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One selection filters the source overview, clinical facts, reports and dose calculator. Literature references are not species-filtered.
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Source overview
Recorded excerpts for one species. Each dose remains a separate source entry; no regimen is selected.
Choose one species to view its source overview. All-species evidence remains available below.
View full clinical evidence and sources ↓Clinical evidence
Pending clinical review (PROPOSED)Rule-based (RULE_BASED)— applies to the facts and dose entries in this species selection; individual source records retain their own status.
Indications2
IMHA, pemphigus, IBD, other immune-mediated diseases (steroid-sparing)
DogExtra-label (EXTRA_LABEL)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Original excerpt: IMHA, pemphigus, IBD, other immune-mediated diseases (steroid-sparing) — Extra-label
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Refractory IBD/skin disease only, with extreme caution
CatExtra-label (EXTRA_LABEL)1 source record · View provenance
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Original excerpt: Refractory IBD/skin disease only, with extreme caution — Extra-label — many clinicians avoid entirely
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Indications table · Not applicable · Extra-label (EXTRA_LABEL) · Pending clinical review (PROPOSED) · Rule-based
Dose regimens2
This calculator performs arithmetic only on the sourced dosing field shown for each result — it does not verify the field's accuracy, does not select which field to use for a patient, and does not replace a veterinarian's order. Not for clinical use. Confirm every result against the primary source before dispensing.
Choose one species above to view its dose calculator.
Adverse effects103
Bone marrow suppression (leukopenia, anemia, thrombocytopenia) — Principal adverse effect
DogCatNot applicable (NOT_APPLICABLE)2 source records · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
GI upset, poor hair growth, pancreatitis, hepatotoxicity — Reported
DogNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Side Effects / Adverse Effects table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
These are counts of spontaneously reported events, not proven adverse effects, causal relationships, or incidence rates.
Bars compare report counts within each species; they do not show incidence.
More reportsFewer reportsDog
- Lethargy (see also Central nervous system depression in 'Neurological')26 reports
- Death by euthanasia21 reports
- Elevated serum alkaline phosphatase (SAP)21 reports
- Anaemia NOS20 reports
- Immune mediated haemolytic anaemia20 reports
- Vomiting19 reports
- Diarrhoea18 reports
- Other abnormal test result NOS18 reports
- Elevated alanine aminotransferase (ALT)17 reports
- Leucocytosis NOS16 reports
- Thrombocytopenia16 reports
- Anorexia15 reports
Monitoring1
CBC with platelets — every 1–2 weeks initially, then every 1–2 months on maintenance; liver enzymes periodically
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Monitoring Parameters · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Contraindications1
Hypersensitivity
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Contraindications & Warnings table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Precautions4
Cats — extreme caution, many avoid altogether; hepatic dysfunction; taper slowly after remission (rapid withdrawal can trigger rebound hyperimmune response, esp. IMHA)
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Contraindications & Warnings table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Cats are disproportionately sensitive due to low TPMT activity — most clinicians avoid azathioprine in cats altogether, using chlorambucil instead for feline immunosuppression.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Taper dogs off slowly (over months) after remission of IMHA specifically — abrupt discontinuation risks rebound hemolytic crisis.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Onset of clinical benefit can take weeks — don't judge treatment failure too early.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Clinical pearl · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Interactions4
Allopurinol — ↓ hepatic metabolism of azathioprine — reduce azathioprine dose to 1/4–1/3 if combined
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
ACE inhibitors, TMP/sulfa, cyclophosphamide — ↑ hematologic toxicity risk
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Corticosteroids — Commonly combined but ↑ toxicity risk (esp. pancreatitis)
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Warfarin — ↓ anticoagulant effect
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Drug Interactions table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Pharmacokinetics5
Bioavailability — Poorly absorbed, rapidly converted to mercaptopurine
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Metabolism — Via thiopurine methyltransferase (TPMT)
DogCatNot applicable (NOT_APPLICABLE)2 source records · View provenance
- Dog · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
- Cat · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Elimination — Renal (metabolites)
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Onset — Clinical response may take up to 6 weeks
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Pharmacokinetics table · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Pregnancy / lactation considerations1
Mutagenic and teratogenic in lab animals. Human FDA category D. Papich class C. Distributed into milk — use milk replacer for nursing offspring of treated dams.
Species not recordedNot applicable (NOT_APPLICABLE)1 source record · View provenance
- Species not recorded · Plumb's Veterinary Drug Handbook, 7th ed., p. 134–136; Saunders Handbook of Veterinary Drugs (Papich), 4th ed., p. 65–66 — Pregnancy & Lactation · Not applicable · Not applicable (NOT_APPLICABLE) · Pending clinical review (PROPOSED) · Rule-based
Literature references20
References are linked to this drug. Species applicability is not recorded here, so the species filter does not narrow this list. Imported dates do not retain their original precision; confirm dates in the original citation.
- Romiplostim Use in Pancytopenia Secondary to Azathioprine Overdose in a Dog.
Study summary not available in the imported record. Open the original citation to review the study.
- Combination of azathioprine and prednisolone as a treatment for meningoencephalomyelitis of unknown origin in dogs: 54 cases.
Study summary not available in the imported record. Open the original citation to review the study.
- Treatment of Reactive Histiocytosis With Oclacitinib: A Retrospective Case Series of 10 Dogs.
Study summary not available in the imported record. Open the original citation to review the study.
- Literature review and authors' consensus recommendations for the medical management of perianal fistulae in dogs.
Study summary not available in the imported record. Open the original citation to review the study.
- [Canine sterile neutrophilic dermatosis (Sweet-like syndrome): A description of 3 cases].
Study summary not available in the imported record. Open the original citation to review the study.
Sources: PubMed, National Library of Medicine; openFDA, U.S. Food and Drug Administration; Plumb DC. Plumb's Veterinary Drug Handbook. 7th ed. PharmaVet Inc; 2011.
Owner information handout
Plain-language medication information to review with the owner. Open the handout to print it or download a PDF.