I would echo the other commenters who suggested that you ask the client how many photos they want. Most owners do enjoy receiving multiple photos, but there can be many reasons why a client might not want that.
Bear in mind that the client might be busy on their trip, but also anxious about their dog. When your name pops up on their phone they will feel they need to drop everything to check that their beloved dog is okay and that there isn't some emergency or even just a kind of pressing query ("Mr Bojangles had an upset tummy and pooped all over your lounge. Where do you keep your cleaning products?"). Instead they find 35 photos of Mr Bojangles playing with his squeaker. Then the same happens an hour later. It's not always appreciated.
I've also had it where the client is so anxious that they tell me specifically not to contact them except if it's urgent and that they will contact me and ask for an update from time to time.
This should all be something to discuss with the client; a lesson I've had to learn is that it's not about me and how much I love taking photos of cute dogs. 😀
I've done pet drop in's for about 10 clients now and sent dozens of photos each day. And all the clients marveled over the pictures and commented about them in their reviews. But the last client who was on vacation reported that my multiple photos froze his phone. Oops. No wi-fi? Lesson learned.
In hindsight, how I would handle is to ask the client if they prefer as many as possible pics or a specific number. I also would not forward the pics all at once. In the future, I will send pics one at a time more slowly in case they are away from a wi-fi connection.
I normally send 2-3 pics every 2-3 hours while boarding or during daycare. It might seem like a lot, but I always assure the owner that there’s no pressure to respond - it’s just that I want them to feel like they’re apart of their dog’s day...Clients/customers have always responded very well 🥰