Ragdoll

Ragdoll

Hypertrophic Cardiomyopathy

Outline: Approximately 30% of Ragdoll cats have sầu a genetic mutation that makes it likely that they will develop hypertrophic cardiomyopathy (thickening of the muscle walls of the heart). Over time this condition leads lớn heart failure and/or other complications such as increased risk of blockage of major blood vessels by blood clots. Heart failure causes increasing discomfort & malaise in affected animals which can occur over a prolonged period. Blockage of blood vessels causes severe pain. Animals with the genetic mutation that causes this condition can be detected before the reach the age they are commonly bred at using a specific genetic demo và ultrasound scanning of the heart. It is thought that the disease could be rapidly eliminated by not breeding from affected animals.

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Summary of Information

(for more information click on the link below)

1. Brief description

Hypertrophic cardiomyopathy (HCM) is the commonest size of heart disease in cats & it is very comtháng in the Ragdoll breed. With Hồ Chí Minh the heart wall abnormally thickens (Liu et al 1981). This thickening causes multiple problems & at some stage prevents normal heart function. Heart failure develops. The severity of the heart failure progresses and causes death - either suddenly, due to the heart failing to lớn pump blood adequately around the body toàn thân or from the effects of a thromboembolus (a clot causing blockage of a blood vessel), or after progressive sầu complications caused by poor circulation và fluid build up in the chest & lungs affecting breathing.

In TP HCM some of the heart muscle cells vì chưng not work adequately because of a genetic fault. The normal unaffected heart muscle cells therefore have sầu to work harder khổng lồ compensate và, over time, they increase in kích cỡ (hypertrophy). This causes abnormal muscle thickness in a heart that cannot work adequately.

Cats with heart disease, but without heart failure, will very likely appear normal khổng lồ their owners. Veterinary surgeons may notice abnormalities on examining the cát eg hearing a heart murmur or an abnormal heart beat or rhythm. Other signs of heart disease & failure are detected using diagnostic equipment such as a chest radiograph, electrocardiogram (ECG) &, most importantly for TP HCM, ultrasonography.

2. Intensity of welfare impact

The intensity of the welfare impacts of this disease depends on the degree of heart failure and secondary effects that it causes. Many cats with Hồ Chí Minh vị not have sầu heart failure và have no welfare problems. However, in severe and terminal heart failure, the presence of fluid inside the lungs (pulmonary oedema), makes breathing very difficult & laboured; a condition that can be assumed to lớn be very unpleasant.

Thromboembolic disease (in which a blood clot forms và blocks a blood vessel) can occur as a consequence of HCD, causing severe pain and digăng tay. It is also difficult lớn treat and some cats may undergo treatments lasting from days lớn weeks và may still kết thúc up with the cat having to be euthanased. Unfortunately, Ragdolls, which are homozygous for the condition are often severely affected & develop heart failure and thromboembolisms before two years of age (Meurs 2010).

Investigations of heart disease and heart failure often need lớn be extensive sầu. These procedures may be unpleasant for the cats involved.

Treatment usually requires regular oral medication (often dosing three times a day is required) and this in itself can be significantly stressful for some cats. As the heart disease progresses signs of heart failure usually return, despite treatment, leading lớn severe heart failure & an unpleasant death unless euthanasia is performed promptly.

3. Duration of welfare impact

Heart failure with episodes of breathing difficulties (that may be alleviated by treatment) often occurs progressively over a period of weeks to months. The welfare impacts will usually vary from mild khổng lồ severe over this period depending on the success & impact of investigations & treatments on the individual. Some cats live sầu for years on medication after an initial episode of heart failure và some die suddenly. Many Ragdolls develop clinical signs before two years of age (Meurs 2010).

4. Number of animals affected

Approximately 30% of Ragdolls in the UK carry a mutant gene that causes Hồ Chí Minh. In the USA 28% were found to carry the gene with 8% being homozygous for it & likely lớn develop severe disease at an early age. Those cats with only one copy of the gene tkết thúc to experience milder disease.

5. Diagnosis

Heart disease is suspected either by the owner noticing one of the signs of heart failure listed (see ‘Clinical and pathological effects’ below) or by a veterinary surgeon detecting a sign of heart disease or heart failure during a routine examination. The diagnosis of Hồ Chí Minh requires the use of ultrasonography. There is a genetic test available for one important ren mutation that is responsible for causing the condition in Ragdolls (but there may be other causal mutations yet to lớn be discovered).

