Questions? Call 1-877-357-9661
Heparin Sodium for Veterinary Use
by Barbara Forney, VMD
Heparin is a naturally occurring glycosaminoglycan that is found in mast cells. Most commercially available heparin is manufactured from porcine or bovine origin. Heparin's mechanism of action is on both the extrinsic and intrinsic coagulation pathways. It does not significantly change the concentration of clotting factors, but rather blocks the clotting pathways. Heparin will not dissolve an existing clot. Heparin does not cross the placenta and is used with caution during pregnancy when the benefits of anticoagulation are felt to outweigh the risks. The FDA classifies it as a Class C drug.
Heparin must be given either intravenously or subcutaneously. It is not absorbed orally and should not be given intramuscularly due to hematoma formation. With the exception of IV catheter maintenance, most heparin use is in animals with serious medical problems and will require close supervision and hematologic monitoring.
Dogs Cats and Horses
Heparin is used in a variety of medical conditions where there is excessive clotting or increased risk of clot formation. These may include thromboembolic disease, pancreatitis, laminitis, endotoxic shock and burns. It also is used commonly for the maintenance of intravenous catheters. Heparin commonly was used to treat disseminated intravascular coagulopathy, but that use is becoming controversial.
Heparin Sodium Side Effects
- Bleeding and thrombocytopenia.
- Hypersensitivity reaction may occur due to the foreign protein.
- Numerous rare side effects include decreased kidney function, osteoporosis, vascular spasm, electrolyte abnormalities and hyperlipidemia.
- Heparin should not be used in animals with severe thrombocytopenia, those that are actively bleeding or have uncontrollable bleeding.
- There is wide variability in the response to heparin and a wide range of recommended doses. Regular monitoring of clotting function is important particularly during the early stages of treatment.
- Heparin should be used with caution when used with other drugs that affect coagulation such as NSAIDs, aspirin and wafarin.
- Heparin may reduce the effects of corticosteroids, insulin and ACTH.
- Antihistamines, nitroglycerin, digoxin and tetracycline may decrease the effects of heparin.
Heparin overdose is associated with bleeding. Before frank bleeding occurs, subtler symptoms may include bruising, petechiaie and blood in the urine or stool. Protamine is the drug of choice for heparin toxicity. Protamine will bind with heparin and neutralize the anti-thrombin effects within five minutes of intravenous injection.
About the Author
Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.
She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.
Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.
You can purchase books by Dr. Forney at
The information contained on this site is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the products shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular product. You should consult your doctor about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the products to diagnose, cure or prevent disease.
Wedgewood Pharmacy's compounded veterinary preparations are not intended for use in food and food-producing animals.