PubMed Health⌕ Search

Biomedical subjects

D B Hunter

Publications and source records attributed to D B Hunter.

34 records · Page 2Linked to original sources
PubMed1987

An outbreak of schistosomiasis in Atlantic brant geese, Branta bernicla hrota.

A heavy infection with schistosomes of the genera Trichobilharzia and Dendritobilharzia was considered the cause of 90% mortality in a group of 40 wild-caught Atlantic brant geese (Branta bernicla hrota) that were maintained in captivity on a fresh-water pond in Aurora, Ontario. Numerous adult worms and eggs were disseminated in many organs throughout the body of all birds examined. The main pathological findings, attributed to both eggs and adults, included emaciation, thrombosis of the caudal mesenteric vein and its branches, fibrinohemorrhagic colitis, and in some birds, heptomegaly. Translocation of brant geese from their natural marine environment to a fresh-water pond may have caused them to be exposed to parasites which they would not normally encounter.

Animals↗
PubMed1986

Effects of feeding hens a high level of vomitoxin-contaminated corn on performance and tissue residues.

A balance experiment was conducted with hens fed a high level of vomitoxin (V) to study the effect on live performance, egg quality, and tissue residues of V. Twenty Single Comb White Leghorn (SCWL) hens, approximately 26 weeks of age, were individually housed in metabolic cages and fed a control (C) or V (82.8 mg/kg) diet for 27 days. No significant differences were observed in feed consumption, body weight gain, egg production, egg weight, haugh units, shell deformation, or egg shell thickness between treatments. No gross pathological lesions were observed in the oral cavity, proventriculus, small or large intestine, liver, spleen, heart, or kidney. Small erosions were present in the gizzard mucosa of birds fed the V-diet. No significant V residues were found in the yolk, albumen, egg shell, liver, kidney, thigh, or breast muscle, but levels of approximately 20 ppb were found in the gizzard. About 4.2% of the total V consumed by hens were recovered in the feces.

Animals↗
PubMed1986

Campylobacter colitis in ranch mink in Ontario.

Outbreaks of colitis, where Campylobacter jejuni and Campylobacter coli were the only pathogens isolated occurred in weanling mink (Mustella vision) on two commercial mink ranches in Ontario. Lesions were restricted to the proximal colon and were characterized by multiple 1 mm focal or 1 mm linear erosions/ulcers in the region 2 cm distal to the ileal-colonic junction. Histological changes included thickening of the colonic mucosa, inflammatory cell infiltrate in the lamina propria and submucosa, cellular debris and inflammatory exudate within cryptal lumens and multiple areas of mucosal erosion/ulceration. Four C. jejuni negative mink were challenged with 5.1 X 10(9) colony forming units of C. jejuni by oral inoculation. Three of four experimentally infected mink developed diarrhea by day 4 postinfection with lesions grossly and microscopically similar to mink in the naturally occurring outbreak. Examination of lesions by transmission electron microscope failed to show evidence of C. jejuni invasion of intestinal epithelium. Feeding uncooked slaughterhouse chicken offal was the likely source of C. jejuni in the naturally occurring outbreaks.

Animals↗
PubMed1979

Avian cholera in waterfowl in Saskatchewan, spring 1977.

Avian cholera was diagnosed in lesser snow geese (Anser c. caerulescens), Ross' geese (Anser rossii) and individuals of several other waterfowl species in a small area of south-western Saskatchewan over a 1 month period during the 1977 spring migration. Approximately 250 dead birds were found. This is apparently the first time avian cholera has been reported in migrating waterfowl in Canada. The site of the mortality was midway between the wintering and nesting areas of the two principal species, and the significance of the occurrence of the disease this far north is discussed.

Animals↗
PubMed1978

Tyzzer's disease in muskrats: occurrence in free-living animals.

Tyzzer's disease was diagnosed in four muskrats (Ondatra zibethica) found dead over a 2 month period in a single feed-house in a Saskatchewan marsh. No dead animals were found elsewhere in the marsh, although several hundred apparently healthy animals were trapped during this period. Similarities in the pathology and epizootiology of Tyzzer's and Errington's diseases of muskrats support an hypothesis that these diseases are a single entity.

Animal Population Groups↗
PubMedDate not supplied

Safety, immunogenicity, and efficacy of two Escherichia coli cya crp mutants as vaccines for broilers.

