Advice needed Tactful but truthful

It’s not what you say but how you say it.
I’m sure you are delighted to receive their invitation...tell them that.
Gently Remind them of the distress from your last visit and, at the same time, you realise their love for their pets....they are, after all, their family.
Be honest in saying you don’t want to upset the dogs again so wonder whether they will be roaming around.
If their response is that the dogs will be as before decline but arrange another joint event for lunch somewhere.
If the dogs will be settled somewhere....have fun...maybe take a little treat for the dogs to show that you respect their family.

My DIL is terrified of my friendly but energetic, large dog. As soon as she told me, he was put out of the way so that she felt comfortable and has been removed the moment she arrives.
To be honest, the dog who bit is probably showing it's anxiety by biting and would be far happier left out of the situation.

Why would you feel the need to tactful? - there is nothing tactful about a biting dog!

Why would you not mention the dog? - that is the reason that you do not wish to go so that is what you need to say. To hell with them being offended! - they should not keep a dog that bites nor invite folk round to get bitten!

Definitely be straight with them Would love to come but since x was bitten last time we feel it’s best not to come to the house Have a lovely time blah blah blah
I see no point in pretended perhaps it ll bite someone else this time

We used to have a very large dog (Great Dane X German Shepherd) who was calm and friendly but could accidentally knock children over just moving around. If we shut him in the extension he would howl. We put a strong fixing in the skirting board and tied his lead to it so that he was in the kitchen corner with his bed and water bowl. That made things far easier when lots of people were in the house.

I don’t think I would mention the dogs. In my experience dog owners seem to be blind to any misbehaviour on the part of the animal, and can also get very offended by any criticism.

I would just claim a prior engagement.

Say you'd love to go but you're both genuinely distraught at the idea both offended them but equally terrified of being bitten. Ask them if they think your being OTT.
If they say yes then there is probably no way they are ever going to recognise the risk their dog is and as such you're better well away.

Flexible!

Well if they're serving Mice pies you've got two reasons not to go.

I'd just be honest with them. Just say "we're wary of the dogs because one of them bit husband last time. Thank you for the invitation".

If they get cross at this, they have the wrong attitude.

Just tell them - not that they should need telling after dog bit OH.

Being invited for mice pies already!?

If they are aware of the previous incident just tell them the truth.

This is another one of those situations where if you don't come clean now, you end up with the same predicament if you are invited around next summer.

Be honest with the friends - you are nervous of being with their dogs and don't want to chance another bite. If they are reasonable people, they will respect your feelings and remain friends. If they take umbrage, they aren't really your friends.

Thank them for the kind invitation but say you have plans in place already for that day

Had. Our current dog loves everyone!

I would speak to them and say something as ohmother has suggested. This will give them a chance to sort something out. Not acceptable to have guests afraid. We have a snappy dog years ago and she went to a bedroom when we had visitors. Problem sorted.

If I had a dog (I don’t) that had bitten a guest on my premises, any future invitations would include an assurance that the dog would be kept locked up for the duration of the visit and unable to repeat its offence.
Since the hosts have apparently not given you this assurance sandelf, tell it how it is.
You are sorry but after last time, you don’t want to visit them.
Anything less than the truth will just result in more invitations and you having to invent more and more excuses.

That sums up things well Urmstongran just the right note.

Just tell the truth - and say ‘but thank you anyway, hope to meet up soon at ours!’

We’d love to come but unfortunately it seems your dog took a dislike to _ last time (inviter). Is there any thing you could do about that?

That way it gives inviter time to think about shutting the dog in a different room.

Sometimes "tactful" is ruder than direct. E.g. if people make half true excuses that then need to be back-tracked on

I understand the need to be tactful, some people are so precious about their dogs.

I would say that since one of the dogs nipped your husband he is nervous about being around them. That way it was not the dogs fault for not being able to go but the husbands.

I dont think you need to beat around the bush on this one just be honest.