Our Team in Annapolis, Towson and Columbia

At AVIM&O, we are proud to have an outstanding team of internal medicine and medical oncology specialists. They dedicate their energies and combined knowledge as committed professionals to the care of their patients and support of their clients. Continuing Education (CE) also plays a large role in keeping them at the forefront of internal medicine and oncology, because the veterinary field is constantly changing. Our team of veterinarians and staff engage fully in their love of veterinary medicine and its relationships at an extraordinary level. 


mark hitt dvm

Dr. Mark Hitt, Internal Medicine Specialist- Diplomate of ACVIM

In 1992, Dr. Mark E. Hitt started Atlantic Veterinary Internal Medicine in Annapolis, Maryland. Dr. Hitt was born in Rockville, Maryland. He graduated from Iowa State University in 1979 with his Doctor of Veterinary Medicine degree. After working in general, small animal veterinary practices in Fort Lauderdale, FL and Richmond, VA, for 4 years he decided to continue his education and was accepted to a residency program in veterinary internal medicine at the University of Missouri College of Veterinary Medicine. This program was completed in 1986. Dr. Hitt was invited to apply for the first internal medicine position at a new veterinary college, the Atlantic Veterinary College at the University of Prince Edward Island in Canada. In this role, he participated in the development of the clinical facilities and curriculum from the ground up. This was a unique and rewarding experience. He then went on to serve terms as chief of the internal medicine section, head of the critical care unit, lecturer in several areas of internal medicine, and the leader of the small animal practice rotations for senior students. During his stay with the AVC, Dr. Hitt earned an MS degree in the Department of Pathology and Microbiology. Promotion to associate professor and tenure were granted in 1991. But after almost seven years, the Hitt family decided it was time to move back “south” to the United States. In 1992, Atlantic Veterinary Internal Medicine joined  with other specialty groups in Annapolis to form the umbrella organization of Chesapeake Veterinary Referral Center, LLC. The second center was opened in the Baltimore area in 1998, joining the Annapolis location.  Dr. Hitt has contributed as an author for  many  textbooks on topics of internal medicine and has published many articles in the veterinary literature over the past years. In past years, he also served as a reviewer for veterinary journals. He continues to be invited as a contributor to veterinary textbooks and frequently lectures on topics of Veterinary Internal Medicine at local, regional, and national veterinary meetings. Although practicing in all areas of internal medicine, his particular interests are in endoscopy, abdominal ultrasound, and diseases of the gastrointestinal tract and liver.

adam gonzales dvm

Dr. Adam Gonzales, Internal Medicine Specialist- Diplomate of ACVIM

Dr. Gonzales was a specialist in northern Virginia before relocating to Atlantic Veterinary Internal Medicine in 2005. He completed his residency training at the Veterinary College at Tufts University. He has strong interest in urinary diseases, along with diagnostic testing and procedures, and is skilled in endoscopy and diagnostic laparoscopy. However, he maintains interests and skills in all aspects of veterinary internal medicine. He is also an avid snowboarder, and has managed to avoid getting hurt (so far).

john paola dvm

Dr. John Paola, Internal Medicine Specialist- Diplomate of ACVIM

Dr. Paola is a native of Pittsburgh (Go Steelers!) and a graduate of the Michigan State University (Go Spartans!) College of Veterinary Medicine.  He worked as a general veterinary practitioner in Pittsburgh for two years after graduation, before moving on to an internship at the Ohio State University (Go Buckeyes!).  This served as a springboard to a residency in small animal internal medicine, also at Ohio State. He passed the certifying examination for the American College of Veterinary Internal Medicine upon the completion of his residency.  After three years as an internist in Pittsburgh, he moved to Annapolis and joined AVIM in 1997. 

A project completed during his residency allowed him to develop a strong interest and ability in gastrointestinal endoscopy and disorders of the GI tract.  While other areas of special interest include hypercalcemia and hematologic disorders, Dr. Paola has maintained a broad interest in many aspects of small animal internal medicine. 

Outside the clinic, his life is enriched by his wife and their two young daughters. The newest additions to the family are two guinea pigs, Snickers and Marshmallow. Dr. Paola is a very proud third-generation Italian-American, and recent travel to Italy has advanced his interest in the Italian language and all things Italian.

janet peterson dvm

Dr. Janet Peterson, Specialty in Oncology- Diplomate of ACVIM

Dr. Peterson is a native of Texas. She completed a veterinary residency in oncology with “the” Ohio State University’s College of Veterinary Medicine. She passed her specialist examinations in 1994. After that she has been recruited to practice in specialty veterinary cancer medicine in California, Texas, Kansas, and finally Maryland. She is now a  happy “Marylander”. Dr. Peterson deals with all areas of veterinary oncology and works with the other specialists of the referral center as well as other specialists in the region to create an integrative multimodality approach to the treatment of cancer. She believes in providing and discussing with owners all options of treatment for cancer before a decision is made as to which plan is appropriate for your pet.

dr. kyle renaldo

Dr. Kyle Renaldo, Practice limited to medical oncology

Dr. Renaldo received his DVM from Kansas State College of Veterinary Medicine in 2013. He obtained his Master of Science degree at Ohio State University, where he also had his medical oncology residency. He received additional training during his rotating internship at the University of Georgia and during his oncology internship at Blue Pearl in Florida.

