TUCSON, Ariz. -- About 800 small dogs, mostly Chihuahuas, were found in filthy conditions in an elderly Tucson couple's home in rural Avra Valley, Pima County sheriff's deputies said.

"This is the largest seizure that's happened in Pima County that I'm aware of," sheriff's Sgt. Terry Parish told the Tucson Citizen newspaper.

The situation came to light when a veterinarian called a woman who bought one of the dogs at the couple's residence to tell her the animal she brought in for an exam was ill and told her to notify authorities, deputies said.

Dozens of dogs were removed from the triple-wide mobile home on Monday, according to the Humane Society of Southern Arizona. Another 700 were rescued on Wednesday.

"That number of dogs in one home, it's beyond imagination," said Barbara Rebe, one of the pet rescuers.

The Humane Society said in some cases more than a dozen dogs were found stuffed into a single crate.

Authorities described the home as being in horrible condition, with urine and feces covering the premises.

The couple that owns the trailer where the animals were discovered has not yet been identified.

Workers said the elderly owners likely started as breeders with good intentions but got in over their heads and began hoarding.

Deputies also found about 80 parrots caged inside the trailer on the city's northwest side.

"That was total disbelief, total disbelief," Rebe said.

The Pima County Animal Control and the Arizona Chihuahua Rescue were among the other groups rescuing the animals and birds late Wednesday.

No charges have been filed but authorities continue their investigation.

The Humane Society said it is assembling pens at its shelter to house the dogs until permanent homes are found.

The group said it hopes to start putting the animals up for adoption in about two weeks.