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Chlorambucil for Veterinary Use

For Veterinary Practices
Prescribe Now
For Pet & Horse Owners
Manage Your Prescriptions

by Barbara Forney, VMD


Therapeutic Class

Dogs, cats and horses

May Be Prescribed by Vets for:
Pemphigus, leukemia, lymphosarcoma, irritable- bowel syndrome, ovarian adenocarcinoma, glomerulonephritis, feline eosinophillic-granuloma complex, plasma-cell gingivitis and pharyngitis.

FDA Status
Chlorambucil is commercially available as Leukeran (2mg).

Search for Available Dosage Forms 

Basic Information

Chlorambucil is an alkylating, cytotoxic, antineoplastic drug that is used to treat a variety of immune-mediated diseases in dogs and cats. Chlorambucil forms covalent bonds with nucleic acids, causing disruption of DNA strands and suppressing antibody production. It usually is used in conjunction with other drugs, most frequently Prednisolone. It is one of the safest cytotoxic drugs. Chlorambucil is well-absorbed orally and is metabolized by the liver.
Dosage Forms

Dogs and Cats

Chlorambucil is used in dogs to treat canine lymphoma, chronic lymphocytic leukemia, lymphoreticular neoplasms, macroglobinemia, polycythemia vera, and inflammatory bowel disease. It also may be used in combination with Prednisone when treating Pemphigus complex.

Chlorambucil is used in cats to treat lymphocytic leukemia, lymphocytic plasmacytic enteritis, Pemphigus, inflammatory bowel disease, and feline eosinophillic granuloma complex. Chlorambucil is considered safer than Azathioprine for use in cats.


Chlorambucil has been used within a multiple-drug protocol to treat lymphoma in horses.

Chlorambucil Side Effects

Side effects primarily are gastrointestinal distress (including vomiting and diarrhea) and bone marrow suppression. Alopecia, particularly in Poodles and Kerry Blues, has been reported. Seizures are a rarer side effect.


  • Chlorambucil should be used with caution in animals with pre-existing bone marrow suppression or infection.
  • Chlorambucil may be teratogenic. Because of the serious nature of the diseases for which it is used, its potential benefit to the patient should be weighed against the possible fetal harm.

Drug Interactions

Chlorambucil should be used with caution with other myelosuppressive or immunosuppressive drugs due to additive bone marrow suppression or increased risk of infection.


Overdose may cause seizures and pancytopenia. Gastric emptying should be considered depending on the patient's neurologic status. Blood component therapy may be warranted based on the degree of pancytopenia.

About the Author

Dr. Barbara Forney is a veterinary practitioner in Chester County, Pennsylvania. She has a master's degree in animal science from the University of Delaware and graduated from the University of Pennsylvania School of Veterinary Medicine in 1982.

She began to develop her interest in client education and medical writing in 1997. Recent publications include portions of The Pill Book Guide to Medication for Your Dog and Cat, and most recently Understanding Equine Medications published by the Bloodhorse.

Dr. Forney is an FEI veterinarian and an active member of the AAEP, AVMA, and AMWA.

The information contained on this site is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the products shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular product. You should consult your doctor about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the products to diagnose, cure or prevent disease.

Wedgewood Pharmacy compounded veterinary preparations are not intended for use in food and food-producing animals.