Cryopreservation of the semen collected by electroejaculation from the Hokkaido brown bear (Ursus arctos yesoensis)

Four adult Hokkaido brown bears were used as semen donors, and semen characteristics were examined before freezing and after thawing. A total of 10 electroejaculates were diluted with Tris-egg yolk extender and cooled to 4 degrees C over 90 min. Spermatozoa were equilibrated with 4.7% glycerol for 80 min. Semen packed in 0.25 ml plastic straws were frozen with liquid nitrogen vapor. Percentages (mean +/- SD) of motile and live sperm were 96+/-2 and 86.5+/-7.2% before freezing, and 43+/-5 and 67.4+/-3.9% after thawing, respectively. Although the number of progressively motile sperm after thawing varied among samples (1.8+/-1.2 x 10(8) cells/ejaculate), frozen semen in the present study might serve for artificial insemination.     

Changes in sexual behavior and fecal steroid hormone concentrations during the breeding season in female Hokkaido brown bears (Ursus arctos yesoensis) under captive condition

The longitudinal changes in fecal steroid hormone concentrations and sexual behavior in 2 mated/pregnant and 3 non-mated female Hokkaido brown bears were investigated during the breeding season. Behavioral estrus (standing) lasted for 14 and 32 days in the mated females and for 25 to 36 days in the non-mated females. In non-mated females, sexual behavior, such as female-female mounting and masturbation, was observed for several days before and after the estrous period. In mated females, mean fecal estradiol-17beta concentrations were higher in the estrous period than in the post-estrous period, while fecal progesterone concentrations were higher in the post-estrous period than in the estrous period. The similar trends of steroid hormone changes were observed in the non-mated females.     

Humeral Chondrosarcoma in a Hokkaido Brown Bear (Ursus arctos yesoensis)

Humeral chondrosarcoma was found in an 18-year-old male Hokkaido brown bear (Ursus arctos yesoensis). Necropsy revealed a large firm mass under the left superficial pectoral muscle at the axillary region. The mass involved the left shoulder joint and peripheral muscles, and connected to the head of the humerus with osteolysis. Histopathologically, the mass was composed of irregularly shaped myxomatous to cartilaginous tumor lobules. The tumor cell showed moderate nuclear atypia with a relatively high mitotic index, especially in the edges of the myxomatous lobules. The tumor cells were positively immunostained with vimentin and S-100 protein. Based on these findings, the tumors were diagnosed as chondrosarcoma. Metastases were found in the left axillary lymph node, lungs, liver and kidney.     

Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method for mtDNA typing in hokkaido brown bear (Ursus arctos yesoensis)

To develop an easy method of typing of mitochondrial DNA (mtDNA) in Hokkaido brown bears (Ursus arctos yesoensis), the PCR-RFLP technique was improved using four restriction enzymes: Mbo 1, Cfr 13 I, TspE 1, and Fok 1. This approach identified seven groups of mtDNA haplotypes, HB1/2/5-7, HB 3, HB4, HB8/9, HB10/11, HB12 and HB13 from 102 brown bears of northern, central and eastern Hokkaido.     

Serum progesterone concentrations using P-EIA kit in captive and free-ranging Hokkaido brown bears, Ursus arctos yesoensis.

Serum progesterone (P) concentrations using P-EIA kit (Ovucheck, Cambridge Life Science Co., Ltd.) were examined in 8 captive and 7 free-ranging female Hokkaido brown bears (Ursus arctos yesoensis). The intra- and inter-assay coefficients of variation were 8.9%, 12.6% and 16.6%, 22.7%, respectively, based on 2 serum samples. There was a significant correlation between EIA and radioimmunoassay results based on 64 serum samples (r = 0.725; p less than 0.01). Serum P concentrations were examined in 5 pregnant, 2 solitary non-pregnant bears and a lactating non-pregnant bear in captivity. Annual changes of P levels in pregnant bears were observed as a small elevation during the mating season (May-June), a re-elevation in September-October and a sharp elevation in November-December. The sharp elevation was suspected to reflect changes when implantation occurred. Annual changes of P levels in solitary non-pregnant bears were similar to those in pregnant bears. An annual change of P levels in a lactating non-pregnant bear maintained levels under 5 ng/ml. Two of 7 free-ranging bears exhibited P levels over 1 ng/ml and the birth of cubs was confirmed in the following year in 1 of the 2 bears. P concentrations of other free-ranging bears exhibited less than 1 ng/ml, and these bears were considered to be non-pregnant. It was concluded that P-EIA kit was available for measuring P concentrations in Hokkaido brown bears.     

