Nandrolone Decanoate — Veterinary Vademecum Drug Reference

Dosage & Administration Guidelines

Species	Route	Dose	Frequency	Duration & Clinical Notes
Dog	IM	1-5 mg/kg	Every 2-3 weeks	Duration: Up to 3-6 months depending on response Notes: Use lower end for cats; monitor liver function and signs of virilization.
Cat	IM	1-2 mg/kg	Every 2-3 weeks	Duration: Up to 3 months Notes: May stimulate appetite in chronic renal failure.
Horse	IM	0.5-1 mg/kg	Every 3-4 weeks	Duration: Variable; often used for 3-6 months Notes: Check competition rules; withdrawal times may apply.
Cattle	IM	0.5-1 mg/kg	Every 3-4 weeks	Duration: Short-term only Notes: Extra-label use; not approved for growth promotion in many regions.
Small Ruminants	IM	0.5-1 mg/kg	Every 3-4 weeks	Duration: Short-term Notes: Limited data; use with caution.
Rabbit	IM	1-2 mg/kg	Every 2-3 weeks	Duration: Short-term Notes: Limited data; use with caution.

Clinical Indications & Species Uses

General Indications

Anabolic steroid for supportive therapy in chronic wasting conditions, anemia, and convalescence

Dog (Canine)

Anabolic support in chronic wasting conditions
Convalescence after surgery or illness
Fracture healing
Anemia (especially non-regenerative)
Muscle wasting due to chronic disease

Cat (Feline)

Anabolic support in chronic renal failure (to stimulate appetite and improve muscle mass)
Wasting syndromes
Non-regenerative anemia

Horse (Equine)

Anabolic support in debilitated horses
Convalescence
Muscle development in performance horses (though controversial and often prohibited in competition)

Cattle (Bovine)

May be used in debilitated animals under extra-label conditions

Pharmacology & Mechanism of Action

Drug Class: Anabolic steroid | Pharmacological Group: Androgen/anabolic steroid (AAS)

Mechanism of Action: Nandrolone decanoate is a synthetic derivative of testosterone with enhanced anabolic activity and reduced androgenic effects. It binds to androgen receptors in target tissues, leading to increased protein synthesis, nitrogen retention, and muscle mass. It also stimulates erythropoietin release, increasing red blood cell production. The decanoate ester prolongs the duration of action by slow release from the injection site.

Pharmacodynamics: Nandrolone promotes positive nitrogen balance, increases appetite, and improves weight gain. It has a high anabolic-to-androgenic ratio (approximately 10:1). It also has anti-catabolic effects, reducing muscle breakdown during illness or stress. In bone marrow, it stimulates erythropoiesis. It may also have beneficial effects on calcium metabolism and bone density.

⚡ Pharmacokinetics Summary

Absorption: After intramuscular injection, nandrolone decanoate is slowly absorbed from the injection site due to the oily vehicle and ester. Peak plasma concentrations occur within 24-48 hours.

Distribution: Widely distributed in tissues, with high affinity for androgen receptors in muscle, bone, and reproductive organs. It crosses the placenta and is excreted in milk.

Metabolism: Metabolized in the liver via reduction and conjugation. The ester is hydrolyzed to nandrolone, which is then further metabolized to various metabolites, including 19-nortestosterone.

Excretion: Excreted primarily in urine as glucuronide and sulfate conjugates. A small amount is excreted in feces.

Half-Life: The half-life of nandrolone decanoate is approximately 6-7 days in dogs and horses, but may vary by species.

Bioavailability: High when administered intramuscularly due to slow release; oral bioavailability is very low due to first-pass metabolism.

Protein Binding: Approximately 95% bound to plasma proteins, mainly sex hormone-binding globulin (SHBG) and albumin.

Available Formulations & Strengths

Injectable Solution (oil-based) 50 mg/mL, 100 mg/mL, 200 mg/mL (IM)

Contraindications & Clinical Warnings

Contraindications:

Pregnancy (may cause virilization of female fetus)
Lactation (excreted in milk)
Known hypersensitivity to nandrolone or other anabolic steroids
Prostatic carcinoma or mammary carcinoma (androgen-dependent tumors)
Hypercalcemia (may worsen)
Severe hepatic or renal disease (use with caution)
Cardiac disease (may cause fluid retention)

Warnings & Clinical Precautions:

Use with caution in animals with pre-existing cardiac, renal, or hepatic disease.
May cause sodium and water retention, leading to edema.
May suppress endogenous testosterone production; long-term use may cause testicular atrophy.
In food animals, observe withdrawal times; extra-label use is regulated.
In performance animals, check for prohibited substances.
Use in young, growing animals may cause premature epiphyseal closure.
May cause aggressive behavior or increased libido.

