Non-invasive cardiovascular assessment of pregnancy in healthy female cats.

INTRODUCTION: The aim of this study was to evaluate cardiac morphology, indices of systolic and diastolic function, systolic blood pressure (SBP), and uterine artery resistance index (RI) during normal feline pregnancy. ANIMALS; MATERIALS AND METHODS: Twenty domestic short-hair pregnant queens, weighing 2.4-3.9 kg. Animals were assessed by two-dimensional, M-mode, and Doppler echocardiography, non-invasive SBP measurement, and uterine Doppler ultrasound every 10 days from mating to parturition. RESULTS: Interventricular septal thickness at end-diastole and end-systole, left ventricular internal dimension at end-diastole, left ventricular free wall thickness at end-diastole and end-systole, fractional shortening, stroke volume, cardiac output (CO), heart rate, and peak velocities of early and late diastolic transmitral flow increased during the second half of gestation, while SBP and RI decreased during the same period (p < 0.01). DISCUSSION AND CONCLUSIONS: Cardiac structure and function varied during normal pregnancy in these queens. Eccentric hypertrophy, increased indices of systolic function, and increased measurements of CO seem to be the consequences of the hemodynamic modifications occurring during pregnancy. The assessment of maternal cardiovascular function may prove a useful screening tool to detect pregnancy complications in feline species.

Dioestrous ovariectomy: a model to study the role of progesterone in the onset of canine pseudopregnancy.

It has been suggested that overt pseudopregnancy in bitches is caused by an increase in the concentration of serum prolactin as a result of an abrupt decrease in progesterone concentration in the late luteal phase. This hypothesis was tested by using ovariectomy at dioestrus as an experimental model. A total of 18 intact cross- and purebred bitches were used. Eleven animals were ovariectomized (day 0) between day 25 and day 40 of the oestrous cycle, and seven intact bitches were used as controls. Blood samples for determination of prolactin and progesterone concentrations were collected on days -1, 1, 2, 3 and 7 in the ovariectomized group, and on day 1 and day 7 in the control group. On day 7, the presence or absence of overt pseudopregnancy was recorded. The four ovariectomized bitches with a history of pseudopregnancy showed signs of overt pseudopregnancy (P < 0.01). On day 7, progesterone concentrations were significantly higher in the control than in the ovariectomized bitches (P < 0.01). The expected decrease in serum progesterone concentration after ovariectomy was similar in pseudopregnant bitches and non-pseudopregnant bitches. However, in pseudopregnant bitches, but not in non-pseudopregnant bitches, there was a marked increase (expressed as percentage change) in the concentration of prolactin between day -1 and day 7 (P < 0.01). It was concluded that the abrupt decrease in progesterone concentrations does not lead systematically to pseudopregnancy. Only in bitches predisposed to pseudopregnancy would an abrupt decrease in progesterone concentrations induce a substantial increase in prolactin concentrations, which in turn would trigger the typical signs of pseudopregnancy.