Page 707 - Small Animal Clinical Nutrition 5th Edition

734 Small Animal Clinical Nutrition

Various types of myocardial disease that were not recog- tric hypertrophy), and hypertension may complicate the treat-
VetBooks.ir nized 40 years ago are now seen relatively commonly in dogs ment of chronic mitral valvular disease in dogs by worsening
valvular regurgitation. It makes good clinical sense to screen
(Buchanan, 1992). Large-breed dogs, especially males, are
dogs and cats with significant heart disease for the presence of
predisposed to dilated cardiomyopathy. Doberman pinscher
dogs are particularly susceptible. Hypertrophic cardiomyopa- systemic hypertension (by repeated blood pressure measure-
thy occurs rarely in dogs. Arrhythmogenic right ventricular ments), and also makes sense to search for underlying heart dis-
cardiomyopathy is common among boxer dogs (Meurs and ease in patients with known hypertension, especially those
Spier, 2009). exhibiting clinical signs that may be referable to heart disease.
Pulmonary vascular disease with secondary cor pulmonale is The most frequently encountered problems associated with
most commonly associated with Dirofilaria immitis infection cardiovascular disease that require nutritional modification are
(heartworm disease). The prevalence of this disease is high in fluid retention states associated with chronic CHF, primary or
endemic areas in those dogs that do not receive appropriate secondary hypertension, obesity, cachexia and myocardial dis-
preventive medication. Pulmonary hypertension unrelated to eases related to a specific nutrient deficiency (taurine- and car-
heartworm disease appears to be more common than previous- nitine-associated cardiomyopathy and electrolyte disorders that
ly believed and the frequency of diagnosis has increased because may predispose to cardiac dysrhythmias.
of heightened awareness about the condition (Henik, 2009)
and the more widespread application of Doppler echocardiog-
raphy. Pulmonary thromboembolism is most commonly asso- PATIENT ASSESSMENT
ciated with renal disease, hyperadrenocorticism, corticosteroid
therapy, neoplasia, nephrotic syndrome, pancreatitis and im- History and Physical Examination
mune-mediated hemolytic anemia. Primary systemic vascular Heart failure is a condition characterized by inadequate cardiac
disease is uncommon, but atherosclerosis and aortic or coronary output and insufficient delivery of nutrients relative to tissue
thrombosis are occasionally recognized, particularly in dogs metabolic needs. Heart failure is not a specific disease, but a
with hypothyroidism and elevated serum cholesterol concen- clinical syndrome caused by a variety of structural and func-
trations. Secondary aortic thromboembolism in cats may occur tional disorders of the heart or great vessels. Clinical manifes-
with any of the forms of cardiomyopathy and is the most fre- tations of heart failure are due to reduced cardiac output (weak-
quently acquired feline vascular abnormality. ness, exercise intolerance, syncope), pulmonary congestion
Systemic hypertension in dogs and cats appears to be more (dyspnea, orthopnea, cough, abnormal breath sounds with
common than studies indicated 40 years ago (Brown et al, crackles and wheezes), systemic fluid retention (jugular venous
2007). Because blood pressure measurement in dogs and cats is distention, hepatomegaly, ascites, pleural effusion) or a combi-
technically challenging compared to measurement in people, nation of these conditions.
and because of the prominent “white coat effect” in animals In general,the clinical manifestations of heart failure are sim-
(elevations in measured blood pressure associated with the ilar irrespective of the underlying cause, although the onset may
stress of the clinical visit) the actual prevalence of systemic vary. Occasionally, for example, heart failure may occur abrupt-
hypertension in dogs and cats is still unknown. Spontaneous ly and lead to acute pulmonary edema (e.g., ruptured mitral
essential hypertension occurs in dogs, but hypertension most valve chorda tendineae). Diagnosis of this fulminant form of
commonly develops secondary to chronic kidney disease in heart failure is based on the history and overt, acute clinical
dogs and cats, hyperadrenocorticism in dogs and hyperthy- signs. In many instances, however, heart failure becomes evi-
roidism in cats (Littman and Drobatz, 1995).The demograph- dent gradually; a long asymptomatic period (years) following
ic characteristics of dogs and cats at risk for the diseases that the diagnosis of chronic valvular heart disease based on the
predispose to systemic hypertension overlap with those of dogs presence of the typical murmur of mitral valve insufficiency is
and cats with acquired heart disease. Although hypertensive typical–this period may be followed by the onset of mild clini-
dogs and cats may present at any age, most often they are mid- cal signs that worsen gradually, or by the sudden onset of severe
dle-aged to geriatric (mean age: dogs nine years; cats 15 years, pulmonary edema. Most of the clinical signs used as the basis
Littman and Drobatz, 1995). The strength of the peripheral for diagnosing chronic heart failure may also occur as a result of
pulses does not help detect systemic hypertension; absolute other conditions.
blood pressure numbers need to be determined. Retinal hem- Validity of a clinical diagnosis of heart failure in human
orrhages and detachments are common end-organ changes in patients was studied in a primary health care setting (Remes et
patients with moderate to severe hypertension. These ocular al, 1991). One-third of human patients who were initially diag-
signs are often the first evidence of hypertensive disease, which nosed with heart failure were subsequently found to have other
suggests that a fundic examination should be included in the conditions that caused their clinical problems. Obesity and pul-
routine evaluation of all dogs and cats. Other clinical signs of monary diseases were the most important conditions leading to
hypertension are most often related to the underlying disease false-positive diagnoses of heart failure in this population of
that causes systemic hypertension. human patients. Obesity and chronic bronchitis often occur in
The effects of long-term or severe systemic hypertension dogs and cats with heart disease and cause clinical manifesta-
may cause significant heart disease (e.g. left ventricular concen- tions similar to those of heart failure, thereby complicating the