During the past two decades, techniques for faecal steroid analysis have been developed and have been used for research with mammalian, bird and, to a lesser extent, reptile, amphibian and fish species. Various techniques for the analysis of reproductive (oestrogen, androgen, progestagen) and adrenocortical (glucocorticoids) steroid hormones have been established and have been applied to a wide range of research questions studying captive and free-ranging wildlife, as well as domestic and laboratory species. Because of species-specific differences in steroid metabolism in even closely related species, careful validation of assay methods is necessary in order to generate meaningful and accurate results. For future research and management of free-ranging and captive wildlife, the great potential of non-invasive endocrine monitoring will be utilized more than ever. In light of this, captive wildlife species are ideal research subjects, as longitudinal sample collection is possible and studies connecting physiology, endocrinology, reproduction and stress with various social and/or environmental factors can be carried out and can be analysed to determine how they impact animal health.

The many uses of non-invasive faecal steroid monitoring in zoo and wildlife species

Elective gonadectomy of dogs and cats is one of the most common veterinary procedures in the United States. Increasingly, dog owners and members of the veterinary profession throughout the world have questioned the optimal age for performance of these procedures and whether these procedure should even be performed as elective surgeries.

Determining the optimal age for gonadectomy of dogs and cats.

Leuprolide acetate is a synthetic nonapeptide that is a potent gonadotropin-releasing hormone receptor (GnRHR) agonist used for diverse clinical applications, including the treatment of prostate cancer, endometriosis, uterine fibroids, central precocious puberty and in vitro fertilization techniques. As its basic mechanism of action, leuprolide acetate suppresses gonadotrope secretion of luteinizing hormone and follicle-stimulating hormone that subsequently suppresses gonadal sex steroid production. In addition, leuprolide acetate is presently being tested for the treatment of Alzheimer's disease, polycystic ovary syndrome, functional bowel disease, short stature, premenstrual syndrome and even as an alternative for contraception. Mounting evidence suggests that GnRH agonist suppression of serum gonadotropins may also be important in many of the clinical applications described above. Moreover, the presence of GnRHR in a multitude of non-reproductive tissues including the recent discovery of GnRHR expression in the hippocampi and cortex of the human brain indicates that GnRH analogs such as leuprolide acetate may also act directly via tissue GnRHRs to modulate (brain) function. Thus, the molecular mechanisms underlying the therapeutic effect of GnRH analogs in the treatment of these diseases may be more complex than originally thought. These observations also suggest that the potential uses of GnRH analogs in the modulation of GnRH signaling and treatment of disease has yet to be fully realized.

Leuprolide acetate: a drug of diverse clinical applications.

Serum estrone, estradiol-1 7!) and progesterone were measured in bitches in which LH, sexual behavior and laparoscopically confirmed time of ovulation had been previously studied. Steroid values from 25 estrous periods were normalized to day of peak LH (Day 0). Estrone, estradiol-17(3 and progesterone concentration did not differ significantly in either dogs subjected to laparoscopy at 48 h intervals or those bitches undergoing no laparoscopy. During the preovulatory interval, mean peripheral estrone concentrations were more variable than estradiol-1713; however, both estrogens tended to rise gradually throughout this time period. Overall maximal estradiol-1 713 concentration was detected on Day -2 with estrone peaking later (Day -0.5). Both estrogens declined (P<0.05) coincidentally with the LH surge. Progesterone from Days -14.0 through -1.5 was maintained at basal concentrations. An increase (P<0.05) in mean progesterone occurred on the day of the preovulatory LI-I peak which correlated with direct observation of apparent preovulatory follicle luteinization. Progesterone increased gradually from Day -0.5 through 8 and then varied for the remainder of the sampling period. Analysis of individual cycles indicated that circulating serum concentrations of reproductive steroids fluctuated from day to day or within days of the proestrous-estrous interval. In dogs subjected to laparoscopy, initial evidence of the presence of visible preovulatory follicles was closely related to the first detectable elevations in both estrone and estradiol-1 713. Either estrone or estradiol-1 713 concentrations or both surged sharply in 24 of the 25 cycles examined; however, only titers of estradiol-17j3 were elevated above baseline in all cycles prior to, or at the time of, the LH peak. In 16 of 25 cycles, estradiol-1713 concentrations declined by 20 pg/mI or more 12-24 h prior to the onset of sexual receptivity. Bitches remained in estrus during periods of declining estrone and estradiol-1 713and increasing progesterone levels. These data integrate the hormonal, ovarian and behavioral events of the estrous cycle of the bitch and suggest that: 1) a preovulatory estradiol-17(3 surge exists and is likely responsible for triggering LH release; 2) estrone may play a supportive role to estradiol-1713 in the endocrine control of LH secretion; 3) preovulatory changes in follicular morphology are distinct and can be correlated with a shift from estrone and estradiol-17f3 to progesterone secretion; 4) prolonged sexual receptivity in this species is supported in the presence of declining estrogen and continuously rising progesterone concentrations.

