The human-animal bond encompasses a wide range of emotional, physical and physiological effects induced by close, especially long-term, close interaction between a human and an animal. Considering it "a mutually beneficial and dynamic relationship between people and animals that is influenced by behaviors that are essential to the health and well-being of both," the American Veterinary Medical Association established a committee that develops policies, for veterinarians and the human companions of the animals, to encourage its benefits.
This bond is best known with companion animals, but there can be close bonds, for example, between zoo animals and the staff that work with them, and, to a lesser extent, between wild and semi-tame animals and humans when their territories cross.
The bond can extend beyond death. The best known example in the Western Hemisphere is probably that of Greyfriars Bobby, a Skye Terrier. Bobby guarded his owner's grave for fourteen years, until his own death. Bobby became extremely well known during his lifetime and his story was immortalised by Disney, making him renowned the world over. In Tokyo, outside the Shibuya Railroad Station, there is a statue of an Akita named Hachiko. Hachiko was born in 1923. He and his human, a professor at the Imperial Museum, moved to Tokyo. Every morning, Hachiko would walk with him to the train station. When the professor died at work in 1925, Hachiko continued to walk to the station and wait for his loved one's return, and did so for ten years, until he died in 1935. Hachiko has become a national legend of loyalty and friendship. 
Physical interactions include safety in both directions, means of communications, and expressions of both hostility and trust.
In the UK, the new Animal Welfare Act (2007) stipulates that all those in contact with an animal have a 'duty of care' towards it, which encompasses both physical and mental needs, health and well being. It is therefore a legal, if not also moral, obligation of veterinary surgeons in the UK to ensure that necessary, effective and humane behavioural management is in place, bearing in mind these requirements. It would however often seem that farm animals have the better deal in this regard. Management systems and environment are routinely considered to have a bearing on the cow, sheep or pig's physical health and the development of disease, and are therefore automatically included in the large animal veterinary surgeon's remit. Not so for the domestic dog, which may be skidding uncomfortably on a fashionable laminate floor, subjected to the impact of noise from a multitude of household gadgets, or contained and punished with electric shock, and yet its small animal veterinary surgeon be completely unaware of its plight. How can we truly say such animals are 'under our care' if this is the case?
Sigmund Freud loved dogs, according to Ernest Jones, his biographer, because they were never ambiguous. The literature is unclear if Jones recorded this before or after he was bitten in the buttocks by a Freudian dog.
There can be physical effects to pet interaction, clearly at the border of physical and emotional states. Clinical trials, in this area, are challenging, in that there is no way to provide a placebo control. Studies have also been small.
One small study found that while the adrenergic beta-antagonist, lisinopril, lowered resting blood pressure, patients with pets and lisinopril showed a lesser blood pressure elevation than the lisinopril-only group.  Blood pressure, as well as depressive symptoms, decreased with institutionalized geriatic patients that had thrice-weekly interactions with a cat. 
There is more and more work in understanding the emotional aspects, including the role of animals in psychotherapy. A Belgian psychoanalytic presentation, by an analyst and his dog Broodje, a Bouvier dog about which he said,
Now Bouviers have something in common with Jews. Hitler hated both the Jews and the Bouviers. It turns out that a Bouvier bit Hitler when he was a soldier during the First World War. Does anyone question the intelligence of this breed?
Hitler's very first decree upon entering Holland and Belgium called for the destruction of the Bouviers des Flandres. His second decree concerned the Jews. Astonishingly, ... enough of the breed was taken into hiding, during the war, which saved the Bouviers from complete extinction. Their fate was not unlike that of the Jews of these countries. The fact that people were willing to risk their own lives to save dogs is a testimony to the capacity to survive and the endurance of affection between people and animals. The human-animal bond.
I believe the human animal bond offers a unique emotional communication and I am going to talk about it in a variety of ways.
- Animals are intimates because they cannot talk.
- Animals keep their silence and they bear witness.
- Animals say no words that hurt
- Animals offer no advice and ask no questions
With advances in veterinary medicine that extend the life of companion animals, there is more time for intense relationships to build, and also new challenges in animal quality of life. A substantial percentage of geriatric cats develop cancer and other illnesses that can benefit from intensive treatment, yet there are cost and other issues that make matter even more complex, in some respect, than in human medicine. While euthanasia is not always an option in human medicine, it is a frequent and difficult consideration in veterinary practice. Hospice and palliative care, however, is also a veterinary option, but is not familiar to many owners and veterinarians.
Extended lifespans, however, are not unique to one side of the bond. People have long been likely to outlive domestic pets, although this becomes more problematic with older people and longer animal life spans.
A special challenge comes when the bond is deep, but the human, for economic or medical reasons, needs to move to alternate housing that does not permit pets.
A different aspect to the accommodations problem comes in disaster situations, either during rescue or in emergency shelters. In a number of recent natural disasters, people refused to be rescued without their animals. The United States Coast Guard has changed its policies, recognizing that they may lose a human life if they fail to save an animal life. There are more emergency housing facilities on Cape Cod, Massachusetts, which have a "pet-friendly policy" than those that refuse to accept pets.
- Human-Animal Bond, American Veterinary Medical Association
- Hachiko Statue, Destination360
- Kendal Shepherd (19 August 2008), "The role of the companion animal veterinary surgeon in behavioural husbandry", Acta Veterinaria Scandinavica 50(Suppl 1): S12, DOI:10.1186/1751-0147-50-S1-S12
- Joel Gold, and Broodje, A speech written by Dr. Joel Gold, Ph.D., former director of IEA, and presented at an IEA conference. A very big dog named Broodje helped Dr. Gold give this presentation., Institute for Expressive Analysis
- Karen Allen; Barbara E. Shykoff; Joseph L. Izzo, Jr. (2001), "Pet Ownership, but Not ACE Inhibitor Therapy, Blunts Home Blood Pressure Responses to Mental Stress", Hypertension 38: 815
- Stasi MF, Amati D, Costa C, Resta D, Senepa G, Scarafioiti C, Aimonino N, Molaschi M. (2004), "(Abstract) Pet-therapy: a trial for institutionalized frail elderly patients", Arch Gerontol Geriatr Suppl 9: 407-12
- "Older people and companion animals", Elderly Client Adviser 9 (4), 14 Jun 2004
- Volunteer briefing, Cape Cod Medical Reserve Corps, 2010