Comparative virulence of NAD-dependent and NAD-independent Actinobacillus pleuropneumoniae strains.

The virulence of a NAD-independent Actinobacillus pleuropneumoniae serotype 2 strain and NAD-dependent serotype 2, 3 and 9 strains was compared under experimental conditions. Hysterectomy-derived piglets were inoculated endobronchially with 50-500 cfu of these strains. All 23 piglets inoculated with the NAD-dependent strains developed acute disease within 12 hours post inoculation. Twenty-two of these piglets died within 24 hours after the first clinical signs. Three of nine piglets inoculated with the NAD-independent strain did not develop clinical disease. In the other six piglets, disease signs were similar as in the piglets inoculated with the NAD-dependent strains. No differences in clinical disease were observed between colostrum deprived piglets and piglets that obtained colostrum from a SPF sow.     

Destruction of Trichinella spiralis spiralis during the preparation of the "dry cured" pork products proscuitto, proscuittini and Genoa salami

Genoa salami, proscuittini and proscuitto were prepared from pork carcasses that were heavily infected experimentally with Trichinella spiralis spiralis. Genoa salami was prepared with salt concentrations of 2.0%, 2.75% and 3.3%. Proscuitto was prepared by two procedures approved by Agriculture Canada. At various times postpreparation, samples of the various cured products were taken and examined by pepsin digestion and rat bioassay for the presence of viable trichinae. Water activity and pH of the cured meat were also determined. Curing of the various products was shown to destroy the Trichinella larvae. Pepsin digestion revealed that larvae progressively became loosely coiled, uncoiled and more subject to digestion (ghost larvae) during the curing process. Rat bioassay revealed the presence of viable trichinae in the proscuitto prepared using a sodium chloride salt mixture at day 34 but not at day 48 postpreparation. All other bioassays carried out on Genoa salami between 13 and 42 days postpreparation, on proscuittini between days 27 and 69 and on proscuitto between days 34 and 69 were negative for viable trichinae. Under the conditions of this study, preparing Genoa salami with salt concentrations as low as 2% did not appear to affect the destruction of Trichinella larvae.     

Subcutaneously implanted tissue chambers — a pharmacokinetic study

The purpose of this study was to characterize the pharmacokinetics of a subcutaneously implanted tissue-chamber model. Thermoplastic tissue chambers were implanted in the paralumbar fossae of six steers. Starting 30 days after implantation, the distribution of intravenously administered antipyrine and phenylbutazone into the tissue chambers was studied. These pharmacokinetic experiments were repeated 10 days later to determine the effect of time after implantation on tissue-chamber distribution. Fifty days after implantation, tissue chambers were drained of transudate, refilled with sterile saline and the rate of influx of endogenous urea, creatinine and albumin was measured. Delayed diffusion of antipyrine and phenylbutazone into tissue chambers was well described using a compartmental model in which tissue-chamber fluid represented the third of three compartments arranged in series. The distribution of antipyrine into tissue chambers was greater than that of phenylbutazone; an observation which is well correlated with the high degree of protein binding of phenylbutazone. There was no effect of time on the penetration of the two agents. Rapid diffusion of urea and creatinine and extremely slow influx of albumin into chambers showed that these chambers formed true interstitial compartments.     

A Quantitative Study of Ganglion Cells in the German Shepherd Dog Retina

As in the number of mammals, the most prominent feature of the ganglion-cell layer in the retina of the German shepherd dog is the sharp increase in the density of ganglion cells in the central area. There is an area of maximum density and also a ‘cat-like’ visual streak, located dorsal to the optic disc. The isodensity lines of ganglion-cell distribution is roughly concentric. Their values vary from 5300-13 000 cells/mm² in the central area, with the cells densely packed, to 1000 cells/mm² or less in the periphery, where the cells are sparsely distributed. There were some individual differences amongst the animals studied, although all of them were pure-bred dogs. This suggests that the configuration of the retina in the canine species is not only dependent on the breed itself but also on some other parameters such as phylogenetic heritage, environment, aptitude, lifestyle, or even training.     

