I certainly think they can, but it probably depends on the strength of the relationship, and on how many other strong relatioships they have to fall back on.

When my parents' wonderful vet came to the house (as is usual routine in these situations) to put their Dachshund, Poppy, to sleep, the other Dachshunds were shut away while the deed was done. Afterwards, he put a blanket on the floor, laid her body on it, and told my parents to let the others in to sniff her until they were satisfied that nature had taken its course and their mother was gone. They did that, and the dogs spent a few minutes sniffing, and spent the rest of the day sitting around quietly. They watched my parents bury her the next morning, and after that went back to their normal selves. They were obviously sad that she was gone, but they had each other, so they coped very well.

__________________
Proud Mummy to:

Sam (born June 1999, found August 1999)
Milly (born May 1999, adopted September 1999)
Eva (born 2010, adopted us August 2011)

I brought Ribs home, they saw her in her blanket, before we buried her.
They do seem to be wondering where she is a bit now.

I worked all day today, and was fine but on my way home the pain in my heart came back, and I didn't want to go in the door. I miss her.