Prevalence of iatrogenic heart murmurs in a population of apparently healthy cats.

OBJECTIVES: To determine the prevalence of iatrogenic heart murmurs in a population of apparently healthy cats and to investigate factors that may predispose cats to iatrogenic murmurs. MATERIALS AND METHODS: Apparently healthy cats presenting for routine examinations were prospectively enrolled. Following a physical examination to confirm there were no abnormalities, a cardiac examination was performed before and during a provocative manoeuvre performed independently by two clinicians. The provocative manoeuvre was performed on the right side of the chest wall by applying gentle pressure with a stethoscope to ascertain whether a murmur became audible, graded using a modified descriptive scale (soft/moderate). The cat's heart rate before and during the provocative manoeuvre and their age, sex, body condition score and bodyweight were recorded. RESULTS: One hundred and six cats were prospectively enrolled. The average prevalence of iatrogenic murmurs was 28.2% with good interobserver agreement recorded on both the presence (kappa 0.67 and 0.62) and grade of the murmur (kappa 0.6 and 0.53). A significant association was noted between age and body condition score, with iatrogenic murmurs more likely in cats with increasing age and decreasing body condition score. There was no association between heart rate and the presence of an iatrogenic murmur. CLINICAL SIGNIFICANCE: Iatrogenic murmurs are a common finding in cats with increasing prevalence noted in older and lean cats. Iatrogenic murmurs should therefore be considered as a differential diagnosis in a cat when an audible soft systolic right-sided murmur occurs with gentle pressure application to the chest wall during auscultation.

Reverse engineering field-derived vertical distribution profiles to infer larval swimming behaviors.

Biophysical models are well-used tools for predicting the dispersal of marine larvae. Larval behavior has been shown to influence dispersal, but how to incorporate behavior effectively within dispersal models remains a challenge. Mechanisms of behavior are often derived from laboratory-based studies and therefore, may not reflect behavior in situ. Here, using state-of-the-art models, we explore the movements that larvae must undertake to achieve the vertical distribution patterns observed in nature. Results suggest that behaviors are not consistent with those described under the tidally synchronized vertical migration (TVM) hypothesis. Instead, we show (i) a need for swimming speed and direction to vary over the tidal cycle and (ii) that, in some instances, larval swimming cannot explain observed vertical patterns. We argue that current methods of behavioral parameterization are limited in their capacity to replicate in situ observations of vertical distribution, which may cause dispersal error to propagate over time, due to advective differences over depth and demonstrate an alternative to laboratory-based behavioral parameterization that encompasses the range of environmental cues that may be acting on planktic organisms.