Month: August 2018

Diabetes mellitus

Diabetes is a relatively common disease in older people and is being recognised more frequently in older pets. If untreated the disease has serious effects and will ultimately result in the death of your pet. The good news is that the majority of diabetic animals can now be treated and may live normal, happy lives if you are prepared to invest time and money in their care.

Diabetes is a disease caused when there is not enough insulin in the body. Insulin is a hormone which keeps blood sugar (glucose) at an optimum level. When there is a lack of insulin, sugar from food builds up in the blood and eventually starts to appear in the urine.

Animals with diabetes have high blood sugar levels and lose sugar in their urine. They are more thirsty than normal and often lose weight despite having a good appetite. If the condition is untreated, liver disease, problems walking or other illness may develop. If the early signs of diabetes are missed, more serious signs such as vomiting and depression may develop. If diabetes is left untreated for weeks or months your cat could go into a coma and die.

If your cat has been diagnosed as a diabetic you may be wondering if you have done something wrong. Unfortunately some cats are just more likely to develop the disease than others. Male cats are most likely to get diabetes but any cat can be affected. Obese cats are slightly more likely to develop the disease, but there are many obese cats who do not develop diabetes.

Some other diseases can cause diabetes to develop and your vet will check to make sure your cat is not suffering from anything else. In a few cases treating the other disease will make the diabetes go away for a while, but it is quite likely to come back again later.

Most diabetic cats require regular insulin injections to control their blood sugar levels. Diabetes rarely goes away completely and so these injections must be given on a regular basis (usually once or twice a day), for the rest of your cat’s life. Your vet may need to help you work out a new diet and management plan for your cat. Injections should be given at set times each day but this can be arranged so that it fits into your usual schedule. Once the whole treatment schedule has been set you will have to stick to it in the future.

Most diabetic cats will need insulin injections to treat their diabetes at some stage. In some obese cats weight loss may control their diabetes for a while. A few other cats can be managed by careful weight control and by giving tablets which lower blood sugar (hypoglycaemic drugs). Although you may be worried about having to give your cat injections – most owners find that, with practice, it is easier to give their cat an injection than a tablet.

Insulin is a protein and (as with any other protein), can be digested. If insulin were given as a tablet, the tablets would be digested by the acid in the stomach and the insulin would have no effect. Insulin injections are given under the skin and do not hurt. VetPens, similar to the epipens used in human diabetes, are now available for cats. Along with insulin cartridges, they allow pet owners to give insulin with minimum preparation time.

Most people are naturally concerned that they will be unable to give injections to their pet. Your vet will teach you how to do this and within a few weeks most owners of diabetic pets are happy to give the injections at home. Until you are confident your vet will probably see you every day at the veterinary surgery and help you give the injections.

Your cat should be regularly monitored to make sure it doesn’t gain or lose weight. Your vet needs to examine your pet regularly and review their notes to see how your pet is progressing. Your vet will probably ask you to monitor how much your cat drinks to help monitor progress. At other intervals your vet may want to take blood samples from your cat – and may need to keep your pet in hospital for a day to do this. If you have any concerns about any aspect of your pet’s treatment discuss them with your vet.

There are two important complications which you must be aware of:

  • Low blood sugar (hypoglycaemia): If this is untreated it may result in permanent brain damage. Symptoms develop rapidly with restlessness, confusion, tremors, twitches, convulsions or coma being the main signs. Sugar should be given by mouth, dissolved in water or as lumps. If your pet is still awake it may be offered food and should eat voluntarily. Contact your vet immediately if these signs develop.
  • High blood sugar (hyperglycaemia): This usually develops more gradually and your pet may become unwell over a number of days. As the disease progresses your pet may go into a coma, although will not respond to sugar solutions. Contact your vet immediately if your pet is unwell and they will probably want to admit him.

Cushing’s disease (hyperadrenocorticism)

Cushing’s disease (also called ‘hyperadrenocorticism’ by vets) is rare in cats. Although it is a severe disease it causes subtle changes in the early stages. Many owners do not recognise the signs of Cushing’s disease in their pet, instead confusing the changes caused by the disease with ageing.

Cushing’s disease is caused by prolonged exposure of the body’s tissues to high levels of the hormone cortisol. It is called Cushing’s disease because it was named after a famous neurosurgeon, Harvey Cushing, who first recognised it. It is also sometimes called“hyperadrenocorticism” or “hypercortisolemia”.

Cushing’s disease is caused by an excess of the steroid hormone, cortisol. In the normal cat cortisol is produced by the adrenal glands, (which are located just in front of the kidneys). Scientists think that cortisol has hundreds of possible effects in the body. Among its other vital tasks, cortisol helps to:

  • maintain blood pressure
  • slow the immune system’s inflammatory response
  • balance the effects of insulin in breaking down sugar for energy
  • regulate the use of proteins, carbohydrates and fats in the body

Because cortisol is so vital to health, the amount of cortisol produced by the adrenal glands is precisely balanced. Cortisol production is regulated by hormones produced in the brain (from the pituitary gland). The hormones produced by this gland stimulate the adrenal glands. When the adrenal glands receive the signal from the pituitary they respond by producing cortisol. In the normal animal cortisol is produced mainly at times of stress – in Cushing’s disease the levels of cortisol in the blood are always too high.

