with DCM is also poor and most only survive for a few months.

Constipation in your cat

Cats are often secretive about their bowel habits and it can be difficult for owners to notice problems. However, if you suspect that your cat is having difficulty toileting or shows a reluctance to go to the litter tray you should make an appointment with your veterinary surgeon. Simple constipation can sometimes be easily treated but it is common for constipated cats to be distressed, significantly ill and permanent damage to the bowel occurs easily. Constipation should always be taken seriously. Also, very similar signs can be seen in cats suffering from lower urinary tract disease which itself is distressing and potentially very dangerous.

To understand constipation it is important to understand how the large intestine normally works. Food passes through the small intestine where it is digested and nutrients are absorbed. The remaining undigested material plus bacteria and some tissue from the gut lining forms the stool.

The stool enters the large intestine where water is removed and it is stored for a few hours before contractions of the intestine push the stool through the pelvic canal and out of the anus.

Constipation occurs if the stool spends too long in the large intestine, too much water is removed, and the stool becomes dry and hard. These hard pellets can be difficult for the gut to move and can soon build up to a concreted mass too large to pass through the pelvis.

There are many causes of constipation, examples are:

  • Management issues: the cat is inhibited from passing faeces because it is being boarded in a cattery, is in pain from arthritis or after a surgery or is being bullied by another cat at home. Some cats will refuse to use a dirty tray.
  • Dehydration: many cats that eat dry food do not take in enough water. Kidney failure is another important cause of dehydration in older cats.
  • Obstruction to passage of stools: especially damage to the pelvis after a road accident or the presence of a growth in, or near, the colon or rectum.
  • Poor function of the colon: due to nerve or muscle damage.
  • Some medical conditions and hormonal conditions.
  • Foreign material in the stool: hair from the cat, especially long-haired cats and cats that are overgrooming because of stress or skin disease; hair, feathers and bone from prey.
  • Obesity and inactivity make constipation more likely.
  • Idiopathic megacolon: this is when the colon becomes weak and ineffective for a reason that is poorly understood. This is common.

Unfortunately there is a cycle of deterioration. When defaecation is painful the cat becomes less inclined to defaecate and can also stop eating and become dehydrated. The stools become harder and drier and more unpleasant to pass and the problem escalates.

When faeces build up in the colon the intestinal walls can become stretched, damaged and eventually are unable to contract at all which will mean that the affected cat will never pass faeces normally again. This is called “megacolon.”

The most common sign associated with constipation is straining to pass a motion. If your cat has a litter tray in the house then you may notice her straining or crying in the tray but only passing small hard faeces. Sometimes a small amount of liquid faeces may be squeezed past the obstruction and it may look like the cat has diarrhoea.

Cats may go to the litter tray frequently or refuse to go at all. They may lick around their bottom more than usual. If the constipation is more severe she may become unwell and be unwilling to eat. Vomiting may occur. Cats with diarrhoea or urinary tract problems will show similar signs.

Your vet may suspect that your cat has constipation from the history you describe. They will want to examine your cat and may be able to feel the hard lumps of faeces inside the colon. However, constipation is just a sign of disease and so your vet will need to do other tests to try to find out what is causing the problem.

X-rays will show any abnormal pelvis. In rescued cats owners may not know about an accident that occurred when they were young. Masses or strictures narrowing the colon or rectum can be detected by digital rectal examination (under anaesthetic), endoscopy or barium-contrast x-rays.

Blood and urine tests will be needed to rule out underlying problems like renal failure, low potassium and high calcium levels. Your vet will want to ensure that your cat is not suffering from urinary tract disease (FLUTD) before treatment for constipation is started.

Your vet may prescribe some laxatives or an enema to soften the stool and make it easier to pass. If your cat is dehydrated your vet may give subcutaneous or intravenous fluids to rehydrate her and soften the faeces.

Often it may be necessary for your vet to take your cat into hospital to remove the blockage. This may be done with the use of enemas and digital manipulation under anaeasthetic. In some cases surgery may be required to remove faeces and in these cats part of the colon is often removed (colonectomy) when it has become stretched and non-functional.

It is important that cats pass a regular motion to keep the bowel healthy and functioning normally. Cats that have had constipation are prone to a recurrence and they are often required to have long-term treatment to attempt prevention and to avoid a major surgery.

Ensure that they have access to a clean litter tray or the outside. In multi-cat households cats may be deterred from using the litter tray if there is competition for it so ensure that there are more litter trays than cats in the household.

Long haired cats should be brushed regularly. Encouraging your cat to exercise – regular play time with an indoor cat can help to keep them fit and active and will ward off many potential health problems.

Since dehydration is a common cause of constipation it is important to encourage your cat to drink as much as possible. Many cats will drink more from a water fountain. Dietary issues can also have an influence on stool quality but there is a lot of variation between individual cats. Adding certain fibre to the food can help in cats that are well hydrated and with mild problems – take your vet’s advice about this. Other cats are usually better on low fibre, low residue diets. Cats are likely to be better hydrated if they avoid dry foods.

