Immunosuppression induced by certain organotin compounds

Various organotin compounds induce lymphocyte depletion in the lymphoid system especially in the thymus. This report reviews the comparative aspects of the lympholytic activity of various organotins. The immunosuppressive effects of di-n-butyltin-dichloride (DBTC) and di-n-octyltindichloride (DOTC) as well as their in vitro effect upon rat and human lymphocytes are discussed in detail.     

Absorption by sheep of dieldrin from contaminated soil

Objective To study the accumulation of dieldrin residues in sheep from ingestion of contaminated soils was studied in two experiments.
Design A controlled feeding study of sheep fed contaminated soils of different type at varying intervals.
Animals and procedure Thirty-four 2-years-old wethers were divided into four groups (one control sheep only) and fed water-soluble dieldrin or soil contaminated with aldrin and dieldrin at varying intervals in the first study. In a second study 34 similar sheep were divided into four treatments with one being a control. Sheep were fed sandy, high clay or high organic matter soils with similar dieldrin and aldrin concentrations.
Results In the first study the concentration of dieldrin in the body fat of sheep dosed with dieldrin-contaminated soil was about half that in the body fat of sheep dosed with an equivalent amount of water-soluble dieldrin. The concentration of dieldrin was almost the same in sheep fed 500 μg of total dieldrin per day as it was in sheep fed 5000 μg every tenth day, over a 50-day period. In the second experiment sheep accumu-lated nearly three times as much pesticide from a soil with a high organic matter content, and about four times as much from a soil with a high clay content, as from a sandy soil with the same dieldrin content, over a 100-day period. The half-life of dieldrin in the fat of all sheep varied between 96 and 116 days after sheep ceased ingesting contaminated soil.
Conclusions Dieldrin concentrations in the fat of sheep that consume dieldrin contaminated soil fall within 10 days of removal from the source of contamination. However, dieidrin accumulates in the wool of sheep that consume dieldrin-contaminated soil.     

Absorption, distribution, and excretion of imidocarb dipropionate in sheep

Spectrophotometric and thin-layer chromatographic methods for determination of imidocarb in biological specimens are described. Following intravenous injection of imidocarb (2.0 mg/kg) into 3 sheep, plasma concentrations, initially averaging 10.8 microgram/ml, decreased to an average of 1.9 microgram/ml within 1 hour and then to less than 1 microgram/ml within the next 4 hours. When imidocarb (4.5 mg/kg) was injected intramuscularly (IM) into 7 sheep, peak plasma concentrations averaging 7.9 microgram/ml were achieved within 4 hours and then rapidly decreased to 4.6 microgram/ml within the next 2 hours. Plasma values then decayed very slowly by first-order kinetics and trace amounts were still present 4 weeks after treatment. Imidocarb was bound to plasma proteins and the apparent volume of distribution was estimated to be slightly higher than the total body water. The concentrations of the drug in the plasma and in the erythrocytes were approximately equal. Detectable amounts were present in all examined tissues 4 weeks after IM administration Twenty-four hours after IM administration, the highest concentrations were in kidney, liver, and brain. The 14C-labeled imidocarb could be detected in all regions of the central nervous system examined, in the hypophysis, and in the pineal body. Metabolic or biotransformation products were not detected by the methods used. Of the administered IM dose, 11 to 17% was excreted in the urine within 24 hours; thereafter, the excretion rate was low, and detectable amounts were still present in the urine for 4 weeks. Renal clearance of imidocarb was less than glomerular filtration rate, indicating net tubular reabsorption. The relatively high concentration of imidocarb in the bile suggests that the bile is an important route of excretion. High concentrations were also found in the mild of lactating ewes, but the drug could not be detected in the plasma of lambs fed milk from these ewes.     

Protection by iron salts against sporidesmin intoxication in sheep

A number of iron compounds have been shown to protect sheep against the harmful effects of the facial eczema toxin, sporidesmin. Various salts were found to be effective; the oxidation state of the metal was not important although water-solubility did appear to be a prerequisite for prophylactic activity. The effect of iron salts was additive with that of zinc, and it is suggested that the protective action of these compounds results from their ability to inhibit the absorption of copper, consistent with the previously-proposed freeradical mechanism for sporidesmin toxicity.     

