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Biomedical subjects

D G Meltzer

Publications and source records attributed to D G Meltzer.

At least 19 recordsLinked to original sources
PubMed2001

Changes in respiratory function following the intramuscular administration of etorphine to boer goats (Capra hircus).

The physiological effects on respiratory function of etorphine (M99, Logos Agvet) (30 microg/kg) administered intramuscularly were determined in boer goats. The goats were habituated to the experimental procedures so that respiratory function could be determined while the animals stood quietly at rest. This enabled the physiological changes induced by etorphine to be measured and compared with those obtained before administration of the immobilising drug. The effectiveness of diprenorphine (M5050, Logos Agvet) (3 mg/l mg etorphine) as an antagonist of the physiological changes induced by the etorphine treatment was also determined. Etorphine depressed respiratory function, which resulted in a decrease in PaO2 and an increase in PaCO2. These changes were limited and occurred as a result of decreases in respiratory minute volume and alveolar minute ventilation caused by a decrease in respiratory rate. The physiological shunt fraction did not change significantly but there was a significant decrease in percentage physiological dead space ventilation. It was not possible to determine how effectively diprenorphine reversed the respiratory effects due to etorphine.

Animals↗
PubMed2000

Capture and immobilisation of aardvark (Orycteropus afer) using different drug combinations.

Nine aardvarks (Orycteropus afer) were captured in the southern Free State, South Africa, for the placement of abdominal radio transmitters. Five combinations of ketamine hydrochloride with xylazine hydrochloride, midazolam or medetomidine hydrochloride were used to induce anaesthesia. In some cases the level of anaesthesia was maintained with 1.5% halothane. A mixture of ketamine hydrochloride and medetomidine hydrochloride was found to be most effective. Atipamizole reversed the affects of medetomidine hydrochloride, resulting in a smooth and full recovery within 8 minutes. The immobilisation and subsequent anaesthesia of these animals on cold winter nights resulted in hypothermia, and keeping the animals warm was essential to the success of the procedures undertaken. Reversal of the sedative medetomidine hydrochloride proved to be important, because animals that were released before they were fully conscious took refuge in their burrows so that care was impossible.

Adrenergic alpha-Agonists↗
PubMed2000

The measurement of glucocorticoid concentrations in the serum and faeces of captive African elephants (Loxodonta africana) after ACTH stimulation.

Conventionally, the assessment of adrenal responses to stress relies on blood sample collection. However, blood collection from animals is impossible without restraint or immobilisation that influences results. This study was undertaken to validate recently established enzyme immunoassays that measure faecal glucocorticoid metabolites in elephants, and to perform a preliminary investigation into the biological relevance of this non-invasive method for use in assessing the degree of stress in this species. Four juvenile African elephants were injected i.m. with 2.15 mg synthetic adrenocorticotrophic hormone (Synacthen, Novartis, Switzerland). Blood and faecal samples were collected over 4 h and 7 d respectively. Concentrations of serum cortisol and faecal cortisol metabolites were determined using immunoassay. Variability of basal and peak values in blood and faeces was observed among the elephants. After ACTH injection, serum cortisol concentrations increased by 400-700%. An 11-oxoaetiocholanolone enzyme immunoassay (EIA) proved best suited to measure cortisol metabolites (11,17-dioxoandrostanes) when compared to a cortisol and corticosterone EIA in faecal samples. Concentrations of faecal 11,17-dioxoandrostanes increased by 570-1070%, reaching peak levels after 20.0-25.5 h. Greater levels of glucocorticoid metabolites were measured in faecal samples from elephants kept in small enclosures compared to levels in the faeces of animals ranging over a larger area. The results of this preliminary study suggest that non-invasive faecal monitoring of glucocorticoid metabolites is useful in investigating adrenal activity in African elephants.

Adrenocorticotropic Hormone↗
PubMed1999

Diseases of captive cheetahs (Acinonyx jubatus jubatus) in South Africa: a 20-year retrospective survey.

