Hematologic and systemic toxicoses associated with carboplatin administration in cats.

OBJECTIVE

To determine prevalence and severity of carboplatin-induced dose-limiting toxicoses in the cat.

ANIMALS

9 healthy, 6- to 7-month-old cats weighing 4.7 (range, 3.0 to 6.5) kg.

PROCEDURE

Cats were given a single i.v. bolus of carboplatin at a dosage of 150 (n = 3), 200 (n = 3), or 250 (n = 3) mg/m2 of body surface area.

RESULTS

Dose-limiting neutropenia and thrombocytopenia were significant in all cats given carboplatin at 200 or 250 mg/m2. Weight loss, changes in appetite, and evidence of respiratory difficulty, as well as vomiting, diarrhea, or lethargy were not observed at any time during the 28-day period. At a highest dosage (250 mg/m2), the neutrophil nadir (560 +/- 303 neutrophils/microliters) was observed on day 17 and the platelet count nadir (96,500 +/- 11,815 platelets/microliters) was observed on day 14 after carboplatin administration.

CONCLUSIONS

Carboplatin appears to be safe and clinically well-tolerated when given i.v. as a single bolus at a dosage of 200 mg/m2 to clinically normal cats. The dose-limiting toxicity of a single i.v. administered bolus is neutropenia. The nadir of a 200 mg/m2 i.v. administered dose occurs on day 17 (1,110 +/- 165 neutrophils/microliters) and neutropenia (< 2,000 neutrophils/microliters) lasts from day 14 through day 25 after carboplatin administration.

CLINICAL RELEVANCE

The fatal dose-related pulmonary toxicosis observed in cisplatin-treated cats was inapparent in carboplatin-treated cats. To adequately determine the therapeutic role of carboplatin in tumor-bearing cats, a moderately tolerated dose of carboplatin of 200 mg/m2 given i.v. once every 4 weeks should be considered.