Drug Monograph
Full clinical overview, indications, dosage references & safety notes.
Overview
Calcitonin (Miacalcin®, Calcimar®) is an osteoclast-inhibiting hormone used in dogs primarily as adjunctive therapy for management of hypercalcemia. Its use in veterinary medicine is limited by expense, short duration of action, and the potential development of resistance (tachyphylaxis) after several days of treatment.
Calcitonin acts principally on bone by inhibiting osteoclastic bone resorption, thereby reducing release of calcium from the skeletal system. It also promotes renal excretion of calcium, phosphate, sodium, magnesium, potassium, and chloride by decreasing tubular reabsorption. Additionally, it increases jejunal secretion of water and electrolytes.
Calcitonin is destroyed in the gastrointestinal tract and must be administered parenterally (IV, IM, or SC). After IV administration, onset of effect is rapid. Following IM or SC administration, onset typically occurs within approximately 15 minutes, with peak effects around 4 hours and a duration of action of 6–12 hours. The drug is rapidly metabolized by the kidneys, blood, and peripheral tissues.
Because of its short duration and variable efficacy, calcitonin is generally considered an adjunct rather than a primary therapy in the management of hypercalcemia.
Indications
In dogs, calcitonin is used primarily as adjunctive therapy in the management of disorders associated with elevated serum calcium concentrations. Its clinical utility is limited by cost, short duration of action, and the potential development of resistance after repeated administration.
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Hypercalcemia (adjunctive therapy):
Used as part of a multimodal treatment protocol to help reduce serum calcium concentrations, including cases associated with vitamin D toxicity or other causes of hypercalcemia. -
Bone-associated pain (adjunctive use):
May provide benefit in selected cases where pain originates from bone, due to its inhibitory effects on osteoclastic activity.
Dosage (Reference)
Dog
Calcitonin is administered parenterally (SC, IM, or IV). In dogs, its use is extra-label and generally reserved for adjunctive management of hypercalcemia. Due to expense, frequency of dosing, variable efficacy, and development of resistance, it is not routinely recommended.
| Clinical use | Route | Dose | Frequency | Notes |
|---|---|---|---|---|
| Hypercalcemia (e.g., Vitamin D toxicity) – adjunctive protocol | SC | 4–6 units/kg 2–3 times daily |
q8-12h | Used as part of a multimodal protocol. Some patients may become refractory; inconsistent results reported. |
• Not routinely recommended due to cost, dosing frequency, and limited efficacy.
• Some patients may develop tachyphylaxis (reduced response) after several days of therapy.
• May increase risk of soft tissue mineralization in certain cases.
• Should be used within a comprehensive hypercalcemia management protocol that includes fluid therapy and additional medical management as indicated.
Warnings & Precautions
Calcitonin should be used cautiously in dogs due to variability in response, risk of hypersensitivity, and potential for electrolyte disturbances. Careful monitoring of calcium status and overall clinical condition is required.
- Hypersensitivity: Contraindicated in animals with known hypersensitivity to calcitonin. Patients with a history of hypersensitivity to related protein products may be at increased risk of allergic reactions.
- Young animals: Reportedly up to 100 times more sensitive to calcitonin than adults; use extreme caution and monitor closely.
- Pre-existing hypocalcemia: Hypocalcemia must be corrected before administering calcitonin when used for indications other than hypercalcemia, as further reductions in serum calcium may occur.
- Tachyphylaxis: Resistance to therapy may develop after several days of treatment, limiting clinical effectiveness.
- Electrolyte monitoring: Because calcitonin promotes renal excretion of calcium and other electrolytes, monitor serum-ionized calcium (if available), phosphorus, renal parameters (BUN, creatinine), and hydration status.
- Drug name confusion: Do not confuse calciTONIN with calciTRIOL. Consider use of tall-man lettering in written prescriptions to reduce medication errors.
Drug Interactions
The following drug interactions have been reported or are theoretical and may be clinically significant in dogs receiving calcitonin. Concurrent use is not always contraindicated, but potential risks should be evaluated and monitoring adjusted accordingly.
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Calcium-containing products:
May interfere with the efficacy of calcitonin by counteracting its calcium-lowering effects. -
Lithium:
Concurrent use may decrease lithium concentrations and reduce lithium efficacy. -
Pamidronate:
Although these drugs may be used together in human medicine, studies in dogs have not demonstrated additional benefit when combined. -
Vitamin D analogues (e.g., calcitriol, cholecalciferol):
May interfere with the efficacy of calcitonin.
Side Effects & Overdose
Side Effects
There is limited documentation of adverse effects in dogs; however, gastrointestinal and injection-related reactions have been reported. Effects are generally dose-related.
- Anorexia: Decreased appetite has been reported in treated dogs.
- Vomiting: May occur and has been reported after administration.
- Injection site reactions: Swelling, pain, or local irritation may develop following parenteral administration.
- Diarrhea (potential): Reported in other species and may occur in dogs.
- Peripheral paresthesias and flushing (rare): Documented in other species and theoretically possible.
- Allergic reactions (rare): Hypersensitivity reactions may occur in susceptible individuals.
- Hypocalcemia: Overmedication or excessive dosing can result in clinically significant hypocalcemia.
- Tachyphylaxis: Reduced clinical response may develop over time with continued therapy.
Overdose
Data regarding overdose in dogs are very limited. Clinical signs are expected to reflect exaggerated pharmacologic effects.
- Nausea and vomiting: Reported after accidental overdose injections.
- Hypocalcemia: Chronic overdosing may result in decreased serum calcium concentrations.
- Management: Provide supportive care and monitor serum-ionized calcium (if available), total calcium, renal parameters, hydration status, and urine sediment as indicated.
- Consultation: In suspected overdose cases, consultation with a veterinary poison consultation center is recommended.
Key Notes
Practical clinical considerations for use of calcitonin in dogs:
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Adjunct, not first-line:
Often considered when rapid but short-term reduction of calcium is needed, particularly while awaiting effects of longer-acting therapies. -
Short duration:
Duration of action is typically 6–12 hours after IM or SC administration, requiring repeated dosing for sustained effect. -
Parenteral only:
Destroyed in the gastrointestinal tract; must be administered IV, IM, or SC. -
Salmon vs. human formulations:
Calcitonin salmon is substantially more potent on a per-weight basis and is the commonly used formulation in practice. -
Storage:
Store injectable calcitonin salmon under refrigeration (2–8°C) to maintain stability. -
Client communication:
Explain that response may be variable and temporary, and additional therapies are typically required for sustained calcium control.
