Texas is a very energetic, smart and playful German shepherd dog. "He always tries his best to please me," said his owner Helene Bäckman.
But when Texas was six months old, Helene noticed that he started to behave unusually.
He started to jump and bite the air repeatedly.
"It´s like he sees something. He jumps and when he´s biting, he bites hard," she said.
"You can hear his teeth against each other.
"He can do this for hours and he gets more and more stressed when he´s doing it. He never rests between jumps."
The reason for Texas' unusual behaviour? Obsessive compulsive disorder (OCD).
OCD is well described in humans and the dog version of the disease presents with similar repetitive behaviours.
Whereas people might wash their hands multiple times or hoard objects, dog symptoms include constantly chasing their own tails or shadows, blanket sucking or repeated grooming.
Texas' symptoms include a behaviour called fly-catching.
This is where dogs snap or chomp at the air as if they're trying to catch imaginary flies.
"It hasn't been easy to get him diagnosed because nearly all people around me have said that just the way he is," said Helene.
"I live in the north of Sweden and had to drive 700km to [the vet who diagnosed him] in Stockholm."
OCD is one of hundreds of disease which the domestic dog suffers from that presents in a very similar way to the human form of the condition.
Other 'human' conditions that dogs are susceptible include:
Although seeing our canine companions suffer may be upsetting, these shared diseases mean that dogs are emerging as one of the most important animal models of human hereditary diseases, advancing our understanding and paving the way for new therapies.
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