Hi there, thank you for your feedback! The issue you are describing is usually an issue of coat length/density more than pet size. Pets with longer/denser coats sometimes have to have the hair trimmed in order to keep the transmitter pointed down, which is what allows the door to receive the signal.
I also noticed that you purchased the collar with the boot (silicone cover for the transmitter) and, again, depending on the pet's coat length/density, sometimes it gets hung up, or stuck to that silicone rather than allowing smooth movement.
If you pet isn't too large, the Designer Series collars may be a better fit for you, as they exclude the boot. This isn't always suitable for very small or very large pets though.
I hope this helps, and you can always call us at 1-800-255-1279 and speak to someone for more recommendations or to discuss other options. We are here to help!

Hi Margi,

I wanted to share that we now offer a cat collar that is significantly more slender than the Designer Collar you originally purchased. While it’s marketed for cats, it includes an added safety feature that allows the collar to slip off if it becomes caught on something.

We’ve also found that many customers successfully use this collar for very small dogs and puppies, so it may be a great alternative for your pet.

I’d be happy to send you one free of charge for you to try. I’ll follow up with you directly to confirm your shipping address and see which color you’d prefer.

Please let me know if you have any questions in the meantime!
wecare@hightechpet.com