Chronic fenthion toxicity in laying hens

Area of Science:

• Veterinary Toxicology
• Neurotoxicology
• Avian Physiology

Background:

• Organophosphate pesticides like fenthion (FEN) are widely used but can pose toxicity risks.
• Understanding the chronic effects of FEN on poultry is crucial for animal welfare and food safety.

Purpose of the Study:

• To evaluate the chronic toxicity of dermal fenthion exposure in White Leghorn laying hens.
• To investigate potential neurological and physiological effects of fenthion in poultry.

Main Methods:

• Hens received weekly dermal applications of low (1 mg/kg) or high (4 mg/kg) dose fenthion for 24 weeks.
• Neurological function, egg production, body weight, and enzyme activity (cholinesterase, neuropathy target esterase) were assessed.
• Electromyography (EMG) and ultrastructural nerve examinations were performed to evaluate neuropathy.

Main Results:

• High-dose fenthion induced transitory neurological deficits (loss of proprioception, perching ability) and behavioral changes.
• Significant inhibition of serum and brain acetylcholinesterase was observed in high-dose hens.
• EMG and nerve examinations indicated a mild peripheral neuropathy in high-dose hens, without affecting neuropathy target esterase.
• High-dose fenthion inhibited egg production and reduced body weight, while low-dose fenthion initially stimulated egg production.

Conclusions:

• Chronic dermal fenthion exposure can lead to mild neuropathy and adverse physiological effects in laying hens.
• Neurological and behavioral changes are not directly correlated with brain enzyme or neurotransmitter levels.
• The findings highlight the dose-dependent toxicity of fenthion, with implications for poultry health and management.