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Biomedical subjects

William F Swanson

Publications and source records attributed to William F Swanson.

7 recordsLinked to original sources
PubMed2006

Application of assisted reproduction for population management in felids: the potential and reality for conservation of small cats.

Assisted reproductive technology (ART), using the primary applied tools of AI, ET, and sperm and embryo cryopreservation, has been promoted over the past decades for its potential to conserve endangered wildlife, including felids. However, if the goal is efficient, consistent production of viable offspring for population management, then the 'potential' of ART has yet to become 'reality' for any non-domestic cat species. For the five small-sized felids (i.e., Brazilian ocelot, fishing cat, Pallas' cat, Arabian sand cat, black-footed cat) managed by Species Survival Plans (SSPs) in North American zoos, achieving this potential may be an absolute necessity if genetically viable captive populations are to be maintained into the next century. Modeling programs suggest that current SSP populations are not sustainable without periodic introduction of new founders and improved demographic parameters, including longer generation intervals and larger population sizes. ART provides the means to address each of these management challenges. In each small cat SSP species, fecal hormone metabolite assays and seminal analysis have proven useful for characterizing basal reproductive parameters, a necessary prerequisite to developing ART. Of the five SSP species, ART has been used to produce living offspring only in the ocelot, including after AI with frozen-thawed spermatozoa and following transfer of frozen-thawed IVF embryos. The true efficacy of these techniques, however, is still unknown. To improve the applicability of ART for population management, priorities for immediate research include further investigation of ovarian stimulation protocols, sperm and embryo cryopreservation methods, embryo culture systems, and fetal and neonatal viability following ART.

Animals↗
PubMed2006

Development, validation, and application of a urinary relaxin radioimmunoassay for the diagnosis and monitoring of pregnancy in felids.

Many nondomestic felids are highly endangered, and captive breeding programs have become essential components of holistic conservation efforts for these species. The ability to diagnose pregnancy early in gestation is fundamental to developing effective breeding programs. The purpose of this study was to develop a radioimmunoassay (RIA) for the detection of urinary relaxin in felids and assess its applicability for early, noninvasive pregnancy diagnosis in domestic cats (Felis silvestris catus) and leopards (Panthera pardus). Urine was collected from pregnant and nonpregnant domestic cats and leopards at mating, and then weekly thereafter for the duration of gestation. Paired serum samples were also collected from the domestic cats. A RIA for relaxin that uses an antiserum against synthetic canine relaxin was validated for felid urine and shown to detect relaxin immunoreactivity in pregnant cat urine subjected to acid-acetone extraction. In the cat, urinary relaxin was first detected between Days 21 and 28 of gestation; levels peaked at 42-49 days, and the concentrations then declined over 2 wk prior to parturition. The urinary relaxin profiles of the cat mirrored those in serum. In the leopard, urinary relaxin was first detected at Day 25-28 of gestation; levels peaked at Day 60-64 and declined in the last 3-4 wk of pregnancy. These results indicate that measurement of urinary relaxin in the cat and leopard provides a reliable method for pregnancy determination from as early as 3-4 wk of gestation. This method of pregnancy diagnosis and monitoring may prove useful in the breeding management of domestic cats and other felid and canid species, and provides a foundation for future studies on pregnancy in captive exotic carnivores.

Animals↗
PubMed2006

Assessment of basic seminal characteristics, sperm cryopreservation and heterologous in vitro fertilisation in the fishing cat (Prionailurus viverrinus).

Conservation of the fishing cat, a threatened south-east Asian felid, could benefit from effective ex situ genetic management and breeding programmes, including the use of assisted reproduction. The aims of the present study were to: (1) characterise basal seminal traits of fishing cats in Thailand zoos; and (2) investigate the effect of cryopreservation on sperm motility, acrosomal integrity and in vitro function. Seminal traits were evaluated in electroejaculates collected from eight males. Spermatozoa were diluted in n-tris(hydroxymethyl)-methyl-2-aminoethanesulfonic acid Tris (TEST)-yolk buffer (TYB) without glycerol, then diluted further with TYB with glycerol (4% final concentration) at either 25 degrees C or after slow cooling to 5 degrees C and frozen in straws over liquid nitrogen vapour. After thawing, sperm function was assessed by insemination of viable domestic cat oocytes. Fishing cat ejaculates averaged (+/- s.e.m.) 43.6 +/- 14.2 x 10(6) motile spermatozoa with 33.5 +/- 6.8% normal sperm morphology. Semen processing had a negligible effect (P > 0.05) on sperm motility and acrosomal integrity, but values were reduced (P < 0.05) after thawing. All thawed samples fertilised domestic cat oocytes, with 62.1% (36/58) of mature oocytes cleaving. Glycerol addition at 5 degrees C resulted in higher (P < 0.05) post-thaw motility and intact acrosomes than glycerol addition at 25 degrees C. In conclusion, good-quality ejaculates can be obtained from Thai fishing cats and their spermatozoa exhibit adequate function after cryopreservation for in vitro fertilisation procedures.

