Help Please! Dog Howling

[BunnyTrouble]

Posting here for traffic.
My Dog, 18 months old is usually placid once hes had his walks. Tonight I took him as usual to our local dog park where we know alot of the dogs and owners. Another Lab had just finished her "heat" and my dog was going crazy, wouldn't leave her alone, wasnt humping her but following her and stuck to her side. It got silly so I bought him home and took hom again a few hours later. He still hasn't settled and has been pacing the house all evening.
I put him to bed, he goes in the utility room, usually as good as gold and sleeps all night.
Well tonight he laid down as normal but then 10 mins later is howling like a wolf!!its so loud I've had to bring him in the lounge with me where he now asleep!
Is this because hes horny? Hes not been neutered yet.

Yes, the scent of a bitch in season can drive entire male dogs crazy. I would avoid that park for a few days, but if you do go keep a close watch on him - dogs can and do take off following the smell that's been left behind (even if the bitch is long gone from the vicinity) and I've seen dogs that have run across roads and been hit by cars in this scenario. He should get over it in a day or two, but howling, going off food and increased marking (even indoors) are not uncommon in this situation. It doesn't mean that the dog needs to or should 'get some' - that often actually makes them even worse - it's just a natural reaction that some dogs exhibit more strongly than others.

Why hasnt he been castrated?

@TheoriginalLEM he hasn't been castrated because the vet informed us that because hes a large breed we should wait until hes 18 months. Something to do with letting their bones get to full size.
And our vet has been closed since lockdown unless it's an emergency. Hes just 18 months old now.
This is the first time hes acted like this.

Have him castrated & get his vocal chords removed also.

Have his vocal cords removed? WTF

Really helpful @flatulencebythebucket🙄