Semen quality, testicular B-mode and Doppler ultrasound, and serum testosterone concentrations in dogs with established infertility

doi:10.1016/j.theriogenology.2015.05.015

Theriogenology

Volume 84, Issue 5, 15 September 2015, Pages 805-810

https://doi.org/10.1016/j.theriogenology.2015.05.015 Get rights and content

Abstract

Retrospective examination of breeding records enabled the identification of 10 dogs of normal fertility and 10 dogs with established infertility of at least 12 months of duration. Comparisons of testicular palpation, semen evaluation, testicular ultrasound examination, Doppler ultrasound measurement of testicular artery blood flow, and measurement of serum testosterone concentration were made between the two groups over weekly examinations performed on three occasions. There were no differences in testicular volume (cm³) between the two groups (fertile right testis = 10.77 ± 1.66; fertile left testis = 12.17 ± 2.22); (infertile right testis = 10.25 ± 3.33; infertile left testis = 11.37 ± 3.30), although the infertile dogs all had subjectively softer testes compared with the fertile dogs. Infertile dogs were either azoospermic or when they ejaculated, they had lower sperm concentration, sperm motility, and percentage of morphologically normal spermatozoa than fertile dogs. Furthermore, infertile dogs had reduced sperm membrane integrity measured via the hypoosmotic swelling test. Infertile dogs had significantly lower basal serum testosterone concentrations (1.40 ± 0.62 ng/mL) than fertile dogs (1.81 ± 0.87 ng/mL; P < 0.05). There were subjective differences in testicular echogenicity in some of the infertile dogs, and important differences in testicular artery blood flow with lower peak systolic and end-diastolic velocities measured in the distal supratesticular artery, marginal testicular artery, and intratesticular artery of infertile dogs (P < 0.05). Notably, resistance index and pulsatility index did not differ between infertile and fertile dogs. These findings report important differences between infertile and fertile dogs which may be detected within an expanded breeding soundness examination.

Introduction

Conducting a breeding soundness examination (BSE) is a well-established method for evaluating the breeding potential of dogs [1]. The principle of the BSE is that it may detect features predictive of poor breeding or fertilizing potential, but despite the wide recommendation for use of the BSE [2], there have been no comprehensive studies examining differences in BSE between fertile and infertile dogs. There are lamentably few investigations comparing even individual components of the BSE between fertile and infertile dogs; the most significant study was performed more than 20 years ago and compared only sperm morphology [3]. More recent and elaborate investigation, for example of sperm DNA peroxidate, has found no differences between infertile and fertile dogs [4].

The key aspects of a BSE include clinical examination of the reproductive tract, observation of libido, examination of semen quality, and in some cases ultrasound examination of the reproductive tract, and endocrine testing [1], [2]. More recently, measurement of testicular artery flow has been purported to be of some value [5] and may form part of an expanded BSE although data are available from only a small number of individuals [5].

The study aim was to establish which aspects of an expanded BSE were different between known fertile and known infertile dogs.

Section snippets

Animals

This study was performed in the Laboratory of Carnivore Reproduction at the School of Veterinary Medicine, State University of Ceará and approved by the Animal Ethics Committee of the institution (protocol 12641034-8).

Animals were selected on the basis of evaluation of detailed breeding records from private breeders who had meticulous records, and two groups were identified. Fertile dogs comprised 10 dogs that had mated at least four bitches during the previous 12 months each achieving at least

Results

The testes of all fertile dogs were reported as being firm in texture, whereas the testes from all infertile dogs were reported as soft in texture. No other scrotal abnormalities were noted.

The second fraction of the ejaculate from the fertile dogs had a white opaque appearance, whereas for the infertile dogs, the ejaculates were colorless in five dogs (these samples were confirmed as azoospermic) and watery white in the remaining five dogs. Semen quality did not differ between the weeks of

Discussion

The central principle of the BSE is that particular components may be useful for the differentiation of normal from abnormal males. In this study, a group of dogs of known fertile status were compared with a group that had failed to achieve any pregnancies over the preceding 12 months.

It was interesting that ultrasound-measured testicular volume did not differ between the fertile and infertile dogs, similar to observations previously made in the dog [10] and in men [11], llamas and alpacas [12]

Acknowledgments

The authors would like to thank the funding agencies for financial support: CAPES (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brazilian Federal Agency for the Support and Evaluation of Graduate Education), CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico - National Council for Scientific and Technological Development) through individual research grants to LDMS (grant number 305420/2013-5) and FUNCAP (Fundação Cearense de Apoio ao Desenvolvimento Científico