Protection by iron salts against sporidesmin intoxication in sheep

A number of iron compounds have been shown to protect sheep against the harmful effects of the facial eczema toxin, sporidesmin. Various salts were found to be effective; the oxidation state of the metal was not important although water-solubility did appear to be a prerequisite for prophylactic activity. The effect of iron salts was additive with that of zinc, and it is suggested that the protective action of these compounds results from their ability to inhibit the absorption of copper, consistent with the previously-proposed free-radical mechanism for sporidesmin toxicity.     

The efficacy of praziquantel against cestodes in cats, dogs and sheep

Praziquantel is a new type of acylated isoquinoline-pyrazine. A single, low oral or subcutaneous dose of the compound is reliably effective against all tested juvenile and adult cestodes in cats, dogs and sheep. Praziquantel is the first cestodicide which is also effective on bile duct cestodes. In cats and dogs, 5 mg praziquantel per kg is completely effective on all stages of Taenia hydatigena, T pisiformis, T ovis, T taeniaeformis, Dipylidium caninum, Mesocestoides corti, Echinococcus multilocularis and E granulosus. Because of its very wide therapeutic index praziquantel is thus particularly suited for eradication programmes, eg, echinococcosis.     

Comparative study of the pharmacokinetics of alfentanil in rabbits, sheep, and dogs

The central arterial pharmacokinetics of alfentanil, a short-acting opioid agonist, were studied in rabbits, sheep, and dogs after short-duration infusion of the drug. Alfentanil was infused until a set end point (high-amplitude, slow-wave activity on the EEG) was reached. This required a larger alfentanil dose and a higher alfentanil arterial concentration in sheep, compared with rabbits and dogs. The plasma concentration-time data for each animal were fitted, using nonlinear regression, and in all animals, were best described by use of a triexponential function. In this study, differences in the disposition kinetics of alfentanil among the 3 species were found for only distribution clearance and initial distribution half-life. In dogs, compared with rabbits and sheep, the first distribution half-life was longer, probably because of pronounced drug-induced bradycardia (mean +/- SD, 48 +/- 21 beats/min). Distribution clearance was faster in sheep, compared with dogs, also probably because of better blood flow in sheep. Elimination half-life was similar in all species (rabbits, 62.4 +/- 11.3 minutes; sheep, 65.1 +/- 27.1 minutes; dogs, 58.3 +/- 10.3 minutes). This rapid half-life resulted from a small steady-state volume of distribution (rabbits, 908.3 +/- 269.0 ml/kg; sheep, 720.0 +/- 306.7 ml/kg; dogs, 597.7 +/- 290.2 ml/kg) and rapid systemic clearance (rabbits, 19.4 +/- 5.3 ml/min/kg; sheep, 13.3 +/- 3.0 ml/min/kg; dogs, 18.7 +/- 7.5 ml/min/kg). On the basis of these pharmacokinetic variables, alfentanil should have short duration of action in rabbits, sheep, and dogs. This may be beneficial in veterinary practice where rapid recovery would be expected after bolus administration for short procedures or after infusion for longer procedures.     

Absorption and use of differently structured protein isolates by rats

Differently structured isolated proteins with the same amino acid composition were tested with growing albino rats in an N-balance and absorption experiment. The following items were tested: --isolated horse bean protein --hydrolysed isolated horse bean protein with an amino acid supplement to make up for losses due to hydrolysis --horse bean protein-casein (1:1) fibres --isolated horse bean protein with an amino acid supplement to achieve the same amino acid concentrations as in the horse bean protein-casein fibres. The lowest digestibility and utilisation values were ascertained for the hydrolysed protein. Endogenous N-excretion calculated according to the isotope dilution method was higher than for intact proteins, the transport of the chyme in the digestive tract and the true absorption of N in the small intestine had significantly diminished. In comparison with horse bean protein supplemented with amino acids, the horse bean protein-casein fibres showed decreased protein utilisation and increased endogenous N-excretion. Independent of the protein fed and of the time after feeding a relatively constant endogenous N-quota of approximately 70% could be ascertained in the chyme in the small intestine. In contrast to this, the relation between exogenous and endogenous N determined from the contents of the large intestine proved to be dependent on the intermediary utilisation of the protein fed.     

