Die Rasse nennt sich nach seinem Züchter, der hieß Karl Friedrich Louis Dobermann mit zwei n.

In Wikipedia, the plural is consistently Dobermans.

The Dobermann has a very adaptable outlook to life and fits into a family well - See more at: http://www.thekennelclub.org.uk/services/publ...

Dobermann is the usual spelling in the UK - see the Kennel Club link above. As to the plural, simply googling "Dobermanns" in the UK brings up the websites of lots of Dobermann breeders - which all use "Dobermanns" as the plural.

And it obviously applies to bitches, as well: no Doberwomen / Doberfrauen

Vielleicht ist der Wörterbucheintrag überarbeitungswürdig, was Plural und AE/BE anbelangt:

Agree with #7: The American Kennel Club does indeed use "Doberman Pinscher" as the official name of the breed (note capitalization, which means that the dictionary entry in Leo should be corrected in that regard for AE as well). The plural of the official name there is "Doberman Pinschers." I assume it would be safe to say that the plural of the "shortened" name would be "Dobermans" since the -man ending does not refer to sex/gender.

#10: Die Welpen nennt man wahrscheinlich Dobermännchen.

@#12: Und weibliche Welpen dann DobermännchenInnen? scnr

@ eastworld: Das sind doch Dobermädchen, oder?

Irene, nöh.

Ich habe einmal versucht, alles zusammenzufassen, aber direkt an der richtigen Stelle: related discussion: doberman - der Dobermann 

I'm still a little astonished by the German -- I thought it was probably just a silly question with an obvious answer, but nooo. Fascinating.

Are there any other proper names in German where this drive to retain the inflected plural has such a powerful effect? If your neighbors, say, were the Neumanns, or the Hartmanns, or the Hoffmanns, would you be desperately tempted to call them the Neumänner, Hartmänner, and Hoffmänner?

Or do you think with all the people doing it with Dobermans it maybe originally started out as cute, wink-wink, just an inside joke, like, um, Purzeltag for Geburtstag?