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Animal Reproduction Science 60–61 2000 375–387 www.elsevier.comrlocateranireprosci
Current state in biotechnology in canine and feline reproduction
W. Farstad
Department of Reproduction and Forensic Medicine, Norwegian School of Veterinary Science, P.O. Box 8146 Dep., N-0033 Oslo, Norway
Abstract
Biotechnology has proceeded much further in cats than in canines, although the pregnancy rate Ž
. Ž
. after in vitro maturation IVM , IVC and embryo transfer ET is still relatively low. The use of
AI with frozen–thawed semen as a breeding tool to overcome breeding incompatibility or to preserve male genetic material has been limited in felines in contrast to the situation in domestic
dogs and foxes. In many research scenarios and endangered felid species programs, the in vitro production of feline embryos with subsequent transfer has complemented the use of AI. Improve-
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ment of IVM, in vitro fertilization IVF and embryo culture coupled with ovarian tissue grafting, cryobanking of follicles, oocytes, semen, or embryos, with subsequent ET into surrogate females,
may render this technology feasible for use in endangered wild felids. In canines, reliable systems for in vitro production of embryos, embryo cryopreservation and transfer are yet to be developed.
The refinement of invasive fertilization techniques, such as intracytoplasmic sperm injection Ž
. ICSI , may eventually provide a tool for removal of recipient oocyte nuclei and transfer of
selected embryonic or somatic cell donor nuclei into domestic cat ooplasm, thereby providing a tool for genetic modification, or for preservation of valuable genetic material. q 2000 Elsevier
Science B.V. All rights reserved.
Keywords: Canine; Feline; Artificial insemination; In vitro fertilization; Embryo transfer
1. Introduction
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Domestic cats Felis catus and dogs Canis familiaris primarily serve as compan- ion animals, and breeding has not been subject to planning on a large-scale basis as in
Tel.: q47-22964855; fax: q47-22597081. Ž
. E-mail address: wenche.farstadveths.no W. Farstad .
0378-4320r00r - see front matter q 2000 Elsevier Science B.V. All rights reserved. Ž
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other domestic animals. Most breeding is within small kennels with a small number of breeding animals, with the exception of large colonies of cats and dogs bred exclusively
for biomedical research. In dogs, the export and import of semen and live breeding animals have shown a steady increase, and semen banks have been established both in
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research institutions and by private companies Farstad, 1996 . In the cat, however, exchange of breeding animals occurs within laboratory animal research institutions, but
commercial initiatives relating to trade with frozen semen are scarce. The semi-domestic Ž
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. fox breeds, the red fox Vulpes Õulpes and the blue fox
Alopex lagopus have been farmed for pelts mainly in Northern America, the Nordic countries, Russia, the Baltic
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states and Poland since the early 1900s Nes et al., 1987 , and in this context planned breeding has been carried out to a larger extent than in dogs and cats. Also, international
trade with live breeding animals was extensive during the 1960s and 1970s, and during the last 5 years, frozen silver fox semen has been exported from Norway to Canada with
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the birth of live pups Fougner, 1999, personal communication . There has been relatively limited interest in conserving the wild members of the canid
family by means of assisted reproduction — in many cases because most of them reproduce well both in the wild and in captivity, but also because progress in reproduc-
tive biotechnology has encountered major problems particularly concerning in vitro Ž
models for female gametes and embryos. At present, both the gray wolf, red wolf C. .
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rufus , Mexican wolf C. lupus baileyi , Egyptian wolf Lycaon pictus , Ethiopian wolf Ž
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C. simensis , South American Savannah dog Speothos Õenaticus , maned wolf Chry- .
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saocon brachyarus and two fox species: the San Joaquin kit V. macrotis and the Ž
. Northern swift fox V. Õelox hebes , are considered to be threatened by extinction
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Gottelli et al., 1994; Goodrowe et al., 1998; IUCN 1996; CITES, 1997, 1998 . In Ž
. Scandinavia, the wild polar fox
A. lagopus is considered vulnerable. Thus, with
limited space in the wild and in zoological institutions, the need for strategies involving multidisciplinary action for enhancing conservation of these species is increasing
rapidly. Most of the 36 wild species of felids are classified as threatened, vulnerable or
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endangered Nowell and Jackson, 1996 , maybe with the exception of the Northern Ž
. European lynx Lynx lynx , which is again hunted, although by restricted licences, in
Norway and Sweden. In wild cats, research for biotechnology development is well underway with the establishment of conservation programs in which assisted reproduc-
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tion plays an important part Wildt et al., 1992 . Research on maturation, fertilization Ž
. and embryo development in vitro, as well as embryo transfer ET and cryopreservation
Ž has increased rapidly during the last decade in domestic cats Goodrowe et al., 1988,
1989, 1991; Johnston et al., 1989; Donoghue et al., 1992; Luvoni and Oliva, 1993; Pope et al., 1993, 1994, 1997, 1998; Schramm and Bavister, 1995; Wood and Wildt, 1997;
. Wood et al., 1995; Wolfe and Wildt, 1996; Luvoni et al., 1997; Howard, 1999 as well
Ž as in wild felids Donoghue et al., 1993, 1996; Howard et al., 1992, 1997a; Swanson et
. al., 1996a; Pope et al., 1993; Jewgenow et al., 1997 . In most of these studies, the
domestic cat has served as a convenient research model species for endangered felids. Further, the possibilities for using domestic cats as models for human disease and for
studies of inherited genetic disorders stimulate the use of biotechniques in felines. Thus, the current state of reproductive biotechnology is somewhat different for canines and
felines, and in the following, a review on recent progress will be given for each of these carnivore families.
2. Canines
