Vetdrugs 2.0Dimercaprol, also called British anti-lewisite or BAL, is a sulfhydryl-containing chelating agent used for selected heavy-metal intoxications. Its veterinary applications include arsenic and some mercury exposures, with a more specialized combination role in severe lead poisoning. Chelation depends on the chemical form of the metal and its distribution in the patient.
Group
Dithiol chelator
Mechanism of Action
Dimercaprol contains two sulfhydryl groups that bind selected metals and form chelate complexes. This competes with metal binding to sulfhydryl-containing cellular enzymes, helping restore enzyme function and reduce further metal-mediated injury. Formation of excretable complexes promotes metal elimination. The effectiveness of this process depends on the metal species and whether it remains accessible to the chelator.
Dose Rates
Dog
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Heavy-metal intoxication | 4 mg/kg | IM | Every 4 h | Select a metal-specific course; early treatment and renal/hepatic monitoring are essential. |
| Arsenic poisoning | 4 mg/kg | IM | Every 4–6 h | Up to 4 days |
Cat
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Heavy-metal intoxication | 4 mg/kg | IM | Every 4 h | Select a metal-specific course; early treatment and renal/hepatic monitoring are essential. |
| Arsenic poisoning | 4 mg/kg | IM | Every 4–6 h | Up to 4 days |
Horse
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Arsenic poisoning staged chelation | Reference only | IM | Give 5 mg/kg initially, then 3 mg/kg every 6 hours for the rest of day 1, followed by 1 mg/kg every 6 hours for at least another 48 hours as needed. Begin promptly; deep IM injections are painful. Remove the exposure and provide supportive care. |
Cattle
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Mercury poisoning staged chelation | Reference only | IM | 3 mg/kg four times daily for 3 days, then twice daily for 10 days. Treatment may fail despite chelation. |
Pig
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Mercury poisoning staged chelation | Reference only | IM | 3 mg/kg four times daily for 3 days, then twice daily for 10 days. Treatment may fail despite chelation. |
Indications
- Treatment of selected acute inorganic arsenic intoxications in veterinary patients.
- Treatment of selected inorganic mercury or gold intoxications under a metal-specific toxicology plan.
- Adjunctive chelation in selected severe lead intoxications, generally in combination with another lead-chelating agent.
Contraindications
- Use is restricted to appropriate heavy-metal intoxications.
Interactions
- Can chelate coadministered metals.
Adverse effects
- Injection-site abscesses
- High-dose vomiting, CNS depression or seizures
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| BAL in Oil 100 mg/mL Peanut-oil formulation; deep IM only. Not an aqueous IV preparation. | Injection | 100 mg / mL | IM |
Monitoring and Administration
Initiate promptly after identifying exposure. Monitor metal concentrations, renal status and response.
DMPS and succimer are distinct chelating drugs, not interchangeable formulations of dimercaprol.
The small-animal section is applied to dogs and cats; the identical general large-animal entry is not assigned to unnamed individual species.
Administer deep IM, maintain hydration and renal surveillance, and alkalinize urine when clinically appropriate; acid urine promotes dissociation of the metal–chelator complex.