Ovarian cysts and one ovarian tumour, uterine tumours, vaginal calculi, abscesses of the broad ligament or undetermined testicular lesions were observed in 25 out of 502 female and male dusky dolphins (Lagenorhynchus obscurus) caught off Peru in 1985-1987 or 1993-1994. Tentative or definitive diagnoses included Graafian follicle cysts, luteinized cyst, ovarian parasitic granulomatous inflammation, dysgerminoma, leiomyoma, fibroleiomyoma and chronic fibrino-suppurative inflammation of the broad ligament. All lesions described represented first reports for L. obscurus, and the diagnosis of dysgerminoma was the first in a cetacean. It is also the first time that trematode eggs have been reported in the ovaries of cetaceans and that a vaginal calculus has been encountered in a sexually immature cetacean. The finding of struvite as a major component in two vaginal calculi suggested an infectious aetiology. Of 11 mature females with ovarian tumour or cysts or uterine tumours, only one (9.1%) was pregnant, i.e., significantly less than the expected pregnancy rate (53.5% in a random sample of Peruvian dusky dolphins). Several females with ovarian or uterine lesions and males with aberrant testes were large animals. It is possible that some of these lesions were associated with normal senescence of the reproductive system. (C) 2000 Harcourt Publishers Ltd.
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We thank Dr Jacques Jedwab for analysing the vaginal calculi, and Joanna Alfaro-Shigueto, Linda Lehman, Jeff McKinnon, Karina Ontón and Dr Andy Read for their help with field work. J. Alfaro-Shigueto also identified the Nasitrema globicephalae of JCR-757 and gave useful information on Nasi-trema spp. Dr Juan Antonio Raga is thanked for identifying the eggs found in JCR-757 at genus level and for constructive discussions on this case. This study was supported by the Gesellschaft zum Schutz der Meeressäugetiere, the IUCN Cetacean Specialist Group, Marine Education and Research, and Idea Wild. MFB received support from the Belgian Agency for Development Aid. Data collection on Peruvian cetaceans by KVW has for many years been supported by the Leopold III Fund for Nature Research and Conservation.