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Maintaining surplus captive male antelope in bachelor groups can result in aggression in some species, leading to injury or death. Suppressing endogenous testosterone using gonadotropin‐releasing hormone (GnRH) analogs has been used in primates to control aggressive behavior, but little information is available on the use of GnRH analogs in nondomestic ruminant species. The aim of this study was to investigate the effect of a slow‐release GnRH agonist (deslorelin) on circulating hormone concentrations, semen and sperm characteristics and behavior in male gerenuk, dorcas gazelle, and scimitar horned oryx. Body weight, testicular volume, circulating hormone concentrations, ejaculate traits, and behavior were recorded before and during deslorelin treatment. A GnRH challenge (with serial blood sampling) was administered to gerenuk and dorcas gazelles before and during GnRH analog treatment. Quantitative behavioral data were collected for gerenuk and dorcas gazelles for 30 min three times a week, starting 1 month before deslorelin treatment, and the mean incidence of combined aggressive behaviors (supplanting, foreleg kicking, sparring, marking, and mounting) was compared before and during deslorelin treatment. No statistical difference (P>0.05) in body weight, semen volume, sperm concentration, percent sperm motility, percent sperm plasma membrane integrity, or percent normal sperm morphology was found before or during deslorelin treatment. The characteristic rise in luteinizing hormone (LH), occurring ∼10 min following administration of a GnRH challenge in untreated males, was not evident during deslorelin treatment, although tonic LH concentrations were maintained. No differences (P>0.05) in the mean incidence of any aggressive behavioral traits in gerenuk or dorcas gazelle were detected before and during deslorelin. The absence of a GnRH‐induced increase in serum LH in treated males indicated that deslorelin suppressed pituitary responsiveness to endogenous GnRH, but that the continued tonic production of LH was sufficient to maintain testosterone production, aggressive behavior, and subsequent semen production. Zoo Biol 21:435–448, 2002. © 2002 Wiley‐Liss, Inc.

In two separate controlled clinical trials, the efficacy and safety of 2.2 mg of the GnRH analogue deslorelin, administered subcutaneously as a short‐term implant to normally cycling mares in oestrus with a dominant ovarian follicle more than 30 mm in diameter, were evaluated, using a placebo as a negative control. The oestrous cycle of each mare was followed by teasing, palpation per rectum and transrectal ultrasonography. Follicles were monitored every 24 hours by ultrasonography until ovulation occurred. The mares were either mated naturally or inseminated artificially. In trial 1, 174 mares were treated at six locations in Canada, and in trial 2, 98 mares were treated at three locations in the USA. In trial 1, the treatment with deslorelin reduced the mean (sd) time to ovulation from 84.2 (48.4) hours to 50.2 (19.6) hours (P<0.001) and in trial 2 it reduced it from 88.8 (40.3) hours to 54.1 (26.5) hours (P<0.001). In trial 1, the percentage of mares ovulating within 48 hours increased from 37.7 per cent in control mares to 86.1 per cent in treated mares (P<0.001) and in trial 2 the percentage increased from 26.5 to 80.9 per cent (P<0.001). In trial 2, the duration of oestrus in the deslorelin‐treated mares was reduced from 6.1 days to 4.3 days and the number of matings or artificial inseminations was reduced from 2.5 to 1.7 (P<0.001). In trial 1, days 12 to 20 pregnancy rates for matings at the treatment oestrus were not different for deslorelin‐treated (75.6 per cent) and placebo‐treated (66.1 per cent) mares. In trial 2, days 12 to 20 pregnancy rates from matings at the treatment oestrus were lower for deslorelin‐treated (58.7 per cent) than for placebotreated (83.3 per cent) mares (P<0.05), although pregnancy rates were similar for deslorelin‐treated (97.1 per cent) and placebo‐treated (95.0 per cent) mares after mating at the second oestrus. In both trials, pregnancy losses due to early or late abortions were within the normally expected range and similar for deslorelin‐treated (3.6 and 3.7 per cent, respectively) and placebo‐treated (13.4 and 7.5 per cent) mares. The treatments did not cause systemic side effects and local reactions at the implantation sites were slight and of short duration.

Seventy‐two healthy dogs required sedation and analgesia for a variety of procedures causing discomfort or pain. They were treated either with the α2‐agonist medetomidine at 40 μg/kg (15 intravenously and 17 intramuscularly), or 80 μg/kg (15 intravenously and 15 intramuscularly) or with xylazine plus 1‐ methadone (1.0 mg) (10 intravenously). The levels of sedation, analgesia and safety were compared clinically and by measurements of the effects on the electrocardiogram (ECG) and blood gases, body temperature, haematology and clinical chemistry. Sedation was achieved reliably with both medetomidine and xylazine plus I‐methadone but its onset, depth and duration were influenced by the dose and route of administration. In the medetomidine‐treated dogs, intravenous administration resulted in more rapid sedation and the effects of the higher dose were deeper and longer lasting. The small dogs receiving 40 μg/kg may have been underdosed. The initial analgesic effects in response to a pin prick to the body surface were sufficient and similar for both drugs, except for the intramuscular dose of 40 μg/kg medetomidine. Analgesia for the clinical procedures was less reliable with medetomidine and was not always adequate even at the high dose, but xylazine plus 1‐methadone assured analgesia in almost every case. Medetomidine resulted in marked bradycardia, lasting as long as the sedation and the ECG revealed a sinus arrhythmia with sinoatrial and atrioventricular blocks grade I and II as a sign of interference with transduction. The bradycardia with xylazine plus 1‐methadone was less pronounced. A decrease in respiratory rate accompanying sedation had no influence on blood gases and blood acidity in the dogs treated with medetomidine but caused a respiratory acidosis with xylazine plus 1‐methadone. Body temperature decreased with all treatments for the duration of the period of sedation. Blood glucose concentration increased to a similar extent in all treatment groups, but all other haematological and clinicochemical variables remained unchanged. Treatment with the specific α2 antagonist, atipamezole, reversed the sedation and cardiovascular and pulmonary effects due to medetomidine within minutes.