6. Genetics

HCM has been shown khổng lồ be inherited in Ragdolls (Meurs et al 2007) The ren defect that has been identified as being associated with the disease appears to lớn be dominant with variable penetration. Individuals with either one or two copies of the gene have sầu a tendency khổng lồ develop TP HCM and those that inherit two copies are much more severely affected (Meurs 2010).

A genetic kiểm tra is available for the ren defect. Unfortunately, although this genetic test is very useful, there appear to be some Ragdoll cats that develop Hồ Chí Minh despite being negative for the ren.

7. How bởi vì you know if an animal is a carrier or likely khổng lồ become affected?

A genetic chạy thử is available but Ragdolls that thử nghiệm negative sầu may still develop TP HCM. It is likely that this is due khổng lồ other, currently unknown, genetic faults. Ultrasonography can be used as a way of screening potential breeding animals for the presence of TP HCM that is otherwise unapparent lớn owners và on routine veterinary examination and which are negative sầu on genetic testing. It can also be used for early detection of heart failure in individuals known khổng lồ carry the mutant ren for HCM so that suitable treatment can be instigated.

8. Methods & prospects for elimination of the problem

A scheme sydneyowenson.comanised jointly by the UK’s Feline Advisory Bureau and the Veterinary Cardiology Society aims khổng lồ eliminate HCM from Ragdolls and other affected breeds in the UK. This scheme uses both the genetic thử nghiệm & annual examinations including an ultrasound scan of the heart for all breeding animals. Cats with signs of HCM or that have sầu one or two copies of the mutant ren should not be used for breeding.

For further details about this condition, please click on the following:(these liên kết to lớn items down this page)

1. Clinical và pathological effects

HCM is the commonest form of heart disease in cats (Tilley & Goodwin 2003). Cardiomyopathy means disease due to an enlargement of the heart muscle. The name of the condition is a description of what happens rather than its cause và, in fact, Hồ Chí Minh can be caused by various diseases. The main cause in Ragdoll cats is the presence of one, or more, mutant genes that directly cause heart muscle lớn develop abnormally.

The heart is a four-chambered pump which is divided into lớn left & right sides. Each side has two chambers: blood enters inlớn the thin-walled upper chamber (atrium). It then flows inkhổng lồ the larger, lower chamber (ventricle). The ventricles have thichồng walls composed largely of heart muscle. Between the chambers of the atria and the ventricles there are valves that prsự kiện blood flowing backwards from the latter lớn the former. On contraction, blood flows from the ventricles into the major blood vessels. There are also valves at the junction of the ventricles & these blood vessels that preventing blood flowing backwards.

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Figure 1. The four chambers of the heart and direction of blood flow. Note the four valves, which in a normal healthy heart prsự kiện the backflow of blood và the thickness of the heart muscle (myocardium) surrounding the ventricles. (Image property of The Cardiomyopathy Association to lớn whom we are grateful for permission for its reproduction here).

The right side of the heart receives blood from the whole of the toàn thân other than the lungs, via the venae cavae. The blood accumulates in the right atrium và during a heart beat it is sucked past the tricuspid valve inkhổng lồ the right ventricle và then as the right ventricle contracts (squeezes) its muscular wall, the blood is pushed through the pulmonary valves inlớn the pulmonary arteries that take it onkhổng lồ the lungs (to take up oxygen).

The left side of the heart receives this oxygenated blood from the lungs, via the pulmonary veins. The blood accumulates in the left atrium & during a heart beat it flows past the mitral valve inkhổng lồ the left ventricle. Then, as the muscular wall of the left ventricle contracts, the blood is pushed through the aortic valves into lớn the aorta and onkhổng lồ the other major arteries which carry it around the body toàn thân to perform all the functions of blood circulation such as delivering oxygene & nutrients và sharing heat and metabolic products throughout the toàn thân.

As the left hvà side of the heart has to pump blood around the major sydneyowenson.comans of the toàn thân, whilst the right hvà side only has to lớn push blood through the adjacent lungs, the muscles of the left ventricle have sầu khổng lồ be much stronger than the right. As strength is largely a function of muscle form size the muscle wall of the left ventricle is thicker than the right.

