Efficiency and Sensitivity of Techniques for Recovering Nematode Eggs from Bovine Feces

Haemonchus contortus eggs were extracted from sheep feces and known numbers were added to helminthologically sterile bovine feces to provide samples with seven, 30 and 60 eggs per gram (epg). At 60 epg, dilution techniques (modified Cornell-McMaster and modified McMaster) tended to overestimate the number of eggs and more eggs were recovered (mean of 121 and 88% respectively) with these techniques than with centrifugal concentration procedures (modified Cornell—63% and Wisconsin— 69%). At 30 epg, all techniques were comparable (modified Cornell-McMaster 67%, modified McMaster 63%, modified Cornell and Wisconsin 64%). At 7 epg, the Wisconsin (61%), modified Cornell (60%) and Cornell-McMaster (94%) techniques were comparable and better than the modified McMaster technique (16%). At all levels of epg, the modified Cornell and Wisconsin techniques recovered eggs from 100% of the samples. The Cornell-McMaster and modified McMaster techniques recovered eggs from 90 and 100% of samples at 60 epg; 40 and 100% at 30 epg; and 21 and 11% at 7 epg. With a gravitational concentration procedure, the Standard Vial, no more than 16% of the eggs at any level of epg were recovered and at 7 epg eggs were recovered from only one-half of the samples. Five gravitational concentration techniques were assessed over 66 to 490 epg. The Ovassay, Fecalyzer and modified Standard Vial techniques were comparable in efficiency (28%, 25% and 24% respectively), but the Standard Vial technique was less efficient (11%).

Introduced into diagnostic parasitology was the concept of predictive values which is the proportion of samples that a technique correctly identifies as being negative for parasite eggs. At 7 epg this was calculated to be zero for the modified Cornell-McMaster, modified McMaster and Standard Vial techniques and 100 for the Wisconsin and modified Cornell techniques.

     

Myasthénie grave chez un jeune chien

Myasthenia gravis in a young dog     

A Serological Survey of Leptospira interrogans serotype pomona in Alberta and Saskatchewan Striped Skunks and Possible Transmission Between Cattle and Skunks

The range of known occurrence of Leptospira interrogans serotype pomona is extended to Alberta in striped skunks (Mephitis mephitis); no evidence of L. sejroe was found. Reacting sera from skunks were confined to the southern portion of Alberta and adjacent Saskatchewan, although a number of reactors were found sufficiently further north in Saskatchewan suggesting that a different mode of infection may be functioning there. Of 95 skunk sera from near a dairy farm infected with serotype pomona 40% were reactors. Of 438 skunk sera from other areas only 5.7% were reactors; that difference was suggestive of transmission from cattle to skunks on the dairy farm. Of 22 skunk sera collected near the dairy farm in summer none were reactors, whereas 52% of skunk sera taken the previous and following winters were. That seasonal difference was not evident among sera from other locations.     

A Study of the Oral Toxicity of Calcium Chloride in Dairy Cows

The effects of oral administration of calcium chloride solutions to dairy cows were studied. When a 0.3 per cent solution was given ad libitum, and as the sole source of water for a period of 75 days, we observed no significant changes in feed consumption, body weight or milk production. The average daily water intake was increased by approximately 20 per cent, and signs of slight gastro-intestinal irritation were seen. No major changes in blood hemoglobin levels, hematocrits, total and differential white cell counts or thrombocyte numbers could be attributed to the treatment. We observed no significant effect on the serum calcium, chloride, magnesium, potassium, or sodium content. The level of inorganic phosphate in the serum rose to higher, but still normal values. During the entire experiment the urine pH was abnormally acid for dairy cows. Electrocardiograms were taken after 45 days of calcium chloride administration, and they appeared normal. When 0.1 and 0.2 per cent solutions were given as the sole source of water for a period of 81 days, the cows remained in good condition, and we observed no changes in appetite, body weight or milk production. In general, dairy cows will refuse to drink calcium chloride solutions when the concentration exceeds 0.5 per cent, even when they have been deprived of water for 18-24 hours. On the other hand, since the administration of lower concentrations for periods of 75 and 81 days did not cause any clinical sign of disease, it seems that on farms where more than one source of water are usually available, poisoning of dairy cattle by calcium chloride in solution is quite unlikely.     

