Visiting family dramas..

This is on your DH for not talking to his own brother and expecting his mum to sort it out. He's the one you should be annoyed at rather than making it your MIL'S fault.

Only if they're really stupid or ill-informed. It's perfectly possible to be allergic to some dogs and not others.

Ive always had cats, no allergies. However was allergic to dsis's cat. I think(but happy to be corrected,) you can get acclimatised to the animal you live with.

Saying 'tell them not to bring the dog' was also not great - at least phrase it as a request. Your husband's communication was poor here and this is the outcome

Is the dog a puppy. I bought a 'hypo allergenic' dog and my son was immediately allergic to it. I spoke to the vet who said it is usually puppy dander that causes a reaction and at about 8 months when the dog has its adult coat the reaction might dissappear.
The reaction did dissappear and we kept the dog.

You and your husband created the drama for yourselves by not speaking to the brother directly. Why should the mum have to do it for you and now you’ve ruined her day of hosting and having all her family together.

I used to be highly allergic to my friends St Bernard. My asthma would flare up. Yet I owned a whippet and had no allergies at all.

Husband should have spoken directly to his brother.
A 3 year old shouldn't have to take medication and/or struggle with an allergic reaction to appease anyone.
Allergic reactions can be mild one day, but then can be very serious another day.... believe me, I have a 3 year old with 16 allergies, and a son with 2.
Next time, share that you would love to attend, but can't as the dog will be there. You take a proactive step to protect your son.
I think you MIL tried to please everyone and doesn't see the effect it has on your son. It's one thing for an adult to choose to put themselves in that situation, but a 3 year old isn't able to have the understanding or communication to share how they feel.
Also, try different brands of antihistamine. Ceitrizine works far better for my two! Try to see.

It's an animal that people are less likely to have an allergic reaction to.

Like hypo-allergenic earrings. I can't wear most of them, as I still react to them - but more people can use them than non hypo-allergenic ones.

That's certainly not why I suggested anti-histamines.

I suggested them because it would allow the family to spend Christmas together without all the potentially unnecessary drama. Do feel free to create hyperbolic narratives though, it does add a certain something to a thread.

What is a hypo-allergenic animal?

I would be suss if someone had a dog but claimed to be allergic to just mine, it just seems hard to believe esp if its a non shedding breed.

It comes across a little like you just dont want them to bring their dog, are there other issues with it or BiL? Seems odd your DH doesnt just speak directly to his brother?

Whatever else happens h needs to engage his brain, open his mouth and speak words instead of getting others to relay messages.
That would irritate the fuck out of me long before the fucking obligatory dog rocking up.

Wild to give a child medication to appease someone that can’t go somewhere without the dog.

You approached it wrongly. Your husband should have talked to his brother and explained it to them nicely and patiently in advance.

by the way were you going to bring your dog or leave at home?

Also not sure allergic is the right word here. As you actually have a dog he's maybe just a bit sensitive to some dog fluff more than others.

Has Granny got a cat?
Is her house full of thick carpets, curtains, feather stuffed cushions?
My guess is that there is another allergen at her house.
Either way, the dog should stay at home

Everyone is being unreasonable here. Your dh should have spoken to his db directly not via the poor dm who would've felt awkward, the db should leave his dog at home.
We have a dog and no way does it come visiting people with us.

* They also generally take time to build up. People with hay fever are advised to start antihistamines before hay fever season starts.*

Totally agree that before is better. Which is why I took my antihistamine before I went to my daughter's. They definitely don't work as well if they are taken during an allergic reaction - which may explain why the piriton wasn't effective.

My DD is allergic to all animal dander. My Aunt has many cats and dogs in her house and when we visit my DD takes an antihistamine. We however have two cats and DD not allergic but strangely enough when they come home from the cattery she gets an allergic reaction.

If you have a witnessed your son become reactive to their dog twice already you and your husband should have been more proactive in speaking to his brother to make sure they understood that and to ask nicely for them not to bring the dog.

You went wrong here by just casually passing the message through the grapevine and expecting a certain result.

Antihistamines only dampen the reaction depending on how bad the allergy is. They also generally take time to build up. People with hay fever are advised to start antihistamines before hay fever season starts.

Allergies in young people often get worse with each exposure.

I love dogs, we have 2 (I’m also allergic but double dosing Claritin daily just about works for me), but I don’t understand why other people take them everywhere. They’re far happier at home than in someone else’s house with far too much going on.

It really isn’t. Different dogs have different coats/dander. I am highly allergic to terriers labradors, retrievers and lots of others… and yet have no issues at all with the cocker spaniel we own!

I have a chihuahua

And what do they have ?

I am allergic to dog, cats, horses ferrets and any other animals with fur; even hamsters! But if im around a particular animal constantly (and taking antihistamines and ventolin and don't touch my eyes) after about 6 weeks I sort of get immune to that particular animal. Otherwise I'm coughing, sneezing and my eyes are steaming and itchy and have been swollen almost shut before. My middle son is the same. So I totally get why ops son is fine with their own dog