Adverse Effects & Reactions

Common:

Injection site pain or swelling
Increased aggression
Increased libido
Mild fluid retention
Changes in liver enzymes

Serious / Severe:

Hepatotoxicity (with prolonged use)
Cardiac hypertrophy
Prostatic hypertrophy
Virilization in females (clitoral enlargement, deepening voice)
Suppression of endogenous testosterone
Premature epiphyseal closure in young animals

Rare:

Cholestatic jaundice
Peliosis hepatis
Hepatic neoplasia (with long-term use)
Hypercalcemia
Erythrocytosis (polycythemia)

Key Drug Interactions

Interacting Drug / Class	Clinical Effect & Mechanism	Severity
Anticoagulants (e.g., warfarin)	May increase anticoagulant effect; monitor coagulation parameters.	Moderate
Corticosteroids	May increase risk of edema and hyperglycemia.	Moderate
Insulin or oral hypoglycemics	May alter glucose tolerance; adjust doses as needed.	Moderate
Hepatotoxic drugs (e.g., NSAIDs, azoles)	Increased risk of hepatotoxicity.	High
Thyroid hormones	May increase thyroid hormone levels; monitor thyroid function.	Mild

Overdose & Toxicity Management

Signs of Toxicity:

Edema
Hepatotoxicity
Aggression
Hypercalcemia
Polycythemia
Virilization
Premature epiphyseal closure in young animals

Emergency Treatment Protocol: Treatment is symptomatic and supportive. Discontinue the drug. Manage fluid retention with diuretics if necessary. Monitor liver function and serum calcium. In severe cases, consider supportive care such as IV fluids and hepatoprotectants. There is no specific antidote.

Food Animal Withdrawal Times

🥩 Meat: 30 days🥛 Milk: 7 days

Withdrawal times are not officially established for nandrolone decanoate in food animals. Extra-label use requires extended withdrawal periods; consult with a veterinarian and follow regulatory guidelines. In the US, the FDA has not approved nandrolone for food animals, so use is prohibited in food animals unless under specific extra-label conditions with a valid VCPR and extended withdrawal times.

Storage, Handling & Regulatory Information

Storage Temperature: Store at controlled room temperature 20-25°C (68-77°F), excursions permitted between 15-30°C (59-86°F).

Handling & Special Conditions: Protect from freezing. Keep in tight container. Store away from direct heat.

Dispensing Status: Prescription Required (Rx Only)

Approval Status: Not FDA-approved for veterinary use; available as a human pharmaceutical (Deca-Durabolin) and may be used extra-label in animals.

Extra-Label (Off-Label) Use: In the US, nandrolone decanoate is not approved for veterinary use in food animals. Extra-label use in food animals is prohibited under AMDUCA because it is not approved for food animals and there is no established tolerance. In non-food animals, extra-label use is allowed under a valid VCPR. In horses, use may be prohibited in competition; check with regulatory bodies.

Clinical Pearls & Practice Notes

💡 Clinical Insights: Nandrolone decanoate is a long-acting anabolic steroid used in veterinary medicine primarily for supportive therapy in chronic wasting conditions, anemia, and convalescence. It is important to use it judiciously due to potential adverse effects, especially with prolonged use. In dogs and cats, it may be beneficial for appetite stimulation and muscle mass preservation, particularly in chronic renal failure. In horses, it is sometimes used to improve muscle mass, but its use is controversial and often prohibited in competition. For food animals, its use is highly restricted due to lack of approval and potential for residues. Always monitor liver function, serum calcium, and signs of virilization. Use the lowest effective dose for the shortest duration. Consider alternative therapies when possible. This drug should only be used under veterinary supervision.

References & Literature

📚 Plumb's Veterinary Drug Handbook
📚 Papich Veterinary Pharmacology and Therapeutics
📚 Compendium of Veterinary Products (CVP)