> and his vet !! told him that dog fleas are extinct in this country now
That may be true, it has been the Cat flea that mainly affects both dogs and cats as cat fleas are not host specific. Many types of fleas are like Rabbit and Hedgehog fleas, you may find some on your dogs if the dog has been in contact with them, but they do not live or breed or even feed off other hosts.
Classic case of misunderstanding what they were told.
Also to some extent it is true that most adult dogs that have been properly wormed as puppies and then do not eat faeces will not often have worms as the Canine roundworm is linked to the canine reproductive cycle and is mainly found in pregnant and lactating bitches and their puppies.
My own vet says for adult non reproductive dogs the four times a year worming is overkill, but eh is a Kiwi. I know most breeders in the USA do not do routine worming of puppies but submit fecal samples to ascertain if it is needed, but then many dogs are on regular monthly heart worm preventative which also kills other parasites, such as worms and fleas.
When I routinely worm my girls wqith Panacur I try to time it for aroudn a month after soemoen has been in season.
When I am planning to breed I worm the bitch and everyone else when she comes in season. Mum to be is done in whelp, then puppies at the relevant time, All the adults are then wormed again when puppies leave.