Dr. Renaldo’s decision to pursue veterinary medicine in college was prompted by an externship he did with the family pet’s general practitioner. Seeing the clients’ gratefulness and experiencing the challenges of the fast-advancing cancer medicine field influenced his decision to then pursue a residency in oncology. His own pet passed away from splenic hemangiosarcoma while he was in high school, and this prompted his initial interest in oncology.

One of the most rewarding aspects of working in veterinary medicine and oncology for Dr. Renaldo is helping people through difficult decisions on behalf of their pet, and experiencing the joy of watching them see their pet survive or at least have a significantly prolonged life after treatment. His ability to communicate with clients and demonstrate empathy in difficult situations is a key strength in medical oncology.

Dr. Renaldo does not currently have pets but is looking to get a Bernese Mountain Dog when his training is over. A Florida native, he loves the beach and living near water, and is also an avid Tampa Bay sports fan (Tampa Bay Rays baseball and Tampa Bay Lightning hockey). Outside of work, he enjoys spending time with his extended Italian-American family from the New York/New Jersey region.


anthony calo dvm

Dr. Anthony Calo, Practice limited to medical oncology

Dr. Calo obtained his DVM degree from Ross University School of Veterinary Medicine in 1999. He interned at the University of Minnesota College of Veterinary Medicine from 1999 to 2000, completed his residency at Cummings School of Veterinary Medicine at Tufts University in 2004, and won the Jules and Lucy Silver Animal Bedside Manner Award in 2003. When he was a child, his parents took him to see 101 Dalmatians. Immediately afterward, he told his parents that he would take care of animals when he grew up. He never strayed from this path. Animals have been ever present in his life, ever since he saw that movie.

Dr. Calo loves figuring out each case. This encompasses the medicine aspect, but, just as important, it means getting to know the emotional and physical characteristics of the patient and the specifics of their family in order to make the best decisions for each individual case. He takes the bond-centered approach to his practice, because the human-animal bond is the foundation of all veterinary medicine. This is especially important in the field of medical oncology.

Dr. Calo lives with his partner of 9 years, William O’Connor, who is an artist, interior designer, and all around creative force. They have 5 pets: Daisy, a 12-year old Yellow Lab; Violet, a 6-year old French Bulldog; Henry, a 3-year old Black Mouth Cur; Emilio, an 18-year old Devon Rex; and Liza, a 7-month old domestic shorthair. Outside of work, he enjoys photography, reading, art, and comic books.

mariah frank dvm

Dr. Mariah Frank, Practice limited to internal medicine

Dr. Mariah Frank was born in Germany on a military base and has lived at bases all over the United States. Her family settled in Maryland in 1994 and she earned a bachelor’s in animal science from the University of Maryland College Park in 2001. She earned her veterinary degree from Ross University in 2007 after spending 3 years in St. Kitts and finishing her year of clinical work at The Ohio State University. Following graduation she completed a 1 year rotating medicine and surgery internship at Metropolitan Veterinary Hospital in Akron, Ohio. She then completed a 1 year internal medicine internship and 3 year internal medicine residency with Northeast Ohio Internal Medicine in Akron, Ohio.

When she is not working, Dr. Frank enjoys spending time with her furry friends: Meisha, (shepherd mix), Piper (Jack Russell Terrier), and Luna (an island dog she picked up while going to school at St. Kitts). She also enjoys horseback riding, hiking and rock climbing.

nivia martinez dvm

Dr. Nivia Martinez, Internal Medicine Specialist- Diplomate of ACVIM

Dr. Martinez was born and raised in Puerto Rico. She graduated magna cum laude with a degree in Biology from the University of Puerto Rico, Rio Piedras Campus, in 1988, and received her DVM degree in 1992 from Ohio State University. Dr. Martinez has always wanted to be a veterinarian, as far back as she can remember. Having grown up in a culture where pet ownership is very different from what it is here, her goal was to change the mentality of those around her and change the way pets are treated. She decided to pursue specialty certification for a more challenging career. After graduating from veterinary school, she spent a year working at a private practice, then attended Purdue University in West Lafayette, IN, to complete a one-year rotating internship in small animal medicine and surgery. In 1999, she began her small animal internal medicine residency and pursued graduate studies at the Virginia-Maryland Regional College of Veterinary Medicine in Blacksburg, VA. During her residency, she received the Bente Flatland Memorial Award in recognition of her clinical abilities and compassion toward pets and their owners. Following the completion of her residency, Dr. Martinez received her Master’s degree in Veterinary Clinical Studies in 2002. She stayed at the VMRCVM for another year as a clinical instructor in the areas of neurology and internal medicine, and joined AVIM&O in August of 2003. Something she finds most rewarding about her profession is knowing that she can make a difference in peoples’ lives by giving them answers to help them make decisions. Her greatest accomplishment is realizing that what matters are not things, but experiences and relationships.

