They're capable of wholesome, untainted love and sometimes it's as if they understand us better than our human counterparts, but is it possible a dog can detect the hormone changes in the human body?
"There is a general belief in the veterinary community that dogs can detect at a subconscious level changes in human hormones," Dr Joanne Sillince, managing director of Pets Australia told The Huffington Post Australia.
Dogs are highly sensitive to human hormones and equally, they are sensitive observers of human behaviour.
Sillince said this can help to explain why pregnant women report changes in their dogs' behaviour, many becoming protective of their owner.
"This works on two levels: first, they pick up on their owner's body language. Obviously, the first thing that changes when a woman falls pregnant is her behaviour. She becomes more cautious and will tend to fend off rough games."
We see all types of behaviour when the owner is pregnant; from the protective dog, the sooky dog, the mushy dog and the safe dog, where it becomes quite cautious itself.
"The dog will pick up on this change in behaviour very quickly. And on top of that, it recognises the change in hormones," Sillince said.
As to whether the dog actually knows there is a human baby on the way, Sillince said it is unlikely.
While there isn't any scientific evidence concluding that dogs can detect human pregnancy, Sillince said it is certainly within the realm of possibility.
"We see all types of behaviour when the owner is pregnant; from the protective dog, the sooky dog, the mushy dog and the safe dog, where it becomes quite cautious itself."
"The one behaviour we don't see is the aggressive dog. In a very small percentage of cases, that protection can result in low-level aggression towards strangers but we never see any aggression towards to the owner," Sillince said.
We know that dogs can detect low blood sugar in people which is why dogs are being trained as diabetic alert dogs. Though some dogs pick up on this automatically without being trained.
Dr Pauleen Bennett, director of Regional Operations in the School of Psychological Science at La Trobe Univeristy said this notion of dogs reacting to both human scent and changes in human behaviour is not unusual.
"We know that dogs can detect low blood sugar in people which is why dogs are being trained as diabetic alert dogs. Though some dogs pick up on this automatically without being trained," Bennett told HuffPost Australia.
Sillince said for owners who are expecting, it is important to be aware that the big changes aren't so much during pregnancy, rather when the baby arrives.
"If the dog is traditionally a high attention inside animal, then you need to phase in any changes to the dog's living or sleeping arrangements, ideally over the last few months of pregnancy."
"For first-time parents, don't underestimate the sheer number of hours you will be occupied and know that any sudden changes to an animal's routine can be quite stressful," Sillince said
In addition, Sillince said there is absolutely no need for an introduction with your dog and the baby.
"The dog obviously knows the baby is there. If, in its own time it wants to come and say hello, fine. But don't force an introduction. Another obvious instruction is to never, ever leave a dog and child alone in a room," Sillince said.