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.
While fleas are annoying, ticks can be deadly. The paralysis tick occurs mainly in spring and summer in Eastern Australia, and is found in long grass and the bush. Tick protection isn't necessary for all dogs and cats, and depending on where you live, may not be needed all year round – your vet can advise you on the situation in your local area. No tick preventative is 100% effective, so you still need to check your pet every day.
As a dog owner you are fully and legally responsible for any harm or damages caused by your dog. If your dog bites a human, kills wildlife, damages property, causes a traffic accident, creates noise or other pollution, or is the direct cause of any other damage to the community, you may have to shoulder a substantial financial (if not legal) penalty. It is in your best interest then to always keep a vigilant eye on your dog in public and provide him with the obedience training and socialisation skills necessary to become a well-mannered and socially well-adjusted dog.