Permethrin and Pyrethrin Toxicity in Rabbits

• Permethrin, pyrethrins. (J213.11.w1)
  • These insecticides are widely used, being considerably safer than the organophosphates. (J213.11.w1)

• Acute toxicity data for permethrin

  • Permethrin is moderately to practically non-toxic via the oral route, with a reported LD₅₀ for technical permethrin in rats of 430 to 4000 mg/kg.
  • Via the dermal route permethrin is slightly toxic, with a reported dermal LD₅₀ in rats of over 4000 mg/kg, and in rabbits of greater than 2000 mg/kg. 
  • Permethrin caused mild irritation of both the intact and abraded skin of rabbits. 
  • Permethrin caused conjunctivitis when it was applied to the eyes. 
  • The 4-hour inhalation LC₅₀ for rats was greater than 23.5 mg/L, indicating practically no inhalation toxicity. 
  • The toxicity of permethrin is dependent on the ratio of the isomers present; the cis-isomer being more toxic.

  (W180.Feb02.WNV6)

• Anorexia.
• Lethargy.
• Twitching.
• Seizures.

(J213.11.w1)

Susceptibility

• Toxic effects have been reported following application of high concentrations of these products (sprays or spot-ons) on rabbits). (B609.2.w2, J213.11.w1)
• Note: pyrethrins are poorly absorbed through the gastrointestinal tract and not significantly absorbed through the skin. They are absorbed via the respiratory route. 

Treatment

Treatment of topically applied or contacted poisons in rabbits aims to reduce absorption, increase excretion, control of toxicity such as seizures, and support the rabbit: (J213.11.w1)

• Bathe the rabbit using a mild shampoo. (see: Bathing Rabbits)
  • Place the rabbit into a suitably-sized container such as a laundry sink.
  • Have one person to restrain the rabbit and one person to bathe it.
  • Use a spray nozzle, warm water (102 -105 ° F) and baby shampoo or a mild puppy/kitten shampoo.
  • Massage the shampoo down to the level of the skin to remove toxin which may have penetrated that far.
  • Rinse well.
  • Towel dry then place in a warm cage until fully dry. 
  • Monitor body temperature carefully to avoid hyperthermia from hot air driers or hypothermia from evaporative cooling. Keep at body temperature 100 - 102.5 ° F.
    • Signs of hyperthermia: auricular vessel dilatation, nasal flare, increased respiratory rate.
      • See: Hyperthermia - Sunstroke - Heatstroke in Waterfowl, Elephants, Bears, and Lagomorphs
    • Signs of hypothermia: shivering, mucus membranes pale, rabbit huddled.

  (J213.11.w1)

• Copiously lavage the eyes with sterile saline. (J213.11.w1)
• Consider giving activated charcoal in case the rabbit has ingested the chemical while grooming. (J213.11.w1)
• Diuresis. (J213.11.w1)
• Force-feeding. (J213.11.w1)
• If seizures occur, control using midazolam or diazepam. (J213.11.w1)
• Additional treatment: Antioxidants may be useful, e.g. Vitamin C, Vitamin E, selenium, zinc and isoflavones. (J213.11.w1)

Prevention

• Education of owners regarding the potential risks associated with use of these products. (J213.11.w1)
• Note: a large overdose would be required to cause toxicity. However, owners should be informed regarding the potential risks if excessive quantities are used. (V.w5)

• Bathing Rabbits
• Environmental Assessment
• History & Documentation
• Physical Examination of Mammals
• Necropsy of Mammals
• Imaging in Lagomorph Diagnosis and Treatment
• Clinical Pathology of Lagomorphs
• Treatment and Care
• Environmental and Population Management
• Preventative Medicine for Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

• Oryctolagus cuniculus domesticus - Domestic European rabbit