Pet Safety / Compounds / Lambda-cyhalothrin

Is Lambda-cyhalothrin safe for dogs and cats?

Low risk for pets

Lambda-cyhalothrin is used in livestock ectoparasiticide formulations and as a grain protectant; dogs are relatively tolerant at typical exposure concentrations. Accidental high-dose ingestion (e.g., licking treated surfaces) may cause mild GI signs and transient tremors; formulation solvents (petroleum distillates in some sprays) can contribute to toxicity via aspiration or GI irritation. No veterinary-approved lambda-cyhalothrin formulations for dogs/cats exist.

What is lambda-cyhalothrin?

The IUPAC name is trans-[(R)-cyano-(3-phenoxyphenyl)methyl] (1S,3S)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropane-1-carboxylate.

Also known as: trans-[(R)-cyano-(3-phenoxyphenyl)methyl] (1S,3S)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropane-1-carboxylate, Karate, Icon, Warrior.

IUPAC name
trans-[(R)-cyano-(3-phenoxyphenyl)methyl] (1S,3S)-3-[(Z)-2-chloro-3,3,3-trifluoroprop-1-enyl]-2,2-dimethylcyclopropane-1-carboxylate
CAS number
91465-08-6
Molecular formula
C23H19ClF3NO3
Molecular weight
449.8 g/mol
SMILES
CC1(C(C1C(=O)OC(C#N)C2=CC(=CC=C2)OC3=CC=CC=C3)C=C(C(F)(F)F)Cl)C
PubChem CID
6440557

Risk for dogs

Low risk

Lambda-cyhalothrin is used in livestock ectoparasiticide formulations and as a grain protectant; dogs are relatively tolerant at typical exposure concentrations. Accidental high-dose ingestion (e.g., licking treated surfaces) may cause mild GI signs and transient tremors; formulation solvents (petroleum distillates in some sprays) can contribute to toxicity via aspiration or GI irritation. No veterinary-approved lambda-cyhalothrin formulations for dogs/cats exist.

Risk for cats

Extreme risk

Lambda-cyhalothrin is a potent type II alpha-cyano pyrethroid with extreme cat toxicity consistent with the pyrethroid class; accidental exposure via household aerosol sprays, foggers, or contact with recently treated surfaces causes rapid-onset tremors, hypersalivation, seizure, and respiratory distress in cats. The alpha-cyano group confers the most severe neurological signs (CS syndrome) in cats. Prompt decontamination (bathing) and emergency veterinary care are critical; prognosis is guarded with intensive care but good if treated before severe hyperthermia develops.

Regulatory consensus

2 regulatory and scientific bodies have classified Lambda-cyhalothrin. The classifications differ — that's the data.

AgencyYearClassificationNotes
EPA CTX / EPA OPP—Group D Not Classifiable as to Human Carcinogenicity
US_EPA2024registered_restrictedEPA restricted-use pyrethroid.

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where pets encounter lambda-cyhalothrin

  • Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
  • Occupational Environments — Factories, Warehouses, Transportation vehicles

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Lambda-cyhalothrin:

  • Physical/mechanical pest control (IPM)
    Trade-offs: More labor-intensive. May not be sufficient for severe infestations.
    Relative cost: 1.2-2×
  • Spinosad
    Relative cost: 1.2-2×
  • Bt
    Relative cost: 1.2-2×
  • Physical barriers
    Relative cost: 1.2-2×

Frequently asked questions

Is lambda-cyhalothrin safe for pets?

Lambda-cyhalothrin is used in livestock ectoparasiticide formulations and as a grain protectant; dogs are relatively tolerant at typical exposure concentrations. Accidental high-dose ingestion (e.g., licking treated surfaces) may cause mild GI signs and transient tremors; formulation solvents (petroleum distillates in some sprays) can contribute to toxicity via aspiration or GI irritation. No veterinary-approved lambda-cyhalothrin formulations for dogs/cats exist.

What products contain lambda-cyhalothrin?

Lambda-cyhalothrin appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).

See Lambda-cyhalothrin in the pets app

Look up products containing lambda-cyhalothrin, compare to alternatives, and explore the full data record.

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Sources (2)
  1. US EPA Pyrethroid Reregistration Eligibility Decision — cypermethrin/deltamethrin/lambda-cyhalothrin/bifenthrin/cyfluthrin/fenvalerate/tau-fluvalinate/fenpropathrin; type I/II classification; aquatic toxicity; cat sensitivity; sodium channel mechanism; human paresthesia; buffer zones (2011) (2011) — regulatory
  2. ASPCA Animal Poison Control Center: Pyrethroid Toxicosis in Cats and Dogs — type I vs type II CS/T syndromes; extreme cat sensitivity (sodium channel/UGT deficiency); bathing decontamination; methocarbamol tremor control; cyproheptadine; lipid emulsion severe cases (2023) (2023) — veterinary

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →