Staphylococcal Phage Lysate
Staphylococcal Phage Lysate (prepared by lysing cultures of Staphylococcus aureus Cowan serologic types I & III by a staphylococcal bacteriophage)
Also known as: Staphage Lysate · SPL Immune Stimulant
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 |
|---|---|---|---|---|---|
| Labeled indications (Highly allergic patients) | Skin test with 0.05-0.1 mL intradermally. Therapy: Initially, 0.2 mL SC, then incremental increases of 0.2 mL once a week to 1 mL (a total of 5 injections). Then continue at 1 mL SC weekly for approximately 10-12 weeks. | SC/ID | Weekly | 10-12 weeks | 🌎 NA |
| Labeled indications (Non-allergic patients) | 0.5 mL SC twice weekly for 10-12 weeks, then 0.5-1 mL every 1-2 weeks. | SC | Twice weekly then every 1-2 weeks | 10-12 weeks initial, then maintenance | 🌎 NA |
| Idiopathic, recurrent pyoderma | 0.5 mL SC twice weekly for 10-12 weeks, then tapered to effect. | SC | Twice weekly | 10-12 weeks then tapered | 🌎 NA |
| Chronic recurrent idiopathic pyoderma | Injections are administered twice weekly (0.5 mL) and slowly reduced to 0.5 mL every 2 weeks. | SC | Twice weekly then reduced | Ongoing | 🌎 NA |
- Labeled indications (Highly allergic patients): Concomitant antibiotic therapy is recommended for an initial 4-6 week period. Maximum dose should be decreased in small dogs and can be increased cautiously, if necessary, in large dogs to 1.5 mL.
- Labeled indications (Non-allergic patients): Concomitant antibiotic therapy is recommended for an initial 4-6 week period.
- Idiopathic, recurrent pyoderma: This agent is rarely needed, because in most cases, an underlying cause can be identified and treated.
- Chronic recurrent idiopathic pyoderma: Pyoderma needs to be under control as this product is not a substitute for antibiotics.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Overview
Staphylococcal Phage Lysate (SPL) is an injectable biologic and immune stimulant primarily utilized in veterinary dermatology. It is specifically indicated for the management of recurrent, idiopathic staphylococcal pyodermas in dogs, often used alongside appropriate antimicrobial therapy.
Clinical Pearl: In an era of increasing antimicrobial resistance (e.g., MRSP - Methicillin-Resistant Staphylococcus pseudintermedius), immunomodulators like SPL offer a valuable adjunctive approach to reduce the frequency and duration of systemic antibiotic use.
The product is prepared by lysing cultures of Staphylococcus aureus (Cowan serologic types I & III; human strains) using a staphylococcal bacteriophage. The prepared solution contains S. aureus components (protein A extracts), bacteriophage, and unfiltered beef heart infusion broth. It is ultrafiltered to achieve bacteriologic sterility.
Mechanism of action
SPL functions as an immunomodulator that specifically enhances cell-mediated immunity (Th1 immune response).
- Cytokine Stimulation: It stimulates the production of key pro-inflammatory and immunoregulatory cytokines, including Tumor Necrosis Factor (TNF-α), Interleukin-6 (IL-6), and Interferon-gamma (IFN-γ).
- Mechanism: By upregulating IFN-γ and TNF-α, SPL enhances the phagocytic and bactericidal activities of macrophages and neutrophils → leading to improved clearance of intracellular and extracellular staphylococcal organisms from the skin.
- Protein A Role: The presence of staphylococcal Protein A acts as a potent B-cell superantigen and immunogen, further stimulating a robust host immune response against staphylococcal antigens.
Safety & warnings
Contraindications
- Prior systemic hypersensitivity reactions to SPL
- Documented hypersensitivity reactions to beef products (contains unfiltered beef heart infusion broth)
Adverse effects
- Post vaccine-type reactions (fever, malaise)
- Injection site reactions (redness, itching, swelling occurring 2-3 hours post-injection and persisting up to 3 days)
- Systemic hypersensitivity reactions (weakness, vomiting, diarrhea, severe itching, rapid breathing, fatigue/lassitude)
Precautions
Hypersensitivity Risk: Use with extreme caution (if at all) in patients with a history of systemic hypersensitivity to SPL or documented allergies to beef products, as the formulation contains unfiltered beef heart infusion broth.
- Administration: Avoid administering subsequent doses at the exact same injection site to minimize local reactions.
- Handling: The product contains no preservatives. It must be handled strictly aseptically. The manufacturer recommends using the entire contents of a vial once opened.
- Allergic Patients: In highly allergic patients, reduced desensitizing doses and prior intradermal skin testing may be indicated.
Drug interactions
May reduce the efficacy of SPL
Monitoring
- Clinical efficacy (resolution of pyoderma)
- Local injection site reactions (redness, swelling, itching)
- Systemic hypersensitivity reactions (anaphylaxis, vomiting, weakness)
Overdose
No specific information was located regarding acute toxicity. Other than an increased risk for local or systemic hypersensitivity reactions, significant morbidity appears unlikely. Should an anaphylactic-type reaction occur, treat supportively; the manufacturer recommends epinephrine and atropine as antidotes.
Available products
Formulations
- Injection: 1 mL ampules
- Injection: 10 mL multi-dose vials
Veterinary
- Staphage Lysate (SPL) in 1 mL ampules (box of 10)
- Staphage Lysate (SPL) in 10 mL multi-dose vials
Regulatory status
No regulatory data for: 🇺🇸 US · 🇪🇺 EU · 🇬🇧 UK · 🇭🇰 HK · 🇹🇼 TW · 🇯🇵 JP · 🇰🇷 KR · 🇦🇺 AU
Storage & stability
Store in the refrigerator (2-7°C); do not freeze. Unopened, properly stored vials and ampules have an average expiration date of one year past the shipment date. The product contains no preservative and must be handled aseptically. It is recommended to use the entire contents of the vial after opening. Do not use if contents are cloudy. Do not mix with other drugs or solutions prior to administration.
Client information
Understanding the Treatment:
- This medication is an 'immune stimulant' designed to help your dog's own immune system fight off chronic or recurring bacterial skin infections (pyoderma).
- It is not an antibiotic, but it is often used alongside antibiotics initially to gain control of the infection.
Administration & Safety:
-
Important: Because there is a rare but serious risk of an allergic reaction (anaphylaxis), injections should ideally be given at your veterinary clinic where emergency treatment is immediately available.
What to Watch For: Contact your veterinarian immediately if you notice any of the following after an injection:
- Local reactions: Redness, itching, or swelling at the injection site (usually occurs within 2-3 hours and can last up to 3 days).
- Systemic reactions: Weakness, vomiting, diarrhea, severe full-body itching, rapid or difficult breathing, or sudden extreme tiredness/lethargy.
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.