Pyridoxine (a vitamin B6) and its derivative pyridoxal as treatment for Albizia versicolor poisoning in guinea-pigs

In the course of three experiments it was established that all the toxic effects of a lethal dose of Albizia versicolor pods (greater than 4.5 g/kg) in guinea-pigs could be countered by concurrent subcutaneous injection of pyridoxine (10 mg/kg). This treatment was also successful once severe symptoms had set in. Pyridoxal, on the other hand, was found to be ineffective as a therapeutic agent. The fact that pyridoxal does not counter the action of the toxin indicates an atypical site of action by the toxin as regards the normal pathways which require vitamin B6 as a co-factor.     

绵羊马铃薯中毒的诊治

近年来,家畜因误食有毒马铃薯发生中毒时有发生,笔者通过采取综合治疗措施,取得了满意效果.现将1例治疗病例介绍如下.     

Tunicamycin and corynetoxin poisoning in sheep

Quantitative toxicity studies were carried out in sheep using corynetoxin, tunicamycin and toxic annual ryegrass (Lolium rigidum). Sheep were very sensitive to these toxins. The lethal dose was about 35 micrograms/kg bodyweight for pure tunicamycin given by subcutaneous injection and 3 to 5 mg/kg for corynetoxin administered orally as slurries of bacterial galls of known corynetoxin content. The total lethal dose was of the same order, whether given as a single dose or as repeated smaller doses, the maximum interval tested being 9 weeks between doses. This finding indicates that a second exposure of animals to toxic rye grass in the one season would present a greater risk than would a first exposure to the same field. It also demonstrates the advisability of the monitoring of pasture levels of gall contamination, as levels below those that produce clinical signs of the disease may still contribute to an accumulating burden of toxicity.     

Sawfly poisoning in sheep and goats

In September 1984 some sheep in a flock of 250 suffered depression, anorexia, incoordination and difficulty in rising; 50 ewes and weaners died. Post mortem examination revealed petechial bleeding, massive acute liver necrosis and in some animals degeneration of the kidney tubules. The rumen and gut contained many larvae of the blue-black birch sawfly (Arge pullata). Laboratory and field observations indicated that these were the cause of the illness.     

Copper poisoning in a flock of sheep. Copper excretion patterns after treatment with molybdenum and sulfur or penicillamine

During an outbreak of chronic copper poisoning, fecal and urinary copper excretion were measured following treatment with molybdenum and sulfur supplementation of the feed (0.1 g ammonium molybdate plus 1 g sodium sulfate/sheep/day) or oral penicillamine (50 mg/kg bodyweight/day) using rams in metabolism cages. Serum glutamic-oxaloacetic transaminase activities and liver levels of molybdenum and copper in sheep that died were also monitored. Within four days of starting molybdenum and sulfur supplementation a highly significant increase in fecal copper excretion was evident and the increase persisted throughout the monitoring period (five weeks — general treatment of the flock continued for another three weeks). There was no effect of the molybdenum and sulfur supplementation on urinary excretion of copper. The molybdenum and sulfur supplementation was very effective, resulting in a rapid marked decrease in mortality. Oral penicillamine treatment induced cupruresis but did not affect fecal copper excretion. The results indicated that, while the cost of penicillamine may be a limiting factor for general treatment of a flock, it may be the drug of choice for the therapy of valuable breeding animals because cupruresis may be accurately and individually controlled. Serum glutamicoxaloacetic transaminase activities were a valuable aid in diagnosing chronic copper toxicosis as well as for monitoring recovery. High initial liver copper levels were gradually reduced following molybdenum and sulfur treatment. However, at the end of the study the liver copper levels of dead sheep varied within wide limits and there were still some sheep with high liver copper levels.     

Experimental trichinosis in sheep.

