Chapter 174 In the dog, persistent patency of the ductus arteriosus (see Web Chapter 64), pulmonary valve stenosis (see Web Chapter 65), and subaortic stenosis (see Web Chapter 66) are the most common forms of CHD. In the cat, ventricular septal defect (see Web Chapter 69) appears to be the most common form of CHD encountered. In both species, less commonly observed defects include atrial septal defect, mitral valve dysplasia (see Web Chapter 62), tricuspid valve dysplasia (see Web Chapter 68), atrioventricular septal defect, tetralogy of Fallot, vascular ring anomalies, and peritoneal-pericardial diaphragmatic hernia, among others. The prevalence of CHD in the dog and cat is difficult to quantify due to a lack of routine perinatal care, occurrence of conditions that are not apparent on routine physical examination, and hospital biases in published reports. The work of Detweiler and Patterson in the Philadelphia area suggested a CHD prevalence rate of 0.56% among 4831 dogs surveyed in the mid-twentieth century (Detweiler and Patterson, 1965), whereas Buchanan found a rate of 0.67% for all dogs brought to the University of Pennsylvania between 1987 and 1989 (Buchanan, 1992). In a study of 1679 puppies aged 6 to 18 weeks at a pet store, murmurs were observed in 11, which suggests an incidence of CHD of 0.66% (Ruble and Hird, 1993). However, this may be an underestimation because it fails to include those puppies that died from CHD before the age of 6 weeks or those animals whose disease was silent to auscultation at that age. Conversely, this study may have overestimated the incidence of CHD because further testing was not performed to determine if the murmur was reflective of true CHD or simply functional or physiologic in origin. Additionally, the pet store population is likely biased toward purebred dogs, which are known to carry a higher proportion of hereditary defects than mixed-breed dogs. Although the true prevalence of CHD in dogs and cats is unknown, data are available that indicate the relative incidence of specific malformations in each species. In an attempt to compile these data, several studies of CHD prevalence were analyzed and the data were combined (Tables 174-1 and 174-2). Ten applicable studies of CHD prevalence in dogs were found in the veterinary literature, comprising a sum of 4694 defects (see Table 174-1). When the defects were totaled, patent ductus arteriosus (PDA) (25.7%), subaortic stenosis (SAS) (23.5%), and pulmonary valve stenosis (PS) (22.1%) were found to be the most common and of nearly equal incidence, together comprising almost three fourths of all instances of CHD in the dog. Defects in the ventricular septum (8.8%) and atrial septum (1.9%) accounted for an additional 10.7% of cases, whereas dysplasias of the mitral valve (4.3%) and tricuspid valve (4.6%) were present in nearly equal frequency. The constellation of defects known as tetralogy of Fallot (ToF) accounted for 2.3% of defects, whereas more complex lesions not easily classified into the aforementioned categories made up 3.4% of CHD. Not all studies provided data on vascular ring anomalies, which may present with noncardiac signs and therefore likely are underrepresented in these data. TABLE 174-1 Congenital Heart Disease in Dogs Combined data from Patterson DF: Epidemiologic and genetic studies of congenital heart disease in the dog, Circ Res 23:171, 1968; Mulvihill JJ, Priester WA: Congenital heart disease in dogs: epidemiologic similarities to man, Teratology 7:73, 1973; Hunt GB, Church DB, Malik R: A retrospective analysis of congenital cardiac anomalies (1977-1989), Aust Vet Pract 20:70,1990; Buchanan JW. Causes and prevalence of cardiovascular disease. In Kirk RW, Bonagura JD, editors: Current veterinary therapy XI: small animal practice, Philadelphia, 1992, Saunders, p 647; Tidholm A: Retrospective study of congenital heart defects in 151 dogs, J Small Anim Pract 38:94, 1997; Kittleson MD: The approach to the patient with cardiac disease. In Kittleson MD, Kienle RD, editors: Small animal cardiovascular medicine, St Louis, 1998, Mosby, p 195; Buchanan JW: Prevalence of cardiovascular disorders. In Fox PR, Sisson DD, Moise NS, editors: Textbook of canine and feline cardiology, ed 2, Philadelphia, 1999, Saunders, p 458; Baumgartner C, Glaus TM: Congenital cardiac diseases in dogs: a retrospective analysis, Schweiz Arch Tierheilkd 145:527, 2003; Gregori T et al: Congenital heart defects in dogs: a double retrospective study on cases from University of Parma and University of Zaragoza, Ann Fac Medic Vet di Parma 28:79, 2008; Oliveira P et al: Retrospective review of congenital heart disease in 976 dogs, J Vet Intern Med 25:477, 2011. TABLE 174-2 Congenital Heart Disease in Cats Combined data from Liu SK: Pathology of feline heart diseases, Vet Clin North Am Small Anim Pract 7:323, 1977; Harpster N, Zook B: The cardiovascular system. In Holzworth J, editor: Diseases of the cat: medicine and surgery, Philadelphia, 1987, Saunders, p 820; Hunt GB, Church DB, Malik R: A retrospective analysis of congenital cardiac anomalies (1977-1989), Aust Vet Pract 20:70, 1990; Kittleson MD: The approach to the patient with cardiac disease. In Kittleson MD, Kienle RD, editors: Small animal cardiovascular medicine, St Louis, 1998, Mosby, p 195; Michaelsson M, Ho SY: Congenital heart malformations in mammals, London, 2000, Imperial College Press. There are few studies evaluating the use of cTnI as a biomarker in animals with CHD. A mild elevation (median, 0.20 ng/ml; range, 0.20 to 1.29) was shown in 30% of dogs with PS before balloon valvuloplasty (Saunders et al, 2009b). However, a study by a different group found normal cTnI values (≤0.05 ng/ml) in dogs with PDA and PS before intervention (Shih et al, 2009). Based on these limited data, cTnI level does not appear to be a reliable screening test for CHD in animals, although further studies are needed.
Congenital Heart Disease
Prevalence
Diagnostic Testing
Congenital Heart Disease
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