Attenuated derivatives (delta cya delta crp mutants) of an O2 and an O78 avian septicemic Escherichia coli strain were used to immunize broiler chickens by spray to determine the safety, immunogenicity, and efficacy of the derivatives in single- and double-dose regimens. In the safety and immunogenicity studies, groups of 10 chickens were vaccinated by spray (droplet size approximately 20 microm) with the parent E. coli, the mutant organisms, or phosphate-buffered saline (PBS) at 14 days of age and euthanatised 21 days later. There was no deaths or gross pathologic finding in any of the chickens immunized with the vaccine strains. Compared with the levels in chickens exposed to PBS, there were significantly higher levels of immunoglobulin (Ig) G antibody in serum and air sac washings and of IgA antibody in air sac washings in response to the virulent parent strains than to the vaccine strains. In efficacy studies, chickens were immunized with the O2 or the O78 vaccine strain or PBS at day 14 and with the O2 vaccine strain or PBS at days 10 and 14 and challenged with the parent strain 10 days after the last vaccination. There was no significant difference in local IgA and IgG and serum IgG responses between vaccinated and control groups. Chickens vaccinated with the O2 strain, but not the O78 strain, had significantly lower air sac lesion scores compared with those of the unvaccinated groups in both single- and double-dose regimens. We conclude that the mutant O2 strain provided moderate protection against airsacculitis.

Air Sacs↗
PubMedDate not supplied

Systemic and mucosal antibody responses to selected cell surface antigens of avian pathogenic Escherichia coli in experimentally infected chickens.

The immune response to four cell surface antigens of avian pathogenic Escherichia coli (APEC) was investigated as the first step in identifying vaccine candidates. F1 pilus adhesin, P pilus adhesin, aerobactin receptor protein, and lipopolysaccharide (LPS) from an O78 E. coli (strain EC99) were used as antigens. The proteins were purified as 6xhistidine-tagged recombinant proteins and LPS was purified from a phenol/water extract. Groups of 12 broiler chickens were vaccinated intranasally with the EC99 strain and challenged with the same strain 10 days later via the intra-air sac route. The chickens that survived were euthanatized 10 days postchallenge. Scores were assigned to infected chickens on the basis of lesions and recovery of the challenge E. coli. The immunoglobulin (Ig) IgG, IgA, and IgM antibodies to the four antigens were measured in serum and air sac washings in an enzyme-linked immunosorbent assay. Among the chickens that were not vaccinated prior to challenge, two died and three of the survivors were ill, whereas, of the chickens that were vaccinated prior to challenge, one died and one of the survivors became ill. After the intranasal vaccination, high antibody activity against all four antigens was associated with each Ig isotype in serum and air sac washings. IgG was the predominant isotype of Ig in air sac washings as detected by radial immunodiffusion. Chickens that were not ill after challenge had greater IgG, IgA, and IgM antibody activity against all four antigens in serum and air sac washings than did sick chickens. Thus, all of the antigens tested appear to be suitable candidates for a vaccine to protect chickens from respiratory tract infections caused by APEC.

Adhesins, Escherichia coli↗
PubMedDate not supplied

Cardiac muscle mass distribution in the domestic turkey and relationship to electrocardiogram.

Ventricular weights were measured in 20-week-old male and female heavy turkeys, and electrocardiograms (ECGs) were recorded in 10- and 20-week-old male and female heavy turkeys. Twenty-week-old males had heavier relative left ventricular and total ventricular weights than females of the same age. Left-to-right ventricular weight ratios were 4.4:1 in males and 4.5:1 in females. Heart rate was faster in young birds and in females, and that influenced the duration of the intervals of the ECG. Wave amplitudes were smaller in 10-week-old turkeys than in 20-week-old turkeys. There was no correlation between electrocardiographic parameters and ventricular weights of male and female turkeys. Two-dimensional ECGs were therefore found to be of minimal value for detecting turkeys with heavier ventricles.

Animals↗
PubMedDate not supplied

Effect of exercise on the cardiovascular and respiratory systems of heavy turkeys and relevance to sudden death syndrome.

The cardiorespiratory response to walking exercise was studied in 14-to-18-week-old male and female heavy turkeys. Blood pressure, electrocardiograms, respiratory rate, body temperature, blood gases, and electrolytes were measured at rest and after exercise at two different room temperatures. After exercise, systolic, diastolic, and mean blood pressures decreased, and heart rate and body temperature increased, while a severe lactic acidosis developed, in both sexes and at both room temperatures. Fifty-four percent of the turkeys developed arrhythmias, mostly a transient post-exercise sinus arrhythmia of no clinical significance. Changes in electrolytes were clinically insignificant. Blood gases remained within normal limits, demonstrating adequate gas-exchange and pulmonary capability. Within the limits of this study, the cardiac capacity of the heavy turkey in response to exercise appeared very limited. The pathogenesis of sudden death syndrome of turkeys is still unknown, but cardiovascular changes occurring after exercise could be severe enough to cause death.

