Effects of Psoroptes ovis (Acarina:Psoroptidae) on certain biochemical constituents of cattle serum.

Sera from Psoroptes ovis-infested calves were examined for 17 selected biochemical constituents to determine if P. ovis caused changes in any of these constituents. In order to recognize a scabies effect, there had to be a statistically significant (P less than or equal to 0.10) scabies exposure X time interaction and the changes in the biochemical constituents should have been correlated with the changes in the mite infestation. Five serum biochemical constituents fulfilled these criteria. Total protein, alpha-, beta-, and gamma-globulin were increased and total cholesterol was decreased at the peak of the scabies infestation. Precipitating antibodies to a P. ovis antigen were detected by immunodiffusion in some of the stored sera of the infested calves just after the peak of the infestation. Total protein, beta-, and gamma-globulin values were probably increased as a result of antibody production; alpha-globulin values were probably increased as a result of inflammation. As the scabies infestation declined, the mean values of all the above constituents from the infested calves, except cholesterol, began declining. Decreases in total cholesterol occurred, but they could not be entirely attributed to scabies. Examination of the serum biochemical constituents from a heavily infested calf that died during the test suggested that, in addition to antibody production and inflammation, kidney and liver damage may have occurred.

Toxicologic evaluation of diisopropyl methylphosphonate and dicyclopentadiene in cattle.

Diisopropyl methylphosphonate (DIMP), and dicyclopentadiene [3a,4,7,7a-tetrahydro-4,7-methyanoindene] (DCPD), were found as contaminants of groundwater in Colorado. Since there was a potential for cattle to be exposed to these chemicals by drinking well water, a study of their effects was initiated. Eight-to-ten week old calves were given a single dose of either DIMP at 62.5, 125, 250, 500 and 1000 mg/kg of body weight (b.w.) or DCPD at 250, 500, 1000 or 2000 mg/kg of b.w. The calves given DIMP developed tympanitis and ataxia, followed by depression, prostration, and death within two hr after dosing. A slight but significant increase in activated partial thromboplastin time was the only change observed in any of the clinical pathologic parameters. The only gross pathologic changes were acute gastroenteritis with hemorrhages in calves given 1000 mg/kg of b.w. Mild signs of intoxication, ataxia and excess salivation, were observed in calves given 250 mg of DCPD/kg of b.w. At higher doses, these signs were intensified; in addition, calves fell and, while prostrate, exhibited running movements and tonic, clonic spasms. The severity of the signs observed increased as the dose of DCPD increased. All calves given 2000 mg/kg of b.w. and one calf given 1000 mg/kg of b.w. died before seven days after dosing. The only clinical pathologic changes found were increased serum levels of creating phosphokinase, glutamic-oxalacetic transaminase, and glutamic pyruvic transaminase. The only consistent gross pathologic change was congestion in a variety of tissues in calves given 2000 mg/kg of b.w. A variety of histologic changes were observed in tissues from calves treated with both chemicals. However, these changes were not consistent for any one dose level and were not dose dependent. DIMP was slightly toxic for calves, since no signs of intoxication were observed at doses less than 1000 mg/kg of b.w. DCPD exerted detrimental effects on calves at 250 mg/kg of b.w. and was classified as moderately toxic.

Lithium toxicity in cattle.

Eighteen mixed-breed beef cattle died as the result of consuming "tacky lithium grease" discarded from a rubber reclaiming plant. Four experimental groups of mature cattle were given oral doses of a lithium salt at levels of 0, 20, 500, and 700 mg/kg body weight. Although all animals in the 250 mg/kg group showed signs of intoxication, the signs were mild and transient. Doses of 500 and 700 mg/kg proved toxic and fatal. Signs, serum levels, and tissue-organ deposition were dose and time-related. Signs of intoxication were salivation, depression, anorexia, hypodipsia, anuria, and diarrhea. The high dose group also showed severe depression and ataxia. The highest mean lithium serum values were 19, 40, and 54 ppm for the 250, 500, and 700 mg/kg groups, respectively. Postmortem and histopathologic examinations revealed dose-related gastroenteritis, slight interstitial nephritis, and hepatic cirrhosis. Tissue residues of lithium were in striated muscle (86.8 ppm), heart (79.3 ppm), liver (68.7 ppm), kidney (67.1 ppm) , and brain (51.8 ppm), in the high dose group. Since serum levels of cattle consuming the "tacky lithium grease" were 0.49 ppm of lithium, we believe other contaminants in this discarded grease may have caused or enhanced the toxic effect of lithium.

