Cytarabine (Cytosar®)

Cytarabine (Cytosar®) Injectable Medication for Dogs & Cats

Cytarabine (Cytosar®) is an injectable treatment that can be administered intravenously or subcutaneously. It’s commonly used to treat inflammatory diseases, such as granulomatous meningoencephalitis (GME) and necrotizing encephalitis, and it’s also used in certain types of cancer, such as lymphoma.

Cytarabine Treatment Plans & Scheduling

Inflammatory disease treatment plan

For inflammatory disease, the initial treatment typically involves an infusion at the hospital, followed by injections under the skin every four weeks. If your pet responds well, the interval may be extended by two weeks at a time until treatments occur every 8–10 weeks. At that stage, your pet’s veterinary team may consider discontinuing the medication. If symptoms recur, it may indicate a need for lifelong treatment.

Each treatment cycle requires your pet to be at the hospital for two consecutive days. The first appointment includes blood work and typically takes 30–45 minutes. The second appointment is usually quicker and involves only the injection. If helpful, overnight boarding can be arranged between treatment days.

Cancer treatment plan

If cytarabine is part of your pet’s cancer treatment plan, your veterinary team will outline a specific schedule. Timing and frequency can vary, so your veterinary team will walk you through the plan before treatment starts.

Monitoring & Lab Work

During the first four sessions, your veterinary team will monitor your pet’s white blood cell count to ensure the medication has not adversely affected it.

Special Precautions After Treatment

For three days following treatment, pregnant women, small children, and immunocompromised individuals should avoid contact with your pet. During that same three-day period, wear gloves and wash your hands immediately after cleaning up any urinary accidents.

Potential Side Effects of Cytarabine

Cytarabine is generally very well-tolerated. Potential side effects include:

  • Gastrointestinal issues: appetite loss, vomiting, and diarrhea

  • Blood cell counts: low levels of red cells, white cells, and platelets may occur (a significantly low white blood cell count may require antibiotics and a delay in treatment)

  • Other rare side effects: eye irritation, oral ulcers, neurotoxicity, and liver toxicity are infrequent but possible

Cytarabine FAQs

  • Cytarabine is an injectable treatment that can be administered intravenously or subcutaneously. Your pet’s veterinary team will guide the treatment schedule.

  • For inflammatory disease protocols, each treatment cycle typically involves two consecutive days at the hospital. The first visit includes blood work and is usually longer, and the second visit is typically quicker and involves the injection.

  • During the first four sessions, your veterinary team will monitor white blood cell count to ensure the medication hasn’t adversely affected it.

  • For three days after therapy, pregnant women, small children, and immunocompromised individuals should avoid contact with your pet. Wear gloves and wash your hands immediately after cleaning up urinary accidents during that same three-day window.

  • While cytarabine is generally well-tolerated, possible side effects include appetite loss, vomiting, diarrhea, changes in red and white blood cell counts and platelets, and rarely eye irritation, oral ulcers, neurotoxicity, and liver toxicity.