VETINUITY
COP gives cyclophosphamide 300 mg/m2 PO every 3 weeks, vincristine 0.75 mg/m2 IV weekly for 4 weeks then every 3 weeks, and daily prednisolone, in dogs and cats with lymphoma.
High-dose COP, BSA-based. Cats receive prednisolone, not prednisone.
Vetinuity’s COP dosing table: high-dose COP gives cyclophosphamide 300 mg/m2 PO on day 1 of every 3-week cycle, vincristine 0.75 mg/m2 IV once a week for the first 4 weeks and then every 3 weeks alongside cyclophosphamide, and prednisone (dogs) or prednisolone (cats) 40 mg/m2 PO once daily, tapered once remission is established. It is the backbone of first-line treatment for feline lymphoma and the doxorubicin-free option for dogs. The Vetinuity COP dose calculator above converts each drug to milligrams and vincristine to milliliters from the patient’s weight and body surface area. The table is kept by Vetinuity, the clinical assistant that Brian Toncray, DVM, an emergency veterinarian, built for the exam room.
| Week | Cyclophosphamide | Vincristine | Steroid |
|---|---|---|---|
| 1 | 300 mg/m2 PO | 0.75 mg/m2 IV | 40 mg/m2 PO daily |
| 2 | none | 0.75 mg/m2 IV | daily |
| 3 | none | 0.75 mg/m2 IV | daily |
| 4 | 300 mg/m2 PO | 0.75 mg/m2 IV | maintenance |
| Every 3 weeks after | 300 mg/m2 PO | 0.75 mg/m2 IV | maintenance |
Protocols differ in how long maintenance continues; the Dutch feline series ran the 3-week cycle for a year in cats that stayed in remission (Teske 2002). Cats get prednisolone because they convert oral prednisone to the active drug poorly.
In cats, COP and CHOP-based protocols are both used for high-grade alimentary lymphoma, and a 2024 multicenter series of 57 cats compared them retrospectively (Bernardo Marques 2024). In dogs, COP is the fallback when doxorubicin is not an option; read the CHOP protocol for the first-line regimen, staging before choosing a protocol, and rescue options for a dog that relapses on COP.
CHOP (cyclophosphamide, doxorubicin, vincristine, prednisolone) is first-line for canine nodal lymphoma: median survival 302 to 321 days; prednisone alone 50 days.
The WHO staging scheme describes how far canine lymphoma extends anatomically; substage a or b separately records whether systemic signs are absent or present.
Single-agent doxorubicin for canine lymphoma is 30 mg/m2 IV every 2 to 3 weeks for 5 doses, or 1 mg/kg in dogs under 10 kg, after a baseline echocardiogram in breeds at cardiac risk.
After CHOP relapse, options are re-induction with CHOP, lomustine 70-90 mg/m2 every 3 weeks, LPP, DMAC every 2 weeks, or rabacfosadine 1 mg/kg IV every 3 weeks.
Lomustine is dosed at 60-90 mg/m2 PO every 3 weeks in dogs and 50-60 mg/m2 PO every 3 to 6 weeks in cats, rounded to whole capsules, with ALT and a CBC checked before every dose.
In dogs, doxorubicin-containing CHOP protocols give longer remissions than COP and remain the first-line standard. COP is chosen when doxorubicin is contraindicated, for example in a dog with poor systolic function, or when cost and visit frequency rule out CHOP.
Doxorubicin adds less benefit and more toxicity in cats, including cumulative nephrotoxicity, so many feline protocols are COP-based, with doxorubicin reserved for selected cases.
Low-dose daily or every-other-day schedules exist, but the cumulative risk of sterile hemorrhagic cystitis rises with continuous dosing. The pulse dose every 3 weeks is the schedule used in high-dose COP.
Vetinuity explains clinical options with journal citations.
The veterinarian diagnoses and prescribes.