Canadian journal of comparative medicine : Revue canadienne de medecine comparee最新文献

Fourteen Pasteurella multocida-free rabbits were inoculated intranasally with a streptomycin-dependent mutant of P. multocida serotype 12:A. Vaccinations with approximately 10(8) colony forming units were done on days 0, 14 and 28. Two weeks later the animals were separated into groups, which included 12 rabbits divided into two control groups of six unvaccinated Pasteurella-free animals. Seven vaccinated rabbits were challenged intranasally with the homologous virulent parent strain and the other seven vaccinates were challenged with a virulent strain of serotype 3:A. Rabbits were necropsied two weeks later. The vaccinated group challenged with the parent strain showed a more rapid nasal clearance of the organism than the vaccinated group challenged with the heterologous strain. However, the number of positive cultures of P. multocida recovered from tissues post-challenge were similar in vaccinated and control animals. In a significant number of animals, vaccination with serotype 12:A induced detectable antibody production to somatic antigens of both 12:A and heterologous strain 3:A.

The involvement of Ca++ ions as secretory mediators in pig jejunal epithelia has been investigated with an in vitro system. Omission of Ca++ from the Ringer-HCO3 bathing media on both sides of the tissue had minor effects on the basal electrical activity of pig jejunal mucosa. There were only slight decreases in transepithelial potential difference and increases in conductance with Ca++ free media. Low EGTA concentrations which reversibly blocked potential difference responses to secretory agents also had minimal effects on basal electrical activity. The in vitro secretory responses to A23187, to theophylline, and to Escherichia coli heat-stable enterotoxin were all eliminated by Ca++ depletion and restored by replacing normal Ca++ concentrations in the bathing media. Dantrolene prevented the secretory response but not the potential difference increases caused by heat-stable enterotoxin and A23187, suggesting that intracellular Ca++ stores may be reservoirs of secretory signal agent. Verapamil only blocked the secretory response to heat-stable enterotoxin. Chlorpromazine had negligible effects on basal conditions, but totally blocked both the secretory response and the Ca++-dependent effects of A23187 and heat-stable enterotoxin on potential difference. The response to theophylline was only partially inhibited by chlorpromazine, implying some involvement of both cAMP and Ca++ as secretory signals for theophylline. Cytoplasmic Ca++ concentrations appear to be at least as important as cyclic nucleotides in regulating the secretory effects of pig jejunum.

Six cesarean-derived lambs were inoculated either with 4.5 X 10(4), 4.5 X 10(6) or 4.5 X 10(8) Mycoplasma mycoides subsp. mycoides intratracheally. One animal receiving the intermediate dose died four days post-inoculation, the two receiving the high dose died six days postinoculation, while one receiving the low dose died eight days postinoculation. The two surviving lambs were challenged on day 20 postinoculation with 1 X 10(8) organisms subcutaneously and 2 X 10(9) organisms intravenously. One animal died eight days following this challenge while the other survived and was killed. Six conventionally reared lambs challenged with 90 to 8500 organisms by intranasal and intraocular instillation failed to become infected. Three conventionally reared calves were each inoculated with 1 X 10(8) organisms by each of intratracheal, subcutaneous and intravenous routes. They were killed 20 days post-inoculation without having shown any clinical signs.

Preputial fluid samples were collected from 90 bulls in two Ontario artificial insemination units using a penial glove swab technique previously developed by one of us for use in donor bulls. No Campylobacter fetus organisms were identified from the prepuce or from samples of semen collected at the same time from these bulls. The distal genitalia of 200 bulls were collected at a slaughter house. One isolation of a Campylobacter fetus subspecies venerealis was obtained on a culture from the fornix area of the prepuce of one of these bulls.

Modern pigs grow fast but are highly susceptible to degenerative joint abnormalities, including osteochondrosis. Normal and osteochondrotic humeri and femurs were obtained from five normal and ten lame adolescent boars to study cartilage proteoglycans. Histological examination of joints indicated a locally-reduced intensity of proteoglycan staining by safranin-O in lesion areas of cartilage. Cartilage proteoglycans extracted with 4.0 M guanidinium chloride were studied using Sepharose 2B gel chromatography. The proteoglycans from severely osteochondrotic joints were less (P less than 0.05) aggregated and contained a greater (P less than 0.05) proportion of smaller monomers than those from normal joints. Loss or damage of core protein, including its hyaluronic acid-binding regions, may account for the greater proportion of small monomers. The results also indicated that the proportion of hyaluronic acid in the total glycosaminoglycan uronic acid fraction, estimated by Sephadex G-200 chromatography and cellulose acetate electrophoresis, was lower (P less than 0.05) for the extracted proteoglycans than for the residual or the whole cartilage proteoglycans in all joints studied.

