Dear Virginia, My five-year-old son has a best friend who often comes round for tea or a sleepover. My problem is his mother, who asks my son back in return. I am nervous of letting him go. She has a large 'tame' dog and the children are allowed to roll around with it. She feeds them piles of junk food, and also has a swimming pool, which is unfenced. Plus, I'm not so sure how vigilant she is when kids are around. Am I being over-cautious? Yours sincerely, Catrina

Years ago, my son, then aged nine, went for a sleepover with a new friend. I had felt uneasy about the set-up, but brushed away my fears. At midnight the phone rang with a reverse-charge call. He'd been on a Tube crawl with his friend and had ended up in Golders Green, and couldn't get hold of his friend's mum, who'd promised to pick them up. What was he to do?

I raced to the scene, dropped the other child off at his house, and fumed. The irresponsible behaviour of the other mother was staggering. My son never visited again.

Despite this experience, I'm torn as to how to answer your letter. I'm a great one for letting children take risks, build tree houses, travel the world – and yet I'd hate to put any child of mine in any kind of danger. I think that perhaps I would like to be the one who decided on the risks, rather than someone else. With other people's children I tend to be super-cautious and I expect other parents to be the same with mine.

Let's take your fears one by one. Junk food: if your son stuffs himself with chips and ice-cream for a day it won't be the end of the world. If he watches rubbish videos, the same – but you don't want him watching ones that will give him nightmares for months. Then this pool. If your child can't swim, you must warn him of the dangers and perhaps tell the mother, too, that you'd rather it were kept out of bounds when he's over. And as for the dog – now there's a problem. The thing is, her son might be used to the "tame" dog, and the dog might be used to him. It might be a dog who's fine when the little boy he knows pulls its tail, but seriously grumpy when someone else tries the same. The other thing about dogs is that they are totally unpredictable. A dog only has to develop a sore place on its back during the night and then, in the morning, if someone whacks it there, could well turn round and deliver a vicious bite. There is no such thing, I'm afraid, as a completely tame dog.

I wouldn't worry about being seen as a fussy mother, Catrina. Explain your fears to the other mum and put your cards on the table. Then leave your son there for a couple of hours only – certainly don't let him sleep over for the first time. When you deliver him, you can get a feel of what the home is actually like and gradually build up a picture of the risks. But maybe yours will always be an unequal relationship, with this boy visiting you more than your son visits him. He may prefer the stability and security of your home – that's fine. Having kids round isn't like dinner parties – "it's your turn to ask me, then my turn to ask you" – it's much more ad hoc.

But remember – your child is only five. He's not able to assess risks on his own. At least my son, on his escapade, was clued-up enough to call me. Until he's older I think, at the risk of sounding like a mad old fusspot, it's better to shield your son from obvious dangers. There are quite enough around without you courting them.

Readers say

A dog and a pool? Sounds fun!

There are dangers in all houses. The main danger for your son is that he will pick up from you the idea that other families' homes are threatening places. Encourage a sense of adventure. A dog? A swimming pool? Hot dogs? He will have a wonderful time with his friend.

Simon Rayner, Staffs

Stop being over-protective

You are being hypocritical. When your son's friend stays over at yours, I'm sure you don't think that his parents may also have concerns regarding how safe it is to leave their son with you. I'm sure the dog is used to children. Regarding the pool, you could always mention that you'd like the main access to it locked while your son is over. And one night of junk food isn't going to kill your son. You should stop being over-protective.

Naomi Bhuiyan, Birmingham

She's a good mother, too

Her own child lives there every day and seems to have come to no harm. You cannot wrap your son in cotton wool. Let him go to visit his school friend, enjoy rough and tumble with the dog, play in the swimming pool, maybe eat junk with his pal. He'll have the time of his life! This woman's parenting may be more laid-back than yours, but I'm sure she will take good care of your son.

Mrs Sandy Griffiths, Lowestoft

Assess the risk first-hand

No, you are not being over-cautious. A five-year-old cannot accurately assess potential hazards, so why put him in danger just to appease your son's friend's mother? You need to have a better understanding of the environment you are letting your son into. New places are always a risk, even if parents are vigilant. If you are still really keen for your son to go round and play, why not invent a reason to accompany him: "My son is nervous of dogs – is it all right if I stay for a coffee and see how he gets on?" Can your son swim? If not, the pool is a real hazard, so ask her if she allows her children to play near the pool.

On the other hand, you do sound as if you have already made judgements about this mother. How do you know how much junk food she feeds them? That is the least of your worries – you can't shield your son from biscuits all his life. And why does the other boy spend so much time at your house? Do you not feel that five is a bit young for sleepovers? So, either do a more realistic "risk assessment"; or don't let your son go. If it is the latter, then don't feel guilty about being protective, a chance may come up with a new friend whose family you feel more comfortable with.

Kathy , by email

Play, not sleepover

I understand why you have concerns, especially if your son isn't used to dogs or can't swim. As he is only five and you don't feel completely at ease leaving him there, perhaps you should only let him stay for a few hours. If you don't allow your son to go over to his friend's house at all, he is going to fail to understand why and he's going to think it's unjust. As for your son's friend's mother not being vigilant, she is, after all, a mother, and you should trust her. Most people take extra care over safety issues once faced with the responsibility of another person's child, so don't worry.

Miss Nowmi Zaman, St Albans