kris van cleave has more on a volunteer-led effort to ease the strain. >> reporter: across the navajo nation's 27,000 square miles, spread over three western states, there's a health care crisis playing out on their rural desert lands. there's an estimated 500,000 dogs and cats, many free roaming, and only three veterinarians. >> thank you for coming out. and helping our dogs. >> reporter: volunteers from the parker project across the u.s. make regular trips to the navajo nation. >> let's get some vaccines. >> reporter: going door to door checking on pets, offering vaccinations and regular pop-up clinics providing treatment and helping ing spay or neuter arou 70,000. >> i saw happy young dogs, adult animals. they needed vaccines. i saw gracious, happy to interact with us owners and locals. >> reporter: nationwide, there are signs of a veterinary shortage. costs are rising. some estimates say the u.s. could be 24,000 vets short by 2030. for dogs like ruby, getting veterinary care can be a challenge up here in northeastern arizona. there's one vet nearby. with limited hours. otherwise,