Page 31 - Small Animal Internal Medicine, 6th Edition

CHAPTER 1 Clinical Manifestations of Cardiac Disease 3

implantable loop recording device. In-hospital continuous The cough associated with cardiogenic pulmonary edema
ECG monitoring for a period of time sometimes reveals a in dogs often is soft and moist; it sometimes sounds like
VetBooks.ir culprit arrhythmia also. gagging. Cats, in contrast, rarely cough from pulmonary
edema. Tachypnea progressing to dyspnea occurs in both
Cardiovascular Causes of Syncope
associated with coughing as well. Mainstem bronchus col-
Various arrhythmias, obstruction to ventricular outflow, cya- species. Pleural and pericardial effusions occasionally are
notic congenital heart defects, and acquired diseases that lapse or compression associated with severe LA enlargement
impair cardiac output are the usual causes of CV syncope. can stimulate a dry or hacking cough in dogs with chronic
Activation of vasodepressor reflexes and excessive dosages of mitral valve disease, even when pulmonary edema or con-
CV drugs also can induce syncope. Arrhythmias that provoke gestion is absent. Concurrent bronchomalacia is likely to be
syncope usually are associated with either very fast or very a contributing factor in these cases. A heart base tumor,
slow heart rates and can occur with or without identifiable enlarged hilar lymph nodes, or other masses that impinge on
underlying organic heart disease. Ventricular outflow an airway also can stimulate this type of cough.
obstruction can provoke syncope or sudden weakness if When respiratory signs have a cardiac cause, other evi-
cardiac output becomes inadequate during exercise or if high dence of heart disease usually is evident, such as generalized
systolic pressure activates ventricular mechanoreceptors, cardiomegaly, LA enlargement, pulmonary venous conges-
causing inappropriate reflex bradycardia and hypotension. tion, lung infiltrates that resolve with diuretic therapy, or a
Both dilated cardiomyopathy and severe mitral insufficiency positive heartworm test. Findings on physical examination,
can impair forward cardiac output, especially during exer- thoracic radiographs, cardiac biomarker assays, echocardio-
tion. Vasodilator and diuretic drugs can induce syncope if gram, and sometimes an ECG, help in differentiating cardiac
given in excess. from noncardiac causes.
Syncope caused by abnormal peripheral vascular and/or
neurologic reflex responses is not well defined in animals,
but is thought to occur in some patients. Syncope associ- CARDIOVASCULAR EXAMINATION
ated with sudden bradycardia after a burst of sinus tachy-
cardia has been documented, especially in small breed dogs The medical history (Box 1.3) is an important part of the CV
with advanced atrioventricular (AV) valve disease; excite- evaluation and can help guide the choice of diagnostic tests
ment often precipitates such an episode. Doberman Pin- because it may suggest various cardiac or noncardiac dis-
schers and Boxers similarly may experience syncope after eases. The patient’s signalment is useful because some
sudden bradycardia. Postural hypotension and hypersensi-
tivity of carotid sinus receptors infrequently can provoke
syncope by inappropriate peripheral vasodilation and BOX 1.3
bradycardia. Important Historic Information
Fainting associated with a coughing fit (cough syncope or
“cough-drop”) occurs in some dogs with marked left atrial Signalment (age, breed, gender)?
(LA) enlargement and bronchial compression, as well as in Vaccination status?
dogs with primary respiratory disease. Several mechanisms What is the diet? Have there been any recent changes in
have been proposed, including an acute decrease in cardiac food or water consumption?
filling and output during the cough, peripheral vasodilation Where was the animal obtained?
after the cough, and increased cerebrospinal fluid pressure Is the pet housed indoors or outdoors?
with intracranial venous compression. Severe pulmonary How much time is spent outdoors? Supervised?
What activity level is normal? Does the animal tire easily
disease, anemia, certain metabolic abnormalities, and now?
primary neurologic diseases also can cause collapse that Has there been any coughing? When? Describe
resembles CV syncope. episodes.
Has there been any excessive or unexpected panting or
COUGH AND OTHER heavy breathing?
RESPIRATORY SIGNS Has there been any vomiting or gagging? Diarrhea?
CHF in dogs produces tachypnea, respiratory distress, and Have there been any recent changes in urinary habits?
sometimes coughing. These signs also can occur with the Have there been any episodes of fainting or weakness?
pulmonary vascular pathology and pneumonitis of heart- Do the tongue/mucous membranes always look pink,
worm disease in both dogs and cats. Noncardiac conditions, especially during exercise?
including diseases of the upper and lower airways, pulmo- Have there been any recent changes in attitude or
activity level?
nary parenchyma (including noncardiogenic pulmonary Are medications being given for this problem? What?
edema), pulmonary vasculature, and pleural space, as well How much? How often? Do they help?
as certain nonrespiratory conditions, also should be con- Have medications been used in the past for this problem?
sidered in patients with cough, tachypnea, or dyspnea (see What? How much? Were they effective?
Chapter 19).