Ovine endometrial estrogen receptor expression is altered following PG-600 administration.

BACKGROUND: Dysregulation of the estrogen receptor 1 (ESR1) expression during the establishment of pregnancy could contribute to reduce fertility reported in ewes treated with PG-600. OBJECTIVES: The objective of this study was to evaluate the effect of treatment with PG-600 on ESR1 expression in the ovine endometrium during early diestrus. METHODS: Polypay ewes (n = 24) that had exhibited an oestrous cycle of normal duration (16-18 days) were treated with intravaginal progesterone-releasing device (CIDR) for 9 days. Cloprostenol was administrated two days before CIDR withdrawal. On the day of CIDR withdrawal (day 0), ewes received a 5 mL intramuscular injection of PG-600 (400 IU equine chorionic gonadotropin and 200 IU human chorionic gonadotropin) or saline. Blood samples were collected before treatment and on the day of tissue collection to determine serum estradiol-17ß and progesterone concentrations using radioimmunoassay. On days 4 and 7, six ewes from each treatment group were anaesthetised and a laparotomy was performed to obtain intercaruncular endometrial samples. Endometrial samples were collected ipsilateral to the ovary bearing the highest number of corpora lutea. An estradiol exchange assay was used to determine ESR1 concentration. RESULTS: Estradiol concentrations did not differ by time or treatment, but progesterone concentrations were significantly higher in the PG-600-treated group on day 7 despite a similar number of corpora lutea. Endometrial ESR1 concentration was significantly reduced on day 7 in the PG-600 group. CONCLUSIONS: In conclusion, although progesterone was higher than controls on day 7, ESR1 did not differ from controls suggesting that treatment with PG600 is unlikely to impair reproductive potential.

Understanding the effects of sustained supraphysiologic concentrations of luteinizing hormone in gonadectomized dogs: What we know and what we still need to learn.

Removal of the gonads with surgical sterilization results in a loss of negative feedback to the hypothalamus and anterior pituitary. The sustained supraphysiologic luteinizing hormone (LH) concentrations in gonadectomized dogs can significantly alter organ function and even induce neoplastic changes. For example, gonad removal has a profound effect on thyroid function and is reported to be the most significant cause for the development of hypothyroidism in dogs. Thirty percent more gonadectomized dogs develop hypothyroidism compared with intact dogs. Within the canine thyroid, LH receptors are co-localized with thyroid stimulating hormone (TSH) receptors. Continuous LH receptor activation in gonadectomized dogs may interfere TSH receptor function by consuming second messengers involved in G-protein receptor cell signaling, preventing the action of TSH when it binds to its receptor in the thyroid, resulting in hypothyroidism. The incidence of anterior cruciate ligament ruptures is significantly increased following gonad removal independent of breed, sex, weight or body condition. Luteinizing hormone receptors are expressed in the cruciate ligament and continuous LH receptor activation may increase laxity in these ligaments, resulting in joint instability. Both male and female gonadectomized dogs are at a significantly increased risk for lymphoma and hemangiosarcoma. Luteinizing hormone receptors are also abundant in these tissues. Research in four canine hemangiosarcoma cell lines found that LH receptor activation induces cell proliferation. In addition, research in three canine T-cell lymphoma cell lines found that LH receptor activation induces cell proliferation, adhesion, and invasion as well as increases LH receptor expression. Research is needed to determine if LH reducing strategies using gonadotropin releasing hormone agonists will increase remission times in gonadectomized dogs with LH receptor-positive tumors. In conclusion, among the non-reproductive functions of gonads, suppression of LH secretion and resulting LH receptor overexpression appear necessary in maintaining endocrine, musculoskeletal, and anti-neoplastic health.

Investigating a method for pharmacologic semen collection in alpacas.

While semen evaluation is standard practice prior to a sale or when infertility is suspected in other species, it is rarely done in camelids due to the difficulties involved in collecting a sample. The reproductive physiology of alpacas differs to that of other domestic animals and is still poorly understood. In the stallion, a technique was developed for semen collection that pharmacologically induces ejaculation without copulation (ex copula). This study investigates whether semen could be reliably collected by ex copula ejaculation in male alpacas. Eleven male Huacaya alpacas were used in this study, and six ex copula treatment protocols were evaluated: (1) saline (control); (2) xylazine only (0.1 mg/kg); (3) xylazine only (0.2 mg/kg); (4) imipramine only (1.0 mg/kg); (5) imipramine (1.0 mg/kg) followed 10 minutes later with xylazine (0.1 mg/kg); and (6) imipramine (2.0 mg/kg) followed 10 minutes later with xylazine (0.1 mg/kg). Each treatment protocol was repeated two to five times. Azoospermic samples obtained from ex copula ejaculation contained numerous epithelial cells but no sperm. A reliable treatment for pharmacologically inducing ejaculation in alpacas remains to be found.

