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25 Valvular Heart Disease 251

or diastolic murmur in a patient with a predisposing
VetBooks.ir condition should be considered suspicious for IE.
Patients with aortic IE and severe aortic insufficiency
may present bounding femoral pulses. Thirty‐seven
percent of dogs with IE present with clinical signs of
CHF at the time of the diagnosis.

Diagnosis
Diagnosis of IE is challenging. Antemortem diagnosis
involves blood cultures, preferably performed before anti-
biotic treatment is started. Three to four blood samples
should be collected aseptically from different venous sites
at least one hour apart and submitted for aerobic and
anaerobic culture. Blood samples should also be collected Figure 25.3 Echocardiographic long axis image of the aortic
and cultured for Bartonella spp. Recently, polymerase valve. A hyperchoic, mobile, irregular‐shaped mass is present
chain reaction (PCR) has been proposed as an alternative adherent to the valve leaflet.
method for the diagnosis of Bartonella infection. A com-
plete blood count (CBC) and serum biochemistry profile the presence of two major criteria or one major and two
should be performed in all patients with suspected IE in minor criteria. The presence of one major and one minor
order to assess multiorgan involvement. Leukocytosis, criteria or three minor criteria is suspicious for IE.
thrombocytopenia, anemia, hypoalbuminemia, increased
liver enzymes, and azotemia are the most commonly Treatment
reported laboratory findings in dogs with IE.
Echocardiography allows the identification of vegetative Long‐term bactericidal antibiotics are the main therapy
valvular lesions and assessment of the severity of the valvu- for patients affected by IE. Broad‐spectrum combina-
lar insufficiency and is complementary to blood cultures in tions of antibiotics such as enrofloxacin and ampicillin
establishing the diagnosis of IE in the dog and cat. Typical should be administered empirically if blood culture is
lesions are represented by an hyperchoic, mobile, irregular‐ not available or pending. Treatment of Bartonella spp.
shaped mass adherent to the valve (Figure 25.3). involves doxycycline, fluoroquinolones, or azithromycin.
Valvular insufficiency is a common finding. Patients In dogs requiring hospitalization, intravenous aminogly-
with chronic valvular IE and severe valvular regurgitation cosides such as amikacin have been recommended.
may present with left ventricular eccentric hypertrophy. Ideally, antibiotic therapy is guided by results of culture
Although the presence of typical valvular lesions strongly and sensitivity testing. Oral antibiotics are often contin-
supports the diagnosis of IE, small lesions on the mitral ued for 6–8 weeks. Serial echocardiograms or blood
valve can be difficult to differentiate from lesions due to cultures are used to monitor response to therapy. Patients
myxomatous degeneration. with heart failure secondary to IE should be treated with
The diagnostic criteria for IE in dogs and cats is modi- standard CHF treatment.
fied from the human “Duke criteria”. Major criteria for
diagnosis are a positive echocardiogram, new valvular Prognosis
insufficiency, and a positive blood culture (≥2 positive
cultures or ≥3 positive cultures with common skin con- Generally, patients with IE have a relatively poor prog-
taminants). Minor diagnostic criteria are fever, medium nosis. Outcome is related to the degree of valvular
to large dog (>15 kg), subaortic stenosis, thromboem- regurgitation and nature of the underlying predisposing
bolic disease, immune‐mediated disease, positive blood cause. Dogs with aortic IE fare worse than dogs with
cultures not meeting major criteria, and Bartonella mitral IE (three days versus 476 days median survival
serology ≥1:1024. A definitive diagnosis of IE involves time).