Veterinary Clinical Medicine-I (General and Systemic)

CANINE CARDIOMYOPATHY

Dilatted form

• The dilated form is the most common form. It occurs in large breed dogs, 3-7 years of age
• Diagnosis
  • History
    • Lethargy , cough , exercise intolerance, anorexia , abdominal swelling.
  • Physical exam
    • Pulses weak, pulses deficits, harsh lung sounds, dyspnea, ascites, pale mucous membranes, cardiac cachexia.
  • Throacic radiographs
    • May possibly see generalized cardiomegaly, pulmonary edema, pleural effusion.
  • Echocardiongraphy
    • Ventricular and artial dilatation, with depressed myocardial systolic function, mitral or tricuspid regurgitation, decreased aortic ejection velocity.
• Prognosis
  • The prognosis is guarded to grave. The average life span after diagnosis is 6 months to 2 years.
• Treatment
  • Inform the client of the diagnosis, prognosis, and cost of the treatment.
  • Immediate stabilization.
    • Place an IV catheter. Evaluate PCV/TP,BUN.
    • Administer furosemide, 2-6 mg/kg q8h; or bumetanide, 0.05-0.2 mg/kg/IV or PO, as needed for severe pulmonary edema (Caution: Most monitor serum potassium levels and maintain with IV fluids to prevent excessive fluid and potassium depletion)
    • Administer a bronchodilator
      • Aminophylline 5-10 mg/kg slow IV,PO q6-8h.
      • Theophylline , 4-8 mg/kg PO q6-8h.
      • Long-acting theophylline (Theo-Dut*), 10-25 mg/kg q12h.
      • Terbutaline (Brethine*), 1.25 mg/PO q8-12h or 0.01 mg/kg q4h.
      • Albuteral (Proventil*), 0.02-0.05 mg/kg q8h.
    • Administer nasal oxygen, apply an Elizabethan collar for hood oxygenation, or place the patient in an oxygen cage, possibly with 35% ethyl alchol (mix 53.5 ml 100 proof Vodka with 100 ml sterile water in the nebulizer).
    • Consider the administration of morphine, 0.1-1mg/kg SC.
    • Consider the application of nitroglycerine cream, 0.25-2 inches q4-6h rubbed on clipped skin on the thorax or abdomen (wear a glove and use a tongue depressor). Cover the area with nonpremeable tape to prevent inadvertent administration to the patient health care provider.
  • After stabilization
    • Throacic, radiogrphs-generalized cardiomegaly, pulmonary, pleural effusion.
    • ECG- variable, possible artial fibrillation, wide QRS complexes, numerous other changes may be observed. Treat arrhythmias as indicated.
    • Consider the administration of digoxin, 0.0025 mg/lb PO q12h * Maximum doses: Doberman = 0.375 mg/day, other breeds =0.500 mg/day.
    • Administer furosemide, 2 mg / day, oher breeds = 0.500 mg / day.
    • Administer an angiotensin-converting enzyme (ACE) inhibitor
      • Captopril, 0.25 - 1 mg / kg PO q8 - 12h.
      • Enalapril, 0.5 mg/kg PO q12-24h.
      • Diltiazem, 1-2 mg/kg PO q812h.
    • Administer β-adrenergic(beta-adrenergic)-blocking medication
      • Sotolol (Betapace^@), 1.0-5.0 mg/kg PO q12h.
      • Metoprolol (Lopressor^@) ,0.5-1.0 mg/kg PO q8th.
      • Atenolol (Tenormin^@), 0.5.-1.0 mg/kg PO q8h.
    • Dobutamine, 5-20 µg/kg/min IV infusion. Positive inotropic agent
      • (Wt in kg)x(no of µg/kg/min) = no of mg to add to 250ml D5W at a drip rate of 15ml/h.
      • Must protect from light.
      • See effect within 3-5 min.
    • Offer a sodium-restricted diet such as Hills h/d^@ and water.
    • Consider supplementation with L-carnitrine, 1-2 g q8-12h PO, and taruine 500 mg/kg PO q12h.
    • Administer conservative intravenous fluids with 5% destrose in water or 2.5% destrose in 0.45% Nacl at 0.5-0.75 times maintenance rates.
  • Arrhythmias-treat accordingly

Hypertrophic form

• Diagnosis
  • History
    • Sudden death, often asymptomatic, or left heart failure.
  • Physical exam
    • In the small number of symptomatic dogs, dyspnea, moist rales and ascities is observed.
  • ECG
    • Possible heart blocks.
  • Thoracic radiographs
    • Possible cardiomegaly (Caution: Plain radiographs may not differentiate between the hypertrophic and the dilated forms.)
  • Echoradiography
    • Left artial enlargement, thickening of the interventicular septum and/or left ventricular free wall.
• Prognosis
  • The prognosis is guarded to grave.
• Treatment
  • Inform the client of the diagnosis, prognosis, and cost of the treatment.
  • Place an intravenous catheter.
  • Administer oxygen as needed.
  • Administer propranolol (Inderal^@) , 0.04-0.06 mg/kg q8h, or 0.2-1 mg/kg PO q8th
  • Restrict exercise, excitement, stress.
  • Administer furosemide or bumetanide.
  • Digitalis is not indicated