Studies of three stranded Delphinus delphis and first record of focal pneumonia abscedativa in Chile

Abstract

The remains of three stranded common dolphins found on beaches in the IV and V Regions of Chile were studied. The specimens were determined to the short-beaked common dolphins (Delphinus delphis), based on the low Rostral Length and Zygomatic Width Index (RL/ZYGW, from 1.31to 1.40), reduced alveoli number (on maxilla from 72 to 90) and small teeth. The observed variation in cranial and dental (both external and internal) morphology seems not attributable to age, but larger samples are required to verify whether the variation is population dependent. Histopathologic, microbiological, and dental cronometric tests were concordant in that the death of individual CHW001 (female), was a result of respiratory failure due to focal pneumonia abscedativa, apparently provoked by Gram and Ziehl Neelsen - negative bacteria that entered via hematíe path from ulcerated injuries on the palate. The age of two of the stranded specimens of D. delphis, (MNHN1488 and CHW001), was estimated, through dentinal cronometric tests (acid etching, decalcification and colouring, and polarized light micrography), to be 4.8 and 8.3 years respectively. The use of high-speed handheld grinding machines and a digital microscope equipped with the appropriate filters, allowed within Iess than four hours, to apply at least two complementary dentinal cronometric techniques on the same tooth. This technique aids in diminishing GLG count interpretation errors, in a way both. economical and portable to suit field studies. With additional samples, the in vivo body length. of D. delphis is expected to the estimated from desiccated strandings by considering that intervertebral space is shortened by 36% during the dryng process.