Internal Medicine


Internal Medicine: Reasurringly Specialist

The Sherlock Holmes of the Specialist Veterinary world, Willows’ Internal Medicine team, has over 70 years of collective experience in diagnosing and treating complex medical conditions.

Working together with our world-leading Specialist Radiologists and with access to the very best diagnostic imaging facilities, our Internal Medicine Specialists provide investigation, diagnosis and treatment for a range of conditions, including; gastroenterology, respiratory medicine, endocrinology, hyperthyroidism, infectious disease, oncology and immune-mediated disease amongst many more.

Working in collaboration with our team of Specialists across 13 disciplines, including Oncology and Soft Tissue Surgery, and with a dedicated medicine nursing team, Willows’ ensures the best possible individualised care for each and every patient.


What Can I Expect if my Pet is Referred to an Internal Medicine Specialist?

Each patient referred to the Internal Medicine service will be examined by a Specialist and their medical problems will be discussed with the owner(s). Following this, an appropriate investigation plan will be discussed which may include lab tests, scans (e.g. ultrasound or CT), endoscopy i.e. camera studies (e.g. of the stomach, intestine, nose, airways, bladder), and other procedures (e.g. bone marrow biopsies, joint fluid sampling). After a diagnosis has been made, an appropriate treatment plan and the likely outcome (prognosis) will be discussed.


What are the Most Common Medical Conditions?

The Internal Medicine service sees cats and dogs with a wide range of problems including vomiting/diarrhoea, weight loss, excessive thirst/urination, anaemia, coughing, jaundice and nasal discharge.


What Facilities are Available at Willows?

Willows has access to a very high level of imaging (scanning) equipment, which is run by a team of highly trained Imaging Specialists. The Internal medicine team also use a large number of scopes to enable camera studies. Most importantly, the Internal Medicine Specialists are supported by a team of highly trained nurses who look after the patients. Willows has a large number of Specialists in other disciplines, including Cardiology, Neurology, Oncology, Emergency and Critical Care, Anaesthesia and Surgery, all of whom work with the Internal Medicine team to provide the best possible level of care to our patients.

Meet The Team

Mark Dunning


Head of Internal Medicine

RCVS Specialist in Small Animal Internal Medicine
European Specialist of Small Animal Internal Medicine
Professor in Small Animal Internal Medicine

Mark qualified from Cambridge in 1997 and spent time in both mixed and small animal practice. He began a residency in small animal medicine at the University of Liverpool in 2000 but interrupted this to undertake a PhD in Neuroscience at the University of Cambridge investigating the use of MRI to monitor the outcome of novel therapies for multiple sclerosis and spinal cord injury in humans. Following the completion of his PhD, Mark completed a residency in Small Animal Medicine at Cambridge. Mark then spent four years in private specialist practice in the south of England before moving to Nottingham Vet School as Clinical Associate Professor of Small Animal Internal Medicine. Mark was responsible for running the final year medicine rotation along with lecturing to all years of the veterinary course. He was responsible for the school’s small animal intern and residency programmes in addition to supervising both undergraduate and postgraduate research students. Mark holds the European Diploma in Small Animal Internal Medicine and is an RCVS and EBVS® recognised specialist in Small Animal Internal Medicine.

Mark remains actively involved in both undergraduate and post-graduate teaching via his ongoing role as Professor of Small Animal internal medicine at the School of Veterinary Medicine and Science, University of Nottingham. Mark remains research active both within the school and with national and international collaborators. These projects include investigations into canine breed-related diseases, canine cancer, canine and feline haematology, canine endocrine disease, how owners and vets make clinical decisions and the development of novel non-invasive biomarkers to help diagnose both simple and complex medical diseases in both primary care and referral settings. Mark lectures both nationally and internationally and has published widely in the field of veterinary medicine.

Mark has a broad interest in internal medicine but particularly enjoys the challenges posed by gastrointestinal, endocrine, haematology and renal medicine. Mark is excited to be joining the outstanding team at Willows and being able to provide both exceptional and compassionate care for the cats and dogs and their owners attending the clinic; along with providing an outstanding service to the referring veterinary surgeons. He particularly hopes to see lots of Norwegian Forest cats and Irish Wolfhounds, his absolute favourites!

Isuru Gajanayake


Head of Clinical Nutrition

RCVS Specialist in Small Animal Medicine (Internal Medicine)
American and European Specialist in Small Animal Internal Medicine
American Specialist in Small Animal Nutrition

Isuru graduated from the University of Sydney in 1998.  After spending two years in mixed practice in rural Australia, he moved to the United Kingdom to work as a small animal vet locum and also travelled around Europe. He then joined Willows’ general practice clinic in 2002. During the following three years in this post, Isuru developed an interest in medicine and successfully completed the RCVS Certificate in Small Animal Medicine. In 2005, he moved to the Royal Veterinary College to undertake a one-year rotating Internship, followed by a combined Residency in small animal internal medicine and clinical nutrition. Isuru was the first resident to undertake a clinical nutrition training programme in the UK. Following the end of his residency, Isuru successfully achieved specialist status from the American College of Veterinary Internal Medicine in 2010. He became a diplomate of the American College of Veterinary Nutrition in 2016.

Isuru has a keen interest in all aspects of internal medicine but particularly enjoys dealing with immune-mediated and gastroenterology cases. He also enjoys the challenges involved in the nutrition of hospitalised patients, using both enteral and parenteral feeding techniques. In addition to his clinical duties, Isuru also enjoys teaching undergraduates, veterinary surgeons and nurses.