The part of the heart’s relaxation & contraction cycle (that together 3D the ‘heart beat’) when contraction (squeezing of blood) is occurring is referred khổng lồ as systole và the relaxation phase is called diastole. In Sài Gòn the heart failure is largely a failure of the diastolic phase (Bonow & Udelson 1992).

To co-ordinate the contractions of the different parts of the heart’s muscle there is a pathway for coordinating nerve impulses. This can be damaged in HCM disrupting the control of the heart muscle

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Figure 2. In a normal healthy heart, nerve signals travel through the heart muscle to lớn stimulate coordinated contractions. However if the muscle tissue becomes thicker, as occurs in hypertrophic cardiomyopathy, the nerve sầu signals are disrupted leading to lớn irregular hearbeats. (Image property of The Cardiomyopathy Association to whom we are grateful for permission for its reproduction here).

In TP HCM the thickness of the ventricular walls is abnormally increased (Liu et al 1981). The heart is a complex, sophisticated sydneyowenson.coman & this muscle thickening causes multiple problems so that, at some stage, it can no longer function normally. Exactly what happens in an individual depends on which parts of the ventricles hypertrophy và over what time scale & to what degree, on whether valves are affected & on the degree to lớn which blood supply to lớn the heart muscle itself is compromised (Peterson et al 1993, Bonagura 1994). These different manifestations of the disease are outline below.

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Figure 3. Hypertrophy can affect the various areas of the heart muscle, with varying effects and consequences. (Image property of The Cardiomyopathy Association khổng lồ whom we are grateful for permission for its reproduction here).

The thickened wall usually can contract & squeeze out blood adequately. The problem is rather khổng lồ bởi vì with the ventricle relaxing and filling again. This relaxation is important as it is this action that helps khổng lồ suck the blood from the atria và allows it khổng lồ fill adequately. When the ventricle is not relaxing enough it causes a backflow problem so that blood cannot enter the heart normally. This is called backward or congestive sầu heart failure. When the left side of the heart is affected this causes fluid lớn build up in the lungs (pulmonary oedema). When the right side is affected the fluid instead builds up in the body toàn thân and usually shows as fluid accumulating in the chest cavity (pleural fluid), the abdomen (ascites) or in the body toàn thân generally (oedema). In each case the thin-walled atrium becomes affected and stretches (dilates). This causes further problems (see below).The valves of the heart are attached to lớn it’s muscle walls. As the walls thicken the valves can become distorted và leak. When the tricuspid and mitral valves are affected this allows blood khổng lồ flow backwards into the atria during contraction which causes further backwards (baông xã pressure) heart failure problems. When the pulmonary and aortic valves are affected then they can fail lớn open properly and so partially blochồng the outflow of blood. One particular consequence of HCM is called systolic anterior motion of the mitral valve sầu (SAM) (Bonagura 1994) when part of the mitral value (which should only be between the left atrium & the left ventricle) becomes caught up in the flow of blood in the left ventricular outflow path. Cardiologists specifically look for this when assessing the patients using ultrasound as it may be a sign of more severe disease.

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Figure 4. Hypertrophic cardiomyopathy with asymmetric septal hypertrophy (ASH) can impact the function of the valves of the heart, leading khổng lồ the backflow of blood as well as systolic anterior motion of the mitral valve sầu (described above). (Image property of The Cardiomyopathy Association to whom we are grateful for permission for its reproduction here).

The thickened muscle often contains scar tissue which interferes with the conduction of the nerve messages through the heart and causes uncoordinated contractions (Bonagura 1994). Irregular heart beats can contribute to forward heart failure. Forwards heart failure is when the left ventricle provides inadequate blood flow khổng lồ the toàn thân which can lead khổng lồ weakness, collapse, fainting & sudden death.The heart muscle itself needs blood, in the same way as other parts of the toàn thân. This is supplied through coronary arteries. As the muscle grows (hypertrophies) it sometimes does not have adequate blood vessels growing with it và this can lead to lớn sections of the ventricular wall getting insufficient oxygen and dying. This causes problems akin to lớn those of human heart attacks (myocardial infarction) when these coronary arteries suddenly block (Bonagura 1994).

