It is our considered view that if you allow tortoises and dogs to mix, then there is a definite element of risk. If a dog has proved agressive to tortoises in the past, then there is no way you should keep both. Either the dog or the tortoises should go. Rats, Racoons, Hedgehogs, Badgers, and Foxes All of the above have attacked tortoises and have caused serious injury or death. They kill not only tortoises but also birds and many other 'friendly' animals.
Some plants are also dangerous to tortoises.
A full list is supplied in our 'Feeding Manual'. These range from the dreaded 'RNS' to viral hepatitis and stomatitis. Some animals which are carriers may themselves be entirely free of symptoms and may appear perfectly healthy. Tortoise club meetings where animals are present are also risky. These problems are greatly magnified when people allow different species or tortoises from different geographical origins to mix with each other.