The population dynamics of nematode parasites of sheep in northern England.

An investigation into the population dynamics of sheep nematodes was carried out between April 1970 and September 1971. Faecal egg counts were made from both ewes and lambs at weeks intervals while grass samples were taken fortnightly throughout the summer and monthly during the winter. From these results absolute numbers of nematode eggs and infective larvae were estimated and these figures used as a basis for determining the level of mortality occurring during development from egg to infective larva. The figures were also used to assess the relative importance of the ewe 'spring rise' and the egg output of the lambs in June while grazing contaminated pasture. These calculations suggest that larval mortality was very high and that it may vary considerably from year to year depending upon the climatic conditions prevailing. There was also an indication that the ewe 'spring rise' was the major source of the wave of infection which occurs in the lambs in late August and September.     

Identification of thiabendazole-resistant cyathostome species in Louisiana

A critical trial was performed with five ponies 6-9 months of age and raised on a horse farm with demonstrated benzimidazole-resistant cyathostomes. Eleven species of cyathostomes were recovered, seven of which had resistance to thiabendazole. Degrees of resistance varied among ponies and from species to species. Resistant species were Cyathostomum coronatum, Cyathostomum catinatum, Cylicostephanus minutus, Cylicostephanus calicatus, Cylicostephanus longibursatus, Cylicostephanus goldi and Cylicocylus nassatus. This is the first study identifying resistant cyathostome species in the Gulf Coast region of the USA and, although no new resistant species were found, results differed somewhat from those of other authors in that none of the cyathostome populations that have been studied contain the same complement of resistant species.     

Recovery of live immature cyathostome larvae from the faeces of horses by Baermann technique

It was demonstrated in the present study that a simple Baermann technique using disposable materials, was successful in detecting living, motile cyathostome larvae in the faeces of horses.     

Observations on the post-parturient rise of nematode egg-output in cattle

The nematode egg-output from 20 young cows with a grazing history of two seasons and all calving for the first time, was followed from 3 weeks before calving until 14 weeks afterwards. The egg-output was measured as the number of larvae cultured per gram of faeces (L.P.G.) accompanied by larval differentiation.In the first 2 weeks after parturition there was a marked rise in parasite egg-output mainly caused by Ostertagia spp., Trichstronglus spp., and Cooperia oncophora.A second peak of C. oncophora occured 4 weeks later. Peaks of Oesophagostomum spp., Haemonchus spp. and Bunostomum spp. were also later.Epidemiolgical consequences with respect to pasture contamination due to the post-parturient rise are possible, particularly when calving takes place in spring or early summer and the cows are kept indoors for only a few days.     

Comparative efficiency of moxidectin gel or ivermectin paste for cyathostome control in young horses

Thirty-six young horses were allocated to three similar groups. Horses in Group 1 were treated with moxidectin gel on Days 0, 90, and 180, Group 2 horses received ivermectin paste on Days 0, 60, 120, and 180, and horses in Group 3 were untreated controls. All horses were maintained on a common pasture for the first 180 days. Immediately after the final scheduled deworming, each group was moved to a separate, clean pasture where it remained until Day 360. At monthly intervals, fecal egg counts, body weights, body condition scores, and pasture larval counts were measured. The cumulative costs of both deworming regimens were calculated. Young horses treated three times at 90-day intervals with moxidectin gel had significantly lower monthly fecal egg counts than untreated controls from Days 30 through 300. Horses given ivermectin paste four times at 60-day intervals had significantly lower egg counts than controls 30 days after each treatment and 60 days after the third dose. Average daily gains of treated horses were significantly greater than controls from Days 120 through 360 (moxidectin) and from Days 210 through 360 (ivermectin). Quarterly moxidectin treatments reduced egg counts more effectively and cost less than ivermectin given bimonthly.     

库布齐沙地五种植物主要品质性状季节性变化研究

对沙打旺、羊柴、草木樨状黄芪、达乌里胡枝子和油蒿营养成分测定结果表明,5种沙地植物叶和茎营养成分均有明显的季节性变化,粗蛋白、粗脂肪和磷含量逐渐降低,而酸性洗涤纤维、中性洗涤纤维和钙含量逐渐上升。7月初,无氮浸出物含量比其他月高,例如,沙打旺叶无氮浸出物含量高达53.5%(P＜0.05);8月初,纤维物质开始显著增加,如沙打旺和羊柴茎中性洗涤纤维和酸性洗涤纤维分别高达55.3%和50.5%,且与前3个月比较差异显著(P＜0.05),因此为获得高品质牧草,采收季节以6月底-7月中旬为宜。油蒿叶中粗蛋白含量虽然很低,但粗脂肪和钙含量却很高,7月初分别高达3.3%和4.1%,且与其他植物比较差异显著(P＜0.05),通过适时刈割和加工调制仍可获得优质牧草。     

Long-term management of sabulous cystitis in five horses

Five horses with sabulous cystitis were managed for up to three years. They were treated by emptying the bladder through a urinary catheter and saline lavage with cytoscopic guidance to remove residual sabulous material. The cystitis was treated with antimicrobial and anti-inflammatory medications, and bethanechol chloride was also administered. Frequent catheterisation and emptying of the bladder was an alternative to regular cystoscopic examination with saline lavage but it resulted in the development of a urethral stricture in one case. Four of the horses returned to work and one was retired owing to persistent incontinence.     