There are also other important pathological consequences of Hồ Chí Minh (& some similar cardiac diseases) in cats (Tilley et al 1977). A major problem arises due khổng lồ the dilation of the atria mentioned above. Because of abnormalities of blood flow và because there may be damage khổng lồ the atrial linings, blood clots may size. These bởi not cause a problem as long as they remain in an atrium but can do when sporadically pieces of clot break off. The detached clot is carried in the bloodstream until it reaches a narrowing that stops it. Further clotting then occurs around it. The blood supply khổng lồ part of the toàn thân supplied by this vessel suddenly ceases &, depending on where this occurs, severe disease can be caused (Bonagura 1994). This is called thromboembolic disease.

Why does heart muscle in some individuals with TP HCM increase in size? Heart muscle increases in size, just like other muscles, in response khổng lồ working harder. Any disease that causes the heart to work hard over a period of time will therefore cause the ventricular wall lớn thicken and eventually may cause heart disease và heart failure by the mechanisms outlined above sầu.

The usual cause of TP HCM in cats (& humans) is that, due lớn a genetic fault, the individual is born with some of its heart muscle cells not working adequately due lớn abnormal proteins. The normal heart muscle cells have sầu to work harder khổng lồ compensate & over time as they work harder they increase in kích thước. This causes an overall abnormally thiông chồng muscle và the consequences listed above sầu.

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There is an important distinction between heart disease & heart failure. Heart disease usually occurs a significant amount of time before heart failure. When any of the abnormalities of heart disease listed above sầu are present it may be possible for a veterinary surgeon to detect them. When changes occur to lớn affect the adequacy of the function of the heart then heart failure is present, which can be categorised into lớn forward và backward heart failure. Both may be present.

The body is able to respond lớn heart disease và compensate for impending heart failure by various mechanisms, outlined below, although some of these themselves cause further problems (Bonagura 1994).

When it detects inadequate blood flow from the heart, the body toàn thân causes the heart rate to increase such that blood supply to the sydneyowenson.comans is maintained. However, this raised heart rate may further restrict the ability of the ventricles khổng lồ relax as there is less time between each contraction; time in which the ventricles can relax and fill. Increasing heart rate can cause backward heart failure to worsen và eventually the amount of blood that the heart can push forwards around the toàn thân also decreases. A further problem is that it is during relaxation that the heart muscle itself receives blood via its coronary arteries so when beating quickly its own oxyren supply can decrease & heart muscle can die.Inadequate blood flow from the heart also causes the toàn thân lớn react as though there has been a loss of circulating blood volume. Hormones are released in response which cause fluid khổng lồ be retained even though there actually has been no loss of blood. The amount of fluid in the toàn thân thus increases and this is one of the reasons that fluid accumulates in the lungs (pulmonary oedema) or elsewhere in the toàn thân (pleural fluid or oedema).

Cats with heart disease, but without heart failure, will very likely appear normal lớn their owners and will not have sầu any welfare problems at that time (Tilley & Goodwin 2003). An owner might be able to detect a fast and abnormally svào heart beat if feeling their cat’s chest. Similarly, a veterinary surgeon may notice a high heart rate or pulse rate when examining a cát. The heart rate is measured by feeling the heart beat, or, more usually, listening khổng lồ the heart beating using a stethoscope. The pulse rate is measured by feeling the pulsing of blood flowing through a major artery. In cats it is usually the femoral artery in the upper inside leg that is felt. In a normal individual the heart rate và pulse rate will be the same – each heart beat produces a pulse; but this is not always the case with heart failure – sometimes an ineffectual heart beat occurs that does not generate a pulse that can be detected. This is called a pulse deficit (Bonagura 1994).

