You're right. We know that in "Pnin" there was Dr. Bodo von Falternfel's obese dog that used to lie on Pnin's three-dollar rug, completing the scenery of Pnin's sudden displacement and that Pnin himself used to feed left-overs to "a mangy little white dog, with pink patches on its back, that visited him sometimes in the afternoon".
The dog may have grown healthier and fatter! It was probably the same dog that reappeared in the end when "a great truck carrying beer rumbled up the street, immediately followed by a small pale blue sedan with the white head of a dog looking out..." So, according to Kinbote, not only Pnin but his dog were both dominating a circular room and the Russian Department at Wordsmith's: a mighty change.
But why should I trust Kinbote's description of a fat sleeping dog lying across the room more than I can believe in his other assessments about Prof. Pnin?

All private editorial communications, without exception, are read by both co-editors.

Subject:	Our Pnin?
Date:	Fri, 04 Aug 2006 12:37:23 -0800
From:	Carolyn Kunin <chaiselongue@EARTHLINK.NET>
To:	Vladimir Nabokov Forum <NABOKV-L@LISTSERV.UCSB.EDU>