Cytarabine is a chemotherapy drug that is used in veterinary neurology as an immunosuppressant. It crosses the blood–brain barrier and suppresses the overactive immune system. It is considered the gold standard treatment for dogs with immune-mediated meningoencephalitis. It is almost always given together with corticosteroids, such as prednisone.
Cytarabine has the strongest scientific evidence of effectiveness among immunosuppressants for treating immune-mediated meningoencephalitis, with relatively few side effects. Unfortunately, treatment can be costly and requires a time commitment for repeated outpatient visits.
A CBC is checked before each treatment to ensure the immune system is not overly suppressed. A comprehensive blood panel is recommended every 3–4 months to monitor organ function.
How It Is Given
Cytarabine is administered as an injection, either:
- An 8-hour intravenous (IV) infusion (most supportive for effectiveness), or
- Multiple subcutaneous (under the skin) injections given several hours apart.
Treatment is typically performed as an outpatient procedure. Your pet is dropped off in the morning and discharged later the same day.
Dosing
Cytarabine is usually given every 3 weeks during the initial months of treatment.If your pet responds well, intervals between treatments may be gradually extended once prednisone is reduced to the lowest effective dose.
Some pets may eventually stop cytarabine after months to a year of successful treatment, but others may need lifelong therapy for disease control.
Possible Side Effects
Cytarabine is generally well tolerated. Side effects are uncommon but may include:
- Gastrointestinal upset:Â Vomiting or decreased appetite may occur around the time of infusion. This is often easily treated with anti-nausea medication.
- Injection site soreness:Â Mild and temporary, lasting up to 24 hours.
- Low blood cell counts. Rarely we may see low red or white blood cell counts. This is why pre-treatment blood work is essential; if levels are too low, cytarabine may be postponed.
Additional Information
Cytarabine is excreted in the urine for about 24 hours after treatment. During this period, Pregnant women, immunocompromised individuals, and small children should avoid contact with urine. You should wear gloves to clean any accidents, and wash hands thoroughly afterward. Outdoors, sunlight breaks down cytarabine quickly, so normal urination outside is safe.