Mass-to-splenic volume ratio and splenic weight as a percentage of body weight in dogs with malignant and benign splenic masses: 65 cases (2007-2008).

OBJECTIVE: To determine whether mass-to-splenic volume ratio or splenic weight as a percentage of body weight was significantly different between dogs with benign versus malignant splenic masses. DESIGN: Retrospective case series. ANIMALS: 65 dogs that underwent splenectomy. PROCEDURES: Medical records of dogs examined between October 2007 and June 2008 because of a splenic mass were reviewed. Information obtained included dog age, breed, and weight; whether hemoperitoneum was present; splenic weight and dimensions (length, width, and height) at the time of splenectomy; dimensions (length, width, and height) of the splenic mass; and histologic diagnosis. Information on survival time was recorded when available. RESULTS: 30 (46%) dogs had hemangiosarcoma, 10 (15%) had other types of malignant masses, and 25 (39%) had benign masses. Dogs with benign splenic masses had a significantly higher mean mass-to-splenic volume ratio and higher mean splenic weight as a percentage of body weight than did dogs with hemangiosarcoma. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that mass-to-splenic volume ratio and splenic weight as a percentage of body weight may be useful in differentiating between hemangiosarcoma and benign lesions in dogs with splenic masses.

Beak gape dynamics during song in the zebra finch.

Bird song is a complex communication behavior that requires the coordination of several motor systems. Sound is produced in the syrinx and then modified by the upper vocal tract, but the specific nature and dynamics of this modification are not well understood. To determine the contribution of beak movements to sound modification, we studied the beak gape patterns in zebra finches (Taeniopygia guttata). Subsyringeal air sac pressure and song were recorded together with changes in beak gape, which were monitored with a magneto-sensitive transducer. Beak gape was positively correlated with fundamental frequency, peak frequency, and subsyringeal air sac pressure in all but one bird. For harmonic stacks, peak frequency increased with increasing beak gape, and the relationship between fundamental frequency and beak gape was no longer significant. Experimentally holding the beak open or closed had acoustic consequences consistent with the model in which beak movements change upper vocal tract length and, thus, the filter properties. Beak gape was positively correlated with sound amplitude in all but two birds. The relationship between beak aperture and amplitude may, however, be indirect because air sac pressure is correlated with amplitude and beak gape. The beak is opened quickly and to its widest aperture immediately prior to the onset of sound and at rapid transitions in sound, suggesting that beak movements may affect vibratory behavior of the labia.