Principles of Therapy of the Reproductive System
Also see Systemic Pharmacotherapeutics of the Reproductive System and Management of Reproduction: Cattle for the various species, et seq.
The increasing demands for production efficiency, along with changes in management systems, have caused a shift in therapeutic strategies in several domestic species. Especially for food and fiber animals, the therapeutic approach of choice often is a combination of pharmacologic agents and correction of management problems targeting the entire herd, with a decreased emphasis on individual animals. This trend is also reflected in the prioritization of disease prevention and implementation of biosecurity programs. The increased use of hormonal pharmacologic agents for reproductive management on a whole-herd basis represents another aspect of this change. Other therapeutic trends in food animals are the result of consumer concerns regarding antimicrobial and hormone residues in tissues and milk, as well as the increasing interest in organic or natural foods.
In small animals, therapeutic strategy has undergone a different but equally dramatic transformation. The individual animal remains the focus of therapeutic efforts, but diagnostic techniques and treatments have become increasingly sophisticated, often reflecting or even presaging advances in human medicine.
More effective therapy for reproductive diseases comes with the risk of propagating a hereditary predisposition for lowered fertility. However, the heritability of most reproductive traits is rather low, so selection programs aimed at improving fertility require a longterm commitment to be successful.
Exogenous hormone therapy can be used to regulate or control reproduction. This control may take the form of suppression or induction and synchronization of reproductive activity. The same hormone may be used for both purposes. For example, progestogens are used to suppress estrus in the mare, bitch, and queen but are also used in the mare, cow, and sow to induce and synchronize estrus for managed mating programs. Steroid hormones with estrogenic, androgenic, and progestational effects are used in a wide variety of applications.
The gonadotropins and GnRH are used to alter gonadal function. Examples include superovulation of cattle with FSH, induction of ovulation in mares with human chorionic gonadotropin (hCG), and stimulation of testosterone production with GnRH for diagnosis of cryptorchidism in dogs and stallions.
PGF2α is used primarily to terminate luteal function. Clinical applications include induction or synchronization of estrus in polyestrous species; treatment of pyometra in dogs, cats, and cattle; and induction of abortion in luteal-dependent species such as goats, alpacas, dogs, and cats.
Depending on the species, glucocorticoids, prostaglandin, and oxytocin, alone or in combination, can be used to induce or manage labor. They should be used with caution at the appropriate time and dosage and accompanied by careful observation for any problems that may develop with the dam or fetus.
Many of the assisted reproductive technologies commonly used today had their origin in veterinary species as either research or commercial programs. Artificial insemination is commonly used to breed cattle, dogs, sheep, goats, pigs, and horses. Other technologies in use include embryo transfer (see Embryo Transfer in Farm Animals) and in vitro fertilization in cattle and horses. Somatic cell nuclear transfer (cloning, see Cloning of Domestic Animals) is more rarely performed but has been reported for a variety of animal species.
Antimicrobial agents, most commonly antibiotics, are used for treatment of infections of the male and female reproductive tracts in all species (also see Antibacterial Agents, et seq). Drug selection should be based, whenever possible, on microbiologic culture and sensitivity tests. The dosage, route of administration, and interval between treatments vary among species. In food animals, proper withholding times must be observed for meat and milk after antibiotic use.
Surgical repair is indicated for acquired conformational damage to the genital system of both sexes. Examples include episioplasty, vestibulovaginal or cervical cerclage, and cesarean section in females and repair of preputial injuries in males. Surgical sterilization is also routinely done, either by gonadectomy in both sexes of most species or by ovariohysterectomy in female cats and dogs.