/pdf/relationship-of-serum-estrone-estradiol-17b-and-progesterone-3o8znx7a8d.pdf

Relationship of Serum Estrone, Estradiol-17β and Progesterone to LH, Sexual Behavior and Time of Ovulation in the Bitch

The necessity, and in particular the timing, of gonadectomy in dogs and cats is still controversial. This is mainly because gonadectomy confers a mixture of benefits and adverse effects that depend upon the age at neutering, sex, species and breed. In this paper, the long-term risks and benefits of gonadectomy, at various ages, in dogs and cats are reviewed using data describing the effects of desexing on the urogenital tract and on other medical conditions, such as orthopaedic diseases, immune-mediated diseases, tumour development and behaviour.

/pdf/gonadectomy-in-cats-and-dogs-a-review-of-risks-and-benefits-pt5ugh25xu.pdf

Gonadectomy in Cats and Dogs: A Review of Risks and Benefits

The effect of GnRH analogs on urinary incontinence after ablation of the ovaries in dogs.

The estrous cycle in the dog: a review.

Objective—To evaluate the clinical and endocrine responses of ferrets with adrenocortical disease (ACD) to treatment with a slow-release implant of deslorelin acetate. Animals—15 ferrets with ACD. Procedure—Ferrets were treated SC with a single slow-release, 3-mg implant of deslorelin acetate. Plasma estradiol, androstenedione, and 17-hydroxyprogesterone concentrations were measured before and after treatment and at relapse of clinical signs; at that time, the adrenal glands were grossly or ultrasonographically measured and affected glands that were surgically removed were examined histologically. Results—Compared with findings before deslorelin treatment, vulvar swelling, pruritus, sexual behaviors, and aggression were significantly decreased or eliminated within 14 days of implantation; hair regrowth was evident 4 to 6 weeks after treatment. Within 1 month of treatment, plasma hormone concentrations significantly decreased and remained decreased until clinical relapse. Mean time to recurrence of clinica...

Clinical and endocrine responses to treatment with deslorelin acetate implants in ferrets with adrenocortical disease

Changes in plasma gonadotropin concentrations and urethral closure pressure in the bitch during the 12 months following ovariectomy.

Effect of a long acting GnRH analogue or placebo on plasma LH/FSH, urethral pressure profiles and clinical signs of urinary incontinence due to Sphincter mechanism incompetence in bitches

Wolfgang Jöchle

Papers

The effect of GnRH analogs on urinary incontinence after ablation of the ovaries in dogs.

The estrous cycle in the dog: a review.

Clinical and endocrine responses to treatment with deslorelin acetate implants in ferrets with adrenocortical disease

Changes in plasma gonadotropin concentrations and urethral closure pressure in the bitch during the 12 months following ovariectomy.

Effect of a long acting GnRH analogue or placebo on plasma LH/FSH, urethral pressure profiles and clinical signs of urinary incontinence due to Sphincter mechanism incompetence in bitches