Many of us who have two or more companion dogs will notice behavioral changes that we perceive as grief-related if one of the pets is very ill or dies. As fellow pet parents, we know this to be true and have our own personal anecdotal stories.
For researchers, anecdotal beliefs or reports are problematic. They recognize that pet parents may be projecting their feelings of grief onto the companion dog. Confounding the matter are factors that may change such as household dynamics, pet parent behavior, or habits that may impact the surviving dog’s behavior.
Researchers have observed mourning habits and rituals of many species such as dolphins, elephants and primates in the wild. In those circumstances, researchers are simply observing and are usually devoid of a personal attachment. True, they could form an emotional bond and project some bias, but they are not interacting or affecting the outcome. Another factor that compounds the issue is that behavioral responses to death have rarely been observed in wild or feral dogs.
A great basic survey that quantified behavioral changes in companion pets was completed in 2016 by Jessica Walker, Natalie Waran and Clive Phillips in Australia and New Zealand titled, “Owners’ Perceptions of Their Animal’s Behavioural Response to the Loss of an Animal Companion”. We encourage you to read it.
A couple of years later, researchers having different specialties published a questionnaire directed at Italian dog owners who had lost at least one companion dog from a minimum of a two-companion dog household. They then applied various methodological scales to analyze the responses not only for pet humanization but also for pet bereavement for another pet. Eventually, they published a paper called, “Pet Humanisation and Related Grief: Development and Validation of a Structured Questionnaire Instrument to Evaluate Grief in People Who Have Lost a Companion Dog.”
With this foundation, the team was able to expand and complete another study: “Domestic dogs (Canis familiaris) grieve over the loss of a conspecific”. This study gets really interesting because it provided comparisons based upon the type of bond two companion dogs may have. They asked if the cohabiting companion dogs were friendly, agonistic, mutually tolerant, parentally based (meaning parent-offspring) on both owner observation and the genetic association towards one another. They also inquired about the activities or areas the two dogs might have done together such as sleeping together, playing, sharing food, and grooming. Then, the observed behavioral changes such as playing, sleeping, eating, fear, vocalization, elimination, attention seeking, and level of activity, once one dog might have passed on.
They found out that a friendly and parental relationship between the two dogs was associated with stronger behavioral changes, while no association was found between behavioral variables and an agonistic/mutual tolerance relationship.