IMHA Toolkit

Clinical protocols & thrombosis prevention awareness

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Vet Portal → Canine IMHA Dosage Calculator

Canine IMHA Dosage Calculator

Clinical Basis: Derived principally from the 2019 ACVIM Consensus Statement on the Treatment of IMHA in Dogs [Swann et al., 2019].

CANINE EVIDENCE REFERENCE
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Important Clinical Notice This calculator is an educational dose-reference tool based on published veterinary literature and consensus guidance. It does not provide a prescription or treatment plan. Drug choice, dose, contraindications, monitoring and treatment duration must be determined by a veterinary surgeon with direct knowledge of the individual patient and checked against current formulary information.
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Weight Parameters
Patient Weight Entry

1. Immunosuppressive Plan

Prednisone / Prednisolone
2–3 mg/kg/day or 50–60 mg/m²
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ACVIM recommends an initial oral prednisone/prednisolone dosage of 2–3 mg/kg/day. For dogs over 25 kg, 50–60 mg/m²/day is given as an alternative dosing approach rather than a mandatory automatic switch [Swann et al., 2019]. Actual regimen must be determined by the treating veterinary surgeon.
Mycophenolate Mofetil
8–12 mg/kg q12h
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Published consensus range: 8–12 mg/kg orally every 12 hours when mycophenolate is selected as an adjunct immunosuppressive agent [Swann et al., 2019]. A 2024 randomised trial did not show a significant haematological-response advantage from routinely adding mycophenolate or cyclosporine to methylprednisolone [Agnoli et al., 2024]. Selection and dose should therefore remain case-specific.

📋 Adjunct Immunosuppression Considerations — ACVIM

Review presenting clinical considerations described in the ACVIM consensus. These are not a validated scoring rule and do not by themselves establish that a second immunosuppressant will improve outcome:

Clinical Decision Support: Select presenting clinical factors above to review ACVIM consensus considerations.

2. Thromboprophylaxis — Strong ACVIM Recommendation

Strong Rec
Clopidogrel Bisulfate
1.1–4.0 mg/kg q24h
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Published consensus range: 1.1–4.0 mg/kg orally once daily. ACVIM weakly recommends clopidogrel in preference to aspirin when an antiplatelet is selected [Swann et al., 2019].
Rivaroxaban
1–2 mg/kg q24h
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Published consensus range: 1–2 mg/kg orally once daily. ACVIM suggests that a regimen incorporating an anticoagulant may be preferred during the first two weeks after diagnosis, when thrombotic risk is particularly important [Swann et al., 2019].
2026 IMHA safety signal A retrospective UK study of 34 dogs with non-associative IMHA receiving rivaroxaban reported gastrointestinal bleeding in 5 dogs (14.7%), including two major events and one fatal event. All five affected dogs were also receiving corticosteroids and mycophenolate mofetil. The study cannot establish that rivaroxaban caused the bleeding, but supports careful individual bleeding-risk assessment and monitoring during combination treatment [Conway et al., 2026].
⚠️ Thrombocytopenia Threshold Note ACVIM recommends thromboprophylaxis for dogs with IMHA except those with severe thrombocytopenia. The consensus uses a platelet count below 30,000/μL as the threshold at which antithrombotics are not recommended, particularly if an antiplatelet drug is selected [Swann et al., 2019].
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Thrombotic disease is a leading cause of morbidity and mortality. ACVIM recommends thromboprophylaxis unless contraindicated. Anticoagulants may be used alone or in combination with antiplatelet drugs based on patient-specific risk assessment and clinical judgment.
⚠️ Please independently verify all calculated values before prescribing or administering medication.

📋 Canine Diagnostic & Clinical Guidelines

🔍 True Spherocytes vs. Artefacts

True spherocytes support immune-mediated red-cell destruction when present in an appropriate clinical context. They are small, dense erythrocytes lacking central pallor and should be distinguished from artefacts, particularly near smear edges [Garden et al., 2019].

🩸 Auto-Agglutination vs. Rouleaux

Persistent auto-agglutination supports immune-mediated red-cell destruction but should be distinguished from rouleaux. Saline dispersion testing can help differentiate rouleaux from true agglutination. Findings should be interpreted alongside other evidence of haemolysis and immune-mediated destruction [Garden et al., 2019].

Mathematical Formulas & Published Reference Ranges
Prednisone / Prednisolone: 2–3 mg/kg/day orally (or 50–60 mg/m²/day for dogs > 25 kg)
Mycophenolate Mofetil: Weight (kg) × 8–12 mg/kg every 12 hours reference calculation
Clopidogrel Bisulfate: Weight (kg) × 1.1–4.0 mg/kg once daily reference calculation
Rivaroxaban: Weight (kg) × 1–2 mg/kg once daily reference calculation
Source: Swann JW, et al. ACVIM Consensus Statement on treatment of IMHA in dogs. JVIM 2019. EDUCATIONAL DOSE-REFERENCE SUPPORT
2026 rivaroxaban evidence update The ACVIM reference calculation above remains unchanged. Conway S, Jenkins L and Reeve J reported a retrospective cohort of 34 dogs with non-associative IMHA receiving rivaroxaban (median 1.2 mg/kg/day). Gastrointestinal bleeding occurred in 5/34 dogs (14.7%), and confirmed or suspected thromboembolic events occurred in 7/34 (20.6%) despite thromboprophylaxis. These findings do not establish a different dose or prove causation, but they reinforce the need to balance residual thrombotic risk against bleeding risk, particularly during multidrug therapy. Conway S, Jenkins L, Reeve J. Journal of Small Animal Practice. Published online 16 September 2026. View in the IMHA Toolkit Evidence Library →
Evidence Library

Review the consensus statements and peer-reviewed studies underpinning the dose ranges and clinical notes used in this calculator.

Open Evidence Library →