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E.D. Plotka

Publications and source records attributed to E.D. Plotka.

7 recordsLinked to original sources
USGS1990

The influence of social and endocrine factors on urine-marking by captive wolves (Canis lupus)

Although serum hormones varied seasonally in all adult animals, only dominant male and female wolves urine-marked. Serum testosterone and urine-marking rates, which increased during the fall/winter breeding season, were positively correlated in both male and female dominant wolves. Estradiol, which increased in conjunction with proestrus and estrus, was not correlated with female urine-marking. These findings suggest that hormonal influence on urine-marking in the wolf is modulated by social factors and contrast with those for both domestic dogs and coyotes, two other members of the genus Canis.

Hormones and Behavior↗
USGS1986

Effect of anosmia on reproduction in male and female wolves (Canis lupus)

Anosmia was produced in two female and three male wolves by transection of the olfactory peduncle and was confirmed by their inability to detect meat, urine, feces, anal-gland secretions, and fish emulsion. All operated animals continued to investigate the environment with their noses, to interact normally with other pack members, and to feed at levels which maintained presurgical body weights. No effect was found on reproductive physiology (females: estradiol or progesterone concentrations, ovulation, pregnancy or parturition; males: testosterone, testicular recrudescence or sperm numbers, motility or maturation). One anosmic female became dominant and although she urine-marked with a flexed leg, the rate was lower than typical for dominant females and perhaps contributed to her failure to pair-bond with the dominant male. One anosmic male raised-leg-urinated while competing for pack dominance and when kenneled away from other males. Precopulatory, copulatory, and maternal behavior were observed for one anosmic female and appeared normal. However, neither male that was sexually naive before surgery showed interest in proestrous or estrous females. The possibility that secondary degeneration of brain regions mediating sexual behavior was responsible for the failure of these males to respond was not supported. Not only was the lack of male sexual response the only serious deficit following transection, but the male which was sexually experienced prior to surgery did copulate successfully during his second postoperative breeding season despite continued anosmia. Chemosensory priming from female urine during the protracted proestrous phase, as well as urinary and vaginal odors during estrus, appear to be critical for induction of full sexual potency in sexually naive males. The importance of urine and vaginal secretions in the sexual response of experienced males is uncertain.

Behavioral and Neural Biology↗
USGS1981

Olfactory pedunculotomy induced anosmia in the wolf (Canis lupus)

A procedure for the surgical induction of anosmia in the wolf is described. Six wolves (4 altered and 2 sham) and one mongrel dog were operated; four wolves and the dog were bilaterally pedunculotomized, and two wolves were sham operated. Behavioral tests with the wolves confirmed that they were anosmic, and anatomical verification in the dog showed that the olfactory peduncle (corresponds to the human olfactory tract) was completely sectioned. Use of this procedure will make possible tests of the role of olfaction in these animals.

Physiology & Behavior↗
USGS1979

Endocrine correlates of reproduction in the wolf. I. Serum progesterone, estradiol and LH during the estrous cycle

The estrous cycle of 10 intact female wolves, aged 8 months-8 years at the initiation of the study, was characterized in terms of vaginal smears, behavioral observations and serum concentrations of estradiol-17β, progesterone and luteinizing hormone (LH) from January through June. No estrous cycles occurred in these animals between June and December. All were housed with male wolves. Two pups and 1 adult remained anestrous during this interval. One pup and 2 adults produced litters between May 4-6. Four adults exhibited endocrine changes similar to those of the pregnant animals but no litters or signs of abortion were observed. The duration of proestrus was 15.7 ± 1.6 days (X ± SEM, n = 6), of estrus 9.0 ± 1.2 days (n = 4) and of the luteal phase 63 ± 2 days (n = 6). The duration of pregnancy was between 60-65 days. The anestrous females (86 blood samples) had 6 progesterone values between 1-2 ng/ml and the remainder below 1 ng/ml. Their estradiol-17β concentrations varied between 5-20 pg/ml. Values for LH varied between 0.1-2 ng/ml, except for 1 value above 15 ng/ml for each of the 2 anestrous pups on 12 January. The 7 estrous animals (260 samples) included 1 pup and 2 adults that delivered litters. Estradiol-17β varied between 10-20 pg/ml during proestrus, peaked at 30-70 pg/ml late in proestrus and fluctuated between 10-30 pg/ml during pregnancy or the duration of luteal activity in the nonpregnant animals. The preovulatory LH rise, 5-15 ng/ml, extended over 3 days during and immediately following the peak estradiol-17β values. An earlier elevation in LH was observed in 3 of the estrous animals. Progesterone began increasing during the LH surge and peaked 11-14 days later at 22-40 ng/ml. Progesterone concentrations greater than 3 ng/ml were maintained for 56-68 days in 6 of the 7 animals exhibiting estrus. Progesterone concentrations declined at parturition but continued to fluctuate between 0.2-3 ng/ml for 3-6 weeks.

Biology of Reproduction↗
USGS1977

Reproductive steroids in the white-tailed deer (Odocoileus virginianus borealis). I. Seasonal changes in the female

A total of 161 blood samples collected from 77 white-tailed does ( Odocoileus virginianus borealis ) during the years 1971 through 1974 in Minnesota were utilized to make a preliminary characterization of the estrogen and progesterone levels in pregnant and nonpregnant animals. Progesterone and estrogen were measured by radioimmunoassay. Progesterone levels during the months of December through February were similar for pregnant and nonpregnant animals (3.98 ± 0.57 vs. 5.50 ± 0.82 ng/ml, x̄ ± S.E., N.S., t = 1.51). The pregnant animals had higher progesterone levels during the March through May period (4.61 ± 0.44 vs. 1.94 ± 0.85, P<0.01). Progesterone levels during the months of June to early November, i.e., anestrus, were low and similar for lactating and nonlactating animals. Estrogen levels did not change during the year except for the period just before parturition in the pregnant does when estrogen levels were dramatically elevated (178 ± 29 pg/ml). Two nonpregnant adult does were sampled every 5 days from late January through early March. Progesterone levels exhibited a cyclic pattern of about 28 days duration. Estrogen levels showed no distinct pattern but tended to be inversely related to progesterone. These data suggest that 1) deer exhibit estrous cycles of about 25 to 30 days in length, 2) that estrous cycles recurred in nonpregnant does from November through early March, 3) that progesterone levels are similar for pregnancy and the luteal phase of the estrous cycle and 4) that late pregnancy is characterized by high estrogen levels as compared to early pregnancy and the estrous cycle.

Minnesota↗