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Biomedical subjects

I D Robertson

Publications and source records attributed to I D Robertson.

At least 19 recordsLinked to original sources
PubMed1992

The epidemiology of Sarcocystis spp. in cattle of Western Australia.

Oesophagus samples from 714 cattle from Western Australia were examined by artificial digestion to detect the presence of Sarcocystis spp. The overall prevalence of infection was 52%. The prevalence of infection increased with age and was highest in the entire males (92%). The prevalence was lower in cattle which originated from arid and semiarid regions (9 and 31% respectively) than those from tropical (87%) and temperate (60%) regions. Possible reasons for these differences are discussed and it is concluded that environmental and management factors as well as host age and sex influence the prevalence of infection with Sarcocystis spp. in cattle.

Abattoirs↗
PubMed1992

A serological survey to determine the prevalence of infection with Treponema hyodysenteriae in Western Australia.

A serological survey to detect antibody titres against Treponema hyodysenteriae was conducted on pigs from 106 herds in Western Australia. Titres indicating a positive result in the tests were determined by examining 400 sera from 4 herds known to be free of swine dysentery, and sera from immunised or experimentally infected pigs. Samples of serum from 40 bacon-weight pigs from each of the 106 herds were then collected at 2 abattoirs. Each serum was tested in enzyme-linked immunosorbent assays (ELISA) against the lipopolysaccharide of T hyodysenteriae of serogroups A, B and E, respectively. To assist in evaluating the test, 19 herds were resampled and retested, and faecal samples from 17 herds were cultured for T hyodysenteriae. Thirty-five of the 106 herds (33%) had serological evidence of infection when only one batch of sera from each herd was tested. The ELISA to detect T hyodysenteriae infection in herds using 40 sera was estimated as having a sensitivity of 77.3% and a specificity of 81.8% based on the owners' opinion of their herds disease status. Prevalence of infection within herds ranged from 2.5% to 47.5%, with a mean of 18%.

Animals↗
PubMed1991

A longitudinal study of natural infection of piglets with Streptococcus suis types 1 and 2.

Streptococcus suis types 1 and 2 were detected in nasal swabs taken from five litters of piglets sampled twice weekly from birth. The two types had been detected in all pigs by the time they were 38 and 25 days old respectively with mean ages of first detectable infection being 13.5 and 8.5 days. The prevalence of infection was not affected by housing conditions or the population density of pigs. Piglets originating from a sow with vaginal swabs positive for S. suis type 2 were infected earlier than piglets from non-vaginal carriers. It is concluded that infection of piglets with S. suis type 2 may occur during the birth process.

Animals↗
PubMed1991

A survey of farmers' attitudes to services provided by consulting veterinarians to the Western Australian sheep industry.

A postal survey was conducted of 80 sheep farmers in the Kojonup and Esperance districts of Western Australia to establish what they wanted from a veterinary service. Twenty five of the farmers surveyed used a sheep consultant, 25 did not, and 30 were interested in employing one. Farmers were asked questions about themselves and their attitudes to private veterinarians who provide specialist services to sheep farmers. Data reported here showed that farmers wanted a veterinarian who lived in the district, was well trained in sheep management and production, was enthusiastic and had good communication skills. The service provided should be whole-farm and available to members of the consultant's group only. Regular newsletters and field days were necessary, but the provision of contract services, such as mulesing, lamb-marking, drenching, pregnancy testing and sheep classing, and 'fire-brigade' services for sick animals, were not rated as important. Most farmers were unwilling or unable to give a dollar value for the likely benefits of a consultancy service. Non-financial benefits included keeping farmers up to date with new technical developments and information. The survey also showed that a veterinarian specialising in services to sheep farmers could be confident of employment.

Agriculture↗
PubMed1991

Assessment of the potential toxicity of a poison for rabbits, pindone (2-pivalyl 1, 3 indandione), to domestic animals.