A veterinary surgeon listening to a cat’s heart beating may also hear an abnormal noise, called a murmur. Hearing a heart murmur is the commonest way for heart disease to lớn be detected in cats. It used to lớn be thought that such murmurs occurred in up to 95% of cats with HCM (Tilley và Goodwin 2003) but Paige et al (2009) reported that only 31% of cats with Sài Gòn, and with no signs of heart failure, had an audible murmur. Murmurs are produced by abnormally turbulent blood flow. They usually indicate the presence of a structural abnormality of the heart, for example: an abnormal valve sầu that is allowing backflow of blood or a bulging part of the heart wall that is causing abnormal flow. On detection of a murmur, further investigations should be carried out lớn find their cause and to lớn determine the health of the heart (Bonagura 1994). Another change that a veterinary surgeon may detect when listening to lớn a cat’s heart is a “gallop rhythm”. This is heard in around 40% of cats with HCM (Tilley & Goodwin 2003). Normally a cat’s heart beat has two sounds, “lub – dub”. With a gallop rhythm three sounds are heard and this is a reliable indication that heart disease is present (Bonagura 1994). Dysrhythmias such as a “gallop rhythm” are heard in around 25% of cats with Hồ Chí Minh (Tilley và Goodwin 2003).

Other more sophisticated methods of detecting heart disease involve sầu the use of radiographs, electrocardiographs & ultrasound. Radiographs of the chest may show evidence of heart enlargement but this is a relatively crude method. (Chest radiographs are very useful for detecting comtháng signs of heart failure – see below). A disadvantage of chest radiographs is the need for a general anaesthetic.

Electrocardiography (ECG) records the electrical activity of the heart as it beats. This usually can be carried out in cats without sedation or anaesthesia and can provide information about the presence of heart disease.

The most powerful tool for examining the heart is ultrasonography. This enables measurement of the thickness of the heart muscle; the form size of each chamber và the position and movement of each valve sầu.

Heart failure occurs when there are complications of heart disease affecting other sydneyowenson.comans (eg the lungs or brain) that can be detected clinically or that are causing changes lớn the cat’s behaviour. There are several quite different ways that heart failure due to HCM can become apparent khổng lồ an owner (Tilley & Goodwin 2003) as outlined below.

Decreased activity & appetite due lớn heart failure causing a build up of fluid in the chest cavity, or in the lungs, or because the heart is unable lớn supply enough blood to the major sydneyowenson.comans (backwards or forwards heart failures). In this case the gums & other mucus membranes will eventually look cyanotic (blue) rather than the normal pink (Bonagura 1994).Breathing difficulties due to backward left sided failure. Blood that cannot get inlớn the small, stiff-walled left ventricle pools in the left atrium, causing it to lớn dilate, and also causes increased pressure in the pulmonary veins which carry blood from the lungs and which drain inlớn the left. As back pressure builds up fluid forms in the lung tissue replacing the cavities that are normally air-filled. Often owners will only notice breathing difficulties when signs become severe and breathing is rapid or the cat is panting (breathing with their mouth open). Unlượt thích dogs, cats vì chưng not pant unless distressed. Cats showing this need immediate veterinary attention. At this stage, investigations will usually find that much of the lung fields are full of fluid (pulmonary oedema) and/or that the lungs are being compressed by large volumes of fluid trapped between the lungs & the chest wall (pleural fluid). This fluid causes some cats to cough và this may be the first sign of heart disease & failure that an owner notices (Bonagura 1994).Through the presence of a thromboembolus (Tilley et al 1977). As previously described, a clot formed in the left atrium can detach & cause blood loss lớn a distant part of the toàn thân. The commonest place of blockage by the clot is at the end of the largest artery, the abdominal aorta, where it splits into lớn three to lớn supply blood khổng lồ each hind leg and the tail. Affected cats suddenly have sầu severe problems with both bachồng legs; often being completely paralysed. This condition is very painful và the cát will be extremely distressed, usually crying out.Embolisms can occur anywhere & if a clot lodges in smaller vessels then it may not be detected. Other common sites of major embolisms are the right front leg, causing pain and paralysis; the kidneys, causing ađáng yêu kidney failure; the small intestine, causing death of a section of bowel, abdominal pain, anorexia (loss of appetite), vomiting và, without treatment – death; and in the brain causing a stroke-like episode, the exact signs will depover on where in the brain the blockage occurs (Bonagura1994).The clots can also size in the right atrium and if these detach they cause blockages in the supply of blood khổng lồ the lungs (pulmonary embolism). The signs of these vary but they can cause breathing difficulties and shock.Disease can show because of severely abnormal heart beats. These can be irregular heart beats that at times fail lớn supply enough blood to the sydneyowenson.comans or which can cause forward heart failure. These dysrhythmias can cause fainting episodes (Bonagura 1994).As forward heart failure becomes worse and blood supply khổng lồ the heart itself is inadequate, heart rate may drop and become subnormal. At this stage circulation throughout the toàn thân is severely compromised, fluid may build up in the lungs (pulmonary oedema) & in body toàn thân cavities (pleural effusion in the chest và ascities in the abdomen) and in peripheral tissues (oedema seen mostly in the lower parts of the body toàn thân – the legs và lower trunk. The toàn thân temperature drops due to lớn inadequate circulation of blood. This process is called cardiogenic shock. Terminally, there is inadequate blood supply lớn the brain and fits, coma và death occur (Bonagura 1994).Cats with hypertrophic cardiomyopathy sometimes show no signs of illness & even no signs of disease on routine veterinary examinations before dying suddenly (Kittleson et al 1999). Sudden death can occur because of a large thromboembolus. It can also occur in those cats with particularly thiông chồng left ventricular walls in which supply of blood via coronary arteries is inadequate leading lớn death of a large part of the muscle. This might be associated with a sudden increase in demvà for heart activity such as occurs with a stressful event. Sudden death can also happen when a severe dysrhythmia occurs.

