This is a team of passionate animal lovers who truly love what we do. We don’t come in to work to earn a paycheck. We come into work to change and save lives. Now, get to know us.


Cassi K. Pettyjohn, B.S., D.V.M.

Veterinarian/Practice Owner

Dr. Cassi Pettyjohn grew up in a small town in Southwest Kansas. She graduated from Kansas State University in 2002 with a bachelor’s degree in animal science and in 2006 with a Doctor of Veterinary Medicine degree from Kansas State University College of Veterinary Medicine.

After graduation, Dr. Pettyjohn pursued a career in equine medicine, which took her to the great states of Iowa, Virginia, and Texas. After moving to the Houston area, Dr. Pettyjohn began to specialize in small animal medicine. Her special interests include dermatology, internal medicine, and dentistry.

She is married with 2 children, two miniature Australian Shepherds (Ankiel and Molina), one cat (Pudge) —all her animals are named after Major League Baseball Players. She enjoys spending time with her family and helping her husband around the farm.

Mandy Hall, DVM-MPH


Dr. Hall is ecstatic to call Stone Ridge her second home. After taking off a year to explore her interests in public health, she has happily returned to the Stone Ridge family.

Dr. Hall’s areas of interest are soft tissue surgery (including high quality, high volume spay and neuter), dentistry, internal medicine, and neurology. Her favorite aspect of veterinary medicine is being able to educate the public on caring for their pets to give them a long and healthy life.

When she is not at work, Dr. Hall can be found spending time with her husband and their two fur-children: Bruce and Perry.

Abby Knoll


Dr. Abby Knoll grew up in rural North Dakota on her family’s cattle ranch, which sparked her interest in veterinary medicine. She received her Bachelors in Animal Science at North Dakota State University and from there went on to receive her Doctorate in Veterinary Medicine at Iowa State University in 2018. Upon graduation, Dr. Knoll continued her venture south where she worked as an associate veterinarian at a mixed practice in north Texas, then a small animal practice in the Permian Basin.

Dr. Abby is excited to assist Stone Ridge Veterinary Medical Center’s clients and their pets with all their veterinary needs. Primary interests include internal medicine, preventative medicine, soft tissue surgery and dentistry.

When Dr. Abby isn’t working, she enjoys outdoor activities that include being out on the water, working out and spending time with her English Bulldog, Ruger.

Ana Teague


I was raised in a small rural town on the Gulf of Mexico and 10 minutes from the border of Louisiana. My mom and I rescued mostly cats, but also dogs, birds, small mammals, and even some farm animals from a young age. We decided to make our rescue official in 2017 and have taken in over 200 cats in the last 10 years. I graduated from Texas A&M University with my Doctorate in Veterinary Medicine in 2022. I accepted a position as an Associate Veterinarian at Stone Ridge Veterinary Medical Center after graduating.

I chose this clinic because of the care we provide to not just owned animals, but also shelter and rescue animals. I have many interests in the veterinary field, such as, soft tissue surgery, neurology, and cardiology. In my off time, I love to travel domestically as well as abroad as often as I can. I love to read, especially Stephen King books, and I am a huge fan of swimming and being outdoors.

“When I look into the eyes of an animal, I do not see an animal. I see a living being. I see a friend. I feel a soul.”

-AD Williams

Care Team

Mandy Spence, B.S.

Practice Manager

Mandy graduated from California State Polytechnic University, Pomona, with a bachelor’s degree in biology in 1994. After graduating from college, she moved back to her childhood home in Willis.

She currently lives in the Woodlands with her husband and pets, which include dogs, cats, and birds.


Veterinary Technician

Holly was brought up in Palestine Texas. Moved all around Texas, including Abilene, but eventually settled in Willis Texas. Holly recently completed her Bachelors in Animal Science at Sam Houston with a minor in Wildlife Management. She is married with three children who take up all of her extra time. Holly and her family also have a German Shepherd mix rescue named Kiera, a white boxer named Lacey, and a blue Quaker named Maize. She has a passion for animals since she was a little girl. She remembers playing vet with her Beanie Babies. When she was living in Abilene, she volunteered at the Abilene Zoo, which ignited her interest in exotic animals, including snakes. From there, she decided to pursue my degree. She loves all animals and is excited to provide love and care for them. If she were to have a side hobby, she would enjoy music and singing. She used to be a part of a praise and worship team at a church in Abilene. She also loves the outdoors whether hiking, fishing, shooting, or horseback riding.


Licensed Veterinary Technician

Born and raised in The Woodlands, Texas; I am a licensed veterinary technician. I graduated from LSC-Tomball with an Associates in Applied Science and a Veterinary Technology degree in 2011. I then got my Bachelors in Wildlife and Fisheries with an emphasis in Vertebrate Zoology from Texas A & M University in 2014. I love working with most exotics, but birds are my ultimate favorite! My passion in veterinary medicine is dentistry as well as client education; but all aspects of this field are fascinating and intriguing. I have three dogs, Wrangler, Cinch, and Keena; three cats named Quill, Groot and Dory; one horse named Red, and two quakers, Gunny and General.