Cushing’s disease can occur following long-term treatment with corticosteroid drugs (so called ‘iatrogenic cushing’s’) or as a naturally occurring disease. The majority (approximately 85%) of naturally occurring cases of Cushing’s disease are caused by a tumour in the pituitary gland. Although this is, strictly speaking, a brain tumour the tumour is usually tiny and benign and causes no effects related to pressure in the brain. A smaller proportion (approximately 15%) of naturally occurring Cushing’s disease cases are caused by a tumour in the adrenal gland.

The two forms of natural Cushing’s disease are:

Pituitary-dependent Cushing’s disease

A tumour in the pituitary causes excess production of the hormone, adrenocorticotropic hormone (ACTH) resulting in enlargement of both adrenal glands.

Adrenal-dependent Cushing’s disease

A tumour of the adrenal gland makes one gland grow bigger and it is therefore able to produce more cortisol.

The signs of Cushing’s disease are extremely variable and can be subtle in the early stages. Cushing’s disease usually affects older pets (average age is 10 years but cats as young as 4 have been diagnosed with this condition).

Because the changes come on slowly it is sometimes easier to spot them if you do not see an animal every day. Often it will be your vet who examines your pet during its annual or bi-annual examination and points out that changes have occurred since your last visit. Many owners do not recognise the signs of Cushing’s disease in their pet, instead confusing the changes caused by the disease with signs of ageing.

The steroid hormones affect almost every tissue in the body and the signs of Cushing’s disease can be diverse. One of the most common problems associated with Cushing’s disease in the cat is diabetes mellitus. In fact most cases of Cushing’s in the cat are recognised because they are being treated for diabetes. The most obvious signs of diabetes are increased thirst and weight loss despite a good (or even increased) appetite. If your cat is drinking more or losing weight you should always take them to the vet for a check-up.

Typically, the diabetes seen in cats with Cushing’s is very resistant to insulin so high doses are needed to control the disease. Affected cats are also often reported to be lethargic and lacking energy. A small proportion of cats with Cushing’s are not diabetic although they may still show signs of increased thirst and increased urination.

Enlargement of the abdomen (a pot bellied appearance) is common and Cushing’s disease can cause changes to the skin and haircoat. The skin may become fragile and thin, lose hair, bruise easily and heal poorly. Minor trauma (grooming or handling) may result in skin tearing and wounds. Often affected cats have a poor haircoat. The tips of the ears may start to curl over.

High levels of steroid hormone in the blood suppress the immune system and healing process; so animals with Cushing’s disease may have repeated infections or wounds that do not heal as quickly as expected.

Iatrogenic Cushing’s is usually straightforward to diagnose as there is usually a history of long-term corticosteroid administration. However, cases of naturally occurring Cushing’s disease can be very difficult to confirm. Your vet may suspect the disease based on simple blood tests but specific blood tests are needed to confirm the diagnosis. These special tests measure the level of cortisol in the blood. However, because the levels of this hormone vary from hour to hour in a normal animal, the disease cannot be diagnosed on the basis of one blood test.

Your vet will need to take a number of blood samples before and after injection of hormones that affect the amount of cortisol produced by your cat. Some of these blood samples have to be handled very carefully and will need to be sent away to veterinary laboratories for analysis.

Ultrasound examination of the abdomen allows your vet to measure the size of each adrenal gland. If a tumour is present in the adrenal gland this should be visible on the ultrasound (and one adrenal gland will appear larger than the other). If the disease is caused by a tumour in the brain then both adrenal glands will be larger than normal.

X-rays may also be needed to show other potential problems caused by the disease.

Examination of a urine sample can be useful in a cat with Cushing’s disease – high levels of cortisol in the blood can cause diabetes mellitus and your vet will want to check for sugar in the urine to rule this out.

Treatment of iatrogenic Cushing’s is relatively straightforward with gradual reduction in corticosteroid administration required. Corticosteroids are potent drugs and it is essential that they are not stopped suddenly. In some cases, successful treatment of iatrogenic Cushing’s can take several months.

Treatment of naturally occurring Cushings disease in the cat is difficult and not without risk. Surgical removal of the abnormal adrenal gland (adrenalectomy) is the treatment of choice for adrenal Cushing’s disease. This is high risk surgery as affected cats are prone to infections and poor wound healing; there are high risks of bleeding at surgery as the adrenals are close to major blood vessels and cats with Cushing’s are more vulnerable to forming blood clots (thrombi) which can have serious consequences.

Pituitary cases are even harder to treat as there is no single perfect treatment. Medical treatment can be problematic in these cats – most of the treatments that have been tried have had poor success, side-effects can be seen and the drugs used are often not licensed veterinary treatments. Radiation therapy has been tried by some clinicians but is not widely available. Surgical removal of the pituitary, the treatment of choice in people with pituitary tumours, is a very high risk surgery that is not often performed in cats.

For these reasons, surgical removal of both of the adrenal glands may be recommended to prevent further cortisol production. This surgery is difficult and should be performed by a specialist in veterinary surgery, but in some cases medical treatment is given before surgery to stabilise the cat. In addition to the risks of surgery itself, it is very important that animals are closely monitored immediately after surgery and they may need to spend time in an intensive care facility.

Most animals with Cushing’s disease are middle-aged or elderly and owners sometimes ask if it is worth treating them. The outcome for cats with Cushing’s disease with treatment is not good. Even with successful treatment fewer than half of all cats will live for more than a year after diagnosis. Unfortunately if a cat had diabetes before treatment for Cushing’s disease there is only a 50% chance that the diabetes will resolve with treatment of the Cushings. Some cats will need to be given insulin to control the diabetes for the rest of their lives. Without treatment the complications can be significant and will seriously affect the quality of your pet’s life.

