SEATTLE — Five newborn kittens found abandoned on I-90 this July were quickly adopted out to their 'furever' homes.

When the kittens arrived at Seattle Humane's Pet Resource Center for emergency care, staff estimated the kittens were no older than five days and gave them a 50% chance of survival without their mother.

Alex McCall, 17, took care of three of the kittens found in a sack on the side of the freeway. He fostered Butch, Patch, and Coco for about nine weeks, bottle feeding them and helping them regulate their body temperature.

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"For the first couple of weeks, they were teeny tiny and they have to be fed every two hours. That was interesting, especially at 3 am when I had to drag myself out of bed. Now I'm ready for a child," he joked.

Luckily Alex had the time because he was home from school on summer break.

"A person who can be around 24 hours a day is tough to find. These kittens needed a very specific type of foster home where someone could be up and functioning every two hours," said Seattle Humane Foster Program Manager Christina Charlton.

As the kittens started to grow, they became more independent. Alex could leave them for longer periods without food. 

He admits giving up the kittens for adoption (on his 17th birthday) was bittersweet. But he considers the fact they survived and thrived a major win, and he's thrilled they were adopted into good families.

"It was kind of emotional all around, but it was a great experience and I loved every second of it," he said.

RELATED: Kittens ditched in bag on I-90 improving at Seattle Humane

More than 5,000 animals each year benefit from the Seattle Humane Foster Care Program. The organization has 1,300 fostering volunteers, but there is always a high need for more. Foster families are needed for a wide variety of animals including kittens, puppies, cats, dogs, rabbits, guinea pigs, and other small critters. Anyone with interest can apply online.

Charlton said any pet lover who is willing to try can make a good foster parent.

"We can find an animal that's a good fit," she said.

Time commitments can range from one to eight weeks. All you need is a little extra space and some spare time. Seattle Humane provides all supplies and any necessary medications.