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| + | == Introduction<br> == |
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| | + | Also called congestive cardiomyopathy, this disease is common in dogs and is rare in cats (with adequate taurine supplementation). In the dog, giant and large breeds (e.g. Dobermann pinscher, Boxer, Great Dane) are most at risk. Male>Females and risk increases with age. In the cat the most commonly effected breeds are the Siamese, Burmese, Abyssinian. Again Male>Female and middle age & old age cats aremost at risk.<br> |
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| − | ''a.k.a. Congestive Cardiomyopathy''
| + | Dilated cardiomyopathy (DCM) occurs when there is a progressive reduction in systolic myocardial contractility. Decreased myocardial contractility affects the removal of blood from the ventricle at systole. A larger volume of blood increases the end diastolic pressures causing dilation of the ventricle and the development of eccentric hypertrophy. |
| − | *Common in dogs
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| − | *Rare in cats (with adequate taurine supplementation)
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| − | ===Signalment=== | + | == Clinical Signs<br> == |
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| − | '''Dog:''' Giant and Large Breeds (e.g. Dobermann pinscher, Boxer, Great Dane); Male>Female; Risk increases with age
| + | Can be aAsymptomatic (Occult) DCM: See in predisposed breeds (e.g. Doberman pinschers). |
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| − | '''Cat:''' Greatest risk in: Siamese, Burmese, Abyssinian; Male>Female; Middle Age & Old Age
| + | Clinical signs include syncope, weight loss, dyspnoea, lethargy, weakness and hindlimb paresis (cats with saddle thrombi). |
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| − | ===Description===
| + | <br> |
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| − | *Dilated cardiomyopathy (DCM) occurs when there is a progressive reduction in systolic myocardial contractility. Decreased myocardial contractility affects the removal of blood from the ventricle at systole. A larger volume of blood increases the end diastolic pressures causing dilation of the ventricle and the development of eccentric hypertrophy.
| + | == Diagnosis<br> == |
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| | + | History and clinical signs suggest heart failure.<br> |
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| − | ===Diagnosis===
| + | Physical examination will show presence of a systolic murmour, a gallop rhythm, S3 heart sound, arrhythmias, pulse deficits and pulmonary crackles. |
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| − | ====History & Clinical Signs====
| + | Blood tests will shos azotemia, elevated liver enzymes (+ Liver Congestion), signs of congestive heart failure, signs of thromboembolism (cats) and plasma taurine reduction (cats). |
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| − | -Asymptomatic (Occult) DCM: See in predisposed breeds (e.g. Doberman pinschers)
| + | Radiography will show left ventricular hypertrophy (Seen in Dobermans & Boxers), left atrial enlargement (Seen in Dobermans & Boxers). generalised cardiomegaly (Seen in Giant Breeds), left sided congestive heart failure signs e.g. pulmonary congestion & edema and right sided congestive heart failure signs e.g. pleural effusion and ascites.<br> |
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| − | -'''Right-Sided Congestive Heart Failure Signs'''
| + | Electrocardiography (ECG) will show rhythm disturbances e.g. atrial fibrillation (Giant Breeds), ventricular arrhythmias (Doberman pinchers, Boxers), conduciton disturbances and characteristic signs of hypertrophy. |
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| − | *Giant Breeds usually prone to these
| + | Echocardiography will show a hypokinetic left ventricle (i.e. reduced fractional shortening therefore reduced contractility), reduced ejection fraction (i.e. % end diastolic volume ejected at systole). decreased ventricular wall thickness, left atrial enlargement and mitral regurgitation. |
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| − | -'''Left-Sided Congestive Heart Failure Signs'''
| + | <br> |
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| − | *Boxers and Doberman pinschers have a higher risk
| + | == Treatment and Control<br> == |
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| − | -Syncope
| + | Treat congestive heart failure (Reduce Preload & Afterload; Improve Systolic Function; Control Cardiac Arrhythmias), therapeutic thoracocentesis (To remove pleural effusion in cats) and taurine supplementation (cats). |
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| − | -Weight Loss
| + | <br> |
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| − | -Dyspnoea
| + | == Prognosis == |
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| − | -Lethargy | + | '''Dogs; '''Poor: Most breeds survive 6-12 monthsand in Dobermans and Boxers the prognosis is grave. |
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| − | -Weakness
| + | '''Cats; '''Good: When cardiomyopathy results from taurine deficiency, but grave if other causes of cardiomyopathyFrom Pathology |
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| − | -Hindlimb Paresis (cats with saddle thrombi)
| + | <br> |
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| | + | == References<br> == |
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| − | ====Physical Exam====
| + | Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company<br>Ettinger, S.J, Feldman, E.C. (2005) Textbook of Veterinary Internal Medicine (6th edition, volume 2)W.B. Saunders Company<br>Fossum, T. W. et. al. (2007) Small Animal Surgery (Third Edition) Mosby Elsevier <br> |
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| − | -Systolic Murmur
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| − | -Gallop Rhythm
| + | <br> |
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| − | -S3 Heart Sound (+/-)
| + | == Test yourself with the Myocardial Pathology Flashcards == |
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| − | -Arrhythmias
| + | [[Myocardial Pathology Flashcards]] |
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| − | -Pulse Deficits
| + | [[Category:Cardiomyopathy]] [[Category:To_Do_-_Review]] |
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| − | -Pulmonary crackles
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| − | ====Laboratory Findings====
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| − | -Azotemia
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| − | -Elevated Liver Enzymes (+ Liver Congestion)
