Using Ceenu, Branded Lomustine for Dogs and Cats How this Medication Targets Mutated Cells to Fight Cancer

BY | September 23 PUBLISHED BY
Mast Cell Tumors Cancer
Indications for Ceenu

Ceenu is a type of chemotherapy, classified as a nitrosourea alkylating agent, used to kill off mutated cells that would otherwise grow into malignant tumors. By bonding to the DNA strands of rapidly dividing cells, like mutated ones, this drug causes genetic defects in the cell, resulting in cell death. Unlike other alkylating agents, Ceenu is capable of crossing between the blood and brain, making it useful in the treatment of brain tumors as well. Not a drug designed for cats and dogs, Ceenu is considered an ‘extra-label’ drug, meaning that it has not been approved for use in pets, but can still be prescribed legally by your vet.


Ceenu should only be used when the risks of taking the drug are outweighed by the potential benefits of receiving treatment. It should not be given to pets that have already received another form of chemotherapy or radiation. Ceenu should not be taken with bone marrow suppressants, corticosteroids, immunosuppressive drugs, or vaccinations, as these drugs can end up exacerbating the preexisting side effects of taking Ceenu. Ceenu should only be given to pregnant pets when it is absolutely necessary, as this drug is a known teratogen.


Being such a high risk extra-label drug, you should never differ from what your vet prescribed. That being said, the normal prescription for dogs is 60 mg/m2 by mouth, increasing the dosage to 80 mg/m2 if the resulting toxicity is minimal. Treatments should be administered once every 5 to 8 weeks.

Side Effects

As with most types of chemo, Ceenu can be expected to cause vomiting, diarrhea, loss of appetite, stomatitis, alopecia, corneal de-epithelization, and rarely renal toxicity, hepatotoxicity, and pulmonary damage. The bone marrow suppression resulting from taking Ceenu can cause anemia, thrombocytopenia, and leukopenia.

Brand/Generic Equivalents


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