Isuru aims to provide the highest level of care for his patients, their owners and referring veterinary surgeons, and he thoroughly enjoys being part of the team at Willows who have the same commitment to the pets under their care.

Kirsty Roe


RCVS Specialist in Small Animal Medicine (Internal Medicine)
American and European Specialist in Small Animal Internal Medicine

Kirsty graduated as a Veterinary Surgeon from the University of Bristol in 2000. She spent five years working in small animal practice in London and Northampton, where she developed an interest in canine and feline internal medicine. In 2005 she completed a Junior Clinical Fellowship in Internal Medicine at The Animal Health Trust in Newmarket and obtained the Royal College Certificate in Small Animal Medicine. Following this Kirsty completed a three year residency at The Royal Veterinary College in London and gained Diplomas of the American and European Colleges of Veterinary Internal Medicine. She is an RCVS Specialist in Small Animal Medicine and has worked at The Willows since 2009.

Kirsty enjoys both the challenge of the Internal Medicine discipline, and also the care element of her role with the seriously ill animals that she treats. She is particularly interested in endocrinology and gastroenterology. Kirsty very much enjoys being part of the top-notch team of multi-disciplinary specialists at Willows, and contributing to the high level of support and expert care provided for her patients, their owners and the referring veterinary surgeons who use Willows’ service.

Outside of work Kirsty has two young children who keep her entertained and on the go!

Fergus Allerton


European Veterinary Specialist in Small Animal Internal Medicine

Fergus graduated from the University of Bristol in 2004. He spent six years working in a mixed practice in Worcestershire. A keen interest in all things medical motivated Fergus to pursue the Royal College Certificate in Small Animal Medicine. He then spent three years undertaking a medicine residency at the University of Liege in Belgium studying for and, later gaining, the Diploma of the European College of Veterinary Internal Medicine.

Fergus is currently the chairman of the Small Animal Medicine Society (SAMSoc) and has been involved in the PROTECT ME initiative to encourage rational antibiotic use in small animal patients. He is currently editing the next edition of the BSAVA formulary. His particular interests include gall bladder disease (especially mucocoeles in Border Terriers), canine sinonasal aspergillosis, haematology, immune-mediated disease and antibiotic stewardship.

Fergus has a cat called Spartacus and a stick insect called Clive.

Bryn Jones


Internal Medicine Clinician

Bryn graduated from the University of Nottingham in 2014, and following this spent four years in a small animal hospital in Southwest Wales. It was during this time that he developed a passion for Medicine, which led him to undertake a Certificate alongside his job. Keen to expand this enthusiasm further, Bryn embarked first on an internship at the Royal Veterinary College, followed by a residency in small animal internal medicine at Anderson Moores Veterinary Specialists, which he completed in 2022. Bryn has a strong interest in all aspects of Internal Medicine, and has a particular focus on gastrointestinal and hepatic disease.

Outside of work, Bryn likes to spend time visiting his friends across the country and following sport, particularly his beloved Wales and West Ham. He lives with his partner and a very spoilt, aging cat, and they plan to continue exploring this country and others. Bryn’s other interests include history, wargaming and cosy pubs.

Cameron Prior


Internal Medicine Resident

Cameron graduated from the University of Pretoria, South Africa, in 2017. Upon graduation, he spent three years working in a busy small animal practice where he did his fair share of spays, castrations, dental and even some orthopaedics. He decided that small animal medicine was definitely where his interests lay during this time.

Cameron then spent a year in Scotland doing a rotating internship. During this time, he also obtained his Masters in Small Animal Medicine, focusing on the prevalence of methicillin-resistant Staphylococcus pseudinteremedius in dogs with skin and ear infections. He is currently enrolled in an advanced practitioner certificate in small animal internal medicine. 

In November 2021, Cameron joined Willows to pursue his goal of completing specialist training in Small Animal Medicine, particularly enjoying endocrinology, infectious disease and antibiotic stewardship. 

At home, he lives with two obstinate but very well-loved Golden Retrievers, Lily and Finley. 

Lucy Yuan


Internal Medicine Resident

Lucy graduated from Cambridge University in 2018, and spent three and a half years working in two busy small animal practices in Bedfordshire and Staffordshire. During this time, she developed an interest in internal medicine, which led her to join Willows in 2022 as a rotating intern to gain further experience in emergency and routine cases.

Following the completion of her rotating internship, Lucy spent some time at Anderson Moores Veterinary Specialists as a medicine intern before re-joining Willows in 2023 to pursue further training as an internal medicine resident.

When not at work, Lucy enjoys hiking, baking and spending time with her two rescue cats, Jack and Pippa.

Jessica Dean

BVetMed(hons) CertAVP(SAM) MRCVS

Internal Medicine Resident

Jess graduated from the Royal Veterinary College in 2015, and went on to work in a busy small animal hospital in London where she developed a keen interest in small animal internal medicine and completed a post graduate certificate through the University of Liverpool.

Jess completed a rotating internship at Southfields Veterinary Specialists in 2021, followed by an internal medicine internship at London Vet Specialists in 2022. Following her internship she joined the Willows Internal Medicine team in November 2023 to pursue further training as an internal medicine resident.

When not at work Jess enjoys long distance running and yoga classes.

Internal Medicine

Find out more

To assist owners in understanding more about Internal Medicine we have put together a range of information sheets to talk you through the some of the more common Medicine conditions seen and treated by our Specialists.