The toxicity of pindone, a rabbit poison, to horses, cattle, goats, chickens, dogs and cats was investigated, using extension of prothrombin time (PT) as an index of poisoning. The daily dose of pindone, administered for 5 days, ranged from 0.3 mg/kg for dogs to 2.5 mg/kg for chickens. This range of dose rates was considered to be indicative of the worst possible case that could arise following a campaign of baiting for rabbits. Although significant elevations in PT (more than double baseline values) were noted in all species other than horses, clinical signs of anticoagulant poisoning were not observed in any of the species tested. From the observed PT, cattle and cats appeared to be the most susceptible, and horses the least susceptible, to pindone toxicity. The half-lives of the elevated PT were calculated as 3.1 days for cattle, 2.8 days for goats and chickens, 1.9 days for horses and dogs and less than one day for cats. It is proposed that these half-lives can be used as a guide for determining the duration of treatment of pindone-affected animals.

Animals↗
PubMed1991

The adoption of management and husbandry procedures by Western Australian pig farmers.

A postal survey was conducted to determine the management and husbandry procedures adopted by a sample of 101 Western Australian pig farmers. Seventy seven replies were received and analysed. Over 80% of farmers vaccinated breeding stock against leptospirosis and erysipelas, 35% vaccinated against parvo virus and 15% vaccinated against Escherichia coli. Most farmers used antibiotics: 72% incorporated them into their pig diets and 60% used parenteral antibiotics. Fifty three per cent of farmers reported that they regularly used a veterinarian. Over 59% of piggeries had another piggery located within 10 km, thus increasing the possibility for disease transmission between herds. It is concluded that there is potential for veterinarians to offer advice to pig farmers, particularly on disease control measures and adoption of technological advances.

Animal Husbandry↗
PubMed1990

Vacuum phenomenon in the metatarsophalangeal joint of a horse.

Vacuum phenomenon was induced inadvertently during radiographic examination of a metatarsophalangeal joint of a lame horse. The phenomenon was recreated in a sound horse when a metacarpophalangeal joint was radiographed in a stress-flexed position. Distraction of apposing articular surfaces may induce the vacuum phenomenon, which could result in misdiagnosis of an osteochondral defect or fracture.

Animals↗
PubMed1990

Experimental studies on the comparative infectivity and pathogenicity of Streptococcus suis type 2. I. Porcine and human isolates in pigs.

Piglets between 1 and 40 days of age were inoculated with varying numbers and with different isolates of Streptococcus suis type 2 by the intranasal, intravenous and subarachnoid routes. Less than 100 organisms of an isolate cultured from apparently normal pigs caused subclinical infection in 1-day-old piglets after intranasal inoculation. This infection was naturally transmitted between litter mates. Intravenous inoculation of a similar isolate in 7-week-old pigs resulted in a sub-clinical bacteraemia in 3 of 8 piglets. One other piglet developed a bacteraemia 7 days after inoculation and concurrently developed signs of lameness and nervous dysfunction. Ten piglets were inoculated by the subarachnoid route with a porcine isolate and two with an isolate from a person with clinical disease. Only the latter two pigs developed the classical signs of nervous disease associated with infection by S. suis type 2. It is concluded that strains of S. suis type 2, of varying pathogenicity for both pigs and man, are endemic in New Zealand. It is suggested that the occurrence of disease is associated with both exposure to a pathogenic strain and other, as yet undetermined, secondary factors.

Animals↗
PubMed1990

Experimental studies on the comparative infectivity and pathogenicity of Streptococcus suis type 2. II. Porcine and human isolates in laboratory animals.