Dr. Martinez has no children, but she comes from a large family and enjoys the company of several nieces and nephews, who keep her very busy. She shares her house with Ramon, a male miniature Dachshund; she believes the world would be a happier place if everyone owned a Dachshund. When she’s not at work, Dr. Martinez can usually be found at the gym practicing Extreme Personal Fitness (XPF), or at food/wine tastings. She is a member of the Maryland Tasters Guild and several other groups that gather together to eat, taste wine, and share experiences. At least once a year, she travels to some of the most remote locations she can find to experience different cultures. Her travels have taken her to Russia, Mongolia, Southeast Asia, and most recently, Cuba. There are still many places she wants to see.

dan petrus dvm

Dr. Dan Petrus, Internal Medicine Specialist- Diplomate of ACVIM

Diplomate American College of Veterinary Internal Medicine – Specialty of Internal Medicine Dr. Petrus completed an internship at North Carolina State University and a three year residency with the veterinary college at the University of Wisconsin. He joined AVIM after a 3 year teaching fellowship with the Royal College of Veterinary Medicine in London, England. Dr. Petrus  has traveled extensively in the world, having lived and visited about every continent.  This continues to be a pursuit in his out of clinic time. He also bikes a lot in the Baltimore area.  Dr. Petrus has a strong interest in medical endocrinology (study of hormonal related diseases) and their interactions with other diseases and disorders of the body. But he likes all areas within internal medicine and sees a diversity of problem cases.

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Dr. Natalie McLewee, Internal Medicine Specialist- Diplomate of ACVIM

Dr. McLewee earned her DVM from the Ross University School of Medicine in 2013. She completed an internship in small animal internal medicine at Friendship Hospital for Animals in Washington D.C., and followed this with her small animal internal medicine residency at Mississippi State University. At a very young age, Dr. McLewee knew she wanted to be a veterinarian and began working at a veterinary hospital when she was just 15 years old. She is proud to know what her life’s purpose is, and finds fulfillment in her career every day. Helping animals and getting to know pet owners are very rewarding aspects of her job, and Dr. McLewee loves being surrounded by people who love and care for animals the same way she does.

Dr. McLewee and her husband, Kevin, have one son named Jackson, and two Pitbull mixes named Roxy and Hooper. In her free time she enjoys spending time with her family, taking trips to the beach, going to athletic events, trying new restaurants, sailing, and exploring her artistic side.


frederic jacob dvm

Dr. Frederic Jacob, Internal Medicine Specialist- Diplomate of ACVIM

Dr. Jacob earned his DVM degree from the University of Montreal in 1995. He interned at Washington State University, and carried out his residency and received his PhD at the University of Minnesota. He and his wife, Kristin Jacob, a cardiologist with CVCA, have twin sons, and a dog named Rico. When he’s not at work, he enjoys running, biking, and traveling.

michelle silver dvm

Dr. Michelle L. Silver, Specialty in Oncology- Diplomate of ACVIM

Dr. Silver completed her residency with the New England Veterinary Oncology Group and earned her DVM degree from Iowa State University in 2004. Like most veterinarians, she realized that she wanted to work with animals at an early age. Her passion for oncology came about after her childhood dog was diagnosed with lung cancer while she was away at vet school. She was immediately drawn to the specialty because of the wonderful bond you form not only with the patient, but with the family as well. She enjoys participating in clinical trials, which bring about new and/or alternative treatment options for patients. She believes in providing and discussing all treatment options with owners before deciding on which plan is most appropriate for their pet. The most rewarding part of her career so far is being able to give owners more good quality time with their four-legged family members.

Dr. Silver is married to her husband, Jason, and they share their home with 3 dogs and 1 turtle: Pipsqueak, a miniature Poodle mix; Grace, a Pit Bull mix; Flanders, a Chocolate Lab; and Flash, a red-eared slider. When she’s not working, she enjoys hiking, kayaking, running, swimming, reading, volunteering with Pipsqueak with the K9 First Responders where they’re brought in to help people after a tragedy, and Pets On Wheels where they visit nursing homes, libraries, and hospitals. Dr. Silver loves being near the water (lake, ocean, or river); she finds it very relaxing! She also loves volunteering with Pipsqueak, because it’s nice to see how he makes people smile.