Acrosome↗
PubMed2005

Inherited motor neuron disease in domestic cats: a model of spinal muscular atrophy.

Juvenile-onset spinal muscular atrophy was observed in an extended family of purebred domestic cats as a fully penetrant, simple autosomal recessive trait. Affected kittens exhibited tremor, proximal muscle weakness, and muscle atrophy beginning at ~4 mo of age. Apparent loss of function was rapid initially but progressed slowly after 7-8 mo of age, and variably disabled cats lived for at least 8 y. Electromyography and microscopic examination of muscle and nerve biopsies were consistent with denervation atrophy as a result of a central lesion. There was astrogliosis and dramatic loss of motor neurons in ventral but not dorsal horn gray matter of spinal cord and loss of axons in ventral horn nerve roots. These phenotypic findings were similar to mild forms (type III) of spinal muscular atrophy in humans caused by survival of motor neuron mutations, but molecular analysis excluded feline survival of motor neuron as the disease gene in this family. A breeding colony has been established for further investigation of this naturally occurring large-animal model of inherited motor neuron disease.

Age Factors↗
PubMed2005

Exploring the ecologic basis for extreme susceptibility of Pallas' cats (Otocolobus manul) to fatal toxoplasmosis.

Recent efforts by North American zoos to establish a genetically viable captive population of Pallas' cats (Otocolobus manul) have been compromised by high newborn mortality (approximately 60%), primarily because of toxoplasmosis. The basis for this extreme susceptibility to toxoplasmosis is unknown. In the present study, the general health status of wild Pallas' cats in Mongolia was evaluated, including assessment of basal hematologic parameters and fecal corticoid metabolite concentrations. The prevalence of exposure to Toxoplasma gondii in Mongolian Pallas' cats, local domestic cats, and prey species also was determined based on serology and/or polymerase chain reaction analysis. Biologic samples (blood, feces, and/or brain tissue) were obtained from 15 wild Pallas' cats, 15 domestic cats, and 45 prey animals (rodents and pikas) captured in Mongolia during the summers of 2000 and 2001. Comparative data were obtained from nine captive Pallas' cats maintained in North American zoos. Based on physical examinations, complete blood counts, and blood chemistry analyses, only minor differences were observed in the general health status of wild and captive Pallas' cats. Fecal cortisol metabolite concentrations did not differ (P > 0.05) between populations, indicating that Pallas' cats in captivity and in the wild have similar basal adrenocortical activity. A pronounced difference (P < 0.01) in seroprevalence to T. gondii was observed between populations. Whereas all captive Pallas' cats exhibited elevated immunoglobulin titers (IgG > 2,048) to T. gondii, only two of 15 (13%) wild Pallas' cats were seropositive, with both cats having lower IgG titers (< 1,024). Furthermore, no evidence of exposure to this parasite was found in any of the Mongolian domestic cats or prey species. These findings suggest that wild Pallas' cats have minimal opportunity for exposure to T. gondii in their natural habitat and, typically, do not become infected with this parasite until being brought into captivity. Accordingly, maintenance of a viable captive population may require implementing effective strategies to prevent exposure of immunologically naive Pallas' cats to T. gondii and to reduce parasite transmission between seropositive females and their highly susceptible offspring.

Animals↗
PubMed2003

Research in nondomestic species: experiences in reproductive physiology research for conservation of endangered felids.

Tremendous strides have been made in recent years to broaden our understanding of reproductive processes in nondomestic felid species and further our capacity to use this basic knowledge to control and manipulate reproduction of endangered cats. Much of that progress has culminated from detailed scientific studies conducted in nontraditional laboratory settings, frequently at collaborating zoological parks but also under more primitive conditions, including in the field. A mobile laboratory approach is described, which incorporates a diverse array of disciplines and research techniques. This approach has been extremely useful, especially for conducting gamete characterization and function studies as well as reproductive surveys, and for facilitating the development of assisted reproductive technology. With continuing advances in assisted reproduction in rare felids, more procedures are being conducted primarily as service-related activities, targeted to increase effectiveness of species propagation and population management. It can be a challenge for both investigators and institutional animal care and use committees (IACUCs) to differentiate these service-based procedures from traditional research studies (that require IACUC oversight). For research with rare cat species, multi-institutional collaboration frequently is necessary to gain access to scientifically meaningful numbers of study subjects. Similarly, for service-based efforts, the ability to perform reproductive procedures across institutions under nonstandard laboratory conditions is critical to applying reproductive sciences for managing and preserving threatened cat populations. Reproductive sciences can most effectively assist population management programs (e.g., Species Survival Plans) in addressing conservation priorities if these research and service-related procedures can be conducted "on the road" at distant national and international locales. This mobile laboratory approach has applications beyond endangered species research, notably for other scientific fields (e.g., studies of hereditary disease in domestic cat models) in which bringing the laboratory to the subject is of value.

Animals↗