🧬💉 Lymphoma Chemotherapy Medications for Dogs and Cats: Vet Oncology Guide for 2025

By Dr Duncan Houston BVSc

When a beloved pet is diagnosed with lymphoma, chemotherapy becomes one of the most effective and widely recommended treatment options. Despite common misconceptions, veterinary chemotherapy is typically far gentler on dogs and cats than human treatment, offering a meaningful extension of life with quality comfort. 🐶🐱💊

This 2025 veterinary oncology guide explores commonly used medications in lymphoma protocols, how they're combined, what side effects to expect, and how veterinarians select the right treatments for each patient. 📘🩺

🔬 What Is Chemotherapy?

In veterinary medicine, chemotherapy refers to using medication—rather than surgery or radiation—to treat cancer. These drugs work by targeting rapidly dividing cancer cells and slowing or halting tumor progression. 💥🧪

Veterinary chemotherapy often uses lower doses than human treatments, as the goal is not just remission, but maintaining quality of life for as long as possible. 🛡️

📋 Understanding Protocols: COP, CHOP, MOPP & More

Chemotherapy protocols often use acronyms based on the drugs included. These combinations are carefully designed to attack lymphoma from multiple angles while managing side effects and resistance. Some common protocols include:

• 📌 COP: Cyclophosphamide, Oncovin (Vincristine), Prednisone
• 📌 CHOP: Cyclophosphamide, Doxorubicin (Hydroxydaunorubicin), Vincristine (Oncovin), Prednisone
• 📌 MOPP: Mustargen, Oncovin, Procarbazine, Prednisone

Protocols may be finite (lasting several months) or indefinite (ongoing treatment until remission is lost). There is ongoing debate about which approach is best. 🎗️

🧬 Common Chemotherapy Medications

Here is a list of widely used drugs in canine and feline lymphoma treatment, with a brief overview of their function and usage: 💊

1. 🧪 Adriamycin (Doxorubicin)

A powerful chemotherapy agent with a broad range of activity against lymphoma. Part of the CHOP protocol.

2. 💊 Chlorambucil (Leukeran)

A gentler oral chemotherapy drug, often used in feline small-cell lymphoma or in older dogs/cats where more aggressive chemo is unsuitable.

3. 💉 Cyclophosphamide (Cytoxan)

An alkylating agent that disrupts DNA and slows cell division. Common in many multi-drug protocols like CHOP and COP.

4. 🧬 Dacarbazine

Used in rescue protocols. This drug is often reserved for cases where first-line therapies no longer work.

5. 💉 L-Asparaginase (Elspar)

Targets lymphoma cells specifically by depleting the amino acid asparagine. Often used to quickly induce remission.

6. 💊 Lomustine (CCNU)

Highly effective in both lymphoma and mast cell tumors. May be used as a single agent or in combination rescue protocols.

7. 💊 Methotrexate

An antimetabolite chemotherapy drug used in some rescue protocols or for specific lymphoma subtypes.

8. 💊 Prednisone / Prednisolone

Not a chemotherapy drug in the traditional sense, but widely used for its potent anti-inflammatory and lymphocyte-suppressing effects. Often used in every protocol. 📉

9. 💊 Procarbazine

Used primarily in the MOPP protocol and in rescue therapy. Often combined with prednisone and other agents.

10. 🧬 Rabacfosadine (Tanovea-CA1)

A newer, conditionally approved drug for canine lymphoma. Given every 3 weeks by injection, with promising results. 🐕

11. 💊 Verdinexor (Laverdia-CA1)

A conditionally approved oral chemo drug for dogs with lymphoma. Acts by trapping tumor suppressor proteins in the cell nucleus. 📦

12. 💉 Vincristine (Oncovin)

A core component of most protocols. Disrupts cell division and is very effective against lymphoma. Can cause GI upset and low white blood cells. 🚨

⏱️ What to Expect from Treatment

The first remission is usually the longest and easiest to achieve. When remission is lost, a different rescue protocol is used. This second remission is typically shorter and harder to attain. 🔁

Common Treatment Timeline:

• 📅 Week 1–8: Frequent visits for injections and bloodwork
• 📉 Monitoring for white blood cell counts and GI upset
• 📈 Remission usually achieved in first few weeks

⚠️ Side Effects to Watch For

Veterinary chemotherapy is designed to minimize side effects, but some pets may still experience:

• 🤢 Vomiting, diarrhea, or loss of appetite
• 🩸 Low white blood cell counts (neutropenia)
• 💉 Hair loss (in certain breeds like Poodles, Terriers)
• 📈 Increased thirst/urination (especially from prednisone)

Most side effects are manageable, and treatment can be adjusted to maintain your pet’s quality of life. 🐕💖

📋 Monitoring During Chemotherapy

Ongoing bloodwork is essential. Before each chemo session, vets check:

• 🩺 White blood cell count
• 🧪 Kidney/liver function
• 🌡️ Weight and hydration status

This ensures treatment is effective without harming vital organs. 📈

💊 Rescue Protocols

When a dog or cat comes out of remission, the original chemotherapy drugs may no longer work. Rescue protocols use new medications to regain control of the disease, often including:

• Lomustine (CCNU)
• Dacarbazine
• Procarbazine
• Newer drugs like Verdinexor or Rabacfosadine

📲 Support with Ask A Vet

Have questions about chemotherapy options, side effects, or protocol timing? The Ask A Vet app connects you with licensed veterinarians 24/7. 🐾💬

Whether you’re weighing treatment decisions or managing at-home care, Ask A Vet helps you stay informed and confident every step of the way. 🩺📱

✅ Final Thoughts

Lymphoma is a serious but treatable condition in pets, and chemotherapy offers the best chance at remission and meaningful time together. With modern protocols and compassionate care, many dogs and cats enjoy months or even years of high-quality life. 🐶🐱❤️

Always consult your veterinarian to create a personalized treatment plan based on your pet’s type of lymphoma, overall health, and lifestyle needs. 🎯

– Dr Duncan Houston BVSc

💡Need guidance during your pet’s lymphoma treatment? Visit AskAVet.com or download the Ask A Vet app today!