In vitro maturation of oocytes derived from the brown bear (Ursus arctos)

This study was conducted to determine whether meiotic maturation could be induced in ovarian oocytes from the American brown bear (Ursus arctos), a model for gamete "rescue" techniques for endangered ursids. The bears were euthanized, and their ovaries were transported to the laboratory within 4 h. The mean ovarian size was 2.4 x 1.8 cm (range: 2.0-3.3 x 1.5-2.2 cm). The ovaries obtained from the 2 brown bears yielded 97 oocytes (48.5/female), and 88 (90.7%) of them were morphologically classified as normal quality. Oocytes were in vitro matured at 38.5 C in 5% CO2 for 24 or 48 h in TCM-199 supplemented with 10% FBS, 1 microg/ml estradiol-17beta, and 10 microg/ml FSH. In Exp. 1, morphologic evaluation of matured oocytes was conducted by measuring the diameters of oocytes with a zona pellucida (ZP) or cytoplasm without a ZP. In Exp. 2, activation was induced by applying two 20 microsec DC pulses of 2.0 kV/cm delivered by an Electro Cell Fusion Generator. The activated oocytes were cultured in TCM-199 containing 2 mM of 6-dimethylaminopurine for 4 h, in Charles Rosenkrans (CR) 1 for 3 days and the in CR2 for another 4 days. The diameters of the matured bear oocytes with a ZP and with cytoplasm without a ZP (161.8 +/- 6.0 and 135.3 +/- 7.5 microm, respectively) were significantly (P<0.05) larger than those of bovine oocytes (150.7 +/- 4.9 and 118.7 +/- 7.5 microm). The maturation rates of the bear oocytes were 17.6 and 59.4% at 24 and 48 h of in vitro maturation, the percentage of activated oocytes that developed to the 2 or 4-cell stage was 31.6%; however, no blastocysts were observed. These results indicate that bear oocytes can develop to metaphase II in an in vitro culture system and that activated oocytes can develop to the 2 or 4-cell stages.     

Spinal spondylosis and acute intervertebral disc prolapse in a European brown bear (Ursus arctos arctos)

A 22-year-old male European brown bear (Ursus arctos arctos) was presented to the Onderstepoort Veterinary Academic Hospital after an acute onset of hind limb paralysis 4 days earlier. Previous radiographs revealed marked degenerative joint disease of the stifles, tarsi and digits. The clinical findings were consistent with acute disc prolapse. Lateral radiographs of the entire vertebral column were made as well as ventrodorsal pelvic radiographs. The latter were within normal limits. The vertebral column revealed multiple lesions consistent with chronic and acute disc herniations. Lateral compression of the caudal lumbar nerve roots could not be ruled out. Owing to multiple significant findings of the vertebral column and the poor prognosis for full recovery after surgery, the bear was euthanased. The diagnosis of an acute disc prolapse and multiple chronic disc herniations was confirmed on necropsy.     

Use of fluoxetine to treat stereotypical pacing behavior in a brown bear (Ursus arctos)

A 12-year-old, male, brown bear (Ursus arctos) named Abdi exhibited stereotypical pacing behavior. He was kept as a pet for 10 years by local villagers, then he was rescued and taken to the Karacabey Bear Sanctuary in July 2001. His physical condition was extremely poor. Because he had never lived with other bears, he was terrified and refused to integrate with them. After 6 months he was healthy physically but observations by the keepers indicated that he was pacing all day. He was treated with fluoxetine (0.62 mg/kg orally every 24 hours) for 6 months, and had been observed totally for 18 months. After stereotypy ceased completely, he was transferred to the large naturalistic enclosure and did not show any stereotypical behavior during the subsequent observation period (1 year). He was treated successfully using a combination of fluoxetine, the provisioning of extra space, and the addition of novel stimulation in a naturalistic enclosure. The space and stimulation could be sufficient to mimic the therapeutic effect of the pharmacological therapy in the long term.     