Observations on equine strongyle control in southern temperate USA

A program of rotational anthelmintic treatments at eight-week intervals had failed to provide satisfactory equine strongyle control at a stable in southern USA. Anthelmintic resistance had rendered benzimidazoles ineffective, and intervals between treatments with other drugs were too great to prevent environmental contamination with ova. Ivermectin treatments at eight week intervals or pyrantel pamoate treatments at four week intervals successfully reduced egg counts for the majority of the summer grazing period. In southern temperate USA, translation of strongyle ova to larvae was most efficient during autumn and winter. Minimal larval translation occurred during summer when meteorological conditions limited pasture infectivity as effectively as anthelmintic treatments.     

Observations on the trajectory of the bullet in 15 horses euthanased by free bullet

The trajectories taken by the free bullets used to euthanase 15 horses were examined. The point of entry of the bullet relative to the recommended site was measured, together with the angle of the trajectory of the bullet relative to a tangent to its point of entry, the deviation of the trajectory from the midline of the brain, the structures of the brain that were damaged and the extent of this damage. Despite a reasonably consistent point of entry, there were wide variations in the damage inflicted, ranging from the total destruction of the hindbrain to injury to the cerebral cortex alone. The extent of the bullet's lateral deviation from the midline appeared to be the most significant factor affecting the level of destruction to the hindbrain, suggesting that angular direction may be more important than precise surface location in effecting a satisfactory kill.     

Seasonal dynamics of Anocentor nitens on horses in Brazil

Anocentor nitens is a widespread ectoparasite of horses in Brazil. A study of the seasonal dynamics of the parasitic phase of this tick was made by regular census of engorging females (>/=4mm) on free-ranging horses, fortnightly from July 1995 to July 1997, at Pedro Leopoldo, Minas Gerais. Twenty horses were divided into four groups of five animals per group, each having a similar mix of resistant and less resistant animals, based on initial infestation. Every 2 weeks, one of the groups, in sequence, was treated with an acaricide to prevent excessive infestations, and female ticks were censused 38 days later. The acaricide dips did not interfere with the seasonal dynamics of the tick population, which produced three major peaks of activity over a 12-month period. The first two peaks were in the hot, wet season and the third in the cold dry season. Tick numbers were similar for the two 12-month periods, decreasing from the spring and summer to the autumn and winter. Infestation rates were not equal among different horses. Twenty percent of the horses were responsible for 48% of the total parasite load, while 30% accounted for only 2.5% of the total parasite load. Principal predilection sites were; the ear (61%), mane (21%), and muzzle and face (6%). Measures for the strategic control of A. nitens ticks are discussed.     

Observations of the potency and duration of vecuronium in isoflurane-anesthetized horses

ObjectiveTo evaluate the potency and duration of three subparalyzing doses of vecuronium (VEC) in isoflurane-anesthetized horses.Study designProspective experimental study.AnimalsThirteen healthy adult horses undergoing arthroscopic surgery.MethodsDuring isoflurane anesthesia, horses received one of three doses of vecuronium (25, 50, or 100 μg kg^?1). Neuromuscular transmission was monitored with acceleromyography (AMG) with train-of-four (TOF) stimulation of the radial nerve. Maximal depression of the first twitch (T1), and onset time were recorded for each dose. Recovery time to a TOF ratio >90% was also evaluated.ResultsVecuronium 25 μg kg^?1 produced no observable T1 depression in four horses. VEC 50 μg kg^?1 (n = 5) produced a maximal T1 depression of [median (min, max)] 41 (20, 71) % in four horses, and no neuromuscular block was seen in the fifth. VEC 100 μg kg^?1 was given to four horses and produced a T1 depression of 73 (64, 78) %. Of the four horses in which VEC 50 μg kg^?1 produced a measurable neuromuscular block, three recovered spontaneously 43 (40, 52) minutes after VEC administration; a fourth subject received edrophonium to reverse residual block at the end of the surgery. Spontaneous recovery after VEC 100 μg kg^?1 occurred by 112 minutes in one horse, and had to be facilitated by edrophonium in the remaining three horses, more than 2 hours after VEC had been given.Conclusions and clinical relevanceA dose of 100 μg kg^?1 VEC in isoflurane anesthetized horses failed to produce complete paralysis. The partial neuromuscular block lasted at least 2 hours after this dose had been administered. Edrophonium was required to reverse the neuromuscular block in three of four horses. It is likely that more than 100 μg kg^?1 VEC would be necessary for complete neuromuscular blockade in horses, and that this dose will last >2 hours.