Page 152 - Clinical Small Animal Internal Medicine

120 Section 3 Cardiovascular Disease

Case History and Owner Complaints respiratory rate of <30/min. As a general rule, long‐
VetBooks.ir A thorough medical history provides important infor- standing (weeks or months) respiratory signs that have
not worsened over time speak against CHF. Respiratory
signs, with or without cough, while lying down or asleep,
mation and is an integral part of the cardiovascular
examination. The questions may vary depending on the a phenomenon called nocturnal dyspnea/coughing, are
nature of the animal’s health problem. Information common early signs of left‐sided CHF. The severity of
obtained from the owner interview and findings at the dyspnea can range from mild, with only minimal changes
physical examination are used to formulate a problem in breathing pattern and respiratory rate, to severe life‐
list, which can be used in the decision to pursue further threatening dyspnea, when the pet is unwilling to lie
clinical testing. down (orthopnea), usually with respiratory rates >50/
Dogs and cats with heart disease can present with clini- min. The owner often describes changed breathing
cal signs related to the heart condition but also, the pet sounds in animals with severe pulmonary edema. Cats
can be completely free of signs of disease and the only rea- with left‐sided CHF frequently develop pleural effusion
son for the cardiac examination is an incidental finding of alone or in addition to pulmonary edema, and these cats
a heart murmur or arrhythmia. Common owner com- can exhibit a paradoxical breathing pattern.
plaints for a pet with heart disease include increased res- Dogs presenting with left‐sided decompensated CHF
piratory rate (tachypnea), difficulty of breathing and may present with cough. Cough is not commonly associ-
changed respiratory pattern (dyspnea), coughing (unusual ated with CHF in cats, and owner complaints of cough-
in cats), abdominal distension (ascites), fainting (syncope), ing in cats should raise the suspicion of other respiratory
tongue and mucous membrane cyanosis, weight loss, and disease. In dogs, there is also a problem distinguishing
weakness and exercise intolerance. These signs of heart cough caused by other diseases, such as small bronchial
disease can be grouped into four main categories: disease and tracheal collapse, from cough associated
with pronounced cardiomegaly with or without CHF.
respiratory abnormalities caused by left‐sided conges-
● There is no definitive way of distinguishing cardiac from
tive heart failure (CHF) noncardiac cough in dogs. A noncardiac cough is more
exercise intolerance, weakness, wasting, and syncope
● frequently nonproductive, loud and “honky,” whereas
caused by low cardiac output cough caused by left‐sided CHF can be softer and may
abdominal distension caused by right‐sided CHF
● have a more productive “wet” character, in particular
cyanosis caused by reduced oxygenation of peripheral
● in large dogs with DCM where co‐existing respiratory
blood. disease is less common.
Unfortunately, none of these signs is specific for heart dis-
ease, and may be caused by a wide variety of disorders. Exercise Intolerance, Weakness, Wasting,
and Syncope
Dyspnea, Tachypnea, and Cough
Variable degrees of weakness and exercise intolerance
The most common sequela of heart disease in dogs and often develop in dogs and cats with heart disease.
cats is left‐sided CHF. The increased pulmonary venous However, exercise intolerance can be difficult to assess in
pressure leads to pulmonary congestion and edema for- cats. Weakness and exercise intolerance can occur as a
mation, causing respiratory signs such as dyspnea, consequence of a reduced cardiac output resulting in
tachypnea, and cough (unusual in cats). Dyspnea may reduced peripheral perfusion with reduced oxygen and
appear in many different forms in pets with heart dis- nutrient delivery to skeletal muscles.
ease. In working dogs, an experienced owner might note Weakness, exercise intolerance, and syncopal events
a changed respiratory character during and/or after work can develop due to pulmonary hypertension or cardiac
at an earlier stage of disease. However, many dogs and arrhythmia, intermittent or sustained, in dogs and cats
cats do not exercise in this intense manner, which means with heart disease. Pets with sustained bradycardia or
that owners do not observe changed respiration until it is tachycardia are often weak even at rest and exhibit sig-
apparent at rest (at a comparably advanced stage). nificant exercise intolerance. In cases of intermittent
In general, the respiratory rate gradually increases fol- arrhythmia, the owner often describes a rapid change in
lowed by a worsening of dyspnea, but the respiratory the dog’s behavior, consciousness, or postural tone.
signs may develop at different rates in different diseases Defecation and urination can accompany these events.
and individuals. Accordingly, it is useful to have the Even though syncope can occur in dogs and cats with
owner monitoring the respiratory rate at home in an ani- heart disease, it is not specific for heart disease or heart
mal at risk for developing CHF. Dogs and cats without failure, which underlines the importance of obtaining an
decompensated CHF have in general a sleeping/resting accurate and detailed case history.