Optimization of glycerol concentration and freezing rate in the cryopreservation of ejaculate from brown bear (Ursus arctos)

In order to establish a semen bank for the endangered Cantabrian brown bear, we tested five glycerol concentrations and three freezing rates for electroejaculated semen. Electroejaculation was performed on nine males. Semen was diluted in TES-Tris-Fructose (20% egg yolk, 2% EDTA, 1% Equex) with 2%, 4%, 6%, 8% or 10% glycerol and frozen at -10, -20 or -40°C/min. Before and after cryopreservation, samples were analysed for motility (CASA), viability and acrosomal status (flow cytometry). Pre-freezing results showed that glycerol concentration had no significant effect on total motility or progressive motility, but it significantly decreased VCL, ALH, viability and acrosomal status (p < 0.05). After thawing, sperm motility was higher at extender with 4%, 6% and 8% glycerol, but only at 4% and 6% glycerol for viability and acrosomal status. For 4% and 6% glycerol, freezing rates did not have significant effects. The curve fitting gave an estimate of the optimal glycerol concentration, with all the optimal values for every parameter between 6% and 7% glycerol falling. We propose using 6% glycerol and a freezing velocity of -20°C/min for freezing brown bear ejaculated spermatozoa.     

Comparative anatomy of the radial sesamoid bone in the polar bear (Ursus maritimus), the brown bear (Ursus arctos) and the giant panda (Ailuropoda melanoleuca).

Since we have clarified the manipulation mechanism using the radial sesamoid (RS) in the giant panda (Ailuropoda melanoleuca), our aim in this study is to examine the position, shape and function of the RS morphologically, and to observe the attachment to the RS of the M. abductor pollicis longus and the M. opponens pollicis in the other Ursidae species. So, we focused on the carpus and manus of the polar bear (Ursus maritimus) and the brown bear (Ursus arctos) in this study. The RS was tightly articulated to the radial carpal, and could not adduct-abduct independently of the radial carpal. The M. abductor pollicis longus tendon and the M. opponens pollicis belly were attached to the RS, independently. In the polar bear, the deep concave and the flat surface were confirmed in attachment area for these two muscles. The morphological relationship between the RS and the M. abductor pollicis longus and the M. opponens pollicis in the two species of bears were essentially consistent with that in the giant panda. It also demonstrated that the manipulation mechanism of the giant panda has been completely based on the functional relationship between the small RS, and the M. abductor pollicis longus and the M. opponens pollicis in Ursidae species.     

Effect of the change of social environment on the behavior of a captive brown bear (Ursus arctos)

We observed the behavior of a captive sterilized male brown bear before and after the death of his female sibling to investigate the effect of the change of social environment on his behavior and welfare. Observations were carried out by continuous recording during daylight for 6 wk prior to hibernation when the bear was kept with the sibling, and they were repeated 2 years later when the bear was alone (total observation time is 108 h). Feeding, moving, and the total amount of time spent resting (including sleeping and alert inactive) were not affected by the change of social environment. However, when the bear was alone, the percentage of time he spent alert inactive almost trebled (pair, 17.7 ± 3.3%; alone, 48.5 ± 5.5%; P < 0.001), and the time spent sleeping was less than one-third (pair, 51.1 ± 6.1%; alone, 14.2 ± 5.0%; P < 0.001) than when the female was present. The bear spent most of his sleeping time in lateral lying posture (a posture probably associated with rapid eyes movement sleep). The percentage of time dedicated to this posture was significantly reduced after the death of his sibling (pair, 35.9 ± 7.4%; alone, 15.0 ± 5.4%; P < 0.05), whereas the percentage of time spent in quadrupedal posture increased (pair, 17.1 ± 5.4%; alone, 37.8 ± 7.8; P < 0.05). One of the possible reasons for these changes may be an increased risk perception of the bear after the death of his sibling. Our results highlight the importance of social environment and of its changes, which should be carefully considered to maintain captive bears in good welfare conditions.     