Mice, rats, guinea-pigs and rabbits were inoculated with isolates of Streptococcus suis type 2. An isolate cultured from the tonsils of a healthy pig, produced disease in rabbits after intravenous inoculation but not in mice, rats or guinea-pigs. An isolate of S. suis type 2, that was pathogenic for pigs and had been cultured from a human patient with clinical disease, produced signs of neurological disease in mice, rats and rabbits following intravenous inoculation. There was an apparent dose response in mice with 31% of mice receiving more than 10(6) organisms developing clinical disease, whilst mice receiving less than this did not develop disease. There were no detectable histopathological lesions in the brains or meninges of mice with nervous signs. It is proposed that the disease in mice may mimic that reported in humans and that mice may be a useful indicator species for determining the virulence of isolates cultured from pigs.

Animals↗
PubMed1990

The effect of radiation therapy on the fixation strength of an experimental porous-coated implant in dogs.

Radiation therapy prevents heterotopic ossification after cemented total hip arthroplasty, but its effect on the fixation of porous-coated devices is not known. The purpose of this study was to determine the effect of irradiation on the pullout strength of a porous implant in the canine model. A custom-designed titanium fiber metal-coated cylinder was implanted into the distal femurs of 12 dogs. One femur of each dog was irradiated with 10 Gy, given in four 2.5-Gy daily fractions beginning one day after surgery. Serial bone scans were performed at one, two, four, and six weeks postoperatively. At six weeks, the femurs were harvested, and eight were randomly selected for mechanical testing. Scintigraphic evaluation showed a significant reduction in uptake at one and two weeks in the irradiated limb, but this had returned to normal at four and six weeks. The failure to pullout was significantly less in the irradiated limb compared with the control limb six weeks postoperatively. In this canine model, the pullout strength of the titanium fiber implant was significantly reduced by a dose of radiation commonly used in the prevention of heterotopic ossification. If irradiation is chosen for prophylaxis, either the porous implant should be adequately shielded or a cemented implant should be utilized.

Animals↗
PubMed1989

Prevalence of Streptococcus suis types 1 and 2 in domestic pigs in Australia and New Zealand.

Using an indirect fluorescent antibody test, 54 per cent of 734 palatine tonsils of conventional pigs slaughtered in Australia and New Zealand were found to be infected with Streptococcus suis type 1 and 73 per cent of 959 were infected with S suis type 2. Variations in the prevalence of infection in pigs from different herds were thought to be due to differences in the sample sizes rather than to real differences in the prevalence between herds. The prevalence of infection with S suis was similar in pigs of either sex and in different age groups. Streptococcus suis type 2 was detected in the blood of 3 per cent of apparently normal pigs slaughtered at a meat processing plant. The presence of this organism in edible tissue may pose a health risk to consumers and meat-workers. Both S suis types 1 and 2 were detected in the vaginas and uteri of slaughtered pigs and the female reproductive tract could be another site for the carriage of infection. Piglets from sows with vaginas infected with S suis type 2 became infected earlier than piglets from sows with uninfected vaginas. No infected male reproductive tracts were detected and venereal transmission of S suis therefore appears unlikely. Three specific pathogen free herds were found to be free from infection with both S suis types 1 and 2. It is concluded that hysterectomy derived piglets are delivered free from infection, whereas some piglets born to sows with uterine and vaginal infections are either born infected or become infected at, or soon after, birth.

Animals↗
PubMed1989

Occupational exposure to Streptococcus suis type 2.

Antibody titres to Streptococcus suis type 2 were measured with an enzyme linked immunosorbent assay (ELISA) in four occupational groups in New Zealand. No veterinary students, 9% of dairy farmers, 10% of meat inspectors and 21% of pig farmers were seropositive to S. suis type 2. The development of antibody to S. suis type 2 was associated with occupational contact with pigs or their meat products. Subclinical infection with S. suis type 2 appears to occur in humans and the antibody produced is of only short duration. The annual incidence of subclinical infection and seroconversion in pig farmers may approach 28%. Thus S. suis type 2 may be one of the most infectious potentially zoonotic agents present in New Zealand, although very rarely resulting in clinical disease.

Animal Husbandry↗