Some Observations on the Diagnosis and Epidemiology of Leptospirosis in Swine

The results of combined epidemiological, clinical, serological, bacteriological and histopathological studies following an outbreak of disease caused by L. pomona on a farm stocked with cattle, sheep, pigs, goats and horses maintained for experimental purposes, are reported.

The incidence of infection was high in horses, cattle and pigs. A few low titres were seen in sheep. The goats were not infected. Apart from a single bovine abortion all the clinical symptoms observed occurred in pregnant sows. Seven of these aborted or gave birth to stillborn pigs within a six week period.

Fifteen species of wildlife were trapped or shot on the farm during the year following the outbreak. L. pomona was isolated from four skunks and a porcupine. Epidemiological studies indicated that wildlife reservoir hosts were the primary source of infection for the domestic livestock.

Leptospiruria and the serological response were studied in a group of eight infected sows. Microscopic agglutination titres of 10² or less could not be associated with leptospiruria and the duration of leptospiruria was found to range from a few weeks to over two years in individual sows. Direct dark-field examination of urine proved superior to guinea-pig inoculation as a method of detecting leptospiruria and it is suggested that the former technique could be adopted with advantage as a routine aid to diagnosis.

     

Expression of β2-integrin on monocytes and blood polymorphonuclear leukocytes in the periparturient period in dairy cows

The hypothesis that an altered expression of CD11/CD18 on bovine circulating monocytes, polymorphonuclear leukocytes (PMN), or both, contributes to an increased mastitis susceptibility in periparturient cows was tested. Expression of CD18 and CD11a, -b, -c on bovine monocytes and PMN were assessed in 8 Friesian-Holstein cows by flow cytometry from 2 wk before calving to 5 wk after calving. Minor changes in adhesion molecule expression levels were detected throughout the experimental period. Compared with PMN, monocytes exhibited an expression level that was similar for CD18, higher for CD11a and CD11c, but lower for CD11b. Differences in density may reflect the relative importance of these adhesion molecules on both leukocyte types. In this study, the decreased number of milk resident macrophages and PMN observed during the periparturient period could not be attributed to changes of CD11/CD18 levels on circulating leukocytes.     

酵母多糖对环磷酰胺所致免疫损伤大鼠的拮抗作用

为研究酵母多糖(YP)对环磷酰胺(CTX)所致免疫损伤大鼠的拮抗作用,本实验将80只雄性SD大鼠随机分为YP(50 mg/kg)+CTX组、YP(100 mg/kg)+CTX组、YP(200 mg/kg)+CTX组、CTX对照组和正常对照组。YP+CTX组按剂量灌胃并称重,CTX和正常对照组则灌胃给予等量生理盐水,连续给药10 d;在第8 d、9 d,除正常对照组外,其余4组腹腔注射CTX 100 mg/kg。第11 d采血及对相关的免疫器官组织进行检测。结果显示,YP(100 mg/kg)组平均日增重和饲料报酬比正常对照组显著增加(p<0.05);胸腺指数,血清中IgA、IgG、表皮生长因子(EGF)、碱性磷酸酶(AKP)含量及空肠SIgA水平显著(p<0.05)或极显著(p<0.01)高于CTX对照组;结肠壁中前列腺素E2(PGE2)含量与CTX对照组相比显著降低(p<0.05)。以上结果表明,YP能提高大鼠的生长性能;YP对CTX所致免疫损伤具有一定的拮抗保护作用,其中100 mg/kg剂量的YP效果最为显著。