Animals↗
PubMedDate not supplied

Effect of exercise on cardiac output and other cardiovascular parameters of heavy turkeys and relevance to the sudden death syndrome.

The cardiovascular response to treadmill exercise was studied in 14-to-18-week-old male and female heavy turkeys. Arterial blood pressure, cardiac output, body temperature, and heart rate were measured before and during each period of exercise. Total peripheral resistance, stroke volume, and stroke index were calculated from those parameters. Systolic, diastolic, and mean blood pressures significantly decreased during exercise. Cardiac output increased during exercise in males and females by 64% and 23%, respectively, while total peripheral resistance fell by approximately 40% in both sexes. Exercise had no significant effect on stroke volume and stroke index. The cardiac functional capacity of the heavy turkey in response to mild exercise appears very limited. This failure of the cardiovascular system to adequately respond to increased metabolic needs suggests that hemodynamic failure is a major component in the pathogenesis of sudden death syndrome of turkeys.

Animals↗
PubMedDate not supplied

Evaluation of different procedures for processing avian air sac lavage fluid.

Air sac lavage has become a routine diagnostic tool used in pet birds; however, cytologic techniques for collection and handling of avian cells have not been reported. In this study, directed endoscopy was used to obtain the air sac washes. Different factors were compared that might affect final preservation of cell morphology, such as centrifugation speed, anticoagulant, storage temperature, time to processing, addition of glutaraldehyde to the sample, and addition of protein. The goal was to find the processing technique best suited for the evaluation of cells from air sac washes. The use of an anticoagulant did not influence cell quality. Optimal cell morphology was achieved when the sample was centrifuged at a speed of 1000 rpm (89.4 X g) and when prepared in less than an hour from the time of collection. Low temperature (5 C) tended to preserve cell quality better. The addition of protein (fetal bovine serum) helped to preserve cell quality and was of value if the sample storage time was greater than 30 min. The addition of glutaraldehyde resulted in a significant reduction in cell quality.

Air Sacs↗
PubMedDate not supplied

Development of the thoracic air sacs of turkeys with age and rearing conditions.

Cytology and structure of the thoracic air sac of turkeys were investigated at four different ages (26-day embryo, 1 day, 2 wk, and 10 wk old) and two rearing conditions (isolation and commercial). Cytology was performed by guided fiberoptic endoscopy on the left thoracic air sac of each bird. The right thoracic air sac was sampled for light and electron microscopy. Heterophils were the most common nonepithelial cell found in air sac fluid. followed by macrophages and lymphocytes. Macrophages were most abundant in 1-day-old turkeys and turkeys raised in commercial conditions. The epithelium of the air sac consisted of squamous and cuboidal cells, with a few ciliated columnar and nonciliated columnar cells. Cuboidal cells had similar characteristics to type II pneumocytes. The mucociliary system was organized in tracts extended from the ostium to the posterior parts of the air sac. The number of ciliated tracts decreased with age, and the air sacs of commercial turkeys had a larger proportion of ciliated epithelium than did those of isolation birds. The epithelium may protect against disease by a structured mucociliary transport system, the production of surfactant, and phagocytosis of foreign particles. Differences in cytology and structure may reflect the maturation of the immune system and/or response to environment.

Aging↗
PubMedDate not supplied

Endoscopic gross anatomy findings of the thoracic air sac of the turkey.

The gross anatomy of the cranial thoracic air sacs was studied in the live turkey with a fiber-optic endoscope fitted with a video system. Thirty-five out of 39 (89.7%) of the turkeys had paired single thoracic air sacs with two ostia. The other 10.3% of the turkeys had paired cranial and caudal thoracic air sacs, each with a single ostium. The air flow pattern through the common thoracic air sac with two ostia is unknown. Furthermore, 42.3% of the turkeys with a single thoracic air sac had an invagination arising from the floor of the air sac that partially divided the single thoracic air sac creating a blind-ended sac. The blind sac formed by the invagination may trap small inhaled particulate matter.

Air Sacs↗