Taking a pet everywhere for emotional support is all the rage, but experts warn animal welfare is at risk of being overlooked.

The use of emotional support animals has boomed in recent years, with many cases hitting the headlines, including the peacock denied a seat on a United Airlines plane.

The focus on human needs shouldn't mean the impact on animals isn't taken into account.

Dr Elena Ratschen is an associate professor in health services research at the University of York and her work has explored animal-assisted interventions.

The benefit of the human- animal relationship needs to be reciprocated in the best possible way.

Many countries, including the UK, do not have the same laws that protect assistance animals as they do for emotional support animals.

They are often pets who help to mitigate the impact of their owner's physical or mental health condition through everyday benefits of human- animal interaction.

There are a number of studies that suggest animal ownership may bring health benefits. Studies suggest that interacting with pets can bring positive effects, such as lowering blood pressure or increasing levels of oxytocin, a hormones associated with bonding.

It was difficult to conduct large, randomized controlled studies of emotional support animals. It is hard to conduct rigorous studies in this field.

A pilot study involving 11 people with serious mental illness was done with a rescue dog or cat. The results suggest the participants experienced an improvement in their mental health, with reductions seen in anxiety, depression, and loneliness, but the pilot was small and lacked a control group.

Being out and about could put animals in situations that cause them stress, a particular concern where undomesticated animals are concerned, which is one of the main concerns raised by Hoy- Gerlach.

She said that service animals such as guide dogs are given plenty of preparation to help them cope.

Ratschen said yes. If we say that animals are allowed to travel on aeroplanes, for example, crowded places where animals are not normally accepted, you could think that this will cause substantial stress on them. Do you think the peacock liked it? It's probably not.

Creature comforts: has the US's emotional support animal epidemic gone too far? – video