As part of a large-scale field feeding system test we were able to collect and study hundreds of aliquots of overnight urine samples obtained immediately prior to a fasting blood sample on days 1, 20, and 44 of the field test. The large number of experimental samples (greater than 650) and concomitant collection of blood and urine aliquots along with data on body weights gave us the opportunity to assess and quantitate the sensitivity of commonly used criteria of hypohydration. Urine aliquots for all test days were initially categorized by specific gravity (SG) greater than or equal to 1.03 (n = 124) or less than 1.03 (n = 540). Creatinine levels were elevated (P less than 0.001) in the concentrated urine samples, but a decreased trend in sodium-to-potassium ratios in these samples failed to achieve statistical significance (P greater than 0.05). However, when individuals with high SG urine were subclassified by a criterion of weight loss greater than 3% from original body weight, then creatinine concentrations were elevated (P = 0.05), whereas sodium-to-potassium ratios were decreased (P = 0.05) when subjects also with high SG but weight loss less than 3% were compared. Because of the moderate altitude (2,000 m) of the field site and the time of sojourn (44 days), there occurred a slight, but significant (P less than 0.001), erythropoietic response. Hematocrit and serum osmolality were not significantly different when examined by the criteria of high or low SG urine and weight loss greater than or less than 3% original body weight.(ABSTRACT TRUNCATED AT 250 WORDS)

The reproductive biology of wild Canis species is often described as unique among mammals because an unusual combination of behavioral and physiological characteristics including a seasonally monestrous cycle, copulatory lock or tie, obligatory pseudopregnancy, social monogamy, and biparental care of the young. We investigated social behavior, endocrine profiles, and vaginal cytology of female coyotes (Canis latrans) during 4 breeding seasons, 2000-2003. Blood levels of estradiol, progesterone, prolactin, and relaxin were measured, and mating behavior and changes in vaginal epithelium were documented. After aligning the data from each individual to her estimated day of ovulation, we compared pregnant coyotes with nonpregnant females and evaluated temporal relationships among hormone levels, behavior, and vaginal cytology. We found that patterns of proceptive and receptive behaviors correlated with the secretion of steroid hormones, as did vaginal epithelial cytomorphosis. In addition, although progesterone levels of pregnant and pseudopregnant coyotes were indistinguishable, prolactin demonstrated a discernible intergroup difference and relaxin was only detectable in pregnant females. Although this study included characteristics not previously published for this species, it also showed how key aspects of reproduction were correlated temporally, and emphasized the importance of an integrated perspective when addressing the reproductive biology of coyotes, or other wild species of canids.

Little is known regarding the physiological rôle of oviduct fluid on ova and spermatozoa in the reproductive tract. VanDemark (1958) and Bishop (1961) suggested that luminal fluids may be an important transport and nutrient medium for the gametes; others felt that oviduct secretions influenced sperm activity (Olds & VanDemark, 1957a) or aided the capacitation process (Austin, 1951: Chang, 1951. Oviduct fluid has been collected from several species by ligation of portions of the genital tract (Blandau, Jensen & Rumery, 1958), flushing portions of the tract (Heap, 1962), expressing the contents of tracts after slaughter (Olds & VanDemark, 1957b), and cannulation of portions of the tract in living animals (Clewe & Mastroianni, 1960;Restall, 1966). To our knowledge, oviduct secretion has never been continuously collected throughout the oestrous cycle and an attempt was made to determine whether the volume, protein content, or glucose content of oviduct fluid varied during the oestrous cycle.Cows of small size were chosen for this experiment because the reproductive tract was more accessible at surgery. Surgery was performed at mid-cycle, either under local anaesthesia (infusion of Xylocaine), or general anaesthesia (Equithesin). In both cases, an incision was made in the flank area and the uterus and oviduct were drawn as close as possible to the opening. The ovarian end of the oviduct was located and one end of a 60-cm long silastic cannula (ID 0-10 cm, OD 0-20 cm) was inserted to a depth of 15 mm. Two collars were placed on the end of the cannula, which was held in place by two Supramid sutures ; the uterine end of the oviduct was ligated with one Supramid suture to prevent flow of oviduct fluid into the uterus. A small amount of air was injec¬ ted into the cannula, which was considered patent if the oviduct distended. The cannula was then brought out through the incision and the animal was given 1 million units of procaine penicillin in oil daily for 4 days.The collection device was contained in a 3-x4-in. aluminium cassette attached to the animal with four sutures. The cannula was inserted through a plastic disc at the surface of the skin and several sutures tied around it to prevent the cannula from slipping through the plastic disc and into the body cavity. The cannula entered a plastic vial within the cassette and the vial was changed daily. The fluid was left in the vial and frozen ; the volumes were later measured with a 1-ml tuberculin syringe. For analysis, the fluid was pooled on a 4-day basis with respect to oestrus, e.g. a sample labelled +1 would include fluid collected on the 1st day of oestrus 549