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| − | -Signs of congestive heart failure
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| − | -Signs of thromboembolism (cats)
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| − | -Plasma taurine reduction (cats)
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| − | ====Radiography====
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| − | -Left Ventricular Hypertrophy (Seen in Dobermans & Boxers)
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| − | -Left Atrial Enlargement (Seen in Dobermans & Boxers)
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| − | -Generalized Cardiomegaly (Seen in Giant Breeds)
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| − | -Left-Sided Congestive Heart Failure signs (pulmonary congestion & edema)
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| − | -Right-Sided Congestive Heart Failure signs (pleural effusion, ascites)
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| − | ====Electrocardiography (ECG)====
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| − | -Rhythm Disturbances (e.g. Atrial fibrillation (Giant Breeds); Ventricular Arrhythmias (Doberman pinchers, Boxers))
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| − | -Conduction Disturbances
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| − | -Characteristic signs of hypertrophy
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| − | ====Echocardiography====
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| − | -Hypokinetic left ventricle (i.e. reduced fractional shortening therefore reduced contractility)
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| − | -Reduced ejection fraction (i.e. % end diastolic volume ejected at systole)
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| − | -Decreased ventricular wall thickness
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| − | -Left atrial enlargement
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| − | -Mitral regurgitation
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| − | ===Treatment===
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| − | -Treat congestive heart failure (Reduce Preload & Afterload; Improve Systolic Function; Control Cardiac Arrhythmias)
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| − | -Therapeutic thoracocentesis (To remove pleural effusion) (cats)
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| − | -Taurine Supplementation (cats)
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| − | ===Prognosis===
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| − | '''Dogs'''
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| − | -Poor: Most breeds survive 6-12 months
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| − | -Grave: Dobermans and Boxers
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| − | '''Cats'''
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| − | -Good: When cardiomyopathy results from taurine deficiency
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| − | -Grave: Other causes of cardiomyopathy
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| − | ==From Pathology==
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| − | ''Incidence:''
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| − | Most common form in the dog. Seen in young to middle aged dogs of large breeds:
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| − | *St Bernard
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| − | *Great Dane
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| − | ''Clinical signs:''
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| − | Disease is a slowly progressive dilation of the ventricles with a loss of contractility. This is seen histologically as random myofibrillar thinning and degeneration of myocyte mitochonria, although it is possible that no histological lesions are present.
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| − | Clinical signs will appear as a sudden onset disease as there will be an acute decompensation for the pathology that had accumulated gradually. Signs include those of a congestive heart failure:
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| − | *Pulmonary oedema.
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| − | *Ascites.
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| − | *Hepatomegaly and splenomegaly.
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| − | ''Diagnosis:''
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| − | Gross cardiomegaly with cardiac hypertrophy, dilation and decreased contractility.
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| − | Histopathologically; increased ''attenuated wavy fibres'' within the myocardium. Fibres are thinner than normal and have a wavy appearance. May develop due to a chronic volume overload.
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| − | *Ventricular dilation, particularly the left ventricle, distorts the AV-valves which often become incompetant.
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| − | *'''Fibrillation''' is a common finding as dilation of the myocardium induces abnormal electrical activity and arrhythmias.
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| − | Variations of the disease exist in specific breeds:
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| − | *'''Doberman''': Present with arrhythmias. Histologically there are lymphocytic infiltrates within the ventricular myocardium. See focal degeneration of the bundle of His, probably due to narrowing of small vessels near the conductive tissue.
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| − | *'''English Cockers:''' Familial with many dogs having sub-clinical disease.
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| − | [http://w3.vet.cornell.edu/nst/nst.asp?Fun=F_Ssrch View images courtesy of Cornell Veterinary Medicine]
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| − | ====Secondary to toxic agents====
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| − | Includes:
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| − | *Dilated myopathy in horses with '''monensin''' toxicity.
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| − | *Dilated myopathy in dogs with long term administration of '''doxorubicin'''.
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| − | *Dilated myopathy in cats due to '''taurine''' deficiency.
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| − | ==Test yourself with the Myocardial Pathology Flashcards==
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| − | [[Myocardial Pathology Flashcards]]
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| − | [[Category:Cardiomyopathy]] | |
| − | [[Category:To_Do_-_Cardiovascular]] | |