Heparin

Major Uses

Heparin is a parenteral anticoagulant that is commonly used to treat disseminated intravascular coagulation (DIC) and thromboembolic disease. For horses, it can be used for treating DIC, and also as prophylactic therapy for laminitis. Heparin is sometimes used to prevent intestinal adhesion formation after surgery, though its usefulness is yet to be determined.

Common Precautions

Heparin should not be used to treat DIC in patients with concurrent inflammatory processes. It should be used cautiously in patients with dysfunctional interactions between inflammatory and hemostatic systems and the endothelium. Heparin should not be administered intramuscularly, as this may cause hematoma formation. Subcutaneous administration may cause hematomas, pain, and irritation.

The most common side effects associated with heparin are bleeding and trombocytopenia. Some rarer side effects include vasospastic reactions, osteoporosis and diminished renal function, rebound hyperlipidemia, hyperkalemia, alopecia, suppressed aldosterone synthesis and priapism. Symptoms of an allergic reaction include severe thrombocytopenia or uncontrollable bleeding.

Heparin should not be used in animals with a known allergy or hypersensitivity to the drug. A veterinarian should be contacted immediately if an overdose is suspected, the most common symptom of which is bleeding. Other signs of an overdose include hematuria, tarry stools, petechiae, and bruising.

Storage

Heparin should be kept at room temperature and stored in a tight, light resistant, childproof container. It should not be frozen and it should be kept away from excessive exposure to heat.

Administration

Heparin is most commonly used in dogs and cats. The standard dose in both cats and dogs starts at 75 units/kg three times daily until the patient's pH has been corrected. At this point, the patient can begin receiving 5-10 units/kg per hour. For treatment of thromboembolic disease in dogs and cats, a typical dose is 250-500 units/kg. When treating horses, the initial dose should be 150 units/kg, followed by 125 units/kg every 12 hours for up to 6 doses, and then decreased to 100 units/kg every 12 hours. Should a dose be forgotten, it should be given as soon as possible. If the next scheduled dose is approaching, the missed dose should be skipped and the next scheduled dose should be administered. Under no circumstances should two doses be given at the same time.

Doses may vary in different species, when the drug is given by a different route or concurrently with other medications, and with regards to a patient's age, breed, and health status. A veterinarian's dosing instructions and/or those printed on the medication label should be followed closely.