After the antidepressants and the hours of therapy, Marco has turned the corner and is a whole new dog.
Gone are the panic attacks, the violent mood swings and the uncontrollable salivating.
Marco is one in a growing number of pets undergoing psychological treatment and taking mood-altering drugs.
"A year down the track and we've got a really affectionate, playful dog that I can't wait to go home and see," his owner Sandy Junior, of Alexandria, said.
The Maltese terrier's journey to a new leash on life has included courses of Prozac and trazodone and ongoing behavioural therapy.
Dogs, however, are not the only pets on the road to recovery.
Cats that obsessively chase their tails, birds that pluck their feathers and puppies with phobias are increasingly receiving treatment for their troubled minds at clinics around the country.
The argument that animals can suffer mental illness and, in a way, are comparable to humans is one put forward by US science historian Laurel Braitman in her new book Animal Madness.
After Dr Braitman's anxious Bernese mountain dog Oliver leapt out of a fourth-storey window, she travelled around the world researching emotionally disturbed animals and their stories of recovery.
There was Charlie the feather-plucking macaw, who fell out of a tree and impaled himself on a metal pole; Gigi the chimp, who suffered panic attacks after being bullied by a male chimp; and Gus the polar bear, who compulsively swam in circles.
"I don't think we've truly made peace with the idea that humans are just another kind of animal," Dr Braitman said on the phone from San Francisco.
"I don't think we are the same as wombats or walruses, but I think we have more similarities than we tend to acknowledge and when it comes to emotional health and wellbeing, it's yet another blow to the idea of human exceptionalism."
Giving pets drugs and therapy is an extension of a pet-care industry that already offers day care, five-star hotels and gourmet food options at restaurants.
"Worldwide, there's becoming a greater awareness of mental illness in animals and that's not just within the veterinary profession, it's within the community as well," said behaviour consultant Andrew O'Shea, who runs a clinic in Camden, south-west of Sydney.
The treatment of emotionally unwell pets commonly involves a mixture of antianxiety and antidepression medication, and ongoing therapy, when techniques for relaxation, mindfulness and combating triggers are taught.
"One in five humans has an anxiety disorder and approximately one in five pets has an anxiety disorder," Dr O'Shea, the former president of the Australian Veterinarian Association's behavioural group, said.
"I really think this is an area where we can make a massive difference to how much these pets enjoy their lives."
Stephen Muscat, from Leichhardt, would have once laughed at the idea that his dogs Jaspa and Snickers needed Prozac to cope with their anxiety.
After years of treatment at the Sydney Animal Behaviour Service and a "myriad medicines", his pooches have a calmer approach to life.
"I was very sceptical at first that an animal could have a mental illness," Mr Muscat said.
"To be honest, it just seemed like one of those buzz things – a fad that comes and goes – but then I started to see the proof. Snickers is definitely happy; Jaspa is more of a work in progress. It's been an eye-opening experience."
The idea that animals could lose their minds had already changed how zoo enclosures, farms and laboratories were designed, said Jacqui Ley, a Melbourne specialist in veterinary behavioural medicine.
There was an increasing amount of research looking at the mental anguish animals could endure and Australians were leading the way in their approach to the subject, Dr Ley said.
"When we first discovered that dogs and cats could have diabetes, people didn't believe it," she said. "Now it's accepted.
"Our understanding of animals' mental health is getting better and I think, with time, it will become mainstream to inquire not only about how well your pet is physically, but how it is doing mentally."
Animal Madness will be released in Australia on September 29 by Scribe Publishing.
SIGNS YOUR PET MIGHT HAVE A MENTAL ILLNESS
- Repetitive behaviours like spinning in circles, pacing or excessive grooming.
- Phobias like fear of storms, vacuum cleaners, slamming doors and cars backfiring
- Self-destructive behaviour like making itself bleed by chewing the end of its tail
- Frequent and intense anxiety
- Inability to learn and difficultly being trained
- Ongoing aggressive behaviour
- Any sudden, major changes in behaviour