Effect of age on tolerance of calves to chlorpyrifos.

Groups of five calves (1 to 2 weeks old) or older calves (4 to 6 months old) were treated topically with increasing concentrations of chlorpyrifos [O,O-diethyl-O(-3,5,6-trichloro-2-pyridinyl) phosphorothioate] to determine their susceptibility to chlorpyrifos toxicity. Newborn calves also were given oral doses of technical grade (97.4%) chlorpyrifos to estimate their susceptibility by this treatment route. Topical applications to newborn calves consisted of 0.02%, 0.06%, or 0.12% chlorpyrifos administered as a spray to the entire body surface. Oral dosages given the newborn calves consisted of 5, 10, or 25 mg of chlorpyrifos/kg of body weight. Topical applications were administered to the older calves in the same manner as were applications to the newborn calves, but at concentrations of 0.25%, 0.5%, 0.9%, or 2.3%. Minimum dosages producing signs of toxicosis in newborn calves which were orally and topically given chlorpyrifos were 25 mg/kg of body weight and 0.06%, respectively. All five newborn calves sprayed with 0.12% chlorpyrifos were severely poisoned and were treated with atropine. One of these calves died within 48 hours after exposure to chlorpyrifos despite antidotal therapy. Signs of poisoning were not observed in older calves sprayed with 0.25%, 0.5%, or 0.9% chlorpyrifos. One Brahman-cross calf sprayed with 2.3% chlorpyrifos developed signs of mild poisoning that dissipated in 72 hours without treatment. Four older non-Brahman calves sprayed with 2.3% chlorpyrifos did not show signs of poisoning. Seemingly, 4- to 6-month old calves have an increased tolerance to topically applied chlorpyrifos compared with the tolerance of newborn calves, and the magnitude of this increased tolerance is 30-fold or higher.

Comparison of two procedures for determination of cholinesterase in livestock.

Our data indicate that the serum or plasma Bio-Dynamics/bmc automated procedure may be substituted satisfactorily for, or used as an alternative method to the Radeleff procedure for determining cholinesterase activity in cattle, swine, and sheep. The automated procedure is capable of 77 determinations/hr, and the Radeleff procedures about 20/hr. Either serum or plasma may be used, but the sample must be hemolyzed.

Chronic lead poisoning in horses.

Lead acetate was fed to 4 groups of 2 horses each to study chronic lead intoxication. A 5th group of 3 horses was maintained as controls. The leas was fed in capsules, with the minimum dosage of 6.25 mg/kg/day of lead as lead acetate (group I). The dose was increased from group I through group IV in an approximate geometric series, with each group being given about 125% of the dose given the previous group. These doses were given for 105 days, a period designated as phase 1. Since clinical signs were not observed after 105 days, the doses were increased and fed for an additional 190 days (days 106 to 295). This period was designated phase 2. The smallest daily dose in phase 2 was set at about 125% of the largest daily dose in phase 1. The doses in each group was increased by about 125% of that of the previous group, as was done in phase 1. Seven horses died or were euthanatized after 18 to 190 days of phase 2 (123 to 295 days after the 1st dose). One horse in group I did not develop any clinical signs of intoxication. Dose-related responses were unnoticed with doses larger than 15.3 mg/kg/day. All horses given lead had increased blood lead and serum iron concentrations. During phase 2, the hematocrit (erythrocyte volume) and hemoglobin contents were depressed. The lead concentration in kidney, liver, spleen, pancreas, brain, bone, and heart was increased in the treated horses. The dose level required to produce lead intoxication was greater than that reported for cattle and that estimated in epizootiologic studies of horses.

Effect of diflubenzuron (Dimilin; TH--6040) on the hyaluronic acid concentration in chicken combs.

The addition of N-[[(4-chlorphenyl)amino]carbonyl]-2,6-difluorobenzamide(diflubenzuron; Dimilin; TH-6040) up to levels of 250 ppm of the total diet of both male broilers and layers for 98 days did not affect the hyaluronic acid (HA) concentration (microgram/g tissue) in the combs. The concentration was measured at 21, 28, 42, 56, and 98 days on feed. The concentration in the combs of the layers were not significantly different at any sampling period regardless of diet. At the end of 56 days on feed, the combs of the broiler controls had a significantly (P less than .025) higher concentration than did any of the groups fed diflubenzuron. There were no differences observed at 21, 28, 42, or 98 days in the broilers. The HA concentration increased as the chickens matured and became larger; however, large variations were observed within the various groups at a given sample period.