Sally Duthie, of Green Island, Dunedin, asks :-

Can garden herbicides harm cats? When my son sprayed our gardens, his cat died and one of mine became ill. They lost weight, their pupils' dilated, and apparently their immune system became depleted. All three cats were from the same litter.

Kathy Parton, a pharmacologist and toxicologist at Massey University's Institute of Veterinary, Animal, and Biomedical Sciences, responded.

Since there are a number of herbicides on the market and you did not specify which one was used, the following information is for glyphosate, the main ingredient in most commonly used home garden herbicides.

It is considered to be very safe for pets when used at the recommended concentration. The ASPCA Animal Poison Control Center (USA) maintains that glyphosate rarely causes poisoning to cats or dogs. However, commercial herbicide products contain surfactants and other chemicals in addition to glyphosate which may be harmful to cats.

While it has a low risk of poisoning, an exposure to a large amount or an improperly diluted product may cause poisoning. The clinical signs associated with glyphosate-containing herbicide poisoning in cats include a loss of appetite, vomiting and lethargy. Other more severe signs include diarrhoea, difficulty breathing, muscle tremors, twitching, dilated pupils and kidney failure.

Cats are more easily harmed than dogs by many household chemicals, plants and medicines due to their inability to break down and eliminate various compounds. To avoid problems, follow the manufacturer's instructions and do not let your pets come into any contact with herbicides while spraying plants or before the herbicide has dried. Ask your retailer to suggest products that are pet friendly.

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