Drugs may help cats that are prone to constipation. Laxatives can be given in the long term. Some will stimulate the colon to secrete fluid, others lubricate the stool directly. Cats will often take these in their food. There are also drugs that stimulate contractions in the large bowel but these are tablets that require long-term pill giving.

Blindness in cats

Just like people, cats normally use their vision for getting around, as well as hunting and interaction with other cats. However, a cat with poor vision or even total blindness can lead a comfortable and fulfilled life.

If a cat loses its sight slowly, behaviour changes are harder to detect because the cat is able to adapt to the disability, learning where furniture and other obstacles in the home are. Sudden blindness is much easier to spot. If your cat is bumping into objects it is obvious that they cannot see normally, but actually this may only happen when furniture is moved, or when doors which are normally opened are closed. This is because cats are able to remember the normal layout of their familiar environment, only getting caught out when it is changed.

If your cat is losing its sight you may notice that it is more hesitant and that is reluctant to jump down from a height. Your cat may even climb down by gingerly reaching the feet down first. Most cats are usually happier climbing up onto objects. Cats with reduced sight may walk in a crouched position with their body closer to the ground and stretch their necks out further, using their long whiskers to feel their way. In some cats with vision problems, you may notice a change in the appearance of their eyes, which are discussed in the section below.

You may notice changes to your cat’s eyes with or without apparent changes in their vision. A milky or cloudy appearance to the eyes can be caused by cataracts, (which is when the lens in the eye becomes white instead of clear). Cloudy eyes can also caused by glaucoma, a raised pressure inside the eye, or uveitis which is the medical name for inflammation inside the eye.

Eyes may be red due to high blood pressure causing bleeding inside the eye, or due to glaucoma, uveitis or a growth in the eye.

Some conditions affect the retina at the back of the eye – if this is damaged the glow from the back of the eye appears more intense. Retinal detachment may be caused by high blood pressure.

In a blind cat the pupils are usually very large and do not contract down to the normal slits in bright light.

If you have noticed a recent colour change in one or both of your cat’s eyes, you should take your cat to your vet to have an eye examination. In many cases, your vet will be able to tell you what is wrong and can therefore advise on the best treatment.

In some circumstances, your vet may recommend that you are referred to a specialist veterinary ophthalmologist. The ophthalmologist is better equipped to be able to diagnose certain conditions, and will be able to offer treatment advice and specialised procedures. Some conditions will be managed with eye drops or oral medications, and all conditions are more successfully treated when diagnosed early on in the course of the disease.

As your cat won’t cooperate with reading a chart, testing vision in cats can be tricky, even for your vet! There are several tests which a vet will perform, some of which you can try at home.

  1. Gently wave a hand towards the eye – this would cause a normal cat to blink. It is important not to create an air current when waving a hand, as even a blind cat will sense this and blink their eye as a reflex.
  2. Shine a bright focused light suddenly into the eye. A normal cat will be dazzled and blink, squint or turn their head away. A blind cat usually continues to stare ahead.
  3. Shine a laser light rapidly over the floor or wall in front of your cat, or drop cotton wool balls from a height beside the cat. A normal cat can’t resist watching the movement.
  4. Closely observe your cat’s behaviour, as mentioned earlier.

Cats with visual impairment function very well in familiar surroundings, and it is important to keep the lay-out of the home consistent. With sudden blindness, it is best to initially confine your cat to one room with food, water and a litter tray available (but all separated from each other). As your cat adapts to one room it can gradually be allowed to explore more and more of the house. Keep the litter tray, food, water and bed in the same place, and if your cat gets disorientated, place the cat in a familiar place such as in their bed so that they can realise where they are and start again.

A clean litter box should always be provided, even if you allow your cat outside. This provides them an opportunity to relieve themselves inside in a safe place should they feel anxious about venturing outside. It also is a useful point of reference as they will be able to smell it from quite a distance away. The garden can be enclosed to make your cat safe.

Safety within the home can be improved by blocking potential hazards such as fireplaces, window ledges and balconies. Ensure that doors to the outside are kept shut. Check that windows are secure as some blind cats can be very adventurous. It may be best to leave toilet seats down.

Some blind cats no longer feel secure jumping up onto things. If your cat has a favourite place such as on a tall sofa or bed, you might consider providing a ramp or a low stool or chair to make the climb easier. Cats do love high resting places. Consider providing a stool or shelf where your cat can feel elevated, although they may still help themselves to the couch or your comfy bed!

Some blind cats will still use scratching posts, and one or more should be provided. Cat gyms can be helpful as these provide a scratching post, a place of elevation, a place to play and a place to rest.

It is important to spend time interacting with your cat, through stroking or playing. Toys with bells or rattles are useful as the cat can follow them, and some cats also like cat-nip impregnated mice, or squeaking mice on elastic.

Blind cats can have a very happy and fulfilled life, with a little help from their owners. Your vet will provide the best advice about health matters and nutrition. Other advice and support is available – often from owners of other blind cats. The main cat rescue organisation is Blind Cat Rescue – www.blindcatrescue.com

  • Natasha Mitchell (2008) Caring for a blind cat. Cat Professional Ltd (ISBN 0955691311).
  • There are also many blogs and websites which give advice about caring for a blind cat.