Love is a complex and difficult to define emotion, but from a biological standpoint researchers have long known that feelings of closeness and intimacy are related to the release of oxytocin, known as the "neurochemical of love".
A study on the brain chemistry of canines is confirming what pet-owners have long suspected - dogs really are capable of loving us, and the warm, fuzzy feeling is mutual. Measuring an increase in oxytocin in the bloodstream can give scientists sense of how strong a feeling of love, an interaction elicits. In summary, when a dog sees its owner, its brain secretes the same substances as those secreted by an addict's brain when on a cocaine trip.
While the meaning of love may be more the purview of poets and philosophers, in terms of chemical response within the brain, animals and humans might just feel the same way about those they are closest with.