Tag Archives: Testosterone

Vertebrate endocrine systems

In contrast to the invertebrate endocrine system, the emphasis in the vertebrate endocrine system is on classical endocrine organs with many physiological processes controlled by these organs. However, the nervous system still exerts an influence over the endocrine system since some of the peripheral endocrine organs are under the control of the anterior pituitary, which… Read More »

Stallion Behavior Problems

This post briefly outlines several of the most common behavior problems of breeding stallions. These problems include self-mutilation, inadequate libido, rowdy breeding behavior, specific erection dysfunction, mounting and thrusting difficulties, frenzied hyperactive behavior, and specific ejaculation dysfunction. Also briefly outlined is the common problem of residual stallionlike behavior in geldings. Inadequate Libido Specific stallion libido… Read More »

Enlarged Ovaries

Anovulatory Follicles Large, anovulatory follicles are a normal finding during the spring and fall transition periods. Anovulatory follicles can exceed 10 cm in diameter and may persist for several weeks. The cause is likely to be abnormal estrogen production by the follicle and/or insufficient release of pituitary gonadotropin to induce ovulation. Often the ultrasonographic image… Read More »

Cutaneous Lymphosarcoma

Clinical manifestations of lymphosarcoma in horses include cutaneous, multicentric, thymic, and alimentary forms. Cutaneous lymphosarcoma can exist as a primary disease entity limited to skin and subcutaneous tissues or concurrently with visceral involvement. Horses of all ages have been diagnosed with lymphosarcoma, with the majority being between the ages of 4 and 9 years. No… Read More »

Dermatological conditions

Acanthosis nigricans This is an uncommon condition which can be primary or secondary to intertrigo, endocrine disorders or hypersensitivities. It is characterised by bilateral axillary hyperpigmentation which progresses to alopecia and seborrhoea. Acquired aurotrichia Silver or black hairs turn gold, especially on the dorsal thorax and abdomen. Acquired depigmentation Affects dogs from about 18 months… Read More »

Drugs Acting On The Reproductive System

Drugs used to promote gonadal function Sex hormones Prostaglandins Myometrial stimulants Myometrial relaxants Prolactin antagonists Non-hormonal abortificants Drugs for uterine infections Many drugs are used at different stages of the oestrous cycle to manage the response of the reproductive system; these are summarised in Table Drags affecting the reproductive system. Table Drags affecting the reproductive… Read More »


Chorionic gonadotrophin (human chorionic gonadotrophin, hCG) is a complex glycoprotein excreted in the urine of women during pregnancy. It has a similar effect to luteinising hormone (LH) secreted by the anterior pituitary gland in both males and females. In veterinary practice, it is used to supplement or replace luteinising hormone in cases of ovulation failure… Read More »


Progestogens are steroids that mimic the effects of progesterone and thus prepare and maintain the female reproductive tract for implantation and pregnancy. They cause development of the mammary glands to the point of lactation. Progestogens exert a negative feedback on the hypothalmic-pituitary axis suppressing the secretion of gonadotrophins, and thereby cyclical ovarian activity, which normally… Read More »


Testosterone esters and methyltestosterone promote and maintain primary and secondary anatomical, physiological, and psychological male sexual characteristics. Anabolic steroids are synthetic derivatives of testosterone. In the female, they can be used to exert a negative feedback effect on the hypothalamic-pituitary axis thereby reducing gonadotrophin secretion. Although androgens are used in the treatment of deficient libido… Read More »

Perineal Hernia

Perineal hernias have been clinically recognized in the dog for more than 100 years and are most common in older, intact male dogs. They are rarely seen in cats or female dogs. Four types of perineal hernias have been described, but the most common type is the caudoventral perineal hernia, which occurs between the levator… Read More »