Olfaction in dogs is crucial for gathering important information about the environment, recognizing individuals, making decisions, and learning. It is far more specialized and sensitive than humans’ sense of smell. Using the strength of dogs’ sense of smell, humans work with dogs for the recognition of different odors, with a precision far exceeding the analytical capabilities of most modern instruments. Due to their extremely sensitive sense of smell, dogs could be used as modern, super-sensitive mobile area scanners, detecting specific chemical signals in real time in various environments outside the laboratory, and then tracking the odor of dynamic targets to their source, also in crowded places. Recent studies show that dogs can detect not only specific scents of drugs or explosives, but also changes in emotions as well as in human cell metabolism during various illnesses, including COVID-19 infection. Here, we provide an overview of canine olfaction, discussing aspects connected with anatomy, physiology, behavioral aspects of sniffing, and factors influencing the olfactory abilities of the domestic dog (Canis familiaris).

The wisent, or European bison (Bison bonasus), belongs to the same family (Bovidae) as the American bison and domestic cattle. The wisent is the largest mammal in Europe, and is called the “Forest Emperor”. The wisent is listed as “Vulnerable” on the IUCN Red List, and is protected by international law. Achievements in reproductive biotechnology have opened new possibilities for the cryoconservation of the wisent germplasm. Therefore, this research aimed to improve a strategy for the protection and preservation of the European bison through the creation of a wisent germplasm bank, based on the following procedures: isolation and in vitro maturation (IVM) of oocytes, in vitro fertilization (IVF) of matured oocytes, in vitro embryo culture (IVC), and embryo cryopreservation. Wisent ovaries were isolated from females outside the reproductive season, and eliminated from breeding for reasons other than infertility. Cumulus–oocyte complexes (COCs) were isolated from follicles greater than 2 mm in diameter and matured for 24 h and 30 h. After IVM, COCs were fertilized in vitro with wisent sperm. The obtained wisent zygotes, based on oocytes matured for 24 h and 30 h, were cultured for 216 h. Embryos at the morula and early blastocyst stages were vitrified and then warmed and transferred to interspecies recipients (Bos taurus). USG and biochemical tests were used to monitor pregnancies. This study obtained embryos in the morula and early blastocyst stages only after oocytes were fertilized and matured for 30 h. On average, per oocyte donor, 12.33 ± 0.5 COCs were isolated, and only 9.33 ± 0.61 COCs were qualified for in vitro maturation (75.68%), while 9.16 ± 0.48 COCs were matured (84.32%). On average, per donor, 5.5 ± 0.34 embryos were cleaved (59.96%) after 48 h post-fertilization (hpf), and 3.33 ± 0.21 achieved the eight-cell stage (36.52%) after 96 hpf, while 1 ± 0.21 morula and early blastocyst stages (10.71%) were achieved after 216 hpf. A total of six embryos (one morula and five early blastocysts) were obtained and vitrified; after warming, five of them were interspecies transferred to cattle (Bos taurus). On day 41 after fertilization, 3 out of 5 pregnancies were detected based on USG, P4, and PAG tests. However, no pregnancy was observed on day 86 after fertilization, indicating embryo resorption. This study shows that obtaining wisent embryos in vitro, and subsequent cryopreservation to create a wisent embryo bank, can be applied and implemented for the wisent protection program.

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Aging is associated with a drastic decline in fertility/fecundity and with an increased risk of pregnancy complications. Resveratrol (RES), a natural polyphenolic compound, has shown anti-oxidant and anti-inflammatory activities in both human and animal models, thus representing a potential therapeutic and prophylactic anti-aging supplement. Here, we investigated whether preconceptional resveratrol supplementation improved reproductive outcomes in mid-aged (8-month-old) and old (12-month-old) C57BL/6J female mice. Female siblings were cohoused and assigned to either RES or vehicle supplementation to drinking water for 10 consecutive weeks. Subsequently, females were mated with non-supplemented males and their pregnancy outcomes were monitored. RES improved mating success in old, but not in mid-aged females, and prevented the occurrence of delivery complications in the latter. These results indicate that preconceptional RES supplementation could partially improve age-related reproductive complications, but it was not sufficient to restore fecundity in female mice at a very advanced age.