Mycobacterial Cell Wall Fraction Immunomodulator
Mycobacterial cell wall extract
Also known as: Regressin-V · Equimune I.V. · Settle · Mycobacterial cell wall extract · Bacillus Calmette-Guerin · BCG
Reviewed by the VetSheet Veterinary TeamUpdated Apr 5, 2026Evidence-based veterinary reference
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Dosing by species
🌎 NA — North America🌍 EU — Europe
Dogs
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Immunotherapy of mixed mammary tumor and mammary adenocarcinoma | Dosage varies with tumor size, but 1 mL should be considered a minimum dose. Infiltrate entire tumor and a small region of adjacent and underlying tissue. | Intratumoral | Once, 2-4 weeks before surgery. If surgery is not to be used, repeat treatment every 1-3 weeks. | Discontinue if no response after 4 treatments | 🌎 NA |
- Immunotherapy of mixed mammary tumor and mammary adenocarcinoma: Using no larger than a 20-gauge needle. Be certain the emulsion is mixed thoroughly and inject quickly as emulsion can separate rapidly. Additional anesthetics or analgesics may be used for pain.
Horses
| Indication | Dose | Route | Frequency | Duration | Region |
|---|---|---|---|---|---|
| Immunotherapy of sarcoids | Dosage varies with tumor size, but 1 mL should be considered a minimum dose. Infiltrate entire tumor and a small region of adjacent and underlying tissue. | Intratumoral | Repeat treatment every 1-3 weeks. | Discontinue if no response after 4 treatments | 🌎 NA |
| Immunotherapeutic agent for the treatment of Equine Respiratory Disease Complex (ERDC) | 1.5 mL (one syringe) | IV | May be repeated in 1-3 weeks | — | 🌎 NA |
| Aid in the treatment of equine metritis caused by Streptococcus zooepidemicus | 1.5 mL (one syringe) | IV | Once during the early estrus period | — | 🌎 NA |
| Aid in the treatment of equine metritis caused by Streptococcus zooepidemicus | Dilute 1.5 mL of Settle in sterile LRS, normal saline, water for injection or semen extender to provide a final volume of 25-50 mL. | Intrauterine | Once | — | 🌎 NA |
- Immunotherapy of sarcoids: Large pedunculated sarcoids should be de-bulked by partial excision prior to treatment. Use no larger than a 20-gauge needle. Inject quickly as emulsion separates rapidly.
- Immunotherapeutic agent for the treatment of Equine Respiratory Disease Complex (ERDC): Inject into the jugular vein.
- Aid in the treatment of equine metritis caused by Streptococcus zooepidemicus: Inject into the jugular vein.
- Aid in the treatment of equine metritis caused by Streptococcus zooepidemicus: Aseptically administer the diluted solution into the uterus using a sterile catheter.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Mycobacterial cell wall fraction immunomodulator is a biologic agent used in veterinary medicine to stimulate the patient's immune system against tumors and specific infections.
- In dogs, it is used as a locally infiltrated injection for the immunotherapy of mixed mammary tumors and mammary adenocarcinomas.
- In horses, it is utilized for treating sarcoids (local infiltration), Equine Respiratory Disease Complex (ERDC) via IV injection, and equine metritis caused by Streptococcus zooepidemicus (IV or intrauterine).
Clinical Pearl: Because this is an immunomodulator, its efficacy relies entirely on the patient having a functional immune system. While local (intratumoral) efficacy is documented, systemic efficacy is not as well established.
Mechanism of action
The drug exerts a non-specific immune stimulatory effect, primarily targeting cell-mediated immune mechanisms and macrophage activation.
- Macrophage activation → Release of Interleukin-1 (IL-1) → Cascade of immune responses targeting abnormal cells (tumors) or pathogens.
- Requires a competent, functional immune system to be effective.
Safety & warnings
Contraindications
- Prior hypersensitivity to mycobacterial cell wall compounds
- Active mycobacterial infections
Adverse effects
- Transient fever
- Depression or drowsiness
- Decreased appetite
- Localized pain and tenderness at injection site
- Tumor necrosis and draining (expected therapeutic effect but can be an adverse event)
- Hypersensitivity or Anaphylaxis
- Severe respiratory inflammatory reactions (reported in horses)
Precautions
Patients receiving cortisone or ACTH may not respond to treatment due to immunosuppression. In case of an anaphylactic reaction, administer epinephrine. The emulsion separates rapidly and must be thoroughly mixed/re-emulsified immediately before administration.
Drug interactions
May reduce the effectiveness of mycobacterial cell wall immunostimulants
Monitoring
- Clinical Efficacy (tumor size, metritis improvement, or respiratory infection improvement)
- Adverse Effects (fever, local reactions, appetite)
Pharmacokinetics
Absorption
No information was located.
Distribution
No information was located.
Metabolism
No information was located.
Elimination
No information was located.
Overdose
No information was located regarding overdosage or acute toxicity.
Available products
Formulations
- Injection (intratumoral, IV, intrauterine)
Veterinary
- Equimune I.V.: 1.5 mL single use vials and 4.5 mL multi-dose vials (Labeled for horses)
- Settle: 1.5 mL single use vials (Contains gentamicin as a preservative. Labeled for horses)
- Regressin-V: 10 mL vials (Contains procaine and a green dye. Labeled for horses and dogs)
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store refrigerated (2-7°C), but do not freeze. Unused product from single-use vials should be discarded after use. The emulsion 'breaks' upon standing and must be re-emulsified before administration. To re-emulsify to a milky appearance, shake vial, roll syringe between hands, or heat in hot water (150°F, 65°C).
Client information
- Injection Site Reactions: Intratumoral injection may cause pain or tenderness at the injection site.
- Tumor Changes: Tumors may drain or become necrotic (tissue death). > Note: This indicates the treatment is working! If this occurs and is bothersome, contact your veterinarian for further instructions on management.
- Systemic Signs: Treated animals may be depressed, develop a fever, or have a reduced appetite for a few days after treatment. If these persist beyond 1-2 days or are severe, contact your veterinarian.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.