As part of an ongoing study to determine the basis for high prevalences of veno-occlusive disease, glomerulosclerosis, and chronic lymphoplasmacytic gastritis in cheetahs, a retrospective pathology survey of captive cheetahs in the Republic of South Africa (RSA) was conducted. The RSA population was selected because its genetic composition and captive management were similar to those of the cheetah population in U.S. zoos, in which these diseases are common. For this study, archived pathology materials at the University of Pretoria Faculty of Veterinary Sciences in Onderstepoort and the Faculty of Veterinary Science, MEDUNSA, from 69 cheetahs that died between 1975 and 1995 were reviewed, and prevalences of common lesions were compared with those in the U.S. population. Gastritis associated with Helicobacter-like organisms was the most prevalent disease, accounting for close to 40% of the mortalities, including several cheetahs < 3 yr old. Glomerulosclerosis and veno-occlusive disease also were major causes of mortality in RSA cheetahs. RSA cheetahs also had adrenal cortical hyperplasia, cardiac fibrosis, lymphocytic depletion of the spleen, systemic amyloidosis, and splenic myelolipomas. The presence in the captive RSA cheetah population of the same unusual diseases that are common in U.S. cheetahs suggests a species predilection to develop these diseases in captivity.

Acinonyx↗
PubMed1999

Influence of lactation on the prolactin secreting cells of the hypophysis of impala (Aepyceros melampus): an immunocytochemical and computer image analysis study.

Acute stress in the course of wildlife management has been intensively investigated. Chronic stress, on the contrary, has not been researched at all, probably due to the difficulty in measuring it as a result of the overriding effect of the physiological response to the restraining of wild animals. It was therefore decided to evaluate the use of immunocytochemistry, combined with computer image analysis to try and determine the magnitude of the structural changes of various hormone-secreting cells of the hypophysis. Since it was a pilot study to determine whether the combination of immunocytochemistry with computer image analysis could be of value to distinguish between two normally diverse groups, it was decided to compare the relative activity of prolactin secreting cells of lactating and non-lactating impala ewes. After transforming the prolactin immunoreactive area data by log10 to fall inside the parameters for kurtosis and skewness, a significant difference (P < 0.05, 5-% level, 2-tail) with the parametric t-test could be shown between the mean prolactin immunoreactive area of lactating (3.0751 micron 2) and non-lactating (3.0467 micron 2) ewes. However, the Pearson product moment (r = 0.03) showed that this difference may not be important for all practical reasons. This may be due to either sampling errors or limitations of computer image analysis, as it was often difficult to distinguish individual prolactin immunoreactive areas. Furthermore, a significant increase in the total prolactin immunoreactive areas of lactating ewes was also established. This technique, however, could distinguish between the hypophysis of lactating and non-lactating impala ewes, and with further refinement could be a useful tool in determining chronic stress in wildlife populations.

Animals↗
PubMed1997

Social dynamics and the cortisol response to immobilization stress of the African wild dog, Lycaon pictus.

The aims of the study were to characterize the cortisol response to immobilization stress in African wild dogs (Lycaon pictus) and to investigate the relationship between stress and sociality in these pack-living canids. Ad lib. observations were made on a captive pack of 19 wild dogs. Individuals were classified as either dominant or subordinate. Cardinal and ordinal dominance indices were also calculated for pack members, as were three other behavioral indices. Active and passive dominance styles were distinguished. Serial blood samples were drawn from animals after chemical immobilization and again after ACTH challenge. The relationship among rank, plasma cortisol concentration, and behavioral style was investigated. When data were combined over the entire study period, there was no obvious relationship between rank and cortisol concentrations or cortisol responsiveness to immobilization stress. Instead, younger animals had higher cortisol concentrations than older ones. Age cohorts were also clearly separated on the basis of behavioral profiles. For males, these distinctions among age classes were especially apparent during the second part of the study period, when subadults occupied dominant positions in the hierarchy. Adult males maintained relatively low cortisol concentrations, despite being involved in and losing a high proportion of dominance interactions. Age-related differences in cortisol profiles of dominant individuals may be explained by differences in the style of dominance employed, with younger males using proportionately more active dominance (threats used to elicit submission). The separation of age classes according to rank, behavioral styles, and cortisol concentrations may reflect improved social skillfulness with age.

