Melengestrol is a steroidal progestin and antineoplastic agent which was never marketed. An acylated derivative, melengestrol acetate, is used as a growth promoter in animals. Melengestrol acetate (MGA) is one of six steroidal hormone growth promoters approved for use in Canada and USA. These products are used to improve growth rate and feed efficiency, as well as to suppress estrus in beef heifers (CFIA 2008). They are not approved for use in any species other than beef cattle meant for slaughter. MGA is the only drug of its kind that is administered in animal feed, and its labelled dose in Canada is 0.4mg per heifer per day (CFIA 2008). A mandatory withdrawal of 2 days before slaughter is applied to any animal that is administered MGA.

Deslorelin is an GnRH agonist used in veterinary. It effects contraception by temporarily suppressing the reproductive endocrine system and preventing production of pituitary (FSH and LH) and gonadal hormones (estradiol and progesterone in females and testosterone in males). The observed effects are similar to those following ovariectomy or castration, but are reversed after the hormone content of the implant is depleted or the implant is removed. As an agonist, deslorelin first stimulates the reproductive system, which can result in estrus and ovulation in females or temporary enhancement of testosterone and semen production in males. Then, down-regulation follows the initial period of stimulation. Although deslorelin can also be an effective contraceptive in males of some species, manufacturer recommends its use primarily in females, since monitoring efficacy in females by suppression of estrous behavior or of gonadal steroids in feces is more straightforward than ensuring continued absence of sperm in males, since most institutions cannot perform regular semen collections. It can, however, be used to ameliorate aggression in males of some species, but higher dosages are usually needed. While the major application of deslorelin was initially male contraception, due to its two differing actions, either the stimulation of oestrus or the sterilization of fertility, its use has been increasing in the bitch as well. SUPRELORIN® F (deslorelin acetate) Implant is a once-yearly, subcutaneous implant that assists in the management of adrenal disease in ferrets.

Nifurpipone is a nitrofuran with a large antimicrobial spectrum. Nifurpipone was shown to be a useful antibacterial agent in urinary tract infections.

Domperidone is a peripherally selective D2 receptor antagonist. It acts as an antiemetic and a prokinetic agent through its effects on the chemoreceptor trigger zone and motor function of the stomach and small intestine. Domperidone was not approved in USA due to risks of cardiac arrhythmias, cardiac arrest, and sudden death, but is available in other countries. However, FDA allows access to Domperidone through an expanded access investigational new drug application (IND) to patients with gastroesophageal reflux disease with upper GI symptoms, gastroparesis, and chronic constipation. As an “off-label” use, domperidone is prescribed to breastfeeding women to enhance their milk production.

Trenbolone is an anabolic steroid. It is used on livestock to increase muscle growth and appetite. Trenbolone compounds have a binding affinity for the androgen receptor three times as high as that of testosterone. Once metabolized, the drugs have the effect of increasing nitrogen uptake by muscles, leading to an increase in the rate of protein synthesis. It also has the secondary effects of stimulating appetite, reducing the amount of fat being deposited in the body, and decreasing the rate of catabolism. Short-term side effects include insomnia, high blood pressure, increased aggression, night sweats, and libido.

p-Chlorocresol (p-chloro-m-cresol; PCMC; brand name: Preventol CMK) possesses disinfectant and antiseptic properties. Chlorocresol is used in various preparations for skin disinfection and wounds. It also used as a preservative in creams and other preparations for external use which contain water. For use as a disinfectant such as a hand wash, it is commonly dissolved in alcohol in combination with other phenols. It is a moderate allergen for sensitive skin. Chlorocresol produces potentially life-threatening effects which include dermatitis, which are responsible for the discontinuation of chlorocresol therapy. The symptomatic adverse reactions produced by chlorocresol are more or less tolerable and if they become severe, they can be treated symptomatically, these include hypersensitivity reactions, irritation of eyes.

Tocophersolan (Vedrop, tocofersolan) or d-alpha-Tocopheryl Polyethylene Glycol 1000 Succinate (TPGS) is a watersoluble derivative of the natural active (d-alpha) isomer of vitamin E. The active constituent of the medicinal product is essentially vitamin E (alpha tocopherol). Chronic congenital or hereditary cholestasis is a clinical condition where vitamin E deficiency results from an impaired bile secretion. Decreased intestinal absorption observed in chronic congenital or hereditary cholestatic patients is due to decreased bile secretion and the resulting decrease in intestinal cellular absorption. As a result, fatsoluble vitamins (i.e. vit. E) are not absorbed properly and deficiency can occur. Tocophersolan (Vedrop) is used to treat or prevent vitamin E deficiency (low vitamin E levels). It is used in children up to the age of 18 years who have congenital or hereditary chronic cholestasis and who cannot absorb vitamin E from the gut. Tocophersolan (Tocofersolan) can be absorbed from the gut in children who have difficulty absorbing fats and vitamin E from the diet. This can increase vitamin E levels in the blood and help to prevent neurological deterioration (problems in the nervous system) due to vitamin E deficiency. No treatment-related findings were reported, as all clinical observations and findings at autopsy were similar in treatment and control groups. In many of the studies, the LD50 was not determined as tocofersolan was well tolerated.