It is every pet owner's nightmare.

On New Year's Eve last year, insurance broker Harry Verveniotis, 27, was on his way home early; he wanted to make it back to his two-year-old Italian greyhound, Lucia, before the fireworks started.

There are paddocks behind his home in Sunshine West, Victoria, and Mr Verveniotis said there were a few families out getting ready to launch fireworks of their own in the space.

He did not make it in time.

"My dad called me about 9:20pm and he said, 'Look, Lucia's gone', and immediately my heart dropped," he tells the ABC.

Mr Verveniotis thinks Lucia escaped during early rounds of fireworks near his home. ( Supplied )

"It would have been very live and very loud for her. I think that's when she ran out — when the first round went out.

"I checked everywhere in the house twice and then I just got in the car, put my high beams on and started driving around calling her name out.

"I had her little squeaky toy and I was squeaking it, just hoping she would pop up.

"I did that for about an hour, then I got home and made about 200 posters, printed them out and then went out again straight after the fireworks and put posters on every pole on my street, and [nearby shops], just anywhere."

He says he did not get home until 5:00am on New Year's Day — but even then he only managed to sleep for two hours, before getting up at 7:00am to look for Lucia again after the sun had risen.

Three weeks have passed, and Mr Verveniotis is still looking for her.

He says he has posted about Lucia on about 12 lost dogs pages on Facebook, and put up "missing" ads on Gumtree, the Trading Post and Facebook Marketplace.

He is visiting Melbourne's Lort Smith Animal Hospital, the RSPCA and the Lost Dogs' Home daily.

Mr Verveniotis made about 200 posters after Lucia went missing. ( Supplied )

He says he has sent emails out to local vets asking them to keep an eye out for Lucia. And he has door-knocked every street in his area, with the help of Sunshine West locals.

"It took me obviously a week to do, but I printed out a map and I highlighted every street that I doorknocked," he says.

All to no avail.

Time is running out — Lucia needs medication

Mr Verveniotis says Lucia needs weekly medicine for her heart condition and epilepsy and only has about 30 days until she will be at risk of experiencing seizures. After that, he says she will eventually stop eating.

"I hope that when she does have the seizure, someone has the heart to take her in," he says.

And so, the search continues. But underneath all the organisation, Mr Verveniotis is struggling. Losing Lucia has taken a toll on his mental health.

"It's getting harder day-by-day. Because I always go [to the shelters] with my hopes up. I'm always envisioning that I'm going to find her. I'm shattered every time I go and it's not good news," he says.

Mr Verveniotis says last year was one of the toughest in his life. He lost a grandparent he was very close to and broke up with his partner. He lost 12 kilograms as a result and was taking medication for anxiety and depression.

But throughout it all, he had Lucia.

"Thank God for Lucia, because she was the only one who got me through it. There were days that I was not wanting to be alive," he says.

"But looking at Lucia … I can't explain it. She could tell. She could read every single time I was down or upset or emotional. There were times I was crying on the couch, and Lucia would come on my lap and lick my tears.

It is not clear how Lucia escaped, but Mr Verveniotis thinks she may have slid under a gate. ( Supplied )

"The only way I got through things was because of Lucia, and this is why right now I'm doing everything that I can."

In Lucia's absence, Mr Verveniotis says he has not been able to sleep properly due to anxiety and constant nightmares.

He is now back on his previous medication and having regular meetings with his psychologist.

His appetite has been affected, and he also injured himself while searching for Lucia the day after she went missing, out of exhaustion.

"I got home at 4:30am and I was exhausted, sleep-deprived and I was in tears because how could this happen? So I closed my car door on my thumb and then had to go to the emergency room [for treatment]."

Mr Verveniotis has since undergone an operation on his thumb to remove the nail to make sure it wasn't infected.

Losing a pet can be 'as intense as losing a loved one'

Judith Murray, a grief and mental health researcher with the University of Queensland's school of psychology, says that for many people, the experience of losing a pet can be "as intense as losing any kind of loved one or relative".

"And for some people, [it can be] more intense because sometimes they've actually developed more of a relationship [to the animal] than they have with other human beings, particularly if they're isolated, lonely, elderly, children who've been abused," she says.

