Page 92 - Problem-Based Feline Medicine

84 PART 2 CAT WITH LOWER RESPIRATORY TRACT OR CARDIAC SIGNS

● Thoracocentesis should be performed in all acutely tive in distinguishing cardiomyopathy from pericardial
dyspneic animals, prior to radiography. These effusion.
patients are extremely fragile, and even the minimal
restraint involved in radiography may be excessive,
Treatment
and they may die during the procedure.
● A transudate, modified transudate, or chylous Emergency thoracocentesis can be life saving in cats
effusion are the most common fluid types in heart with severe respiratory distress.
disease. ● A 23 G butterfly set on a 60 ml syringe is introduced
● Heart sounds are often more apparent after the at the 5th–7th intercostal space (ICS) on the right,
chest tap, and murmurs, gallops or dysrhythmias just above the costochondral junction. Remove as
may be heard. Be certain to remove as much fluid much fluid as possible, or until breathing improves.
as possible, do not stop after you have a diagnostic Thoracocentesis can usually be performed without
sample. sedation or local anesthetic block
● A negative tap for fluid suggests pulmonary edema
Oxygen therapy should be administered using an O
rather than effusion from cardiac disease. 2
chamber, masks or tents.
Thoracic radiography
Furosemide (1–2 mg/kg IV or IM) should be admin-
● This is best performed in the acutely dyspneic patient
istered without stressing the patient.
after thoracocentesis and stabilization.
● Findings may include enlarged cardiac outline, pul- Use sedation if the cat is frantic (morphine 0.1 mg/kg
monary venous distention, and patchy alveolar infil- IM prn, or butorphanol 0.2–0.4 mg/kg IM q 4–6 h as
trates indicating pulmonary edema. needed).
Echocardiography Nitroglycerin 2% cream – 1/8 to 1/4 inch applied to
● This is the definitive modality for diagnosis of car- the skin of the medial pinna q 4–6 hours for 24 hours.
diomyopathy, as well as the primary tool for catego-
Take a “hands off” approach until stable, as the slight-
rization of the type and severity of disease. Various
est stress can cause lethal decompensation in these
forms of cardiomyopathy include hypertrophic
fragile cases.
(HCM), dilated (DCM), restrictive (RCM) and inter-
mediate (ICM). Therapeutic strategies and prognosis Definitive therapy is based upon ultrasonographic
rely heavily on the echocardiographic information. characterization of the type and severity of the car-
Thoracocentesis should be performed prior to echocar- diomyopathy present, but this is not performed until
diography in the severely dyspneic patient, otherwise the patient is stable.
death may occur during the procedure.
● Electrocardiography is important if an arrhythmia
Prognosis
is detected during physical exam or ultrasound
exam. The prognosis is related to the clinical and echocar-
diographic severity. Severe left atrial enlargement pre-
Differential diagnosis disposes to aorto-iliac thromboembolism, which
worsens the prognosis.
Other forms of pleural effusion are not associated
with abnormal heart sounds (murmurs, gallops,
arrhythmias). Prevention
Pericardial effusion may create pleural effusion, an Taurine supplementation of commercial cat foods in
enlarged heart shadow on radiographs and possibly an North America has dramatically decreased the inci-
abnormal ECG pattern. Electrical alternans on ECG dence of dilated cardiomyopathy in cats. Causes for
tends to signal pericardial effusion, especially if the the other cardiomyopathies remain unclear at this
pleural effusion has been drained. Ultrasound is defini- time.