Age-related variations in the testes and prostate of beagle dogs

James, R.W.; Heywood, R.

doi:10.1016/0300-483x(79)90073-8

Cited by 47 publications

(31 citation statements)

References 16 publications

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“…This is a new finding, as in most published studies only beagle dogs were used (James & Heywood 1979, Lowseth et al 1990 or differences in body and thus testes size were ignored (Taha & Noakes 1982). Our finding is in accordance with those of a study in which no relation was found between the size of the animal and testosterone concentrations in 10 different species (Wichmann et al 1984).…”

Section: Discussionsupporting

confidence: 91%

Ageing, testicular tumours and the pituitary-testis axis in dogs

Peters

Jong²,

Teerds³

et al. 2000

Journal of Endocrinology

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Dogs of different ages without testicular diseases were evaluated to study possible age-related changes in hormone concentrations in serum. Dogs with testicular tumours were also investigated to study the relation between tumour type and hormone concentrations; in this study, dogs with Sertoli cell tumours, Leydig cell tumours and seminomas were included. We measured testosterone, oestradiol, LH, FSH and inhibin-like immunoreactivity concentrations in peripheral venous and testicular venous blood of these animals.In normal dogs there appeared to be no age-related changes in the concentrations of the investigated hormones, except for a significant age-related decrease in oestradiol concentrations in testicular venous blood (P<0·02). Dogs with a Sertoli cell tumour had greater oestradiol concentrations and inhibin-like immunoreactivity in both peripheral and testicular venous blood than did dogs without a neoplasm (P<0·05). Testosterone concentrations were reduced in dogs with Sertoli cell tumours, as were FSH and LH. Feminisation occurred in eight of 13 dogs with a Sertoli cell tumour and in two of 14 dogs with a Leydig cell tumour; it was accompanied by a significantly greater oestradiol concentration than in normal dogs and in dogs with Sertoli cell tumours without signs of feminisation. Dogs with a Leydig cell tumour had greater concentrations of oestradiol and inhibin-like immunoreactivity in both peripheral venous and testicular venous blood than did dogs without a neoplasm (P<0·05). The testosterone concentration in testicular venous blood of these dogs was lower than that in dogs with normal testes. The concentration of LH in peripheral venous blood was also reduced (P<0·05). Hormone concentrations in dogs with a seminoma were not different from those in normal dogs.It was concluded that seminomas are not endocrinologically active. In contrast, both Sertoli cell tumours and Leydig cell tumours can cause increased oestrogen production leading to signs of feminisation. These tumours also have considerable amounts of inhibin-like immunoreactivity, but only in Sertoli cell tumours does this result in a reduction in FSH concentrations, suggesting that Sertoli cell tumours secrete dimeric inhibin, whereas Leydig cell tumours presumably produce loose -subunits that cross-react in the inhibin assay but are not biologically active.

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Section: Discussionsupporting

confidence: 91%

Ageing, testicular tumours and the pituitary-testis axis in dogs

Peters

Jong²,

Teerds³

et al. 2000

Journal of Endocrinology

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“…The incidence was not greater in younger dogs excluding delayed maturity, and neither did the incidence increase with age, suggesting that lesions did not progress with age and/or may be reversible. Previously it was reported that up to 6% of beagle dogs aged 2.5-7.75 years showed incomplete spermatogenesis, characterized by a lack of mature spermatids in the lumen of the seminiferous tubules (8). Further descriptions or discussions were not provided, but this observation could be similar to the current finding of segmental hypospermatogenesis.…”

Section: Methodssupporting

confidence: 47%

Spontaneous Testicular Lesions in Purpose-Bred Beagle Dogs

Rehm

2000

Toxicol Pathol

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“…The potential for spontaneous changes in the testes of dogs to confound the interpretation of toxicology studies is well documented, 5,8,14,17,25 especially when sexually immature animals are used. Even in young adults, a number of seminiferous tubular changes can occur, such as hypospermatogenesis and segmental atrophy, which can resemble low-grade effects of some testicular toxicants.…”

Section: Discussionmentioning

confidence: 99%

Spontaneous Pathology and Routine Clinical Pathology Parameters in Aging Beagle Dogs

et al. 2015

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AstraZeneca ran a bespoke study to generate age-matched clinical pathology and histopathology data from a cohort of Beagle dogs aged between 25 and 37 months to support the use of these older animals in routine preclinical toxicology studies. As the upper age range of Beagle dogs routinely used in toxicology studies does not normally exceed 24 months, there is an absence of appropriate age-matched historical control data. The generation of such data was crucial to understand whether age-related differences in spontaneous findings might confound the interpretation of toxicology study data. While the majority of the histopathology findings in all the older dogs occurred at a similar prevalence as those expected in young adult dogs (<24 months), a number of differences were observed in the thymus (involution), bone marrow (increased adiposity), testes (degenerative changes), and lung (fibrosis, pigment and alveolar hyperplasia) that could be misinterpreted as a test article effect. Minor differences in some clinical pathology values (hemoglobin, alkaline phosphatase, absolute reticulocytes) were of a small magnitude and considered unlikely to affect the interpretation of study data.Keywords aging, background lesions, beagle, dog, clinical pathology, incidental findings, histopathology, toxicology studies While Beagle dogs were originally developed for hunting, they have been extensively used as a species for the toxicity testing of agrochemicals and pharmaceuticals. 2,4,22 Olson 21 provided data that supported the use of nonrodents in safety testing by comparing human toxicities with those identified in animals. The results showed the true positive concordance rate of 71% for rodent and nonrodent species combined, with nonrodents alone being predictive for 63% of human toxicities.Chronic toxicity testing in dogs is normally confined to studies with a maximum duration of 1 year, with animals typically being 6 to 12 months old at study start. As a result, publications detailing the incidence of spontaneous pathology findings in Beagles are confined to animals no older than 2 years. 12,[16][17][18]28 While chronic lifetime studies in Beagle dogs have been undertaken at the Lovelace Respiratory Research Institute (LLRI), 19 published data from these studies does not include detailed observations of the spontaneous pathology noted in dogs aged between 2 and 5 years.AstraZeneca had a cohort of older beagle dogs available for use on routine toxicity studies, with the age of all animals exceeding the upper age limit of Beagles routinely used in toxicity testing (>24 months), raising concerns about a lack of suitable age-and strain-matched historical control data and potential impact on the interpretation of histopathology findings.AstraZeneca has a commitment to fully implement the principles of replacement, reduction, and refinement (3 Rs) for the use of animals in research; therefore, the aim of the study described here was to generate a complete ''guideline compliant'' set of hematology, clinical chemistry, and ...

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Age-related variations in the testes and prostate of beagle dogs

Cited by 47 publications

References 16 publications

Ageing, testicular tumours and the pituitary-testis axis in dogs

Ageing, testicular tumours and the pituitary-testis axis in dogs

Spontaneous Testicular Lesions in Purpose-Bred Beagle Dogs

Spontaneous Pathology and Routine Clinical Pathology Parameters in Aging Beagle Dogs

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