Illustrated report of a vertebral column disorder in a Kodiak bear (Ursus arctos middendorffi)

Autopsy of an old male Kodiakbear (Ursus arctos middendorffi), who had suffered from extreme motor disturbances, revealed haemangioma of the liver and severe osseous changes, particularly of the spine. A photographic documentation is given.     

Physiologic evaluation of capture and anesthesia with medetomidine-zolazepam-tiletamine in brown bears (Ursus arctos)

Physiologic variables during anesthesia with medetomidine-zolazepam-tiletamine were evaluated in 52 free-ranging brown bears (Ursus arctos) darted from a helicopter and in six captive brown bears darted at a zoo. During anesthesia, rectal temperature, respiratory rate, heart rate, and pulse oximetry derived hemoglobin oxygen saturation were recorded. Arterial blood samples were collected and immediately analyzed for evaluation of pulmonary gas exchange, acid-base status, and selected hematologic and plasma variables. At the end of anesthesia, atipamezole was administered intramuscularly at five times the medetomidine dose. Capture-induced hyperthermia and lactic acidemia were documented in free-ranging bears. Hypoxemia during anesthesia was documented in both free-ranging and captive bears. In free-ranging bears, rectal temperature, heart rate, lactate, hematocrit, and hemoglobin decreased significantly during anesthesia, whereas partial pressure of arterial carbon dioxide, pH, potassium, and glucose increased. Yearlings had a significantly higher heart rate, pH, base excess, bicarbonate, and glucose, and had a significantly lower rectal temperature, sodium, hematocrit, and hemoglobin when compared with subadult and adult brown bears. In conclusion, alterations in pulmonary gas exchange and acid-base status in brown bears during anesthesia with medetomidine-zolazepam-tiletamine with the doses and capture methods used in this study were identified. Oxygen supplementation is recommended to counteract hypoxemia during anesthesia.     

Accessory corpora lutea formation in pregnant Hokkaido sika deer (Cervus nippon yesoensis) investigated by examination of ovarian dynamics and steroid hormone concentrations

Generally, sika deer conceive a single fetus, but approximately 80% of pregnant females have two corpora lutea (CLs). The function of the accessory CL (ACL) is unknown; moreover, the process of ACL formation is unclear, and understanding this is necessary to know its role. To elucidate the process of ACL formation, the ovarian dynamics of six adult Hokkaido sika deer females were examined ultrasonographically together with peripheral estradiol-17β and progesterone concentrations. ACLs formed in three females that conceived at the first estrus of the breeding season, but not in those females that conceived at the second estrus. After copulation, postconception ovulation of the dominant follicle of the first wave is induced by an increase in estradiol-17β, which leads to formation of an ACL. A relatively low concentration of progesterone after the first estrus of the breeding season is considered to be responsible for the increase in estradiol-17β after copulation.     

Matrilinear hierarchy in the American black bear (Ursus americanus)

The American black bear (Ursus americanus) was long thought to be solitary and its social organization has not been well described. Here, we present new data on black bear social structure. The objectives of the study were to make detailed observations of the behavior of wild black bears to determine their social interactions and structure. We tested whether black bears interacted socially beyond mating and competing for resources, if black bears tracked relationships and interacted regularly even when resources were not limited, and whether the social structure of a population of black bears was based on a matrilinear hierarchy. We collected data by direct observation of bears from 1993 to 2014. Observations of 1210 social interactions at a provisioning site indicated that females compete and form matrilinear hierarchies. Dominant bears established a hierarchy for food, control of space, and control of younger bears. Post interaction scent marking took place, which suggested that dominant females were conditioning subordinates to their scent marks. Affiliative behavior occurred between related and unrelated bears and helped to establish the social structure of the bear community. Based on our data, human–bear conflicts can be reduced by behavioral modifications by humans when they encounter bears. Knowledge of bear behavior and the matrilinear hierarchy provide a basis for non-lethal management of bears that find themselves in a bear–human conflict situation.