You’ll be activating it with your eyes shut presumably?
I'd love to see an aggressive dogs reaction to a blinding light!
I have found the old advice works fine.
Ignore them, no eye contact, poles by your side, keep walking.
I met numeros dogs everyday on my Camino this year.
The VdlP is 'awash' with them!
Some quite aggressive.
But if they see you are no threat, they leave you alone.
The 'standard' advice worked fine every day, with dozens of dogs.
Except once, though it might have worked had we waited............a bit longer........but we were not willing to take the risk.
Dog Story 1. This was VERY rare and a one off! And it occured on a remote section of the VdlP.
Three Pilgrims strung out along the path over about 200 metres.
Rear Pilgrim sees three dogs approaching fast at 9 o'clock across a field.
Still about 300 metres from us he yells out a warning.
We all stop and look towards the dogs.
They are heading right for us at full speed.
Now 200 metres and closing fast.
Lead Pilgrim who speaks Spanish, points his poles at the dogs and let's rip with a stream of abuse in Spanish! Dogs stop dead in their tracks, now about 100 metres from us.
We ignore them and keep walking, as they watch us depart.........
Reflection on the incident.
It was quite scary for a moment, but even so I think the dogs might have stopped at the end of 'their' field which was sunken a couple of metres below the path.
We didn't see them initially, as they were so far off. Probably 400 metres away, protecting a small flock of sheep in the middle of a huge field. We only noticed the distant sheep as we were leaving the area.
It really was a one off, and the dogs were just doing what all dogs in that area do, protecting their sheep / property.
Dog Story 2. What normally happens.......though this was a bit of a scary example.
Again on the VdlP. Walking a remote track I passed an open gate to a Finca (farm)
As I passed I heard a large dog barking behind me. It had come out of the open gate onto the path to check me out........
A moment later another large dog appeared on the path to my front.
So now I have one 50 metres behind me and one 50 metres in front of me.
Both barking.
So.............
Ignore them, no eye contact, poles at my side, move to the side of the path furthest from them and keep going. They let me pass and watched me go on my way............
I knew a couple of other Pilgrims were about 30 minutes behind me so I sent a Whatsapp message to warn them. But the dogs were gone by the time they passed. The owner probably closed the gate after hearing the commotion.
Any other dogs I met, did not even leave their property. Just barked as I passed.
Yes dogs can be a bit scary in remote locations, particularly when you are alone.
But I never really felt that I needed protection from dog repelling devices.
I would be concerned that they might just escalate the situation.
No doubt we shall get some dog 'expert' jumping in shortly with the right advice.
I just stuck with what seemed to work.
I've had dogs, and like dogs. Maybe that helps.
As an aside, I was initially, during planning, more concerned about cattle on the VdlP.
Having read that Pilgrims need to pass through whole fields of them.
Nothing to worry about.
They were wonderful and very curious.
Often the calves would come quite close to check me out.
Sometimes I'd walk slowly through quite a large herd of cows.
If there was a Bull in the field, and sometimes there was, I kept a close eye on him!
But it was never a problem.