American Fancy Rat & Mouse Association

This article is from the WSSF 2009 AFRMA Rat & Mouse Tales news-magazine.

Breeding & Stuff

Type Question: Square Butts on Rats

Amanda Brewer, Bloomingfield Rattery, CA, e-mail
Q If a rat, at say 4 months, does NOT have a square butt can he essentially turn into a square butted rat?

I’d love to learn more about the type and breeding. I was wondering is there any way you can actually tell any type on a young pup? Or do you basically choose on size?

I know I’m young and if I were an adult, I doubt I would trust myself either. But I’m willing to learn, and I don’t “give” up easily. Not in the sense of being nagging, but I see SO many breeders come and go very quickly.

Anyways, thanks for your time.

A I wish more people would ask questions like this. We would much rather have this discussion now rather than explaining it once an entire litter is born with square butts.

Let’s start with some basics so you’ll understand my philosophy on breeding. The core group of breeders, those you see winning at shows most often, believes in breeding “from the inside out.” We don’t all say it that way, but it all comes down to the same thing. Here are the basics in order of priority:

  1. Excellent health and temperament are rarely discussed because those are a given. If you want to see either Karen or I get upset, just mention that the mother of your litter is a little sneezy or that the father can’t live with other males but that it’s okay because he’s great with people. We don’t even TRY to breed these things out . . . we simply don’t breed them.
  2. Bone structure. This is the hardest part of the rat to change through breeding and can take many generations before you see improvement. If a rat has a long narrow head, a flat rump, a square butt, a short or thin tail, or a short body, the base of these problems is often bad bone structure. While poor bone structure isn’t always easy to see on babies, it’s usually obvious at a young enough age that you know that the rat should be pet-placed rather than kept for breeding (#1 reason for showing your kittens!!!).
  3. Soft tissue. This is a little easier to change and can be accomplished in a few generations if you are very persistent. Soft tissue is anything between the rat’s bones and skin—it includes eyes, ears, tail (to a degree), muscle mass, facial structure (to a degree). Much of a rat’s head structure is based on how the soft tissue (muscle and fat) lays over the bone, it can make them cheeky, heavy in the neck, give them a pinched muzzle.
  4. Coat and color. This can be changed in a single generation and should be one of your lowest concerns when you begin breeding.

sq. butt
7-week-old Black Satin female showing a very square butt, owned and bred by Karen Robbins.
male good tail set
Black Variegated Standard male showing good tail set, owned and bred by Karen Robbins.
female good tail set
Russian Blue Standard female showing a good tail set (nice taper from hips to tail) and thick tapering tail, owned and bred by Karen Robbins.

Now, all of that said, I’ll answer your question. Because a square butt is often based on bone structure, it’s something that can change as the kitten matures. But once they’re about 6 weeks old you pretty much know what you’ve got. If a rat developed a square butt after 6–8 weeks, I would be very concerned that there may have been some kind of degeneration in the hips. But chances are he had a square butt as a baby and it was just missed. Carol Lawton

Ed. Note: see the new Official Rat Standard page on the web site for photos of the ideal show rat

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Updated February 18, 2015