Ventricular septal defect (VSD)

Ventricular septal defect (VSD) is one of the more common congenital heart defects in cats. It is sometimes referred to as a ‘hole in the heart’. The condition is often discovered in apparently healthy cats by a vet during a routine examination (such as before vaccination).

Ventricular septal defect (VSD) is a congenital heart defect, i.e. it is caused by abnormal development of the kitten before birth. 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 of the heart pumps the blood around the body. The heart is divided into left and right halves by a muscular wall (the septum). The ventricular septum separates the right and left ventricle.

In a VSD the septum doesn’t develop properly resulting in a small ‘hole’ in the septum allowing some blood to divert from the left side of the heart to the right side. The effects of this on the cat depend on the size and location of the defect. Most cats have small defects that are well tolerated. In some cases, very small VSD holes may close spontaneously. Larger defects can lead to congestive heart failure.

Although the condition is present from birth, signs of a ventricular septal defect (VSD) are usually not noticed until later in life. Many cats with VSD have no outward signs of illness. The murmur caused by a VSD is often detected by a vet (often during a routine health check). When you bring home a new kitten it is always advisable to ask your vet to check for any heart murmurs.

If the defect is large, clinical signs may be seen when the cat is less than two years of age. Severely affected animals may have stunted growth, although this can be difficult to recognise without direct comparison to their littermates. If the condition goes unrecognised and heart failure develops the affected animal may be reluctant to exercise, cough, or have difficulty breathing.

If your vet hears a murmur when listening to your cat’s heart they will want to do some other tests. Heart murmurs are caused by the sound of abnormal and high-speed blood flow and are very common findings in cats with VSD. Very quiet heart murmurs can be present in an otherwise healthy pet so a diagnosis of VSD or other congenital heart disease is not necessarily inevitable.

Ultrasound is the method of choice for finding the cause of a heart murmur. If a heart murmur is heard, an ultrasound examination is recommended. Ultrasound examination of the heart requires considerable knowledge and experience and should be performed by someone with experience in examining young cats.

X-rays are important in the diagnosis and monitoring of heart disease. In cats with severe VSD, evidence of heart enlargement on the left side is often evident. X-rays are also used to see if signs of heart failure are present, if there any signs of further heart failure treatment is usually started immediately.

If the VSD is very small, then your cat may lead a normal life with no treatment being necessary. However, if the defect is large, the outlook is worse and your cat may have a significantly reduced life expectancy. Your vet will discuss the outlook and long term management of your cat with you.

If the ventricular septal defect is small, then no treatment is needed and the hole may spontaneously close. Large VSDs may need medical management to treat heart failure if it develops. Some surgical options are available to help reduce the flow of blood across the hole but definitive repair to actually close the hole is typically not possible

Many animals with ventricular septal defect live a normal life with no signs of heart disease but this depends on the size and location of the defect. Affected cats and their parents (who could be genetic carriers of the condition) should be not be allowed to have kittens.

Cats with more severe defects are likely to develop heart failure at a relatively early age and the long term outlook is poor. Life-expectancy may be reduced and long term medication will be required.

Investigating heart disease

It is important that your vet can recognise the early stages of heart failure (and therefore when to begin therapy, if necessary). Investigations of animals with heart disease are important to identify early signs of failure and to establish the appropriate timing and type of therapy. Heart disease and heart failure are not the same thing. In the early stages of heart disease most animals are able to cope although their heart is not working as well as normal. Animals can live with some forms of heart disease without showing any signs of illness at all. Heart failure occurs when the heart disease is more severe and signs of malfunction (usually coughing or breathlessness) develop. Investigations of animals with heart disease are important to identify early signs of failure and to establish the appropriate timing and type of therapy.

When heart function is compromised there are many mechanisms that come into play to reduce the impact on the animal. Since few pets are athletic, heart disease can be present in many without their owner noticing any ill effects. Many cases of heart disease are detected by the vet at routine examination, e.g. before vaccination. Abnormalities are often detected in the first 2 years of life, if congenital lesions are present; or in middle-aged to older pets when acquired degenerative changes develop. Owners generally notice signs once heart failure has developed or if their pet has problems during periods of stress or excitement.

Clinical signs of heart disease vary according to the area of the heart affected. They range from coughing and weight loss to abdominal distension (ascites) or collapse.

Clinical examination

A full clinical examination is essential in all patients with suspected heart disease. Abnormalities in the heart may cause changes to the pulse rate, rhythm or strength. The pulse should be assessed at the same time as listening to the heart to confirm that every heartbeat generates a strong pulse. Poor heart function may also result in congestion of the veins (fluid retention). By listening to your pet’s heart with a stethoscope your vet can determine the rate and rhythm of heartbeats and hear murmurs or other abnormal heart sounds. Ideally blood pressure should be measured in all patients with heart disease.

X-rays

X-rays are very important in the diagnosis and monitoring of heart disease. Assessment of the heart size and shape itself is important but the lungs and blood vessels visible on the radiograph are also examined. At least two pictures of the chest (one with the animal lying on its side and one lying on its belly) are needed for complete x-ray assessment of the heart. In almost all cases it is safer to administer a low dose of an appropriate sedative than to risk a patient struggling when x-rays are being taken.