The diagnosis of pregnancy in the domestic dog (Canis familiaris) often employs specialized equipment, experienced staff, and the cooperation of the bitch. These procedures can be challenging when the subject is a wild canid, particularly in a field setting. In addition, reproductive hormone assays are unreliable as a diagnostic tool because the estrous profiles of pregnant and pseudopregnant canines are similar. However, research has demonstrated that the hormone relaxin can be detected in maternal blood after embryonic implantation, but remains negligible in non-pregnant females. We investigated the use of relaxin as a diagnostic marker of pregnancy in the coyote (C. latrans). A commercially available canine relaxin enzyme immunoassay (ReproCHEK TM ) was used to test plasma collected from 124 female coyotes over four consecutive breeding seasons. Mating activities of the captive females were observed; then peripheral blood samples were collected at intervals throughout pregnancy, as well as after parturition. Results demonstrated that relaxin could be detected in the plasma of pregnant coyotes after 28 days of gestation, and in some cases as early as 23 days, while non-pregnant females and male coyotes consistently tested negative. Relaxin also remained detectable in the plasma of the majority of females tested 10-12 weeks after parturition. This qualitative assay for relaxin proved to be a reliable diagnostic tool for pregnancy in the coyote. In addition, blood sampling was relatively easy, could be accomplished with minimal handling, and did not require sedation or anesthesia.

Coyotes (Canis latrans) are seasonally monestrous and form perennial pair-bonds. Breeding is dominated by each pack's alpha male and female, and both sexes share responsibility for territory defense and pup-rearing. They are also opportunistic predators on domestic livestock and pets. But while dominant adults have been implicated as primary killers, depredation is reduced when coyotes are without pups. Contraception, therefore, may represent a non-lethal solution for conflicts between coyotes and humans. Steroid hormones successfully control fertility in some species, but have been considered contraindicated in wildlife and canids in particular; specific concerns include possible induction of aberrant behavior, or uterine and hematopoietic pathologies. Herein we describe a study examining the physiological effectiveness, health safety, and behavioral consequences following treatment of estrous coyotes with exogenous estrogen. We treated captive adult female coyotes in estrus with 0.01mg/kg estradiol benzoate (EB), either before (n=5) or immediately after ovulation (n=6), then documented reproductive outcome, physiological variables and behavioral responses, during and after treatment. Pregnancy was averted in six females treated after ovulation, suggesting that appropriate timing of treatment proved crucial. A transient suppression of sexual behavior was observed, and in some cases, estrus appeared slightly lengthened. However, neither ovulation nor mating behavior was fully suppressed. Importantly, non-pregnant females (and their mates) displayed diestrous socio-sexual behavior similar to pregnant coyotes (behavioral pseudopregnancy). Furthermore, non-pregnant coyotes did not mate again until the next native breeding season, and we observed no deleterious physiological effects during diestrus or subsequent ovarian cycles.