For Rent/Cats & Dogs: Can't treat pet on residential rental lot

@OmegaGamer123456 Does it work on a normal residential lot ?

If it does, it's best to report it in the bug forum as suggested above.

In my experience treatments are deducted from your veterinary clinic and not your household fund, if you own a clinic, so it kinda works as a supplier. Only if you bring the cat or dog to an npc clinic is the treatment deducted from your household funds. I have a veterinary clinic and have an exam table at my resident lot. My veterinary sim is able to give treatments to my pets at the resident lot, but all treatments are deducted from my veterinary clinic funds not my household funds. Every treatment in the veterinary clinic is usually deducted first from your clinic funds and then your veterinary sim or the npc veterinaries will bill the pet owner. Since it is your own pet, you are only deducted the treatment and not the price a pet owner pays at your clinic.   My suggestion would be to own a clinic, and make sure it has funds and veterinaries to run it for you and your sims can give treatments to your pets at your resident lot and the costs will be deducted from your pet clinic. 

I apologise if I'm breaking any rules in commenting here. But I'm really struggling to find the answer to my issue.

I purchased a bunch of those treats from the vet's vending machine, including the poop randomiser but I'm unable to gift it to my puppy. There's a prompt in my inventory for the plain ‘treat’, but only to put away or put in inventory for that one. Do you know how to give them to our pets, please? 

@Marley-FoxHi there, if you have vet treats in your inventory you click on a pet to give one to them. It's in the Friendly Social Interactions and usually on the first page.
I'm not in my game right now so I'm not sure which treats can be given to puppies except for the age up treat. But when you click on the puppy or pet and choose the vet treat option if I remember rightly it will show you which treats you can select. The only treats that you gift directly from the inventory are the ones bought from the pet food stall. Regular and vet treats are all in the social wheel. I'll add an image for you when I'm in my game.

Edit: tested in my game and the only vet's treat I can give a puppy is the age up treat. So it won't let you give them the poop randomizer, etc. With all treats in my Sim's inventory it's only the age up treat that appears as an available item. Without the age up treat in the inventory I don't get the vet treat interaction in the social wheel at all when interacting with a pup. But when I click on an adult dog the vet's treat option shows all treats in my inventory (image 3).

If you ever have other questions about the game there's a section here and we're always happy to hear them.
https://answers.ea.com/t5/Game-Questions/bd-p/the-sims-4-game-information-en