Intramammary antibiotics with complementary acupuncture decreases milk serum N-acetyl-beta-D-glucosaminidase concentrations in dairy cattle with subclinical mastitis.

The objective of this research is to determine whether intramammary antibiotics with complementary acupuncture can reduce bovine mammary inflammation due to subclinical mastitis. Lactating cows were selected based on milk with a somatic cell count (SCC) greater than 500,000 cells/ml. Pre- and post-treatment milk samples were collected to determine SCC, aerobic bacterial content, milk ion conductivity, total protein, lactate dehydrogenase (LDH) and N-acetyl-beta-D-glucosaminidase (NAGase) concentrations. Milk serum was prepared from milk samples by double centrifugation. Concentrations of LDH and NAGase were determined using commercial enzyme-linked immunosorbent assays. Cows being treated with intramammary antibiotics were separated by random assignment to the acupuncture group (n = 10) and a no-acupuncture (control) group (n = 9). Both the acupuncture and control group were restrained for 30 min in a head catch 12 hr apart for a total of four times. For front quarters affected by subclinical mastitis, the acupuncture points used were spleen (SP) 12, SP 17, SP 18, SP 21, stomach (ST) 18 and conception vessel (CV) 12. For rear quarters affected by subclinical mastitis, the acupuncture points used were bladder (BL) 30, BL 30-1, BL 49, kidney (KI) 10, conception vessel (CV) 2 and CV 3. All parameters were compared using a Student t test. Significance was defined as p < .05. Compared to control cows, complementary acupuncture treatment reduced NAGase enzymatic activity in quarters of cows with subclinical mastitis. The reduction in NAGase suggests that complementary acupuncture treatment may be associated with healing of the damaged mammary epithelial cells, which are the primary source of NAGase activity in milk serum.

Estrous Cycle Manipulation in Dogs.

Since 1939, scientists have studied estrous cycle manipulation in dogs resulting in more articles published in this field that any other area of canine reproduction. Estrous cycle manipulation in dogs must be safe and reliable. Dopamine agonists, gonadotropin-releasing hormone agonists, and gonadotropins are hormones that have been used for estrus induction in bitches but each treatment has advantages and disadvantages. Despite widespread availability of these medications throughout the rest of the world, there are no drugs currently labeled for canine estrus induction in the United States.

Estrus Suppression in Dogs.

Since 1952, scientists have studied estrus suppression in dogs. Estrus suppression in dogs must be safe and reliable. Medications used for estrus suppression in bitches include gonadotropin-releasing hormone (GnRH) agonists, GnRH antagonists, progestogens, and androgens. Despite widespread availability of these medications throughout the rest of the world, there are no drugs currently labeled for canine estrus induction in the United States.

Semen collection in the dog.

This review will discuss semen collection in the dog. Semen samples may be collected from male dogs for the purposes of artificial insemination, cryopreservation or diagnosis. The materials needed for semen collection depend on which method is used and the collector's level of expertise with this procedure. At minimum, two sterile centrifuge tubes or specimen cups can be used to collect semen as it is ejaculated (for the combined first and second fractions and for the third fraction). The most common method for semen collection in the dog is by digital stimulation. Under ideal conditions, this procedure is performed in the presence of an estrous bitch. Initially, the dog's penis is vigorously massaged through the prepuce at the level of the bulbus glandis (caudal-most aspect of the prepuce) until a partial erection develops (initial engorgement of the bulbus glandis). The prepuce is quickly retracted past the bulbus glandis and firm constant pressure is applied to the penis behind the bulbus glandis by squeezing the penis between index finger and thumb. Pelvic thrusting may occur following application of pressure behind the bulbus glandis during the development a "full" erection. The ejaculate is composed of three fractions: first (sperm-poor), second (sperm-rich) and third (prostatic fluid). In addition to digital stimulation of the penis, spermatozoa have been collected from dogs using electroejaculation and pharmacologic methods.

Induction and synchronization of estrus in dogs.

Indications for estrus induction in the bitch include missed breeding opportunities or conception failure, the treatment of primary or secondary anestrus and synchronization of ovulation for embryo transfer programs. Reported methods for canine estrus induction include the use of synthetic estrogens (diethylstilbesterol), dopamine agonists (bromocryptine and cabergoline), GnRH agonists (lutrelin, buserelin, fertirelin, deslorelin, and leuprolide) and exogenous gonadotropins (luteinizing hormone, follicle stimulating hormone, human chorionic gonadotropin, pregnant mare serum gonadotropin, and human menopausal gonadotropin). These methods vary widely in efficacy of inducing estrus, as well as in the fertility of the induced estrus. The applicability of some of these methods for clinical practice is questionable. This review will summarize published reports on estrus induction and synchronization in bitches and summarize preliminary results using a long-acting injectable preparation of deslorelin.