Use of Insecticides in Dogs and Cats

Insecticides in the form of dusting powders, sprays, baths, shampoo and collars are used for the control of lice, fleas, ticks and fleas. The various types of insecticides in common use for pets are organophosphates, carbonates, chlorinated hydrocarbons and pyrethrin which are all toxic to insect’s central nervous system and rotenone paralyses the respiratory and cardiovascular system of insects.

In case of heavy infestation with ectoparasites, these drugs can be used at an interval of 7-14 days for 2-3 applications. The pet owners using these insecticides are advised to wash exposed hand after use and not to direct these sprays or powders towards peoples, foodstuffs, poultry and lactating females.

Users should warned not to inhale these products and to avoid contact with direct skin and the eyes. Use of mask and hand gloves is advised while spraying these products on animals. Least side effects are expected if these drugs are used as per recommendation of the manufacturers.

Toxicity of insecticides

In recommended doses and precautions, these products are seldom toxic. In heavy doses, the pet may be excitable, ataxic with muscular twitching and occasional collapse. Treatment consists of confining the animal in darkroom, basket or cage. Insecticides with plant origin are usually non-toxic.

Insecticides belonging to group of chlorinated hydrocarbons usually cause neurological signs such as hyperexcitability, apprehension, pyrexia and convulsions. The pet may show exaggerated responses to stimuli e.g. tough, light and sound. Treatment is non-specific which consists of removal of the insecticides from the coat by bathing, prevention of absorption from the gut by use of activated charcoal, adequate sedation with barbiturates to control seizures and the use of parenteral fluids.

The organophosphorus and carbonate insecticides exert their effect by reversibly binding acetylcholinesterase, thereby permitting continuous cholinergic stimulation. Cats are more sensitive to these insecticides as compared to dogs.

Ataxia, incoordination, muscle tremors, convulsions, respiratory depression, salivation and diarrhoea are most commonly seen signs of toxicity of these compounds. Usually not all signs need necessarily be present in any one case, but one or more is usually observed in such pets.

Treatment of Toxicity

Atropine sulphate is the drug of choice and should be given by IV route at the rate to effect mydriasis and cessation of salivation. Further doses of atropine at a dose rate of 0.2 to 0.5 mg/kg body weight may be given by subcutaneous route. Cats usually require dosing every 45 to 60 minutes.

Oximes such as 2-PAM (2-pyridine aldoxime methyl chloride) are specific antidotes for organophosphate poisoning. The dose required for dogs and cats is 20-40 mg/kg body weight and may be repeated at every 4-6 hours, if required.