Experimental induction of contact allergy in dogs by means of certain sensitization procedures

Three contact allergens; dinitrochlorobenzene (DNCB), nickel and formalin, were determined allergenicities. Contact allergies were induced in 24 dogs and 15 guinea pigs (used as a comparative animal species) by means of Draize test, Maximization test, Open Epicutaneous test and Buehler test, and evaluated by means of closed patch testing. Results showed that, in dogs, nickel produced allergic responses of the skin in the Open Epicutaneous test, but formalin did not produced it. In the Maximization test, however, both nickel and formalin failed to induce a contact allergy, although DNCB showed a high allergenicity. The appropriate concentration of test solutions for the closed patch test in dogs were 1.0% for DNCB, 0.1% for nickel and 1:10 dilution for formalin, respectively.     

Serum zinc, chromium, and iron concentrations in dogs with lymphoma and osteosarcoma

We compared serum concentrations of zinc, chromium, and iron in dogs with cancer to those of normal dogs. Dogs with lymphoma (n = 50) and osteosarcoma (n = 52) were evaluated. Dogs with lymphoma had significantly lower (P = .0028) mean serum zinc concentrations (mean +/- SD; 1.0 +/- 0.3 mg/L) when compared to normal dogs (1.2 +/- 0.4 mg/L). Dogs with osteosarcoma also had lower mean serum zinc concentrations (1.1 +/- 0.4 mg/L), but this difference was not significant (P = .075). Serum chromium concentrations were significantly lower in dogs with lymphoma (2.6 +/- 2.6 microg/L, P = .0007) and osteosarcoma (2.4 +/- 3.1 microg/L, P = .0001) compared to normal dogs (4.7 +/- 2.8 microg/L). Serum iron concentrations and total iron-binding capacity were significantly lower in dogs with lymphoma (110.8 +/- 56.7 microg/dL, P < .0001, and 236.6 +/- 45.6 microg/dL, P < .0001, respectively) and osteosarcoma (99.6 +/- 49.3 microg/dL, P < .0001, and 245.0 +/- 43.8 microg/dL, P = .0011, respectively) when compared to normal dogs (175.1 +/- 56.7 microg/dL and 277.1 +/- 47.4 microg/dL). Mean ferritin concentration was significantly higher in dogs with lymphoma (1291.7 +/- 63.0 microg/L) than in normal dogs (805.8 +/- 291.1 microg/L, P < .0001) and dogs with osteosarcoma (826.5 +/- 309.2 microg/L, P < .0001). Further investigation is needed to explore the clinical significance of these mineral abnormalities in dogs with cancer.     

如何搞好规模养羊场

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Echinococcus granulosus in dogs and sheep in central Utah, 1971-1976

During 1971 to 1976, a survey was conducted to determine the prevalence of Echinococcus granulosus infection among dogs and sheep in central Utah. For each year, the number of dogs positive for adult tapeworms of the total number examined and the percentage infected were: in 1971, 14 of 51 infected (27.4%); in 1972, 13 of 46 infected (28.3%); in 1973, 7 of 36 infected (19.4%); in 1974, 34 of 244 infected (13.9%); in 1975, 13 of 267 infected (4.9%); and in 1976, 14 of 195 infected (7.2%), or a 6-year total of 95 of 839 infected (av = 11.3%). For each year, the number of sheep positive with hydatid cysts of the total number examined and the percentage infected were: in 1971, 103 of 1,007 infected (10.2%); in 1972, 235 of 1,808 infected (13.0%); in 1973, 242 of 2,003 infected (12.1%); in 1974, 105 of 1,406 infected (7.5%); in 1975, 96 of 1,599 infected (6.0%); and in 1976, 96 of 1,171 infected (8.2%), or a 6-year total of 877 of 8,994 infected (av = 9.8%). These results represent a definite decline in numbers of infected animals and suggest that preventive and control measures advocated in central Utah are being implemented.