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Veterinary Reproduction


Name of supervisor:Tatsuya Hori, DVM, PhD
Position: Professor
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KAKEN researcher number:80277665
ORCID ID:0000-0003-4996-6327
Main research theme: Research on canine reproductive physiology, research on assisted reproductive technologies for dogs and cats (and wild Felids)
Research keywords: dog, cat, frozen semen, artificial insemination, frozen embryos, wild animals (Felids), breeding
Lab location: Laboratory of Veterinary Reproduction, 3rd floor, Building D
E-mail:t-hori(@mark)nvlu.ac.jp

Research

The reproductive physiology of dogs differs from that of other mammals in many unique ways. A comprehensive understanding of these traits is essential for successful breeding. Our research endeavors to apply the findings from these studies clinically.
Of particular interest is our investigation into frozen dog semen, an area where research has lagged behind that of other mammals. Canine sperm exhibits lower freezing tolerance and is more susceptible to damage from low temperatures compared to other animals. Our research on frozen dog semen has revealed that a high conception rate can be achieved through surgical intrauterine insemination using frozen-thawed semen. However, the surgical method causes stress on the animal, necessitating the development of a nonsurgical transcervical intrauterine insemination. However, the current lifespan of frozen dog semen post-thawing is brief, and in transcervical intrauterine insemination, sperm may not be able to reach the oviduct, resulting in slightly lower pregnancy rates compared to surgical methods. Moreover, this nonsurgical method requires expensive equipment and technical skills.
Considering dogs’ monoestrous nature and long estrous cycles, infertility can represent a considerable loss in their fertile age. Therefore, ensuring pregnancy through artificial insemination with frozen semen becomes. We believe it is imperative to enhance the qualities of frozen dog semen after thawing, aiming for improves sperm motility and extended lifespan. By doing so, we aspire not to only increase the conception rate through transcervical intrauterine insemination, previously challenging, a viable option. We believe that the progress of these studies could address the global need for assistance dogs.
Furthermore, we engage in joint research with zoos and breeding facilities, focusing on the artificial breeding of rare wild animals such Felids and Canids. We apply our expertise in assisted reproductive technologies developed for dogs and cats.

Our laboratory includes Associate Professor Masanori Kobayashi and lecturer Masato Kobayashi. Associate Professor Masanori Kobayashi’s research focuses on establishing the mechanism of onset of prostate cancer in dogs, early diagnosis methods, new treatment methods, treatment of reproductive dysfunction, and elucidation of testicular cancer pathogenesis. Lecturer Masato Kobayashi primarily investigates fetal immune tolerance involved in maintaining pregnancy in dogs and its clinical applications.

Guidance policy for graduate students

To date, I have guided one working graduate student to obtain a degree, and we are currently guiding two working graduate research students. Given the constraints on research time inherent to graduate school for working adults, we adapt our teaching approach to accommodate their individual circumstances and pace.

Publications

1.Tajima H, Yoshizawa M, Sasaki S, Yamamoto F, Narushima E, Ogawa Y, Orima H, Tsutsui T, Toyonaga M, Kobayashi M, Kawakami E, Hori T. A trial of semen collection by transrectal electroejaculation method from Amur leopard cat (Prionailurus bengalensis euptilurus).
J Vet Med Sci. 2016 Jul 1;78(6):1067-1073. doi: 10.1292/jvms.15-0439.
2.Tajima H, Yoshizawa M, Sasaki S, Yamamoto F, Narushima E, Tsutsui T, Funahashi T, Kusuda S, Doi O, Tateyama Y, Kobayashi M, Hori T, Kawakami E. Intrauterine insemination with fresh semen in Amur leopard cat (Prionailurus bengalensis euptilurus) during non-breeding season.
J Vet Med Sci. 2017 Jan 20;79(1):92-99.
doi: 10.1292/jvms.15-0683.
3. Hori T, Tajima H, Sasaki S, Karasawa M, Yoshizawa M, Kuribara T, Hori H, Yamamoto F, Narushima E, Nagai K, Nippashi K, Sataka Y, Kobayashi M, Kobayashi M, Tsutsui T. Quality of cauda epididymal sperm immediately after collection and after freezing-thawing from Amur leopard cats (Prionailurus bengalensis euptilurus) and a local population of the subspecies Tsushima leopard cats.
J Vet Med Sci. 2023 Jan 20;85(1):117-122.
doi: 10.1292/jvms.22-0230.
4.Kobayashi M, Onozawa M, Watanabe S, Nagashima T, Tamura K, Kubo Y, Ikeda A, Ochiai K, Michishita M, Bonkobara M, Kobayashi M, Hori T, Kawakami E.Establishment of a BRAF V595E-mutant canine prostate cancer cell line and the antitumor effects of MEK inhibitors against canine prostate cancer.
Vet Comp Oncol. 2023 Jun;21(2):221-230.
doi: 10.1111/vco.12879.