Echocardiography

Ultrasound is the method of choice for determining the cause of structural heart disease. It allows the vet to see the heart structures, ie myocardial thickness, the relative sizes of the heart chambers, and the position of the valves and major blood vessels. Echocardiography also allows the vet to watch the heart beating. The motion of the valves, contraction of heart walls and abnormal patterns of blood flow can be seen. Echocardiography requires considerable knowledge and experience and should always be performed by experts.

Laboratory tests

Routine laboratory tests (particularly assessment of liver and kidney function) are important for monitoring of animals with heart disease. The dose of many drugs used in the treatment of heart disease may need to be altered in patients with reduced liver or kidney function. It is important to assess kidney function in all patients before they start on long-term therapy for heart failure.

Electrolyte abnormalities are common in patients with heart failure and some drugs can make these imbalances worse. Low potassium levels can develop as a result of inappetence and the use of some diuretics, e.g. furosemide.

There are now some laboratory tests which allow us to measure substances produced by damaged hearts and these tests are likely to become increasingly important in the diagnosis and management of heart disease in the future.

Electrocardiography

The electrocardiogram (ECG) measures the electrical activity in the heart. Although measurements made on ECG can provide an approximate guide to the size of specific heart chambers, x-ray or ultrasound are better for assessing heart size. The most important use of ECGs is in the monitoring of abnormal heart rhythms (arrhythmia).

High blood pressure (hypertension)

Hypertension (high blood pressure) has long been known to be a problem in people and is being increasingly recognised in pets. Hypertension is very common in older people and is often associated with smoking, or with stressful living. In animals, hypertension is almost always caused by an underlying disease.

When the heart contracts a pulse of blood is forced through the arteries. This pulse generates the systolic blood pressure. In between the heart contractions the pressure in the arteries falls – this is the diastolic blood pressure. In animals we mostly measure systolic blood pressure.

Systolic pressure does not stay the same at all times. Arteries are constantly being constricted (narrowed) or dilated (widened) so that blood can be diverted to whichever organs are most active at the time. A dilated artery has a larger diameter, making it easier for blood to flow through. Less pressure is needed to pump blood through the dilated artery and so blood pressure is lower if arteries are dilated.

Blood pressure also tends to increase a little with age. The arteries of older pets tend not to be as elastic as in younger animals. These arteries do not dilate easily so the overall resistance to blood flow is increased, resulting in higher 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.

In hypertension the increased pressure in the blood vessels damages the vessel walls, causing bleeding and blood clot formation. This causes particularly severe problems if blood vessels in the eye, kidney, heart or brain are affected. In addition when blood pressure is high the heart has to pump against a greater resistance and this places increased strain on the heart muscle.

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.

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.

Measurement of blood pressure is becoming more common in veterinary practice although it is not yet part of the routine examination in most cases.

The method used to measure blood pressure is very similar to that used routinely in people, but because of the small size of the arteries more specialised equipment is needed. An inflatable cuff is placed around one of the cat’s legs (or sometimes round its tail) and the vet uses a small receiver held against the arteries in the foot (or tail) to detect the pulse. The cuff is then inflated and deflated a number of times and the vet listens for changes in the sound of the pulse as the pressure in the cuff increases and decreases.

The process only takes a few minutes; does not hurt and most animals do not object at all. Blood pressure needs to be monitored regularly in animals that have been diagnosed with hypertension and most cats soon become used to the procedure.

Most healthy cats have a systolic blood pressure of between 120 and 180 mmHg. A cat with a blood pressure that is consistently over 180-190 mmHg is considered to be hypertensive, although older animals do tend to have slightly higher blood pressure than young cats.

If an underlying cause of hypertension can be identified this disease should be treated, and if the blood pressure is only slightly elevated then this may be sufficient to bring blood pressure down into the normal range. However in most cases it will be necessary to use additional treatments that are specifically aimed at lowering the blood pressure. In cats the calcium channel blocking drug amlodipine is usually most effective and can safely be used in cats with kidney failure. Other groups of drugs which may be effective include ACE inhibitors and beta-blockers.

Animals with hypertension have individual responses to treatment and it is important to monitor the blood pressure closely once treatment has been started, altering the dose of the drugs, or altering the medication as necessary. In patients with kidney failure, it is also important to monitor kidney function when using anti-hypertensive drugs.

Feeding a low salt diet may also be of value although it is unlikely to be sufficient as a sole treatment of hypertension. You should avoid feeding pet treats to cats with high blood pressure since most of these are quite high in salt. Most hypertensive cats can be fed a normal commercial cat food, although your vet may recommend the use of a prescription diet for management of underlying disease, e.g. chronic kidney failure.

If your cat has suffered sudden onset blindness emergency treatment to rapidly lower the blood pressure may be recommended. Blood pressure must be measured regularly whilst this emergency treatment is given to ensure blood pressure does not drop too low – so your cat may need to be admitted to hospital during the first stages of emergency treatment. If treatment can be started at an early stage of the disease then there is a chance that your cat may regain its sight.

If an underlying cause can be identified and treated then blood pressure may return to normal without the need for any specific medication. Unfortunately in most cases this is not possible and additional drugs are needed to reduce blood pressure. Fortunately in most cases treatment is effective, and blood pressure can be brought into the normal range within a few weeks of starting treatment. For the majority of cats treatment will then be required for the rest of the cat’s life and in all cases it remains important to continue to monitor blood pressure as accurately as possible in order to identify any recurrence of the problem.

In cats where blindness has already occurred treatment of hypertension is still beneficial as it will prevent continued damage to the brain, kidneys and heart. Affected cats often live for several years, with a good quality of life, once their blood pressure has been brought under control.

