Enoxaparin: veterinary dose and monograph

At a glance

Drug class

Veterinary drug

Also known as

Lovenox, Clexane, LMWH

Species with doses

Dogs, Cats and Horses

General dose range

1–1.5 mg/kg SC q6–12h (SC) — check the species tables for the indication

Routes

SC

Last reviewed

1 October 2026

Indications

• Feline arterial thromboembolism (ATE) — treatment/prophylaxis in cardiomyopathy
• Thromboprophylaxis in hypercoagulable disease (IMHA, protein-losing nephropathy, sepsis, neoplasia)
• Venous/pulmonary thromboembolism management

Enoxaparin dose by species

Doses are per administration unless stated. mg/kg doses scale with body weight; per-animal, per-quarter and infusion-rate doses are shown as the reference writes them.

Dogs

• Thromboprophylaxis (IMHA/PLN/hypercoagulable): Papich 5e and Plumb’s p.462 (Lunsford): 0.8 mg/kg SC q6h maintains therapeutic anti-Xa in normal dogs; 0.8–1 mg/kg SC q6–8h (Alwood). Adjust to anti-Xa where available.

Cats

• Arterial thromboembolism (prophylaxis/treatment): Papich 5e: 0.75–1 mg/kg SC q12h, up to 1.25 mg/kg SC q6h (q6h preferred by many). Plumb’s p.462: 1 mg/kg SC q12h gives a measurable antithrombotic effect (Van De Wiele); cats clear LMWH quickly — 1.25 mg/kg SC q6h is the current recommendation (Alwood). Titrate to anti-Xa 0.5–1 IU/mL where available.

Horses

• Thromboprophylaxis: Papich 5e: prophylaxis 0.5 mg/kg SC q24h; 1 mg/kg q24h for high-risk patients. Plumb’s p.462: no published recommendation, but once-daily SC dosing appears useful (Schwarzwald 2002).

Contraindications

Active uncontrolled haemorrhage, severe thrombocytopenia, and recent surgery/trauma with bleeding risk. Significant renal impairment (LMWH accumulation → bleeding). Known heparin/LMWH hypersensitivity (or history of heparin-induced thrombocytopenia in people). Concurrent other anticoagulants unless intended. Neuraxial procedures (bleeding).

Species-specific warnings

Cats: Cats clear LMWH rapidly — q12h dosing is often inadequate; frequent (q6–8h) dosing or anti-Xa-guided dosing is needed. Combine with clopidogrel for long-term ATE prevention.

Adverse effects

• Haemorrhage (the principal risk) — dose-related
• Injection-site bruising/haematoma
• Thrombocytopenia (uncommon)
• Short duration → frequent dosing needed (a practical limitation)

Drug interactions

• Other anticoagulants/antiplatelets (clopidogrel, aspirin, warfarin, NSAIDs): additive bleeding risk (clopidogrel often combined deliberately in feline ATE)
• Protamine: only PARTIAL reversal of LMWH
• Drugs reducing antithrombin: reduced efficacy

Pregnancy and lactation

Does not cross the placenta — LMWH is the preferred anticoagulant when anticoagulation is needed in pregnancy.

Monitoring

• Anti-Factor-Xa activity (peak ~0.5–1 IU/mL) where available — the appropriate LMWH monitor (NOT aPTT)
• Bleeding signs / PCV; platelet count
• Renal function (accumulation/bleeding risk)
• In feline ATE: transition/combination with clopidogrel for long-term prevention

Toxicity and overdose

The dose-limiting toxicity is HAEMORRHAGE, increased by renal impairment (accumulation) and concurrent antithrombotics. Bleeding can occur at any site; overdose prolongs anti-Xa activity. Heparin-induced thrombocytopenia is rare in animals. Protamine only partially reverses it, so over-anticoagulation is harder to neutralise than with unfractionated heparin.

Management: Stop the drug. PROTAMINE provides only PARTIAL reversal of LMWH (≈1 mg protamine per 1 mg enoxaparin given in the last few hours; give slowly). For significant bleeding, supportive care with fresh frozen plasma/transfusion as needed; monitor anti-Xa where available. Reduce dose/extend interval in renal impairment.

Clinical pearls

• A more predictable, anti-Xa-targeted heparin — but in cats and dogs its SHORT half-life means FREQUENT dosing (often q6–8h in cats), unlike the once/twice-daily human regimen
• Monitor with ANTI-Xa activity, not aPTT (LMWH has little effect on aPTT)
• Protamine only PARTIALLY reverses it — over-anticoagulation is harder to neutralise than with unfractionated heparin; reduce dose in renal impairment
• For feline arterial thromboembolism, it is commonly used acutely and combined with/transitioned to clopidogrel for ongoing prevention

Mechanism of action

A depolymerised (low-molecular-weight) fraction of heparin that binds antithrombin and PREFERENTIALLY accelerates inactivation of factor Xa (with relatively less anti-thrombin/IIa activity than unfractionated heparin) — inhibiting clot propagation. The higher, more consistent anti-Xa:anti-IIa ratio gives a more predictable dose-response (less monitoring) and longer human half-life — though in cats and dogs clearance is rapid, necessitating more frequent dosing than in people.

Formulations and products

• Pre-filled syringe 100 mg/mL (40/60/80 mg)
• Clexane — 40 / 60 / 80 mg pre-filled syringe (100 mg/mL), SC injection (human-label)
• Lovenox / generic enoxaparin — 40 / 60 mg syringe, SC injection (human-label)

Storage

Pre-filled syringes: 15–25 °C, do not freeze; protect from light.

Before you use this dose

Reference doses for veterinary professionals. Confirm the dose against the product label, the patient’s condition, current guidance and local regulations before use; the attending veterinarian remains responsible for every clinical decision.

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Frequently asked questions