for 48 years we thought it was important for our pets to have company. HAH!!!
none of them ever even liked each other and when our tenzing died, shuju practically sang and danced. she started bouncing around like she never did before. she gained weight and smiled all day long. she lived another 5.5 years as a very happy only child, which she should have been all along, i guess.
your dog may have been expecting this. your other dog was sick a long time, and i believe they can sense that. if she isn't losing weight, eating as usual, and isn't depressed or crying, i say let it be. she'll tell you when she's unhappy. but it doesn't sound like it'll be about this.
does your dog need a buddy or does karla need a buddy?