Warning - Roundup Gel

Earlier this evening I used some Roundup Gel on some stubborn weeds in my front garden. I thought this would be a better option than spraying as I did not want to get any on the grass which might be eaten by my cat. I did not for one moment imagine that, 15 minutes later, my cat would actively seek out the weeds that had been treated and lick off the gel! Result - a costly trip to the vet for a charcoal treatment to counteract the poison. I appreciate the need to keep pets away from products like this but It would seem that this product is actually attractive to cats, if not other animals too. Surely, as it is a poison, the contents could include something that would repel animals? 
In a way it was lucky that it was my cat and I saw what happened. Had it been one of my neighbour's cats , the movements of which I cannot control, I dread to think of the possible outcome!

Be warned!