Chronic plumbism in rabbits: a comparison of three diagnostic tests.

Three groups of rabbits (A, B, and C; 6 rabbits/group) were fed a lead supplement of 25, 50, and 100 mg of Pb/kg of live weight/day for 87 days to compare the efficacies of 3 diagnostic tests--whole blood lead concentration, urinary delta-aminolevulinic acid (UALA), and fluorescent erythrocyte test (FET)--and to determine the clinicopathologic changes of experimentally induced lead poisoning in rabbits. All rabbits given lead had whole-blood lead concentrations greater then the maximum value (0.030 mg/dl) for control rabbits (group D), indicating that this measurement is a reliable indicator of lead ingestion. All group A rabbits (fed 25 mg of Pb/kg) and 66% negative UALA test results, with values less than the maximum value (0.12 mg/dl) for group D (control) rabbits. Only group C rabbits (fed 100 mg of Pb/kg) had consistently positive UALA FINDINGS. The test was therefore considered unreliable for detecting daily lead intakes less than 100 mg/kg of live weight of rabbits. All rabbits given lead had erythrocytes which fluoresced red when exposed to light rays with wavelenghts from 320 to 400 nm; fluorescence was not observed in erythrocytes of control rabbits. The FET appears to be a convenient and reliable diagnostic test for lead ingestion. In groups B and C, clinical signs of lead poisoning were mild, nonpersistent anemia characterized by the presence of poikilocytes, hupochromic erythrocytes, target cells, erythroblasts, erythrocytes with punctate basophilic stippling, reduced mean corpuscular hemoglobin concentrations, and relative lymphocytosis, neutropenia, and eosinopenia. One rabbit from the group fed the largest dose displayed partial anorexia.

Morphologic alterations associated with decreased cerebrospinal fluid pressure in chronic bovine hypervitaminosis A.

Arachnoid granulations and villi, choroid plexuses, and ependymal epithelium from 18 male Holstein-Friesian calves fed 108 (control), 8,800 (midly toxic), or 17,600 (severely toxic) mug of vitamin A/kg of live weight per day for 12 weeks were examined by light and electron microscopy for structural changes which could be used to explain the decreased cerebrospinal fluid (CSF) pressure seen in chronic hypervitaminotic A animals. In the toxic calf group, granulations were reduced to approximately two-thirds the size of those in the control calves, with the fibrous cap particularly being thinner and smaller. Second, height of epithelial cells of the lateral and 3rd ventricular choroid plexuses decreased significantly and that of the 4th ventricular choroid plexus, only slightly, as vitamin A intake increased. Structural differences of ependymal cells were not apparent between control and hypervitaminotic A calves. It is hypothesized that the thinner and less extensive fibrous cap of the arachnoid granulations in the toxic calves may result in increased permeability to CSF outflow.