Heparin (unfractionated)
Also known as: Heparin, Hepsal
Heparin is used to prevent dangerous blood clots. * **Watch for bleeding:** The most common side effect is bleeding. Contact your veterinarian immediately if you notice pale gums, unexplained bruising, nosebleeds, blood in the urine, or dark/tarry stools. * **Prevent injury:** Keep your pet calm and avoid rough play or activities that could lead to injury or bruising while they are on this medication. * **Do not mix medications:** Never give your pet aspirin, NSAIDs, or any other over-the-counter medications without consulting your veterinarian, as this can cause fatal bleeding.
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
What it is used for
How it is given
Possible side effects
- Hemorrhage (most common)
- Heparin-induced thrombocytopenia (HIT)
- Injection site reactions (hematoma, pain)
- Hypersensitivity reactions
Cautions & contraindications
- Active bleeding or severe bleeding disorders
- Severe thrombocytopenia
- Recent neurosurgery or ocular surgery
- Known hypersensitivity to heparin
- > **Important:** Do NOT administer intramuscularly (IM) due to the high risk of severe hematoma formation. Monitor activated partial thromboplastin time (aPTT) closely during therapeutic use. Extreme caution is advised in patients with severe hepatic or renal disease.
Drug interactions
- Aspirin: Increased risk of bleeding due to platelet inhibition
- NSAIDs: Increased risk of gastrointestinal ulceration and bleeding
- Warfarin: Synergistic anticoagulant effect; increased bleeding risk
- Clopidogrel: Increased risk of bleeding
Frequently asked questions
What is Heparin (unfractionated) used for in pets?
Heparin is used to prevent dangerous blood clots. * **Watch for bleeding:** The most common side effect is bleeding. Contact your veterinarian immediately if you notice pale gums, unexplained bruising, nosebleeds, blood in the urine, or dark/tarry stools. * **Prevent injury:** Keep your pet calm and avoid rough play or activities that could lead to injury or bruising while they are on this medication. * **Do not mix medications:** Never give your pet aspirin, NSAIDs, or any other over-the-counter medications without consulting your veterinarian, as this can cause fatal bleeding.
Is Heparin (unfractionated) safe for my pet?
Dosage must be set by your veterinarian for your specific pet. Never give human medication or another pet’s prescription without veterinary guidance.
This article is for general education and is not a substitute for professional veterinary advice. If your pet is unwell, please consult a veterinarian.
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