Age Factors↗
PubMed1997

Sites of attachment and density assessment of ixodid ticks (Acari:Ixodidae) on impala (Aepyceros melampus).

During 1994 and 1995, 45 impala ewes, Aepyceros melampus were examined at Letaba Ranch in the Northern Province. Tick counts were made from 15 animals on three occasions, in July, October and February. The objective was to determine whether the total body tick counts can be estimated from counts done on specific, selected sampling sites on the skin. Twelve sites were shaved within ten predilection sites and the parasite numbers counted from these samples. These counts were compared to the total body parasite count as determined by the scrub and digestion techniques. More than 80% of all the ticks were present on the muzzle, the head, the pinna and the legs. Larger numbers of ticks were collected in October than in July or February. Two mathematical models were tested for the tick counts. The first model was made up of tick counts from a single shaved sampling site, the pinna. The correlation between the tick counts on the pinna and the total tick counts was highly significant (p values ranging between 0.0208 and 0.0001). The second model was developed based on tick counts from four regions, namely the head, the pinna and the front and hind feet. A less significant correlation was obtained between the number of ticks counted on the four sites and the total tick count.

Animals↗
PubMed1997

Parafilariosis in African buffaloes (Syncerus caffer).

This is the first report on the occurrence of Parafilaria bassoni in the African buffalo (Syncerus caffer). Previously this parasite has been recorded only in springbok (Antidorcas marsupialis) in Namibia. Haemorrhagic perforations (bleeding points), the usual lesions seen in infected animals, were caused by gravid female parasites ovipositing embryonated eggs. These lesions occurred mainly on the dorsal and lateral sides of buffaloes. Complications of these lesions developed in a small number of buffaloes because of secondary bacterial infection [subcutaneous abscesses (3/178)] and as a consequence of a localized Type 1 hypersensitivity [large cutaneous ulcers (7/178)]. Red-billed oxpeckers (Buphagus erythrorynchus) appeared to play an important role in the epidemiology of this parasite as well as in the pathogenesis of the lesions. They reduced the likelihood of spread by ingesting blood containing embryonated eggs, and caused the development of large ulcers by feeding on superficial necrotic skin. From the results of an ELISA test it was determined that P. bassoni-infected buffaloes occur throughout the Kruger National Park complex, with a seroprevalence of approximately 34%.

Animals↗
PubMed1995

Handling-induced stress and mortalities in African wild dogs (Lycaon pictus).

Recently it was suggested that the handling of wild dogs (Lycaon pictus) by researchers in the Serengeti ecosystem created stress, resulting in the reactivation of latent rabies viruses in carrier animals. We present data from ongoing studies on free-ranging and captive wild dogs elsewhere in Africa which do not support this hypothesis. Cortisol profiles suggest that immobilization of wild dogs does not cause the chronic stress required for stress-reactivation of latent viruses. Furthermore, there is no evidence of handling-related mortalities in wild dogs: the survivorship of unhandled and handled free-ranging wild dogs did not differ and no captive animals died within a year of handling (immobilization and/or vaccination against rabies). We suggest that the mortalities observed in Tanzania were due to an outbreak of a disease which rabies vaccination was unable to prevent. Intensive monitoring and active management research programmes on wild dogs are essential as without these, critically endangered wild dog populations have little hope of survival.

Africa↗
PubMed1995

Veterinary wildlife research and its role in community development.

