SANTA CLARA, Calif. -- A new movie set to hit the big screen is raising some major concerns over how it could contribute to the already skyrocketing number of Chihuahuas ending up at animal shelters.

Right now four out of every ten dogs up for adoption at the Humane Society Silicon Valley are Chihuahuas or Chihuahua mixes. Most were left at the shelter by owners who were moving or couldn't afford them anymore.

Workers at the humane society worry the new Disney movie 'Beverly Hills Chihuahua' could both help and hurt the Chihuahua explosion.

Adopting a dog brings a whole cage full of options.

My son is looking for a dog. He's not sure which type. He's leaning towards the small ones right now," said Jez Caampued, who was looking at possible new pets at the humane society with her son, Kenneth.

Workers at the Humane Society Silicon Valley hope the small dog they decide on is a Chihuahua. In the last year, more than 500 of the 2,000 dogs up for adoption have been that breed.

"The new throwaway pet is the Chihuahua," said Humane Society Silicon Valley spokeswoman Laura Fulda. She says Chihuahuas have replaced pit bulls as the most common unwanted breed. She believes the new Fido fad is a result of celebrity Chihuahua owners like Paris Hilton.

"What a lot of people forget is they're not an accessory. They're an animal," said Fulda.

Workers at the Humane Society Silicon Valley think 'Beverly Hills Chihuahua,' which opens this weekend, could either help or hurt the problem.

"Chihuahuas are hard to adopt right now, just because there's so many of them out there," said humane society employee Beth Ward. "I'm afraid what people are going to do is find Chihuahuas through other ways and maybe not get the education they need. And then we'll end up seeing the Chihuahuas come through our doors at a later time."

Laura Fulda has similar concerns: "If you're inspired after seeing this movie to go out and get an adorable Chihuahua, think first. 'Do I really have the time to put into this dog?' If you do and you still really want one, we encourage you to adopt a dog from a shelter."

The shelter will be playing an advertisement in several South Bay movie theaters before and after the movie encouraging people who want to adopt to come to shelters.

The shelter says it will not euthanize any Chihuahuas not adopted, but will keep them here until they find homes.