Trichinella spiralis spiralis infections were established in sheep by administering infective larvae via gavage or feeding infected musculature. Trichinella spiralis nativa infective larvae had a low infectivity for sheep although light infections may be established in some animals with large infective doses. For the most part, sheep were averse to ingesting musculature mixed in a grain ration unless it was camouflaged with molasses. The heaviest infections usually occurred in the masseter muscle. The fact that sheep are averse to ingesting muscle tissue may reduce the likelihood of trichinosis. Anti-Trichinella antibodies to both T: spiralis spiralis and T. spiralis nativa were produced as demonstrated by the enzyme-linked immunosorbent assay. Seroconversion occurred in several sheep challenged with T. spiralis nativa even though larvae were not recovered from the musculature by pepsin-digestion.     

Experimental transmission of a goat strain of Sarcoptes scabiei to desert sheep and its treatment with ivermectin

Desert sheep were experimentally infected with a goat strain of Sarcoptes scabiei, proving that this mite is not completely host specific. More severe lesions were produced on sheep when the mites were applied to lacerated than when applied to scarified or non-scarified areas. Lesions were more pronounced on moistened areas than dry areas and lesions produced on dry scarified areas resembled those produced on non-scarified moistened ones. Skin scrapings from the experimental lesions in the sheep contained numerous mites of all stages, proving the goat mites had become well established and were reproducing actively in the experimental lesions. Severe histopathological changes were observed in skin sections, comprising mainly thick crust formation, mites beneath the keratin and severe degenerative and necrotic changes. Treatment of sheep with ivermectin at a dose rate of 200 micrograms kg-1 body weight produced rapid and excellent cure.     

Use of ammonium tetrathiomolybdate in the treatment of copper poisoning in sheep

Intravenous administration of ammonium tetrathiomolybdate (three doses on alternate days) appeared to be an effective means of containing the acute phase of copper toxicity in sheep, whether this arose from continuous ingestion of high copper feeds or by injudicious use of copper preparations for the control of copper deficiency. No adverse effects were recorded on lamb numbers, birth weight or survival of lambs born to ewes of normal to low copper status when the treatment was applied at sensitive periods of the reproductive cycle. Decreases in 'available' plasma copper and in liver damage occurred rapidly in response to intravenous tetrathiomolybdate and it is suggested that all animals at risk be treated.     

Experimentally-induced Cestrum laevigatum (Schlechtd.) poisoning in sheep.

Dried, milled Cestrum laevigatum plant material was drenched to 6 ewes at doses ranging from 2,5 to 10 g/kg/day for 1 to 47 days. The most noticeable clinical signs were depression, anorexia and ruminal stasis. These signs were accompanied by clinical pathological changes indicative of liver involvement such as increases in the serum activities of aspartate transaminase, lactate dehydrogenase and gamma-glutamyltransferase. Hepatosis characterized by accentuated lobulation, and centrilobular to midzonal coagulative necrosis, haemorrhage and congestion occurred in 2 of the 3 ewes given high doses of plant material. Liver lesions in the other animals included disappearance of hepatocytes and collapse of the reticulin stroma in the centrilobular areas. Spongy changes in the cerebral white matter were evident in the ewes of the high-dose group. Ultrastructural changes in the liver comprised degeneration and necrosis of hepatocytes and occasionally endothelial cells, and disruption of sinusoidal walls.     

Experimental treatment ofBrucella melitensis infection in sheep with oxytetracycline alone or combined with streptomycin

The efficacy of oxytetracycline (OTC) alone or combined with streptomycin in the treatment of 118 Najdi ewes believed to have been naturally infected with Brucella melitensis, was evaluated by culture of selected tissues and organs at slaughter. Groups of sheep were given 250, 500 or 1,000 mg of OTC intraperitoneally (i/p) daily for six weeks and in the respective groups at necropsy 52, 69 and 100% of sheep were found to be Brucella-free. Treatment with 250 mg OTC (daily for six weeks i/p) combined with 1,000 mg streptomycin (daily for three weeks intramuscularly) increased the percentage of Brucella-free sheep to 82%. When a group of sheep were each inoculated i/p with 1,000 mg of long-acting OTC every three days over a period of six weeks, 75% of them were Brucella-free at necropsy. B. melitensis was isolated from all (24) non-treated (control) sheep. The results showed that long-term treatment with a high dose of OTC alone had succeeded in eliminating B. melitensis from a group of 16 naturally infected sheep.