Heart rhythm disturbance (atrial fibrillation)

There are many different heart problems that can affect cats. Some of these affect the rhythm of the heart beat and one such condition is atrial fibrillation. This is most commonly seen in association with severe heart disease. Atrial fibrillation does not cause any specific signs so it is unlikely that you will identify this as a cause of illness in your pet. Signs of heart disease can also be hard to recognise in the cat but may include excessive lethargy, inappetence and rapid or laboured breathing. However, any heart disease should be taken very seriously and an early visit to your vet can help to achieve the best outcome.

Atrial fibrillation is one type of disturbance of the normal heart rhythm (dysrhythmia). To understand this condition we first need to know how the normal heart functions:

In the normal heart electrical activity is initiated from a natural pacemaker in the heart and follows a set path around the heart muscle. As the electrical activity moves through the muscle the muscle begins to contract. The electrical signals move in an ordered way like a wave over the heart surface, from the chambers at the top of the heart (atria) to the lower chambers (ventricles). As the electrical signals pass through the heart muscle contracts in a synchronised fashion, like squeezing a tube of toothpaste.

The heart is divided into a left and right side and there are 2 chambers on each side (one atrium and one ventricle, linked together through a valve). In the normal heart the upper chambers (the atria) contract first squeezing the blood out of the atria and into the main pumping chambers, the ventricles. When the ventricles are full they begin to contract to pump blood around the body (from the left side of the heart) or around the lungs (from the right side).

Atrial fibrillation normally occurs in enlarged hearts where the atrial muscle is already stretched. Damage to the muscle caused by the stretching can make it more likely that a spontaneous electrical pulse will be generated in an area outside the pacemaker.

In atrial fibrillation there is disruption of the normal electrical activity throughout the atria resulting in random and chaotic atrial muscle contractions and preventing normal atrial contraction. The electrical pathways in the ventricles are still intact, allowing the ventricular muscle to contract in an organised manner. But because the electrical signals that the ventricles receive from the atria are random and so much more frequent and chaotic than normal, the ventricles often do not have time to contract and relax before a new signal arrives telling them to contract again.

Hence the contractions are not regular and there is a variable time between each heart beat. When you listen to a heart in atrial fibrillation you hear an erratic jungle drum beat rather than the regular lup-dup sound. Some people say that atrial fibrillation sounds like shoes in a tumble dryer.

Atrial fibrillation is normally a rapid heart rhythm and because the ventricles are contracting so often they do not have time to fully fill with blood between each beat. The amount of blood leaving the heart is therefore reduced and this poor blood supply can result in signs of lethargy and exercise intolerance and even exacerbate heart failure.

Atrial fibrillation usually only occurs in cats with enlargement of the upper chambers of the heart (the atria). This enlargement can be caused by a variety of diseases. Occasionally it is caused by congenital heart disease (where the heart develops abnormally from birth). More commonly it is caused by heart muscle disease (cardiomyopathy) that develops after birth, normally during adult life.T here are several forms of cardiomyopathy, with hypertrophic cardiomyopathy (HCM) being the most common. Dilated cardiomyopathy (DCM) is now rare in cats.

A few drugs (most notably digoxin, which may be used in the treatment of some heart diseases) can also cause atrial fibrillation. If your cat is receiving any medication make sure you mention this to your vet even if you think they already know.

Your vet may suspect that your cat has atrial fibrillation when they listen to your cat’s heart. However, in order to confirm the diagnosis an ECG examination is essential. This is a simple test which records the electrical activity from your cat’s heart. If atrial fibrillation is detected then other tests are indicated to look for underlying heart disease. These tests will almost certainly include X-rays and ultrasound examination of the heart but sometimes blood tests are also required.

Even for a vet, it is very difficult to accurately assess heart rate in atrial fibrillation without an ECG. This is because some of the heart beats are so weak that they are very hard to hear with a stethoscope and do not result in a pulse that is strong enough to feel.

Although in people there are some treatments specifically aimed at converting the heart rhythm back to normal this is rarely undertaken in cats. Cats with atrial fibrillation usually have an underlying heart disease that requires management. Some drugs can be given to try to slow the heart rate and allow more time for the heart to fill properly between contractions. It is very difficult to effectively monitor your cat’s heart rate at home when they have atrial fibrillation, but your vet may well ask you to monitor breathing rate and other symptoms to ensure that the heart condition is adequately controlled.

It is unusual for cats with atrial fibrillation to ever go back to having a normal heart rhythm. Since cats with atrial fibrillation usually have a severe underlying heart disease the long term outcome is unfortunately not good in most cases.

If you have any concerns about your cat contact your own vet for further advice.

Heart disease in your cat

Heart disease is increasingly common in cats, probably because their average life expectancy has increased due to improved veterinary care. Some heart defects may be present from birth (congenital heart defects) but only show symptoms as the cat gets older. Other diseases develop later in life as a result of the effects of ageing or damage to the heart. The most common heart disease which develops later in life is hypertrophic cardiomyopathy.

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. The chambers are separated from one another by a series of valves that ensure that blood can only flow in the right direction around the heart.

Heart disease may affect any area of the heart:

Heart valves

The valves within the heart may fail to develop properly, e.g. mitral dysplasia, or may degenerate as a result of ageing (endocardiosis). Specific infections can affect the heart valves (endocarditis). Abnormal valves allow leakage of blood between heart chambers even when they are closed. When valves leak abnormal blood flow can be detected when listening to the heart (a murmur) and on ultrasound.