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Low testosterone concentrations, for example may lead to small and soft testicles and a decline of the volume and function of the prostate. However, despite the wide recommendation for examinations of breeding dogs, there have hardly been comprehensive studies evaluating differences in examination outcomes between fertile and infertile dogs [7] and potential confounders. Over the last years, several advanced ultrasound technologies have been developed which provide additional information of the examined organs.
Dog breeders often require breeding soundness evaluations which include andrological examinations of the genital organs, hormone measurements, and semen analyses. During the past decades, a considerable number of research results have been published, allowing diagnoses of specific andrological conditions and fertility assessment.
For specific examinations, however, no standard procedures have been defined and for some parameters different reference ranges have been published. Therefore, examination results from different facilities are difficult to compare and profound conclusions regarding health and fertility of a male dog are not always possible.
Conventional semen examination, however, is still useful in identifying deviations or no deviations from normality, especially if confounding factors are taken into account and if the exam is repeated in case of inconclusive findings. A standardization of examination procedures and reference ranges would help to harmonize the exchange of examination results and interpretation of the findings.
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Senescence leads to deleterious effects in testicular function, sperm quality and fertility in dogs. There, however, are no consistent results of vascular changes in the testes and epididymis during natural ageing in dogs. The aim of this study, therefore, was to compare testes and epididymis blood flow, biometry and echodensity between young and senile dogs. Ten young dogs (1–4 years) and eight senile dogs (over 7 years) were selected and assigned to two experimental groups: Young Group and Senile Group. Dogs were evaluated using testicular and epididymis B-mode (dimensions and echodensity) and Doppler ultrasonography (tissue perfusion parameters and blood flow velocity of the testicular artery). There were no differences between experimental groups for the echographic evaluation of testicular and epididymis parenchyma and biometric variables. The dogs in the Young Group had greater (P = 0.02) testes vascularization score and greater (P = 0.06) testicular artery blood flow velocity than those in the Senile Group. Furthermore, the older dogs had a greater (P = 0.06) pulsatility index of the testicular artery than those in the Young Group. Ageing, therefore, seems to cause natural hemodynamical changes to the testicular artery, resulting in reduced blood flow (ischemia) and tissue damage. Testes and epididymis vascular characteristics, therefore, may represent the causal factors for changes in spermatogenesis and, as a consequence, negatively affect the sperm quality of older dogs. In conclusion, senescence alters testicular artery blood flow and vascularization of the testes, without changing testicular and epididymis ultrasonographic dimensions and echodensity in dogs.
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Pulse-wave Doppler (PWD) ultrasonography of the testicular artery was recently used to compare parameters in fertile and infertile males, or males with normal and abnormal semen quality, while no studies verified the concomitant histological feature of the testis. The experimental hypothesis of the present study was that the blood flow parameters measured by PWD at different levels of the testicular artery reflect sperm attributes evaluated on spermatozoa collected from the tail of the epididymis and testicular histological characteristics. Pulse-wave Doppler parameters were recorded on both testes from 16 dogs of unknown fertility. After routine castration, epididymal spermatozoa were collected and evaluated for sperm total and progressive motility, membrane integrity, and sperm morphology. Testes were submitted to histological and immunohistochemical evaluations to quantify microscopic attributes and connective tissue and vascular area extent, respectively. The findings showed that the increased PWD indexes were suggestive of testicular histological alteration since negative correlations were found between pulsatility index and resistive index, measured in the marginal testicular artery, and histological attributes such as the seminiferous epithelial thickness (R = −0.528, P = 0.016 and R = −0.554, P = 0.005, respectively) and the tubular area/total area ratio (R = −0.494, P = 0.024 and R = −0.563, P = 0.004, respectively). Some histological characteristics, such as tubular diameter, seminiferous epithelium thickness, and the tubular area/total area ratio of the testis are correlated with the percentage of primary abnormalities (R = −0.874, P = 0.001, and R = −0.847, P = 0.001, and R = - 0.865, P = 0.001, respectively). In testes with increased sperm primary abnormalities, higher pulsatility index was found compared with testes with normal spermatogenesis in supratesticular artery (1.07 ± 0.06 vs 0.82 ± 0.23, P < 0.05), marginal artery (0.73 ± 0.04 vs 0.61 ± 0.07, P < 0.05), and intratesticular artery (0.67 ± 0.03 vs 0.43 ± 0.1, P < 0.05). Similarly, the resistive index was found significantly higher in the same vessel tracts in testes with abnormal and normal spermatogenesis (0.62 ± 0.02, 0.53 ± 0.02, and 0.46 ± 0.02 vs 0.51 ± 0.06, 0.44 ± 0.04, and 0.32 ± 0.06, respectively; P < 0.05). Our data demonstrated for the first time the relationship between PWD indexes and the contextual testicular architecture, suggesting that the pulsatility and resistive indexes could be an effective tool in andrology. In light of different histological alterations in the testis, caution is warranted in the definition of thresholds for normal and abnormal testicular blood flow indexes.
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Research articleSemen quality, testicular B-mode and Doppler ultrasound, and serum testosterone concentrations in dogs with established infertility

Abstract

Introduction

Section snippets

Animals

Results

Discussion

Acknowledgments

Theriogenology

Vet Clin North Am Small Anim Pract

Res Vet Sci

Theriogenology

Theriogenology

Theriogenology

Theriogenology

Sperm morphology and fertility of the dog

J Reprod Fertil Suppl

Evaluation of sperm DNA peroxidation in fertile and subfertile dogs

Reprod Domest Anim

Reproduction in the dog and cat

Water-induced hypo-osmotic test for the evaluation of canine sperm membrane integrity

Anim Reprod

The relationship between ultrasonographic appearance, testicular size, spermatozoal output and testicular lesions in the dog

J Small Anim Rep

Assessment of the intratesticular resistive index by colour Doppler ultrasonography measurements as a predictor of spermatogenesis

BJU Int

Determination of testicular blood flow in camelids using vascular casting and color pulsed-wave Doppler ultrasonography

Vet Med Int

Research article
Semen quality, testicular B-mode and Doppler ultrasound, and serum testosterone concentrations in dogs with established infertility