Veterinarians, biologists and administrators attended a workshop 'Veterinary science and wildlife utilisation for the benefit of community development' which was held during March 1995 as part of the Veterinary Science Research Programme of the Foundation for Research Development. The workshop was the first step in the establishment of a veterinary wildlife research forum which aims to integrate veterinary research with that of other disciplines in addressing issues that have an impact on wildlife. Initially, discussions covered a broad perspective of worldwide approaches towards the conservation of the environment and the upliftment of rural communities. Thereafter the dialogue focused upon the objectives of the workshop which were: (1) to identify areas in wildlife and nature conservation where veterinary research is needed; (2) to identify specific projects within these areas. Seven areas were identified in which veterinary research was needed: the promotion of the free flow of products and animals; extensive husbandry; intensive husbandry; pharmacology and toxicology; public health; ethical issues; forensic and diagnostic techniques. A steering committee was elected to coordinate veterinary wildlife research; establish relevant data bases; to facilitate cooperation between researchers; and to organise regular contact through annual workshops.

Animals↗
PubMed1991

An outbreak of babesiosis in imported sable antelope (Hippotragus niger).

A complete necropsy performed on 2 sable antelope (Hippotragus niger), revealed lesions concomitant with a massive haemolytic crisis. These included widespread oedema and anaemia of the carcass, severe oedema of the lungs, petechiae and echymoses of the epicardium, a moderate splenomegaly and a severe haemoglobinuria. The histopathological lesions included a moderate alveolar oedema, the presence of haemosiderin in the spleen and lymph nodes, and mild degenerative changes of the renal tubular epithelium. Peripheral blood and brain smears contained numerous parasitised red blood cells. The parasites were round or oval in shape containing a single or double area of purple-staining chromatin along a portion of the margin of the organism. It was identified as Babesia irvinesmithi Martinaglia, 1936, which is unique to sable. Seven sable antelope were subsequently treated with imidocarb diproprionate at a dose of 1.2 mg kg-1. No adverse side-effects have been noted in these animals.

Animals↗
PubMed1990

Prevalence and implications of feline coronavirus infections of captive and free-ranging cheetahs (Acinonyx jubatus).

The extent and progression of exposure to feline infectious peritonitis (FIP) virus in the cheetah, Acinonyx jubatus, was monitored by a world-wide serological survey with indirect fluorescent antibody titers to coronavirus. The indirect fluorescent antibody assay was validated by Western blots, which showed that all indirect fluorescent antibody-positive cheetah sera detected both domestic cat and cheetah coronavirus structural proteins. There was a poor correlation between indirect fluorescent antibody results and the presence of coronaviruslike particles in cheetah feces, suggesting that electron microscopic detection of shed particles may not be an easily interpreted diagnostic parameter for FIP disease. Low, but verifiable (by Western blots [immunoblots]) antibody titers against coronavirus were detected in eight free-ranging cheetahs from east Africa as well as from captive cheetahs throughout the world. Of 20 North American cheetah facilities screened, 9 had cheetahs with measurable antibodies to feline coronavirus. Five facilities showed patterns of an ongoing epizootic. Retrospective FIP virus titers of an FIP outbreak in a cheetah-breeding facility in Oregon were monitored over a 5-year period and are interpreted here in terms of clinical disease progression. During that outbreak the morbidity was over 90% and the mortality was 60%, far greater than any previously reported epizootic of FIP in any cat species. Age of infection was a significant risk factor in this epizootic, with infants (less than 3 months old) displaying significantly higher risk for mortality than subadults or adults. Based upon these observations, empirical generalizations are drawn which address epidemiologic concerns for cheetahs in the context of this lethal infectious agent.

Acinonyx↗
PubMed1989

Erythrocyte glutathione peroxidase activity as an indicator of selenium status in an intensively-managed beef herd.