If this grief is not heard, the person experiencing it "can feel so much worse," she says: "They feel bad because the world around them tells them they shouldn't feel like that. And that makes it worse because they try to pretend it's not there or they become isolated."

Associate Professor Murray says feelings of grief after the loss of an animal are sometimes dismissed as people tend to "rate" the grief of others.

"But you can't rate someone's grief," she explains. "For example, if someone has a miscarriage or has an abortion or something like that, that is not given the same distress as, say, someone who has a stillbirth. Yet, for the person, if they've had fertility treatments, this can be absolutely as massive.

"And so, people who don't necessarily have that very intense attachment to animals don't see it as important."

So, how can we help those around us going through the loss of a pet?

Associate Professor Murray says the answer lies in listening — rather than trying to "talk grief away".

"Listen, listen, and accept. And don't judge it or try and fix it. Grieving is a natural, normal process. It's the most powerful human process that we have.

She recommends "letting people grieve the animal that's gone, letting them deal with the memories, letting them talk about it and letting them find ways of honouring that pet, [rather than] trying to dissolve it".

"You just need to treat it as you would let someone talk about someone they love. Because this is someone they love."

With Australia Day approaching, 'make your pet your priority'

While Mr Verveniotis says he is not sure how Lucia got out as she is an inside dog, but he suspects she may have squeezed through a gap under a side gate after the fireworks started, when she was out the back relieving herself.

He says the gap is small, but that animal shelter workers have told him "they've heard stories of animals doing impossible things just to get out of any situation — especially when fireworks are happening".

Mr Verveniotis is visiting animal shelters daily in the hope of finding Lucia. ( Supplied )

With less than a week to go until Australia Day, he is warning pet owners to make sure their animals are their priority on the day.

"It's good to have family time and to celebrate, but people don't realise how important this is until it happens to them," Mr Verveniotis says.

"Last year with the fireworks it was the same scenario, it was pretty loud, but what I did was I was with Lucia and I had her with me on my lap to keep her comfortable.

"This time I was on my way to be there for the big New Year's Eve fireworks, but for some reason, they run early fireworks as well. So I didn't make it in time."

How to protect your pets when fireworks are happening

"[Fireworks displays] can indirectly pose risks to animal safety by causing them to take flight and try to escape the loud noises," acting RSPCA Victoria chief executive Tegan McPherson says.

"Dogs have been known to jump through plate glass windows to escape loud noises, and easily jump over, or dig their way under fences that would normally contain them."

Ms McPherson says the RSPCA recommends dog owners:

Prepare early

Prepare early Talk to your vet about treatment options for managing noise phobias

Talk to your vet about treatment options for managing noise phobias Take your dog out for exercise before the fireworks start

Take your dog out for exercise before the fireworks start Stay home with your dog if you can, remain calm and perform your normal activities

Stay home with your dog if you can, remain calm and perform your normal activities Keep them inside if possible

Keep them inside if possible Distract your dog with games and food

Distract your dog with games and food Do not punish your dog if they show signs of fear and distress

Do not punish your dog if they show signs of fear and distress Never tether your dog during these times and never use a choke chain to restrain your dog

Never tether your dog during these times and never use a choke chain to restrain your dog Make sure your dog has an up-to-date microchip and ensure they are wearing an ID tag with up-to-date contact details

The animal welfare organisation recommends cats:

Are kept comfortable indoors during fireworks displays

Are kept comfortable indoors during fireworks displays Have access to safe and comfortable places to hide

Have access to safe and comfortable places to hide Have an up-to-date microchip in case they escape and get lost

What should you do if your pet goes missing?

Ms McPherson says the best things to do when looking for a missing pet are to carefully search your home, including any unusual places they have access to.

She advises telling family, friends and neighbours that your pet is missing and showing a recent photo of your pet to them, as well as walking around the neighbourhood calling your pet's name.

As Mr Verveniotis did, the RSPCA recommends making a detailed missing pet flyer and posting it around your neighbourhood.

On top of this, Ms McPherson says it is important to make sure your pet's microchip details are current.

She says the RSPCA recommends contacting your local council, animal shelters in your region and surrounding areas, reporting your lost pet to RSPCA online or calling your local shelter, your local vet, local paper and listening to your local radio station.