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Anabolic steroids are synthetic derivatives of testosterone with enhanced anabolic activity and reduced androgenic activity (see Systemic Pharmacotherapeutics of the Muscular System: Anabolic Steroids ). Testosterone or its derivatives diffuse through cell membranes of target organs and combine with specific receptor proteins in the cytoplasm. The receptor-hormone migrates into the cell nucleus and binds to nuclear chromatin, stimulating the production of specific messenger RNA. The messenger RNA then regulates the enzyme synthesis responsible for the physiologic activity of the anabolic steroid.
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Table 3
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Anabolic Steroids |
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Drug
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Dosage
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Boldenone undecylenate
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Horses: 1.1 mg/kg, IM, every 3 wk
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Nandrolone decanoate
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Dogs: 1–5 mg/kg, IM, once/wk
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Cats: 10–20 mg, IM, once/wk
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Stanozolol
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Dogs: 1–4 mg, PO, bid; 25–50 mg, deep IM, once/wk
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Cats: 1–2 mg, PO, bid; 25 mg, deep IM, once/wk
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Horses: 0.55 mg/kg, deep IM, once/wk
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Anabolic steroids stimulate and maintain a positive nitrogen balance by reducing renal elimination of nitrogen, sodium, potassium, chloride, and calcium. Production of myosin, sarcoplasm, and myofibrillar protein is enhanced. Anabolic steroids promote appetite, weight gain, and improved mental attitude, so they are used to reverse debilitation associated with surgery, trauma, illness, glucocorticoid-induced catabolism, and aging. In all cases, improved well-being depends on adequate intake of protein and calories and on treatment of the underlying disease.
Anabolic steroids have a variety of undesirable effects. They induce androgenic effects, such as increased libido in males and abnormal sexual behavior in females, along with adverse reproductive effects, including azoospermia, anestrus, testicular atrophy, and clitoral hypertrophy. They promote edema formation due to sodium and water retention. Icterus can develop due to intrahepatic cholestasis. Anabolic steroids can induce epiphyseal plate closure, thereby retarding growth. Anabolic steroids are used in the treatment of debilitated animals; however, they are often misused to gain a competitive advantage in performance animals.
Last full review/revision March 2012 by Patricia M. Dowling, DVM,MSc, DACVIM, DACVCP
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