Heart muscle

In general terms the heart muscle may be either too thick or too thin. If the muscle is too thin the heart is unable to contract properly and if the muscle is thick the heart cannot relax and therefore does not fill with blood between contractions. In either case the heart is unable to pump sufficient blood out.

Electrical conduction

Abnormal electrical conduction affects the rate and rhythm of the heart. Electrical abnormalities can be caused by disease outside the heart. If the heart beats too quickly there is not enough time for it to fill properly between beats and so it pumps less blood with each beat. If the heart beats too slowly there are not enough pulses to supply enough blood to the body. Chaotic rhythms occur where contractions of different parts of the heart are not synchronised and so pulse volume is reduced.

Pericardium

The pericardium is a strong sac that surrounds and supports the heart. Changes to the pericardium usually result in constriction of the heart, preventing it from filling properly between contractions. The right side of the heart (because it has thinner walls) is usually more easily compressed than the left. Diseases of the pericardium are very rare in cats.

Kittens can be born with heart defects (congenital heart problems) because the heart does not develop normally. The most common problems are leaky valves and holes inside the heart that allow blood to flow in abnormal directions. Heart disease in older cats is usually caused by changes in the heart muscle.

The most common forms of heart disease in adult cats are those affecting the muscle of the heart itself (cardiomyopathy):

Hypertrophic cardiomyopathy

The most common form of cardiomyopathy is hypertrophic cardiomyopathy, in which the heart muscle becomes abnormally thick which prevents the heart from working properly and reduces the amount of blood flowing through it. Hypertrophic cardiomyopathy can be caused by an increased workload for the heart. If the heart has to do more work to pump blood out then the muscles in the heart get bigger (just like a weight-lifter’s muscles get bigger when they work-out a gym). However, hypertrophic cardiomyopathy can also occur in otherwise healthy animals and the exact cause is often unknown. It is more common in certain breeds, e.g. Persians, which suggest that it may be inherited in some cases.

Dilated cardiomyopathy (DCM)

This disease is caused by the stretching of the heart muscle walls so that the heart swells (like a balloon filled with water). The contractions of the heart muscle become very weak so blood is not pumped around the body effectively. 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. In humans, heart disease is usually the result of damage to the heart muscle caused by blood clots (myocardial infarction) – this causes the signs of a heart attack. However, cats do not get this kind of heart disease.

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. Many of the effects of heart disease are similar to those changes that occur naturally as your cat gets older – poor appetite, low energy levels with reduced activity and longer rest periods. Your cat’s tongue or gums may turn bluish red as a result of oxygen starvation. 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.

Sometimes the first sign of heart disease in cats are ‘fainting fits’ or seizures (fits). Panting, weight loss, restlessness, coughing, fainting and swelling of parts of the body because of water retention are signs of very severe heart disease and are not normally seen until the disease is advanced.

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.

If the heart is not working properly the blood may start to clot inside the heart. Fragments of clot can break off and escape into the circulation where they may cause a blockage in one of the blood vessels. If the clot blocks the vessel taking blood to the hind legs it may cause sudden paralysis. This condition is very painful and cats may be found lying outside, unable to walk and very distressed. These signs are frequently misinterpreted as being the result of a traffic accident. If your cat is found like this it needs emergency veterinary treatment.

A thorough examination of your cat will often be enough to tell your vet that your cat 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, which suggests that heart disease is present.

X-rays and ultrasound scans may also be used. X-rays will usually be needed to see if the heart is enlarged or abnormally shaped. Ultrasound scans allow measurements to be made of the heart muscle to see if it is too thick or has become stretched. Ultrasound can also let your vet see if the heart valves are working properly and if there are any holes in the heart.

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.

If your vet has identified a cause of the heart disease and this can be treated (such as removal of an over-active thyroid gland) the damage to the heart muscle might actually repair with time.

Unfortunately, it is unusual that the root cause can be treated so easily and in most cases long-term medication is needed to control the signs.

Sometimes your vet will recommend a special diet that may have low salt to reduce water retention. However some cats do not like these diets and will refuse to eat them. It is much more important that your cat eats than has any special food.

If the heart disease is diagnosed early enough long-term medication and other measures can slow the disease down but they will probably 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).

Your vet will prescribe some drugs to improve the heartbeat and others to help get rid of the excessive fluid that can accumulate in your cat’s chest and interfere with its breathing. Aspirin may also be prescribed (as in human heart disease patients) to stop the formation of blood clots. This drug can be dangerous in cats and the dose has to be carefully controlled. A single dose of aspirin may last as long as three days in your cat (not three hours as in people). Never give medication to your cat unless it has been prescribed by your vet.

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.

Feline aortic thromboembolism

Cats may be struck ‘out of the blue’ by a blood clot resulting in dramatic signs (sudden onset of lameness and pain) and potentially devastating damage. The back legs and the right front leg are most often affected and may be paralysed. This is an emergency – if you suspect that your cat has suffered a blood clot, you must seek veterinary help as soon as possible.

The term thromboembolism is made up of two words: ‘thrombo’ and ’embolism’. A thrombus is a blood clot within the heart or in a blood vessel; an embolus is something that travels through the bloodstream, lodges in a blood vessel and blocks it. Therefore thromboembolism is the formation of a blood clot in the circulatory system (thrombus) that breaks loose and is carried by the blood stream until it lodges in a blood vessel and blocks it.