So, the signs of heart failure vary considerably (Tilley et al 1977). Many cats will have early heart failure without their owners being aware of it.

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2. Intensity of welfare impact

The intensity of the welfare impact varies greatly with the degree of heart failure và the presence or absence of secondary affects. Many cats with hypertrophic cardiomyopathy do not have sầu heart failure và have no welfare problems. Severe & terminal heart failure has severe welfare implications. Pulmonary oedema, the presence of fluid inside the lungs, causes breathing difficulty & this can be assumed lớn be very unpleasant.

Thromboembolic disease (depending on where the clots occur) can cause severe pain, dibít tất tay và paresis (inability khổng lồ use the hindlimbs normally). It is also difficult lớn treat & some cats may undergo treatments lasting from days to lớn weeks and may still kết thúc up with the cát having khổng lồ be euthanased.

Unfortunately Ragdolls, which are homozygous for the identified genetic mutation, are severely affected & develop heart failure và thromboembolisms often before two years of age (Meurs 2010).

Investigations of heart disease and heart failure often need to be extensive sầu. As well as repeated clinical examinations, blood tests, ECGs, ultrasound examinations and radiographs, often under anaesthesia, are required khổng lồ manage these problems. These procedures may be unpleasant for the cat.

Treatments for both forward & backward heart failure are available & usually help to lớn reverse signs of heart failure. Reversing actual heart disease is much more difficult although there is some evidence that the kích cỡ of the left ventricular wall can be reduced sometimes. Treatment is usually dependant on regular oral medication; for hypertrophic cardiomyopathy this unfortunately often means dosing three times a day, a process which in itself can be significantly stressful for some cats. As the heart disease progresses signs of heart failure usually return, despite treatment, leading to lớn severe heart failure & an unpleasant death unless euthanasia is performed.

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3. Duration of welfare impact

Homozygous Ragdolls (those in which both copies of the gen are of the mutant form) are often less than two years old when heart failure và thromboembolisms develop (Meurs 2010). Heart failure with episodes of breathing difficulties, alleviated by treatment, often occurs over a period of weeks to months. The welfare impact may be mild or severe over this period depending on the success of treatment and the impact of investigations và treatments on the individual. Some cats live for years on medication after an initial episode of heart failure và some die suddenly. The average life expectancy of one group of cats (of various breeds) with Sài Gòn was found to be 492 days (Ferasin et al 2003). Tilley & Goodwin (2003) stated that, in general, cats with HCM và no signs of heart failure have sầu an average life expectancy of five sầu years from diagnosis và those with heart failure of three months.

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4. Number of animals affected

Approximately 30% of Ragdolls in the UK carry the mutant gene that causes Hồ Chí Minh (FAB no date). In the USA, 28% of Ragdolls carry the ren with 8% being homozygous for it ie they have two copies of the mutant gene. Homozygous individuals develop severe, early disease. Those which are heterozygous (have sầu only one copy of the mutant gene) tend khổng lồ develop a much milder khung of the disease (Meurs 2010).

