The cardiopulmonary effects of dobutamine and norepinephrine in isoflurane-anesthetized foals

OBJECTIVE: To evaluate the cardiovascular effects of norepinephrine (NE) and dobutamine (DB) in isoflurane-anesthetized foals. STUDY DESIGN: Prospective laboratory study. METHODS: Norepinephrine (0.05, 0.10, 0.20, and 0.40 microg kg(-1) minute(-1)) and dobutamine (2.5, 5.0, and 10 microg kg(-1) minute(-1)) were alternately administered to seven healthy, 1- to 2-week-old isoflurane-anesthetized foals. Arterial and pulmonary arterial blood pressure, right atrial pressure, pulmonary artery occlusion pressure, heart rate, body temperature, cardiac output, arterial and mixed venous blood pH, partial pressure of carbon dioxide, partial pressure of oxygen [arterial partial pressure of oxygen (PaO(2)) and mixed venous partial pressure of oxygen (PvO(2))], and packed cell volume were measured. Standard base excess, bicarbonate concentration, systemic and pulmonary vascular resistance, cardiac index (CI), stroke volume, left and right stroke work indices, oxygen delivery (DO(2)), consumption, and extraction were calculated. Results Norepinephrine infusion resulted in significant increases in arterial and pulmonary arterial pressure, systemic and pulmonary vascular resistance indices, and PaO(2); heart rate was decreased. Dobutamine infusion resulted in significant increases in heart rate, stroke volume index, CI, and arterial and pulmonary arterial blood pressure. Systemic and pulmonary vascular resistance indices were decreased while the ventricular stroke work indices increased. The PaO(2) decreased while DO(2) and oxygen consumption increased. Oxygen extraction decreased and PvO(2) increased. CONCLUSIONS AND CLINICAL RELEVANCE: Norepinephrine primarily augments arterial blood pressure while decreasing CI. Dobutamine primarily augments CI with only modest increases in arterial blood pressure. Both NE and DB could be useful in the hemodynamic management of anesthetized foals.     

Sex difference in the morphology of erythrocyte nucleus and melanising activity of blood of one-day-old chicks

Erythrocyte nuclear breadth and area were found to be less in the male than in the female of 1‐d‐old chicks. The nuclear length and area of erythrocyte as a whole did not vary between sexes. The percentage of erythrocytes with narrow nuclei was higher in the male than in the female. Blood from males showed higher melanising activity than that from females.

From the results obtained it is suggested that these sex differences are due to the male's higher oxidation rate.     

THE PREVENTION AND TREATMENT OF BIRDSVILLE DISEASE OF HORSES

In a feeding experiment with eight horses fed toxic levels of Indigofera dominii, the poisonous plant which caused Birdsville disease of horses, three of four supplemented with peanut meal and one supplemented with gelatin did not develop the disease. Two non-supplemented control horses, one supplemented with peanut meal and another who was fed gelatin but rejected it, contracted Birdsville disease. This experiment, along with treatment trials in field cases is presented as evidence of the value of arginine-rich protein supplement in protecting and treating horses against the toxic effects of Indigofera dominii. The possible mode of action is discussed.