The clot may block a vessel anywhere in the body. The more commonly recognised sites are the legs (most frequently the back legs), lungs (pulmonary embolism), the kidneys, the gastrointestinal tract and the brain (stroke).

When a blood vessel becomes blocked, the tissue it normally supplies is deprived of a blood supply (and therefore oxygen). The signs will depend on the location of the affected blood vessel. In the cat clots most often get stuck in the main blood vessels providing blood supply to the back legs. One or both back legs may be affected.

Your cat will be lame or might not be able to stand or use the affected leg or legs at all. The legs may be colder, the muscles may be firm and the nails and foot pads (if not pigmented) may be pale. In the beginning this condition is very painful and your cat might cry, look at or even chew the affected leg(s). The condition comes on very suddenly so a cat may go out of the house apparently completely healthy and later be found on the doorstep unable to stand on their back legs.

If a blood vessel in the lung is blocked, your cat may breathe more heavily, more rapidly and may start to breathe through its mouth. A clot in the brain can cause seizures or altered behaviour. Your vet will be able to identify this.

Thromboembolism is an emergency and it is important to get your cat to your vet as soon as possible.

Your vet will already have a suspicion of a blood clot if your cat has suffered a sudden onset of these signs. However, cats suffering from back injuries or involved in a road traffic accident can show similar signs. When your vet examines your cat they will have a close look at its legs and will check for pulses in the legs. If these are absent, it is very likely that your cat has a blocked artery to one (or both) of its legs.

A blocked artery is a serious problem. The reduced blood flow results in a build up of toxic substances in the tissue. This can be life-threatening and if the blood vessel to an organ is blocked the function of that organ will be impaired. This can cause changes in the blood which your vet can detect with some simple blood tests.

There are several reasons why blood clots form and although your cat may not have shown any other signs of illness it is likely that a severe, life-limiting disease is present. Your vet will investigate these to be able to provide the best treatment for your cat and to give you an indication of what the outcome is likely to be. Most blood clots in cats are the result of heart disease and your vet may take X-rays of the chest and/or perform an ultrasound investigation of the heart. Some tumours can also cause clots to form and, if your vet suspects this, they might also take X-rays and/or obtain an ultrasound of your cat’s belly.

Once treatment is started long term monitoring will be required to check that treatment is being effective and well tolerated and to follow the progress of the underlying disease.

Treatment is possible in all cases but often it is not possible to resolve the clot. ‘Clot-busting’ drugs can only be used in cats shortly after development of the clot. These drugs can have severe side effects which might even result in the death of your cat so even if your cat is presented immediately for treatment your vet will want to explain all the options available and discuss if the use of these drugs is appropriate for your cat.

However, cats have extra blood vessels, which open up to provide an alternative blood supply to the legs if the main supply is blocked. This doesn’t happen immediately and to buy the time for recovery your vet will provide your cat with pain-killers, drugs which prevent further clot formation, and medication for any underlying disease, which caused the clot in the first place.

As treatment progresses (which may take many weeks) your vet will let you know if your cat is improving as expected. Once cats are discharged from hospital they will stay on long-term treatment for the underlying disease (frequently these diseases cannot be cured). Clot-preventing medications will also need to be continued. These modern drugs are quite good and cause only very rarely cause bleeding.

It depends on the disease which caused the clot in the first instance, and the possible organ damage caused by clots. Sadly, the outlook for cats with thromboembolism is not good. Around one-third of all affected cats do not recover from the initial episode (although in many cases this is because their owner elects for euthanasia). However, depending on the severity (and your vet can advise you on this) it is worth starting treatment to buy some time.

If your cat improves over the first few days, there is a chance that further improvement will occur and your cat may recover and have a good quality of life. In cats that do recover, complete function of the affected leg(s) is often not achieved. As most of the underlying diseases which cause clots cannot be cured, your cat is at risk of developing another clot (even if on long-term treatment with anti-coagulation drugs) and around 50% of cats will develop a further thrombembolism.

Thromboembolism is a serious, life-threatening disease, which can come out of the blue. Affected cats will have a serious underlying disease which can be treated, but almost certainly not cured. If affected your cat will be on treatment for the rest of its life and is at risk of developing another clot. Your vet will be able to give you an idea of how badly affected your cat is and whether treatment is worth trying. Cats that do respond to treatment can have a good quality of life, and may live for several months or sometimes even years.

Congenital heart diseases

Bringing a new kitten into the family is an exciting time and should a time of great joy. It can be particularly distressing to find that your new arrival has a problem. It is important that you get your new kitten checked over by your vet so that any obvious problems can be identified before you become too attached to it.

Congenital defects are caused by abnormal development of the foetus and disease is present from the time that the animal is born. However, although the disease is present from birth, signs may not be noticed until later in life.

Congenital defects can occur in any part of the body and the heart is no exception. The heart is a complicated structure and as it develops there are many things that can go wrong.

As many as 1 in 100 cats have a congenital heart problem. No-one knows why the heart develops abnormally in some animals. It is probably usually the result of a combination of environmental conditions and genetic factors. Some diseases are more common in particular breeds and so it is likely that they are partly passed from parents to offspring. For this reason animals with congenital diseases should not be allowed to breed.

If defects are severe then signs can be marked, but in some cases you may not ever know that there is something wrong with your pet. Often one of the first signs of a heart defect is a heart murmur detected by a vet during routine examination. When you buy a new kitten you should take them to your vet so that your vet can check them over. Your vet should listen to their heart and will be able to tell if a murmur is present. However there are some diseases that cause no signs in the early stages.