Pulmonary function tests were performed in seven conscious, standing horses. Changes in pulmonary mechanics and ventilation volumes were measured after inhalation challenge with saline (baseline), histamine (1% w/v solution for 5 min) and carbachol (0.5% w/v solution for 3 min). Comparisons between baseline and posthistamine values revealed a significant (P less than 0.05) increase in nonelastic work of breathing (Wb), maximum change in transpulmonary pressure (max delta Ppl), and pulmonary resistance (RL), while dynamic compliance (Cdyn) decreased (P less than 0.05). Tripelennamine completely abolished these histamine induced changes suggesting the involvement of H1 receptors. A nonsignificant increase occurred in functional residual capacity. However, the amount of nitrogen retained in the lung at the end of a nitrogen washout test was significantly (P less than 0.05) greater after histamine when compared to baseline values. The effect of carbachol was qualitatively similar to that of histamine, Wb and max delta Ppl increased while Cdyn decreased (P less than 0.05). The increase in lower RL reached statistical significance (P less than 0.05) only at the beginning of expiration (/ 25% VT). The present investigation demonstrates that the physiological measurements of lung function could be carried out in conscious, unsedated horses and that the pulmonary function test methods could be used as a tool for study of drug induced changes in pulmonary mechanics.

Pulmonary function values were measured in five Friesian calves of five months of age during the patent phase of an experimental moderate lungworm infection and were compared with the pulmonary function values recorded in four control animals. All the nine calves were free of any previous challenge with Dictyocaulus viviparus and were submitted to the same standardized conditions of body conformation, housing, feeding and procedures for pulmonary function testing. A significant increase of respiratory rate, minute ventilation, total pulmonary resistance and power of breathing and a significant decrease of tidal volume, dynamic lung compliance and PaO2 were observed in the infested animals. The absolute intrapleural pressure values were also significantly more negative. The conclusions of the statistical analysis were almost identical when predicted instead of measured pulmonary function values were used in the control group. The clinical, functional and pathological findings in the infested animals were all consistent with the picture of a lower airway obstructive disease.

The lungs of 334 pigs were obtained from two slaughter plants in Minnesota and examined in detail. Macroscopic and microscopic evaluation, direct fluorescence for Mycoplasma hyopneumoniae and bacterial culture were done on all of them and a subsample of 50 were selected for virus culture. Mycoplasma hyopneumoniae, Pasteurella multocida and Haemophilus spp. were detected in 24.0%, 34.1% and 27.0% of the lungs, commonly in conjunction with each other. One isolate of Haemophilus pleuropneumoniae serotype 2 was detected and this represents the first report of its presence in the United States. No virus was detected in any of the lungs. Lungs with both M. hyopneumoniae and Pasteurella multocida had the greatest amount of macroscopic pneumonia (9.8% of the lung). Lungs with M. hyopneumoniae or P. multocida alone had 4.9% and 5.2% of the lung involved with pneumonia respectively. Lungs with Haemophilus sp. Taxon "minor group" had 3.8% of the lung involved which was not significantly different from lungs with none of these organisms being detected (1.6%). There was a positive correlation between the extent of M. hyopneumoniae infection, as scored by FAT and the amount of macroscopic pneumonia present (r = 0.46; P less than 0.001). Likewise, there was a positive correlation between the estimated concentration of P. multocida present, as scored by the relative number of colonies on blood agar and the amount of macroscopic pneumonia present (r = 0.60; P less than 0.001). Microscopically, the amount of lymphoreticular proliferation, polymorphonuclear cells and alveolar macrophages were evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Clostridium perfringens type A live cultures or sonicated sporulating cells, all containing enterotoxin, were repeatedly inoculated into sheep and calves by the intraduodenal route over periods of 30 to 35 days. Serum antibody to C. perfringens enterotoxin, tested by ELISA, developed in four of seven sheep and in two of four calves. The titers ranged from 400 to 1600. The live organism introduced into the duodenum did not become established in the bacterial flora of the intestinal tract.

Levels of arsenic, cadmium, copper, mercury and lead were determined in approximately 650 samples of liver and kidney from cattle, swine and poultry slaughtered in Canada during 1979-81. In addition zinc levels were determined in livers and kidneys from swine, and selenium and zinc levels were determined in the livers and kidneys from cattle. Depending on the element several methods of atomic absorption spectroscopy were used to analyze samples including flame, hydride generation, cold vapour generation and graphite furnace atomization. Analyses were also done by plasma emission spectroscopy. Levels of arsenic over 2.0 micrograms/g were detected in 0.9% of swine livers and 0.3% of swine kidneys. Cadmium levels higher than 1.0 micrograms/g were detected in 0.3% of cattle livers, 10.8% of cattle kidneys, 1.8% of swine kidneys, 0.4% of poultry livers and 0.3% of poultry kidneys. Levels of copper over 150 micrograms/g were detected in 0.4% of cattle and swine livers. Levels of lead over 2.0 micrograms/g were detected in 1.4% of poultry livers and 1.6% of poultry kidneys. The highest level of mercury detected in all species was 0.25 micrograms/g and the highest level of selenium was 1.9 micrograms/g. Zinc levels of over 100 micrograms/g were detected in 1.7% of cattle livers, 0.2% of cattle kidneys and 5.0% of swine livers.