Corneal lesion models were developed in dogs. In trial 1, the left cornea was scratched under general anesthesia; in trial 2, standardized excisions of corneal tissue were made. All corneal lesions were infected with Pseudomonas aeruginosa cultured from a canine eye lesion, and covered for 24 h with a soft contact lens. The slow healing of these lesions, even under local antibiosis (Gentamicin sulfate) enabled the authors to evaluate the effects of drug preparations on healing processes.In two double-blinded trials with these models, a protein-free dialysate from calf blood (SolcoserylR) in an ophthalmic gel preparation(SOG), and its hexosylceramide fraction of Solcoseryl in an ophthalmic gel preparation (FR3) were tested against a placebo ophthalmic gel (POG). Local treatments, thrice daily, commenced two days after setting corneal lesions and lasted 14 days. In trial 1, 20 dogs were treated with either SOG or POG; half of each group received concomitant gentamicin treatment. In trial 2, 30 dogs received SOG, FR3 or POG, together with gentamicin. Treatments with either SOG or FR3 accelerated significantly the repair of corneal lesions, as confirmed by the rapid reduction in areas taking up significantly the repair of corneal lesions, as confirmed by the rapid reduction in areas taking up fluorescin (p < 0.02), reduction or disappearance of blepharospasms and lacrimation (p < 0.02), and the lack of opacities and vascularization (p < 0.05). In the fourfold concentration used, FR3 was consistently more effective than SOG. Antibiosis alone showed little effectiveness.

In a blinded trial, the effectiveness and safety of 2.2 mg of the GnRH analog deslorelin acetate, administered in a short–term implant (STI) to normally cycling mares in estrus with a dominant ovarian follicle of 30 mm in diameter or larger, were evaluated, using a placebo implant as a negative control. A total of 39 mares received treatments at admittance with pre–randomized implants containing either 2.2 mg or 0 mg deslorelin. Mares were teased daily and examined rectally with ultrasound at 24 h intervals to determine time to Ovulation and duration of estrus. The number of breedings and the pregnancy rate at 18 (±3) and 38 (±3) days were recorded, as were systemic side effects and local reactions at the implantation sites. Pregnancies resulting from breedings during the treatment estrus and/or from breedings during the next estrus were followed and the early and late pregnancy loss rate, the number of pregnancies going to term and of live–born foals was recorded.

Analysis of breeding records from a large, well managed Zebu cattle (BOS INDICUS) herd in the Mexican Gulf Coast area and calculation of Spearman rank correlations with local meteorological data (monthly means for temperature, pressure, precipitation, humidity) revealed significant seasonal fluctuations in reproductive functions. This seasonal influence was evident for the onset of puberty; for all consecutive conceptions and for all conceptions in relation to the length of the calving interval. Fertility maxima coincided with the onset of the rainy season (June to August), with significant rank correlations between conceptions and temperature (+ 0.827), pressure (- 0.751) and precipitation (+ 0.632). A second fertility maximum was revealed late in the dry season (February to May), showing significant effects during early puberty and in situations where conceptions after calving were delayed. No single meteorological factor was significantly rank correlated with this pre-rainy season effect.

A polyphenolic acid, not previously described, was isolated from the roots of L. ruderaleand named “lithospermic acid” (LA). LA showed no biological activity in the rat or the chicken. However, when oxidized enzymically a substance was obtained which inactivated exogenous and endogenous gonadotropins in the female rat and prevented ovulation in the laying hen. In one experiment a cold water extract of the roots was partitioned into 5 fractions which were administered orally to immature female rats. Only the original extract and one fraction (11), composed of oxidized LA showed any significant inactivation of exogenous gonadotropin. In another experiment cold water extract, II, as well as enzymically oxidized lithospermic acid showed antiovulatory properties when injected into the laying hen. These experiments indicate that oxidized LA present in the roots is responsible for some of the antigonadotropic effect noted with cold water extracts of L. ruderale.

Progesterone (100 mg) applied 3 days before and 5 days after a single administration of 10 mg flumethasone on Day 270 of pregnancy in sixteen cows and thirteen heifers, successfully prevented premature parturition which was otherwise promptly induced by the corticoid. At this dose level and timing, progesterone interfered significantly with the sequence of events preceding, accompanying and following parturition. As a result, preparation of presentation of the fetus for parturition was either delayed or prevented, dystocia was frequent, the percentage of stillborn calves was significantly elevated, calf viability was impaired and placental retention, which occurs in about 80% of corticoid-induced parturitions, was not influenced.

This paper records observations made on conception in sows treated with a long-acting androgen-oestrogen mixture. The observations were made as part of an experiment originally undertaken to examine the value of treatment with this agent for the diagnosis of pregnancy in pigs. It has previously been observed that administration of a similar mixture was followed by heat in cattle previously showing ovulation in the absence of heat. By the same treatment an ovulatory heat was induced in anoestrous, barren animals, but existing pregnancies were not disturbed (Jöchle, 1964). It seemed probable that the existence of pregnancy would be established if heat failed to occur following administration of the agent.Two milligrammes oestradiol valerate and 5 mg testosterone enanthate were administered to sows 9 to 12 days following service. The experimental group comprised ninety-eight German Landrace