Veterinary Technician

My name is Christy DuVall and I have been married for over 25 years to my husband, Jason. We have a daughter, Taylor and her husband Ryan who live in north Fort Worth. We are empty nesters who have a Boston named Durham, a dachshund mix named Beltre, two cats Stitch and Creed, and a few fish pets. I have been a Veterinary Technician since 1999.

Brenda, B.F.A.

Client Care Specialist

I was born and raised in a small Texas town. I attended Sam Houston State University where I earned a degree in Mass Communication. I am lucky to be in a profession that allows me to pursue an array of areas: animal advocacy, client relations, and social media management being my favorites.

Outside of work, I enjoy cooking and baking, tackling Pinterest projects, and celebrating all of the holidays. I currently reside in Huntsville with my college sweetheart husband, our spoiled rescue Doodle-mix Goldie, and our rotten felines, Duke and Eloise.


Client Care Specialist

Paige was born in The Woodlands but raised in Willis, Texas. She is currently attending school at Lone Star Community College. She has always had a special place in her heart for animals since she was a toddler. She has one dog, Ace, and two horses that she loves very much. In her free time she’s usually in the arena with her horses or out on Lake Conroe.


Veterinary Technician

I grew up in Spring, Texas for most of my life and slowly made my way up to the Huntsville area. I am currently a student at Sam Houston State University aiming for a bachelors degree in Animal Sciences and a minor in Equine Sciences. I have always enjoyed being in the presence of animals and strive to be apart of the change to make veterinary medicine better each and every day.


Licensed Veterinary Technician

Rhonda grew up on a farm in South Dakota where she learned she loved veterinary medicine. An accomplished barrel racer, she helped the local veterinarian to pay for her horses. She always loved animals and hand raised a fawn, several orphaned raccoons, bunnies and even a couple of foxes. She attended school in Arizona, and in 1989 she became a licensed technician. In 1995, she moved to San Antonio. Wanting to leave the city, she came to Stone Ridge in June of 2020. She has a special interest in feline medicine and behavior and uses a fear free approach. During her off time she is an advocate for wild mustangs, likes to hike, zipline and skydive.


Client Care Specialist

Lacey was born in Houston, Tx but was raised in Willis, Tx. She is married, has three children, and four dogs. Lacey decided to buy a house in New Waverly where she enjoys spending time with her kids and extended family.


Licensed Veterinary Technician

My name is Aubrey. I was born and raised here in Houston, Texas. I’ve been an animal lover since I was a child. I have a 10 year old daughter who loves animals almost as much as I do. I have 3 dogs (Riley, Max, & Sugar) and 3 cats (Tigger, KiKi, and Toby). I was in college & became a Nursing Assistant (for humans) in 2012 & worked at a Neurorecovery center for 4 years. I decided after that to pursue my ultimate passion of working with animals and went back to school to obtain my Associate of Applied Science in Veterinary Medicine. I recently passed the Texas State Board Exam to become a Licensed Veterinary Technician. I have major interests in anything neuro, but also exotics! Outside of work I enjoy games, watching cartoons, spending time with family and friends.


Veterinary Assistant

I am a Texas native. In high school, I was involved in FFA: I showed steer and pigs and participated in livestock judging. I am excited to start a career centered around helping (and cuddling) all the animals. I am currently a “CCS,” but I’m also training to be a technician assistant.

I currently reside in Willis with my high school sweetheart and a rescue feline, June Bug (Bug). My dream is to live on a farm with lots of farm animals and dogs.


Veterinary Technician

Born and raised on a cattle ranch Coldspring, TX. I am a veterinary technician. I graduated from Vet Tech Institute in 2016 with my associates of applied science and a veterinary technology degree. I love working in large animal medicine. Goats are my favorite. I have a Husky named Danica and a spaniel named Harry.


Veterinary Assistant

Tiffany was born in raised in the Conroe-Willis area. She has five years of experience with small animals and some experience with large and exotic animals. She takes interest in dentistry, pharmacology, and rehabilitation. Tiffany was employed with The Pet Resort in 2019, but took some time away to learn more on the medical side of the animal field and to be a stay at home mom. Always eager to learn, Tiffany is excited to be back in the Stone Ridge family!

At home, Tiffany is engaged to her high school sweetheart, Dillon. Together they have a one year old son named Lucas and a five year old Great Pyrenees, Rolex. The three of them take up a majority of her free time.


Veterinary Assistant

Hi my name is Shardria. I was born in Houston, but raised in the California sun. I have two dogs (Zeus and Ace) that are two goofballs.

I graduated from Willis High School from which I received my CVA.


Goodwill Ambassador

Push is our resident cat. He came to us as an orphaned kitten in 2013. One of our clients found him on a golf course with a seemingly broken leg. During his exam, he persistently “pushed” the technicians’ hands for optimum pets and scratches, earning him his name.

Push’s road to recovery started off bumpy with the possibly of a leg amputation in his future. The technicians and veterinarians nursed Push back to health, and his broken leg healed on its own- perks of being a strong, feisty kitten!

If he’s not napping in his cat tower, Push loves begging for dog jerky treats, greets clients and patients, and loves to investigate carriers as well as oversized handbags.