Hello folks, I am new owner of ACD and I want to install dog's flap door. Our dog is female dog, but it is still puppy. I cannot wait until it grows up. So I would like to kindly ask other owners to help me estimate right door size ( height and width ). Of course I want to install minimum size needed in order to make sure human beings is not able to pass thru and enter the house. Thank you in advance for you kind support and advice! BR Mira
The KC breed standard gives the desirable height for an ACD bitch as 17 - 19 inches. (This is measured at the shoulder). You are the best person to judge whether your puppy will be large or small for her breed, but I can't see her managing with anything less than an 18 inch pet door. Depending on where you site it, if needed the opening could always be made larger at a later date, so go for your best guess now and be prepared to enlarge it if your puppy turns out to be a big girl.
As you indicate that you want to be sure a person cannot get through it, then you are really limited to no bigger than a medium which has a flap opening of about 8" wide x 12" tall. You don't need it to be as tall as the dog, you just need it to be bigger than their chest area. Their head and front feet will go through first and then their torso and then their back feet. The head and feet can be bent down/up to go through. It is recommended that you raise the opening to a botton height that doesn't require your dog to have to crawl to get through. So a whippet and a shih tzu may be good with the same size door, but the whippet would need it positioned higher in the door. A large has a flap opening of about 10 x 16. But remember a person can remove the framing so that opening would increase to around 11 x 19 (versus 9 x 14 for a medium). But it's not just about a person getting through, it's can they get far enough in to reach the door lock(s). The taller (or higher placement) makes it more likely for someone be reach the locks. After being burglarized while on vacation by thieves who accessed the inside via the dog door, I won't put another one back in. I'd rather the inconvenience of letting the dogs in and out, than risk another burglary.
As you can tell, someone with experience of the problems. I tend to over-estimate as I have had a dog who popped a disc when running into a crate. (He did recover with 3 days on a drip and 6 weeks of cage rest). I hadn't considered the possibility of access by a burgler.
You really have to position it just right if you size it as small as possible. Too low and you risk that exact problem. Better to have the dog raise its feet to go out than to lower its body. My parents has a cat-size one going from the house to the garage. My dad's akita thought he heard my dad and shoved his head through the flap. Since he couldn't get through, he pulled back and the entire cat door came with him. He pranced around with it around his neck for several minutes before my Mom could get it off him. And even though they come with covers to prevent anything coming in or out when you don't want them to, the covers are VERY easily breached. For me, I pretty much let my dogs out for a few minutes whenever I get up for any reason. That way they never need to go when I'm caught up in something.
