Love can transcend many boundaries including species. It would be easy to verify as all you need is a stethoscope and tell your dog you love them. We tell our dogs we love them numerous times each day and I can tell by their reaction they understand. The average dog understands 89 words in English, but it all depends on the dog and their training. It can be from 15 to over 200 words. Our dogs are highly intelligent and we talk to them all the time so I would guess ours know well over 200 words.
Some people only talk to their dogs rarely and hence the dog only knows a few words. People underestimate the ability of dogs to comprehend words, phrases and sentences and know their meaning. All of our dogs - past and present - understand words and love can cross all boundaries. It helps if you can follow up telling your dog you love them with action that confirms it.
Have you told your dog lately that you love them? Might be a good habit to get into.