Observations on the Bovine Blood Picture in Health and Under Parasitism

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Observations made on 6 normal Jersey and Holstein calves between the ages of 2 days and 6 months showed an average of 8.70 million red cells, 10,674 white cells per cubic millimeter of blood and a differential leucocytic count as follows: Lymphocytes, 64.4%; monocytes, 12.2%; neutrophils, 19.6%; eosinophiles, 3.3%. Six counts made on each of 5 adult animals between the ages of 3 years and 6 1/2 years, which were on range and which were considered to be normal from the standpoint of the absence of disease, revealed an average of 6.39 million red cells and 10,225 white cells per cubic millimeter of blood, with a differential leucocytic count of: Lymphocytes, 58.1%; monocytes, 8.0%; neutrophils, 25.9%; eosinophiles, 7.0%. The feeding of a pure nodularworm culture produced in calf No. 95 a sharp drop of 2 1/2 million red cells 5 days after the administration of the larvae, with an increase of 5000 in the total number of white cells caused by an increase above the previous range of 17% in the number of neutrophiles. These general changes were of constant occurrence, though not so sharply shown in the 6 individuals which had a mixed infection of hookworms (Bunostomum phlebotomum) and nodularworms (Oesophagostomum radiatum) as in the 2 animals with the pure nodularworm infection. The calves used in all these experiments were kept under controlled conditions preceding and during the period of infection. For each experimentally parasitized calf, a control calf was kept under similar conditions. The same picture found in experimentally-produced cases of parasitism was noted in a naturally infected Brahma heifer about 1 1/2 years old. This animal was brought to the laboratory in a much weakened condition, greatly emaciated, and passing very small quantities of liquid fecal material with a very fetid odor.