To a child-less couple, a pet can become like a child very quickly, and so the loss of that pet can hurt deeply. That is not to say that a family with a pet does not feel the same grief or loss, but perhaps the family group deals with it differently as the pet may be seen as a pet, and not as the pseudo-child or “fur-baby”. My husband and I have been unable to have children of our own, and so we gave ourselves the pseudo-child of a pet. We have lost two fur-babies, both cats, one just over 3 years ago now, and the other, very suddenly, just today. For 16 years and 4 months, my husband and I have had either one or two fur-kids in our family, and now all of a sudden, we are again child-less. But really, what does this have to do with family history and ancestors?
The family pet, no matter what species it is, no matter who first obtained it, who fed it, or who it preferred the company of, the family pet has played a part in many families lives throughout generations. Children will make short term pets of lizards, or tadpoles, or caterpillars; while longer term pets of dogs and cats were historically speaking probably seen more as a working animal – herding sheep or keeping rodents at bay. Attachment and bonds are still made by all concerned, some of those are stronger than others, but those attachments help form the memories of the non-human family members.
I have an undated photo of a dog, “Nugget”, that my grandparents owned, I think the photo was taken about 1947 based on where it appears in the photo album, but given that there are no people in the photo I can not be sure, but to have not one but two photos of this dog in the photo album shows to me the emotional attachment that my grandparents must have had to “Nugget” before they welcomed their first child into the world. Was their view of “Nugget” one of a “pseudo-child”? Did that view change after their children were born?
Historically it’s not often that the ordinary everyday pet gets recorded for all time. But some 1911 census returns do show that some people recorded their pets for posterity, even if they didn’t know it at the time. The pet’s portion of this one below I think is comical in nature.
Roger, an Airedale terrier, 5 years of age, not married, yet apparently having fathered over 100 offspring, is “employed” as a watchdog looking after the house, and was born in Keighley Yorkshire. 
Of course, having been a cat owner myself, having grown up with a dog, and knowing that my grandparents had a dog at one point, I wonder, how many of my other ancestors also owned a pet during their lifetime. How many of these pets have been consigned to “the forgotten memories” files due to no recorded evidence, and no memories or stories passed on to following generations. How many non-human family members will never be recorded in the human family tree, yet were in their time and their own way, just as much family as the humans were.
Nugget – dates unknown
Winston – c1982-c1992
Goth – July 1997-Sept 2010
Faolan – Aug 2005-Jan 2014
 1911 census of England, London, RG 78 PN 82, RG 14 PN 2457, registration district (RD) 27, sub district (SD) 1, enumeration district (ED) 7, schedule number (SN) 49, 118 Turney Road Dulwich, Camberwell, Roger.