Low Molecular Weight Heparin (Dalteparin, Enoxaparin)
Low Molecular Weight Heparin
Also known as: Clexane · Fragmin · LMWH · Dalteparin · Enoxaparin
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Thromboembolic complications and hypercoagulable syndromes | Target anti-Factor Xa activity of 0.35-0.7 IU/ml | SC/IV | variable | As directed | 🌍 EU |
- Thromboembolic complications and hypercoagulable syndromes: Doses are controversial. Requires sufficient AT III. May use constant IV infusions.
Cats
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Thromboembolic complications and hypercoagulable syndromes | Target anti-Factor Xa activity of 0.35-0.7 IU/ml | SC/IV | variable | As directed | 🌍 EU |
- Thromboembolic complications and hypercoagulable syndromes: Cats appear to require higher dosages of LMWH to achieve proposed therapeutic targets.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Low molecular weight heparin (LMWH), including dalteparin and enoxaparin, is an anticoagulant used to treat thromboembolic complications and hypercoagulable syndromes such as pulmonary thromboembolism (PTE) and immune-mediated haemolytic anaemia (IMHA).
Clinical Warning: Its use in Disseminated Intravascular Coagulation (DIC) is controversial and it is no longer used to try to prevent DIC. Heparins are only effective if sufficient Antithrombin III (AT III) is present.
Clinical Pearl: LMWH has better pharmacokinetic properties than unfractionated heparin (UFH) and its actions are more predictable, though it is considerably more expensive.
Mechanism of action
LMWH is an anticoagulant that inhibits Factor Xa and thrombin.
- Compared with unfractionated heparin (UFH), LMWH has reduced anti-IIa activity relative to anti-Xa activity (ratio of anti-Xa to anti-IIa is 2-4:1 compared with UFH 1:1).
- → At therapeutic doses, LMWH has minimal effect on aPTT.
- → Therapeutic monitoring is performed by measuring anti-Xa activity.
Safety & warnings
Contraindications
- Bleeding disorders
- Severe renal dysfunction
Adverse effects
- Haematoma formation (if administered IM)
- Haemorrhage (especially in thrombocytopenic patients or those with DIC)
Precautions
Do not administer intramuscularly (IM) as it may result in haematoma formation. Use with extreme caution in patients with DIC, as it may worsen haemorrhage, especially if the patient is thrombocytopenic. Do not mix other drugs in the same syringe as heparin.
Drug interactions
Can cause changes in coagulation status, increasing bleeding risk
Can cause changes in coagulation status, increasing bleeding risk
Heparin may antagonize ACTH
Heparin may antagonize corticosteroids
Heparin may antagonize insulin
Heparin may increase plasma levels of diazepam
May partially counteract the actions of heparin
May partially counteract the actions of heparin
May partially counteract the actions of heparin
Monitoring
- Anti-Factor Xa activity (target 0.35-0.7 IU/ml)
- aPTT (Activated partial thromboplastin time)
- PT (Prothrombin time)
- Fibrin degradation products
- Fibrinogen
- Clinical signs of bleeding
Pharmacokinetics
Absorption
Reliable and consistent absorption when administered subcutaneously compared to unfractionated heparin.
Distribution
Remains primarily in the intravascular space.
Metabolism
Primarily metabolized by the liver and endothelial cells.
Elimination
Renal clearance is more significant for LMWH than for unfractionated heparin.
Overdose
If an overdosage occurs, protamine can be used as an antidote.
Available products
Formulations
- Injectable: 2,500 IU/ml, 100,000 IU/ml ampoules (dalteparin)
- Injectable: 25,000 IU/ml multidose vial (dalteparin)
- Injectable: 12,500 IU/ml and 25,000 IU/ml pre-filled syringes (dalteparin)
- Injectable: 100 mg/ml pre-filled syringes (enoxaparin) [Note: 100 mg enoxaparin = 10,000 IU anti-Factor Xa activity]
Human-labeled
- Clexane (enoxaparin)
- Fragmin (dalteparin)
Regulatory status
Human authorized products used off-label in veterinary medicine under the cascade.
Human authorized products (POM) used off-label in veterinary medicine.
No regulatory data for: 🇺🇸 US · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Normal precautions should be observed. Store according to manufacturer guidelines, typically at room temperature. Do not mix with other drugs in the same syringe.
Client information
Low molecular weight heparin (LMWH) is an injectable medication used to prevent or treat dangerous blood clots.
- It is usually given as an injection under the skin. Your veterinarian will show you how to administer this safely.
- Watch closely for any signs of unusual bleeding, such as bruising, pale gums, nosebleeds, or dark/tarry stools. Contact your vet immediately if these occur.
- Do not give your pet any other medications, especially pain relievers like aspirin or NSAIDs, without consulting your vet, as this can severely increase the risk of bleeding.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.