If heart disease progresses then an animal with a congenital condition can go on to develop heart failure. This may occur relatively quickly within the first few weeks of months of life if the defect is serious. However in many cases no signs are shown until the animal reaches adulthood.

There are a number of congenital heart diseases and some of these more commonly affect some breeds of cat than others. The diseases are caused by abnormal development of the blood vessels (abnormal connections or narrowing), the valves or as a result of abnormal connection between different parts of the heart (hole in the heart).

In cats the most common form of congenital heart disease is a ‘hole in the heart’ (which is rare in dogs). Sometimes there is abnormal development of the valves between the various chambers of the heart. Other defects include PDA (patent ductus arteriosus) where there is a communication between blood supply into and out of the heart; narrowing of the large blood vessel taking blood away from the heart to the body (aortic stenosis). Male cats are more likely to have a congenital heart disease than females.

If your vet detects a heart murmur on examination they will need to do further tests in order to find out what is causing the problem. X-rays might help but ultrasound will be needed to find out exactly what is wrong with the heart. Your vet may need to refer your pet to a vet who specialises in heart disease for detailed examination. This will allow the best treatment plan to be formulated.

Unfortunately the long-term outlook for animals with severe congenital heart disease is usually not good. The only cure for heart defects is surgical correction and this is rarely performed in cats. In some cases animals have no problems with their disease and can live with the condition. If animals develop heart failure then this can be managed with drugs to control signs.

If your pet can have surgery to correct their heart defect they will probably need to be sent to a specialist surgeon. However recovery from the operation is usually rapid and they may be back to normal in a week or two. Unfortunately if there is no surgical option for your pet then they may need drug treatment for the rest of their life. It can be very distressing to watch a young animal suffer with heart disease and, if there is no treatment for your pet, you should discuss with your vet whether euthanasia might be the kindest option.

Vomiting and diarrhoea

Vomiting and diarrhoea are common in cats. Both are symptoms of other conditions rather than diseases in their own right and there is a vast range of cat diseases in which diarrhoea and/or vomiting may occur. In many cases the problem may be successfully treated without ever pinpointing the actual cause. However, the information that you give your vet may be vital in deciding whether the case is serious enough to need further detailed investigations.

Diarrhoea occurs when the normal functioning of the large bowel (intestine) is disturbed. The large bowel is responsible for absorbing water from the gut and if it does not do this properly, very liquid faeces (droppings) are produced.

Vomiting occurs when stomach juices are expelled from the mouth. It is important to distinguish vomiting from regurgitation. Regurgitation only occurs after a meal and the material will have visible lumps of undigested food which are often eaten again.

The causes of both diarrhoea and vomiting include viral, bacterial or parasitic infections; changes in diet, stress or excitement, poisonous drugs or chemicals, blockages or damage to the digestive system or other body organs.

It is often difficult to know that your cat has diarrhoea if it goes to the toilet outside the house and immediately covers up the faeces (droppings) with soil. But the problem becomes obvious if it uses a litter tray, if it has an accident indoors or in long haired cats whose back ends can become soiled with diarrhoea. A cat will readily vomit indoors.

Both diarrhoea and vomiting occur as short lived (acute) conditions lasting 1-2 days which will often clear up on their own, and as long-term (chronic) problems which are usually more serious. If your cat does not appear to be in distress or be losing weight, all you may need to do is to withhold all food for a day and then give your cat small amounts of cooked fish, chicken or some other food which is easily digested. Make sure clean fresh water is available but do not give milk.

If vomiting or diarrhoea is continuous for more than 24 hours, despite starvation, your cat could become dangerously dehydrated and should be taken to your vet.

Contact your vet sooner if a kitten is ill (because they get dehydrated more quickly than adults), if there is blood in the vomit or diarrhoea, if the faeces (droppings) are of a black and tarry appearance.

Never treat your cat yourself with drugs from your own medicine cabinet because some human drugs are poisonous to cats.

Your vet will manage acute diarrhoea or vomiting by starvation unless your cat is dehydrated then it may be given fluids and essential minerals by mouth or injection. Your vet may not give antibiotics because bacterial infections are one of the rarer causes of these problems and because ‘good’ bacteria are always present in a normal gut, antibiotics (which kill these too) could actually make the problem worse.

Your vet will ask you questions about your cat, such as:

  • Is your cat ill or depressed?
  • Has your cat eaten any unusual foods?
  • Is there anything unusual about the colour and smell of the your cat’s faeces or vomit?
  • When and how often is your cat being sick or having diarrhoea?
  • Are there other cats in the household and have these also been affected?
  • Has your cat been hunting or scavenging left over human food?
  • Has your cat been given any medical treatment or been exposed to any potential poisons?
  • Think about these questions before going to your vet and see if you can identify any possible reason why your cat may be ill.

If the illness continues for more than a couple of days it may be necessary for your vet to carry out a range of tests to find out the cause of the problem. A small sample of your cat’s faeces will be examined for bacterial infections or parasites in the gut. Blood tests may also be taken to check for infection, kidney or liver disorders.

An x-ray may be needed to see if there is anything abnormal in the gut. Sometimes your vet will put an endoscope into your cat’s stomach and intestine to try and see the cause of the problem, and a small biopsy sample of intestine may be removed for examination.

Digestive upsets are unpleasant for you and your cat but in most cases your cat will be better within 1-2 days. If your cat is not improving after 24 hours make an appointment with your vet for further advice.