San Diego, CA (KGTV ) -- An Otay Mesa father and dog owner says he did a double-take after he says surveillance video revealed who was hurting his dog.

Wherever Pupa the poodle mix goes, little Alfonso Jr.,3, and Regina,1, usually follow. Their father Alfonso Galindo calls the 7-year-old rescue a beloved member of the family, which is why his recent discovery was so tough to swallow.

"It's heartbreaking," said Galindo.

It all started when the strange stains that have been appearing for months appeared again last week in the patio of his home on Agosto Street. He checked his recently installed cameras and couldn't believe what he saw.

"I'm at a loss for words," said Galindo.

Just after 11 a.m. last Tuesday, surveillance video shows a postal carrier walks up to his mailbox and past the metal front gate. Behind the gate is Pupa. As the mail carrier places the mail in the mailbox, you can see a cylindrical something in his left hand. At the same time, from another camera, you can see Pupa behind the gate begin to convulse for several minutes.

"The dog is withering in pain ... makes me sick to my stomach," said Galindo.

Galindo says he searched through his videos - about a month's worth - and found nine similar incidents, where his dog convulses after the postal carrier walks by. Galindo believes the mail carrier was casually and quickly spraying the pepper spray at Pupa's face.

"It's a total betrayal of the trust. You would think the Postal Service is somebody you can trust," said Galindo.

Galindo went through the last few months in his mind. Pupa did sometimes turn up with red eyes, but it would always go away. But was someone else in the home hurt? In the last six months, both of Galindo's children - who are constantly touching and hugging Pupa - have developed mysterious respiratory problems.

"Countless trips to the ER and Urgent Care, and countless medications," said Galindo.

Galindo now believes he knows the cause.

"I get livid thinking about it. This is the health of my children," said Galindo.

He's filed a complaint with the Postal Service, along with a police report.

"I believe what he's done to our family is criminal," said Galindo.

A Postal Service spokesperson says they've begun a internal investigation. Anyone who thinks their pet may have been pepper sprayed in that same area is asked to call San Diego Police at 619-531-2000.