Most poisoning of dogs is accidental. Garden poisons, such as snail baits, are the main cause. If your dog is known to eat just about anything, then be particularly careful to store poisons where they will not be accessible to him. Dogs found foaming at the mouth, with muscle tremors or staggering gait, or unable to stand, should receive immediate veterinary treatment.
Ideally, dogs should be taken to council-designated areas where they can be safely let off the leash to run free. It is important to use these specifically designated areas not only to ensure their own safety (preventing the risk of being hit by a car) but also the safety of farm livestock and wildlife which can be threatened by a dog let loose in their habitat.
There are various intestinal worms that can infect dogs and cats, with hook worms, round worms (ascarids), whip worms (mainly in dogs) and tapeworms being the main groups. Symptoms can include diarrhoea, bloody stools, weight loss, anaemia, pot belly, dry hair and/or general poor appearance. If left untreated, worm infestations can be fatal. Worms can be picked up from the mother (either in utero or via milk), from the environment (infected stools), from eating infected prey (lizard or mouse), or, in the case of tapeworms, from fleas. Worms can also be transmitted to humans.
If dogs live indoors they need to be provided with a dog bed. Most dogs though are hardy enough to sleep outdoors in a well-built, well-furnished and weatherproof kennel. The kennel should be warm, dry and draught free, elevated from the ground, near the house and human activity but not in a thoroughfare. It should be protected from rain and excessive sun, and the bedding should be changed regularly. Washable rugs, cushions or blankets are suitable as bedding.
Lungworm larvae may be present in slugs and snails, and if eaten, pets may be infected with worms that make their way to the lungs, where they block airways and make breathing difficult. Most dog wormers don't claim to treat lungworm, although some cat wormers do. Research conducted internationally has found moxidectin, which is found in some heartworm treatments for dogs, to be effective against lungworm, but this claim can't be made for dogs on packaging in Australia. Check with your vet as to whether it's an issue in your area, and discuss the best preventative treatment.