Doxorubicin
Doxorubicin is an anthracycline antineoplastic agent used extensively in veterinary oncology. It is a major component of multidrug lymphoma protocols and is also used for several sarcomas and carcinomas. Clinical applications include remission induction, adjuvant treatment after local tumor control and palliation, depending on the tumor and treatment plan.
Group
Anthracycline antineoplastic
Mechanism of Action
Doxorubicin intercalates between DNA bases and inhibits topoisomerase II by stabilizing DNA–enzyme cleavage complexes. This prevents normal rejoining of DNA strands and promotes lethal DNA damage. Redox cycling also generates reactive oxygen species that damage cellular macromolecules. Together, these effects impair replication and transcription and activate tumor-cell death pathways.
Dose Rates
Dog
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Chemotherapy | Reference only | IV | 30 mg/m² every 21 days. Lifetime cumulative exposure and marrow recovery determine whether further courses can be given. | |
| Small-dog chemotherapy | Reference only | IV | Dogs under 15 kg: 1 mg/kg every 21 days as an alternative to BSA dosing. Requires cumulative-dose tracking; not flattened into an uncapped calculator entry. |
Cat
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Chemotherapy | Reference only | IV | 20 mg/m² every 3 weeks; selected protocols use 25 mg/m². The approximate 1.25 mg/kg comparison is not an exact interchangeable dose. |
Horse
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Chemotherapy | Reference only | IV | 70 mg/m² every 3 weeks for six cycles. Approximate 0.84–0.96 mg/kg values are examples, not a replacement for BSA calculation. |
Ferret
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Cancer chemotherapy | Reference only | IV | 30 mg/m² every three weeks, selected within an oncology protocol. Body-surface-area arithmetic is unsupported. |
Indications
- Treatment of canine and feline lymphoma, including CHOP-based combination chemotherapy and selected single-agent protocols.
- Adjuvant or palliative chemotherapy for canine hemangiosarcoma.
- Treatment of selected soft-tissue sarcomas, including some feline injection-site sarcomas, within tumor-specific protocols.
- Treatment of selected mammary carcinomas and other epithelial malignancies in dogs and cats.
- Selected adjuvant or rescue chemotherapy for canine osteosarcoma.
Contraindications
- Cardiomyopathy
- Significant neutropenia; use extra caution in ABCB1-deficient dogs.
Interactions
- P-glycoprotein inhibitors such as cyclosporine or ketoconazole may increase toxicity.
Adverse effects
- Myelosuppression with nadir around 7–10 days
- Cumulative cardiomyopathy and acute arrhythmias
- Vomiting, diarrhea, alopecia
- Renal injury in cats
- Severe extravasation injury
Toxicity
Bone marrow injury and irreversible cumulative cardiomyopathy are major dose-limiting toxicities.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Doxorubicin injection 2 mg/mL Vesicant; use a secure catheter and protect from light. | Injection | 2 mg / mL | IV |
Monitoring and Administration
Monitor CBC before each course and near nadir, renal parameters especially in cats, and cardiac function/ECG.
Use secure IV access. Dilute in compatible saline and generally infuse over 15–30 minutes; feline protocols may use 1 mg/mL over 5–10 minutes with fluid support.
Track lifetime exposure: many oncology protocols limit cumulative dose to 180 mg/m²; cardiac risk rises with increasing cumulative exposure and can occur earlier.
Extravasation requires immediate oncology management; dexrazoxane is used for tissue protection. Do not flush a suspected infiltrated catheter.