Suppurative Inflammation of Apocrine Sweat Glands (Suppurative Hidradenitis) in the Dog: A Retrospective Clinicopathological Analysis of 100 Cases

Résumé— Une analyse rétrospective clinicopathologique a été menée chez 100 chiens présentant une hydradénite suppurative diagnostiquée par biopsie cutanée. Aucune prédisposition d'âge, de race ou de sexe n'a été mise en évidence. Tous les chiens présentaient cliniquement une folliculite bactérienne, ou une furonculose, ou les deux, qu'elle soit primaire ou secondaire à d'autres dermatoses. Aucene lésion clinique n'était pathognomonique d'hidradénite suppurative. Chez 73 chiens, l'hidradénite suppurative était associée microscopiquement à des degrés variables d'inflammation du follicule pileux. Chez 27 chiens, l'hidradénite suppurative était la seule évidence histologique d'inflammation annexielle. L'observation histopathologique d'hidradénite suppurative suggère l'existence sur le plan clinique d'une folliculite bactérienne, d'une furonculose, ou des 2. [Scott, D.W. Suppurative inflammation of apocrine sweat glands (suppurative hidradentis) in the dog: a retrospective clinicopathological analysis of 100 cases (inflammation suppurative des glandes sudorales apocrines (hidradénite suppurative) chez le chien: une analyse rétrospective clinicopathologique de 100 cas). Resumen— Se llevó a cabo un estudio clinicopatológico retrospectivo en 100 perros con hidradenitis supurativa diagnosticada mediante biopsia cutánea. No se detectó predominancia alguna de raza, sexo o edad. A todes los perros se les habia diagnosticado clinicamente foliculitis o furunculosis bacteriana, o ambas, ya sea de forma primaria o secundaria a otras dermatosis. No se encontraron lesiones clinicas especificas indicativas de hidradenitis supurativa. En 73 animales, la hidradenitis supurativa estaba asociada con varios grados de inflamación folicular a nivel microscópico. En los 27 casos restantes, los anejos presentaban unicamente hidradenitis supurativa. La presencia de hidradenitis supurativa a nivel microscópico sugiere la existencia de foliculitis o furunculosis bacteriana clinicas, o de ambas. [Scott, D.W. Suppurative inflammation of apocrine sweat glands (suppurative hidradenitis) in the dog: a retrospective clinicopathological analysis of 100 cases (inflamación supurativa de las glándulas sudoriparas apocrinas (hidradenitis supurativa) en el perro: estudio clinicopatológico retrospectivo de 100 casos). Abstract— A retrospective clinicopathological study was conducted on 100 dogs with suppurative hidradenitis as determined by skin biopsy. No apparent age, breed, or sex predilections were recognized. All dogs had been given a clinical diagnosis of bacterial folliculitis, furunculosis, or both of these, whether primary or secondary to other dermatoses. There were no clinical lesions that uniquely suggested the presence of suppurative hidradenitis. In 73 dogs, suppurative hidradenitis occurred in conjunction with varying degrees of hair follicle inflammation microscopically. In 27 dogs, suppurative hidradenitis was the only histological evidence of adnexal inflammation. The histopathologic finding of suppurative hidradenitis suggests the existence of clinical bacterial folliculitis, furunculosis, or both of these.     

果树授粉昆虫——紫壁蜂、凹唇壁蜂生物学研究

紫壁蜂、凹唇壁蜂喜在人工巢管内营巢,在果园中用芦苇管和纸管设巢可回收大量蜂种.它们均为一年一代.卵、幼虫、蛹在巢管内生长发育,成虫羽化后以滞育状态在茧内越冬.早春用0—4℃冰箱冷藏蜂茧,待果树开花前1周左右在园内释放.两种壁蜂访花范围是杏、樱桃、李、桃、梨、苹果等.壁蜂访花采蜜繁衍后代,同时提高了花朵坐果率及果品质量.两种壁蜂访花速度快、工作时间长、授粉能力强,因此成为我国北方果的优良授粉昆虫.