Doses - HYDRALAZINE HCL
Because of the sodium/water retention associated with this drug it should be given concurrently with a diuretic. Many clinicians recommend adding a venous dilating agent (e.g., nitroglycerin ointment) to also reduce preload. Dogs:
For adjunctive therapy in treatment of heart failure:
a) Get initial baseline monitoring parameters. Initial dose of 1 mg/kg PO. Measure bloodpressure in 1 hour and blood gas in 3 hours, or reevaluate clinical signs from 5 hours to1 day later. If mean blood pressure has decreased by 15-20 mmHg or is < 70 mmHg; orif venous pO2 was <35 mmHg and is now > 35 mmHg; if mucous membrane color hasimproved dramatically and pulmonary edema is decreased, the titration is complete andgive 1 mg q12h. If the 1 mg/kg dose was ineffective, give another 1 mg/kg if the lastdose given was less than 8 hours previous; if greater than 12 hours ago, give 2 mg/kg.
Evaluate as above. If still no response, increase dose to 3 mg/kg. Maintenance dosingcan be given at 12 hour intervals. (Kittleson 1985b)
b) 1-3 mg/kg PO bid (Morgan 1988)
For treatment of systemic hypertension:
a) 0.5 - 2.0 mg/kg PO bid-tid (Morgan 1988)
For acute arterial embolism:
a) 1 - 2 mg/kg PO, IM bid (Morgan 1988)Cats:
For adjunctive therapy in treatment of heart failure:
a) See (a) above (For adjunctive therapy in treatment of heart failure in dogs:), but starttitration at 2.5 mg (total dose) and if necessary, increase up to 10 mg. (Kittleson 1985b)
For treatment of systemic hypertension:
a) 2.5 mg PO bid (Morgan 1988)
For acute arterial embolism:
a) 2.5 mg PO bid (Morgan 1988)
Monitoring Parameters -1) Baseline thoracic radiographs 2) Mucous membrane color 3) Serum electrolytes 4) If possible, arterial blood pressure and venous PO2 5) Because blood dyscrasias are a possibility, an occasional CBC should be considered.
Client Information - Compliance with directions is necessary to maximize the benefits from this drug. If possible, give medication with food. Notify veterinarian if patient's condition deteriorates or if the animal becomes lethargic or depressed.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times - Veterinary-Approved Products: None
Dogs: 
For adjunctive therapy in treatment of heart failure: a) Get initial baseline monitoring parameters. Initial dose of 1 mg/kg PO. Measure bloodpressure in 1 hour and blood gas in 3 hours, or reevaluate clinical signs from 5 hours to1 day later. If mean blood pressure has decreased by 15-20 mmHg or is < 70 mmHg; orif venous pO2 was <35 mmHg and is now > 35 mmHg; if mucous membrane color hasimproved dramatically and pulmonary edema is decreased, the titration is complete andgive 1 mg q12h. If the 1 mg/kg dose was ineffective, give another 1 mg/kg if the lastdose given was less than 8 hours previous; if greater than 12 hours ago, give 2 mg/kg.
Evaluate as above. If still no response, increase dose to 3 mg/kg. Maintenance dosingcan be given at 12 hour intervals. (Kittleson 1985b)
b) 1-3 mg/kg PO bid (Morgan 1988)
For treatment of systemic hypertension:
a) 0.5 - 2.0 mg/kg PO bid-tid (Morgan 1988)
For acute arterial embolism:
a) 1 - 2 mg/kg PO, IM bid (Morgan 1988)
Cats: 
For adjunctive therapy in treatment of heart failure: a) See (a) above (For adjunctive therapy in treatment of heart failure in dogs:), but starttitration at 2.5 mg (total dose) and if necessary, increase up to 10 mg. (Kittleson 1985b)
For treatment of systemic hypertension:
a) 2.5 mg PO bid (Morgan 1988)
For acute arterial embolism:
a) 2.5 mg PO bid (Morgan 1988)
Monitoring Parameters -
Client Information - Compliance with directions is necessary to maximize the benefits from this drug. If possible, give medication with food. Notify veterinarian if patient's condition deteriorates or if the animal becomes lethargic or depressed.
Dosage Forms/Preparations/FDA Approval Status/Withholding Times - Veterinary-Approved Products: None