A survey of erythrocyte glutathione peroxidase (GPx) activity was undertaken in a herd of crossbred cattle after 3 cases of white muscle disease had been diagnosed. All animals examined, appeared to be deficient in selenium, relative to control animals sampled. Oral administration of sodium selenite or sodium biselenite was followed within 30 d by an increase in erythrocyte GPx activity. Despite an apparent improvement in the selenium status of cows after supplementation with selenium, no difference was seen in the conception rate after artificial insemination.

Animals↗
PubMed1988

Blood biochemical parameters and meat pH of feedlot cattle slaughtered on arrival or after overnight rest at an abattoir.

The effect of different pre-slaughter rest periods at the abattoir before slaughter on the blood biochemical parameters and meat pH of a number of cattle were studied on 2 occasions, once in summer and once in winter. In the first trial, 42 out of a consignment of 50 and in the second trial, 45 out of a consignment of 54 feedlot-finished oxen were randomly selected and divided into 3 groups each. One group was slaughtered on arrival at the abattoir, a second group 3 h after arrival and the third group was rested in the lairage prior to slaughter the following day. Carcasses were subjected to low voltage electrical stimulation at slaughter. Significant differences between the values obtained at the feedlot and those at the abattoir were found in respect of haematocrit, total plasma protein concentration, plasma glucose, plasma creatine kinase, plasma lipid and cortisol concentration in both the trials. In general, however, no great differences were found between the 3 groups in either of the trials. If any, results in respect of some of the blood parameters were in favour of the groups slaughtered as soon as possible after arrival at the abattoir. No significant differences were found in the initial (35-45 min) and ultimate (24 h) pH of the meat between the 6 groups of slaughtered animals in the 2 trials. Exsanguination appeared to be satisfactory in all groups and no differences between groups were found. It was concluded that feedlot cattle transported to an abattoir over a relatively short distance, need not necessarily be rested in the lairage overnight before slaughter.

Abattoirs↗
PubMed1988

The suppression of electro-ejaculation in the chacma baboon (Papio ursinus) by azaperone.

Six baboons (Papio ursinus) males were immobilised on five occasions at intervals of two weeks using a combination of ketamine hydrochloride and xylazine. The animals were subsequently successfully electro-ejaculated. No semen was obtained from animals when azaperone was used instead of xylazine, despite the use of a successful standardised method of electrical stimulation.

Animals↗
PubMed1988

Quality of semen obtained by electroejaculation from chacma baboons (Papio ursinus).

Fifty-four baboons (Papio ursinus) were subjected to an electro-ejaculation procedure that yielded 683 usable ejaculates in 705 attempts. Quality evaluations by usual human spermiogram methods were applicable with only minor modifications to the procedures. By human criteria these wild baboons remained fertile after capture, and their use as a fertility model in pharmacological studies appeared to be appropriate.

Animals↗
PubMed1983

Some physiopathological features of experimental Homeria glauca (Wood & Evans) N. E. Br. poisoning in Merino sheep.

Five Merino sheep were dosed 3 g/kg of dry, finely-milled Homeria glauca (Natal yellow tulp) plant material. An electrocardiogram was recorded and the arterial and central venous blood pressure, blood gases, haematological variables, plasma electrolytes (Na+, K+, Ca2+, Mg2+, Cl- and PO4(2-) ) and a variety of serum enzymes and chemical constituents were measured hourly until death (3 sheep) or until sheep were in extremis (2 sheep). Heart rate rose progressively as a result of sinus and, later, ventricular tachycardia. Systolic blood pressure rose, but there was little change in the mean and diastolic arterial pressures and central venous pressure. There was progressive hypoxaemia, hypercarbia and acidaemia with depletion of plasma bicarbonate. Haemoconcentration, hyperkalaemia and hypochloraemia were found along with rising serum creatinine and plasma glucose. Rises in serum enzymes indicated widespread tissue damage. Electrocardiographic recordings were being made at the moment of death in 3 of the 5 sheep. In these 3 sheep the cause of death was ventricular fibrillation.

Animals↗