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5. Diagnosis

Heart disease is suspected either by the owner noticing one of the signs of heart failure listed above or by a veterinary surgeon detecting a sign of heart disease or heart failure on an examination for another reason or a routine check. In the UK, many cases of HCM in Ragdolls are detected through the ultrasonography screening scheme sydneyowenson.comanised by the UK’s Feline Advisory Bureau (FAB) and Veterinary Cardiology Society (VCS) (see below) or by owners using the specific genetic screening thử nghiệm. This demo detects the presence of the mutant gen (not whether the cát actually has heart disease or heart failure). However, many cats with this ren will go on to develop disease & failure.

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6. Genetics

Hypertrophic cardiomyopathy has been shown to lớn be inherited in Ragdolls (Meurs et al 2007). A defect has been found in the myosin binding protein C gene (MYBPC3) with a change in a single nucleotide base - from cytosine to thymine - that alters the conformation of codon 8trăng tròn. The defect appears to be dominant with variable penetration so that individuals with either one or two copies of the ren have the tendency khổng lồ develop HCM (Meurs 2010). Factors, other than the presence of the gen, have an important influence on whether or not TP HCM develops và the severity of disease. However, what these factors are is currently unknown.

Unfortunately, although the genetic thử nghiệm for congenital Sài Gòn is very useful, there appears khổng lồ be a number of Ragdolls that develop Hồ Chí Minh despite having tested negative sầu for the presence of this gene. In humans, there are more than 1000 known defects in 10 genes that can cause HCM so it is likely that there are other genetic mutations in Ragdolls & other cát breeds và investigations lớn find these are underway (Meurs et al 2009). It is also possible that false negative sầu genetic results occur sometimes (Lyons 2010).

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7. How bởi you know if an animal is a carrier or likely to lớn become affected?

A genetic chạy thử is available for this condition and is available from several laboratories around the world, eg the Molecular Diagnostics Unit, University of Bristol Veterinary School http://www.langfordvets.co.uk/lab_pkdsampling.htm.

An individual only needs khổng lồ be tested once during its lifetime but there are significant limitations lớn the genetic test. Ragdolls that have sầu a negative test result may still develop Sài Gòn & it seems likely that this is because other, currently undiscovered, genetic defects can also induce it.

Routine ultrasonography can be used both as a way of screening potential breeding animals for the presence of TP HCM, that is not apparent lớn owners, & on routine veterinary examination. All Ragdoll kittens should have the genetic demo prior to lớn purchase (unless both their parents are known khổng lồ be không tính tiền of the mutation) and their parents should also have sầu been declared healthy on an ultrasound examination.

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8. Methods và prospects for elimination of the problem

There are schemes in operation that may use both genetic testing and annual examinations, including an ultrasound scan of the heart, to lớn identify affected individuals. One is sydneyowenson.comanised by the UK’s Feline Advisory Bureau (FAB) và Veterinary Cardiology Society (VCS): it aims to lớn eliminate TP HCM from Ragdolls in the UK. (see: http://www.langfordvets.teo.uk/lab_pcrnews.htm or http://www.fabcats.sydneyowenson.com/hcm/).

Cats that have Sài Gòn, or that have sầu one or two copies of the mutant MYBPC3 gen, should not be used for breeding.

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Only microchipped cats can be listed on the FAB VCS register of HCM-negative sầu Ragdolls. The veterinary surgeon must read the microchip lớn confirm the identity of the cat at the time of sampling for the genetic kiểm tra or each time the cardiac ultrasound thử nghiệm is performed,

Examinations are arranged with individual veterinary cardiologists, a danh sách of whom for the UK can be found at: http://www.fabcats.sydneyowenson.com/hcm/.

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9. Acknowledgements

sydneyowenson.com is grateful lớn Rosie Godfrey BVetMed MRCVS và David Godfrey BVetMed FRCVS for their work in compiling this section

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10. References

Bonagura JD (1994) Cardiovascular diseases. In: Sherding RG ed The Cat: Diseases and Clinical Management, 2nd edition. Churchill Livingstone: New York. pp

Bonow RO and Udelson JE (1992) Left ventricular diastolic dysfunction as a cause of congestive heart failure. Mechanisms và management. Annals of Internal Medicine 117: 502-10

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