COMBINED CARBON DIOXIDE CONTENT OF BLOOD PLASMA IN THE HORSE

Studies in acidosis have recently made a remarkable progress and many valuable reports in connection with it have already been published. The subject is, as is widely known, of great interest both from a physiological and pathological point of view. It would be of no benefit, however, to describe here what acidosis is or what kinds of researches have hitherto been made on the subject. For three years I have devoted myself to the study of this subject with the view of finding out its practical value in veterinary science.As a first step in my experiments, I have measured the CO2 content of horse blood plasma by means of VAN SLYKE'S method which was pulished in 1917 and is now generally recommended as the best method for diagnosing acidosis.The blood used for my experiments was obtained from the jugular vein of the horse, care being taken in doing so not to allow the blood to come in contact with the air. According to the studies of STADI and VAN SLYKE, it is not necessary, for the measurement of the CO2 content, to saturate the venous blood with CO2, at the same tension as in alveolar air, if the blood is drawn from a vein without any stasis. The venous blood employed in my experiments, therefore, is not subjected to any process which was to be carried out for the purpose of saturating the blood with CO2.The results obtained from a number of experiments are as follows:(1) CO2, content of blood-plasma in the normal horse.Experiments in 30 horses (military) show that the CO2, content of blood-plasma varies from 72.1 to 52.8 vol %, that is, 62.6 vol % on the average.It must be noticed here that even in one and the same horse there is a difference between the CO2 content measured in the morning and that obtained in the evening.(2) CO2, content of blood-plasma in the horse under abnormal conditions.(a) Fatigue.In horses which have taken a run of about 390km, the CO2, content has fallen below normal, all of them being in a condition of acidosis; the content of CO2, in 8 tired horses averages 47.0 vol % (53.2-38.1). Comparing the condition of some excessively tired horses with that of horses in a state of slight fatigue, I have found that the CO2, content in blood-plasma, that is, the lowered alkaline reserve, decreases according to the degree of fatigue, so the blood-plasma of the most severely tired horse contains the least volume of CO2.(b) Podophyllitis, colic, influenza pectoralis, and morbus maculosus.In podophyllitis caused by severe exercise, the CO2 content of blood plasma decreases considerably. An examination of the blood-plasma obtained from 7 horses suffering from an attack of podophyllitis showed that the CO2 content averages 54.1 vol %, which means that almost all of them were in a condition of acidosis.It is no unusual matter to find acidosis is proved in a case of severe colic. According to my measurements, the CO2 content of the blood-plasma taken from a horse which has been suffering from colic so severely that he died several hours later, was 32.7 vol %.In influenza pectoralis I have found that the CO2 content of the blood-plasma is 27.1 vol % in its severe form and 50.0 vol % when mild.The blood-plasma taken from a horse affected with morbus maculosus contains 45.7 vol. % of CO2.(3) Chlorine and phosgen gas poisoning.In a room which was tightly shut up, a horse was exposed for 10 minutes to chlorine gas, the concentration of which was 0.2 vol. ‰. The CO2 content of the blood-plasma taken from the animal decreased from 67.3% to 49.4%, and when the blood concentration increased to its maximum the symptom of pulmonary oedema was most remarkable.