This article is from the WSSF 2017 AFRMA Rat & Mouse Tales news-magazine.

By Karen Robbins

Chrystina Lammers, e-mail
Q I’ve had rats for over 30 years and have often referred to your pages and guides to answer questions. Recently I have been participating in a few breeder pages so I can learn and eventually become a good ethical breeder. I asked one question that so far no one has answered accept for what I read was... or I have heard.

As far as standards for the perfect looking rat according to AFRMA, are there specific reasons for every standard? Obviously for some or even most it’s obvious...thicker tails...large eyes, but I’d like to know if there are some standards that if changed, for example (example ONLY), if I bred rats with ears that sit higher then standard, would it negatively effect the rat? I know rats in the wild normally have ears that are set on the tops or higher up on the head but now we have a standard for Dumbos so a change like that I’m guessing didn’t negatively effect the rat.

Thank you for any info you can give me.

A While most deviations from the ideal will not cause health issues, there are some that would. Your example of high set ears would not harm the rat per se but it is not pleasing to the eye and gives a Mickey Mouse look; high set ears give a narrow skull which then usually translates to a narrow body. No rat is perfect, but show breeders will strive for all parts to be as close to the written standard as possible. We have an article on type that includes some examples that can cause health issues. You can also see examples of problems on our Type Issues page.

Dumbo rats have an actual skull difference from normal rats and there are two research articles about this:

• Expression of Msx1 and Dlx1 during Dumbo rat head development: Correlation with morphological features KATERJI, Suhair et al. Genet Mol Biol. 2009 Apr-Jun; 32(2): 399–404.
• Deletion of a conserved regulatory element required for Hmx1 expression in craniofacial mesenchyme in the dumbo rat: a newly identified cause of congenital ear malformation Quina LA, Kuramoto T, Luquetti DV, Cox TC, Serikawa T, Turner EE. Dis Model Mech. 2012 Nov;5(6):812–22.

There are some types of rats that poor breeding can cause harmful effects for the rat and these should only be bred by advanced and knowledgeable breeders. There are also problems associated with some types that have to be selected against and those that have the problem not bred and lines discontinued if it shows up.

Breeding for the whole rat is the goal of every show breeder, not just one part.

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