Solution for Case 14

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Radiographs show reverse ‘D’ appearance of heart on VD/DV views. Enlargement of right ventricle on lateral view. Enlargement of main pulmonary artery and tortuous appearance of pulmonary arteries.


Diagnosis: Heartworm disease


Differentials for the signs presented:

• Dilated Cardiomyopathy
• Congestive Heart Failure (Right-sided)

Further diagnostic tests:

• Heartworm snap test
• Echocardiography
• CBC, Chemistry and urinalysis.

Radiographic findings are suggestive of heartworm disease. 2/6 Right AV systolic murmur may be due to heartworm disease. Other causes of the murmur could be dilated cardiomyopathy or congestive heart failure. Murmurs are caused by turbulent blood flow through the heart and vessels, a grade 2 murmur is a faint murmur restricted to a localized area.


Dilated cardiomyopathy (DCM) is an acquired disease characterized by progressive loss of cardiac contractility, ultimately leading to both left and right-sided congestive heart failure. It was ruled out based on radiographic findings.


Congestive heart failure (CHF) results in pulmonary edema (left-sided heart failure) or ascites (right-sided heart failure). With DCM and CHF, tachycardia is usually present. The absence of pulmonary edema and/or ascites rule out dilated cardiomyopathy and congestive heart failure.


Definitive diagnosis is heartworm disease based on thoracic radiographs and a positive heartworm test.


Treatment:

• Prednisone 0.5mg/kg PO EOD for 10 days to combat any inflammation and as preventative for pulmonary thromboembolism.
• Immiticide treatment- alternative dosing: 1 injection of Melarsomine HCL 2.5mg/kg deep IM, repeat injection in 1 month with 2 injections 24 hours apart.
• A month after the third injection, give heartworm prevention.
• Heartworm test 4 months after second set of immiticide injections.
• Monitor for pulmonary thromboembolism, possibly administer anticoagulants. 
• Strict cage rest while being treated.
• Monitor heart rate, respiration and attitude.

Solution for case 12

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Radiographic findings: Thoracic radiographs showed a valentine shaped heart with significant generalized cardiomegaly and enlarged pulmonary arteries and veins. Abdominal radiographs showed homogenous soft tissue opacities with little visceral details which strongly suggest the presence of a significant amount fluid in the abdomen.

Tentative diagnosis: Congestive heart failure (Hypertrophic cardiomyopathy).

Differentials:

• Heartworm
• Restrictive and Dilated cardiomyopathy
• Hyperthyroidism
• Feline infectious peritonitis (FIP)
• Feline asthma

Hypertrophic cardiomyopathy is common in the cat and is characterized by concentric ventricular hypertrophy in which the ventricular walls become thickened. The heart pumps well but cannot relax well during diastole. In addition, the thickening of the ventricles results in malorientation of the AV valves so the cat may develop mitral regurgitation. The cat may also develop dynamic aortic outflow obstruction secondary to the systolic anterior motion of the mitral valve.

Cat was positive for heartworm, and can be further confirmed by ultrasound which is more reliable in cats.

This patient is suffering from ascites and dyspnea secondary to hypertrophic cardiomyopathy complicated by heartworm disease. Thorax radiograph showed enlarged pulmonary arteries and veins which may be supportive of heartworm disease.

Two possible differentials are dilated cardiomyopathy caused by a taurine deficiency and restrictive cardiomyopathy caused by fibrosis of the endocardium, myocardium, or subendocardial tissues. These can be differentiated from HCM because dilated cardiomyopathy is rare since most cat foods are supplemented with taurine and restrictive cardiomyopathy usually shows enlargement of one or both atria and not a generalized hypertrophy.

A T4 test was done to rule out hyperthyroidism.

In FIP we will see presence of an exudate aspirated from the abdomen as well as an inflammatory CBC.

There was no eosinophilia present in the CBC to support a diagnosis of feline asthma; however, eosinophils in a transtracheal lavage would be more diagnostic.

Treatment:

Due to the dyspnea, the patient was immediately started on oxygen therapy with a pulse oximeter and oxygen levels increased from 80% to 98% oxygen saturation. A catheter was placed, IV fluids were started.

The patient was placed on furosamide (10mg IV twice a day) and diltiazem (10 mg/kg PO q24h) (Ca channel blocker) to treat the hypertrophic cardiomyopathy, pulmonary edema, and ascites. Fluid therapy was continued at twice the maintenance dose (2-3ml/kg/h) for 4 days.

Client education: The patient needs to be on daily heart medications for the rest of its life. Heartworm preventative needs to be given monthly to help prevent the heartworm disease from getting worse.