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The Practice
The Practice: +44 (0)1638 782000 The Hospital: +44 (0)1638 782020

Conditions treated by our internal medicine team include diseases of the airways, heart, digestive tract, liver, kidneys and nervous system.

Our Intensive Care Unit provides around the clock care with veterinary surgeons on-site 24/7 and CCTV monitoring of critical cases. For cases with infectious diseases, treatment can be provided in our separate isolation unit. The on-site laboratory enables rapid results from blood and other diagnostic tests.

Intestinal disorders & gastric ulcers

Acute colic is the most common gastrointestinal disorder in the horse. Other less common conditions include weight loss, diarrhoea, and chronic or recurrent colic. After a thorough clinical examination, diagnostic techniques that can be performed at NEH for investigation of these cases will be selected, and may include blood tests, faecal analysis, oral/dental examination, rectal examination, abdominal ultrasonography, gastroscopy, abdominal radiography, peritoneal fluid analysis, rectal biopsies, and glucose absorption tests. Where appropriate, laparoscopic (keyhole) surgery can be performed to explore the abdomen, or in some cases full exploratory surgery may be required.

Gastroscopy is used primarily for the identification of gastric ulcers. At NEH all cases are examined using a 3.5 metre videoscope. The horse’s stomach is divided into squamous and glandular portions. Ulcers are most commonly identified in the squamous mucosa, but they can also be seen in the glandular portion of the stomach. The duodenum is the first part of the intestine after the stomach, and is also examined routinely, where ulcers and other problems are less commonly found.




The hospital neonatology service provides specialised 24/7 care for critically ill foals in the Intensive Care Unit. There are specially designed divided stables available in ICU to allow foals to be treated without disturbing the bond between mare and foal. There is also an additional foal intensive care unit separate to the ICU for treatment of foals with possible infectious diseases. These facilities are all equipped with video monitoring, heat lamps and padded beds if required for recumbent foals. Around-the-clock care is provided by a dedicated team of veterinary surgeons, nurses, and technicians.

Foals may be admitted for treatment of a variety of problems, including Neonatal Maladjustment Syndrome, sepsis, prematurity, colic, diarrhoea, and neonatal isoerythrolysis. As well as medical care for sick foals, our surgical team has a great deal of experience and expertise in problems such as orthopaedic infections (septic joints or growth plates) or angular and flexural limb deformities.

Many conditions in neonatal foals have a much better outcome if they are recognised, and treatment implemented, as early as possible. Our hospital team is available 24/7 to provide diagnoses and treatment to emergency cases.

Respiratory diseases

Respiratory disease is common in the horse, with Equine Asthma and infectious conditions encountered most frequently. Investigation of these cases can include videoendoscopy, ultrasonography and radiography along with sampling of fluid from the respiratory tract. Our on-site laboratory allows rapid analysis of airway samples.

Liver & kidney disorders

Liver disease in horses often presents with non-specific clinical signs such as lethargy and weight loss. Identifying the underlying cause of liver disease requires further investigation which is often necessary to guide treatment. Investigation of liver disease includes blood tests to evaluate the damage to, and function of, the liver and ultrasound examination to assess its size and structure. Ultrasound-guided liver biopsy can help identify the underlying cause of disease and provide important prognostic information.

Kidney disease is uncommon in the horse. When it does occur the the kidney damage is usually detected on blood results. Further investigation of these cases includes additional blood tests and concurrent urine analysis, ultrasound examination, bladder endoscopy, rectal palpation and biopsy.


Injuries or abnormalities of the eyes should always be treated as an emergency Some conditions can be treated with a short course of topical medication (eye drops or ointment), however, others require further investigation or more intensive treatment than can be administered at home, sometimes as frequently as every hour.

Our internal medicine clinicians are supported by specialist veterinary ophthalmologists.


Cardiac abnormalities in horses include heart murmurs and dysrhythmias. Further investigation of these abnormalities is important to determine the severity of the disease and the suitability of the horse to continue in ridden work.  Investigation of these cases includes a thorough examination of the cardiovascular system, specific blood tests, cardiac ultrasound (echocardiography) and electrocardiography (ECG). Our telemetric ECG equipment can be worn by the horse in the stable to allow 24-hour monitoring of heart rhythm at rest, and be worn during exercise to allow assessment of heart rhythm during exercise. 

For horses diagnosed with atrial fibrillation, the most common arrhythmia in horses, treatment can be performed at NEH with both electrical cardioversion (TVEC) and quinidine. The most suitable treatment is influenced by the duration of clinical signs.

Neuromuscular disorders

When a horse is suffering from a neurological disease or injury, careful clinical examination and neuroanatomic localisation is critical. Diagnostic techniques that may then be required include blood tests, radiography or scintigraphy of the spine and sampling of cerebrospinal fluid. Radiography following injection of a dye into the spinal canal, called myelography, is performed under general anaesthesia to look for lesions that cause compression of the spinal cord.

Muscular disorders can cause a variety of symptoms, ranging from tying up, focal or generalised muscle atrophy (wastage), altered gaits, or more vague signs of poor performance. For generalised muscular disorders, blood tests pre- and post exercise are routinely performed, and definitive diagnosis most reliably obtained by histopathological examination of a muscle biopsy.


Our internal medicine team can investigate a variety of skin conditions. Dependent upon clinical findings this may include skin scrapes, hair plucks, skin biopsy or intradermal skin testing. Our team works in conjunction with specialists in dermatology from Dick White Referrals.


Endocrine diseases are very important in the horse, commonly predisposing them to laminitis which can be life threatening. Investigation of horses and ponies prone to laminitis includes testing for underlying hormonal disorders such as Cushing’s disease or insulin dysregulation. Assessment and monitoring of body condition score and bodyweight, in conjunction with dietary management, are critical. At NEH our orthopaedic consultants also work closely with farrier Will O’Shaughnessy AWCF to deliver a holistic approach to the laminitic patient.

Our Internal
Medicine Team

Mark Hillyer

Mark Hillyer


Specialist in Surgery and Medicine


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  • Head of Internal Medicine and Intensive Care
  • European Specialist in Equine Internal Medicine

Mark graduated from the University of Bristol in 1987. After graduation he worked at the Veterinary School at the University of Bristol as an equine and farm animal clinician. Here he developed his interests in equine internal medicine and soft tissue surgery. Following completion of a residency training, he became a Lecturer in 1995 and completed a PhD on equine colic in 2002. The same year he moved to Newmarket providing a hospital based referral service in equine internal medicine and soft tissue surgery. Mark has RCVS certificates in equine practice, equine soft tissue surgery and equine internal medicine and is also a Diplomate of the European College of Veterinary Surgeons and a Diplomate of the European College of Equine Internal Medicine.

Mark has published over 45 scientific papers, written 5 book chapters and is co-author and editor of Diagnostic Techniques in Equine Medicine, which is now in its second edition. In addition Mark has given presentations at over 30 national and international meetings. He is an Editorial Consultant of Equine Veterinary Journal as well as co-chairman of the Clinical Evidence Board. In 1997 he was awarded the Equine Veterinary Journal Richard Hartley Clinical Prize. Mark is a member of the Royal College of Veterinary Surgeons Equine Board and has been both a regular examiner and advisor for the RCVS equine certificates.

Hayley Chidlow

Hayley Chidlow


Specialist in Medicine


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Hayley graduated from Liverpool University Veterinary School in 2011. She then worked in mixed general practice as an equine ambulatory vet for a number of years before commencing an equine internal medicine Fellowship in the USA. Having completed this, she undertook a 3-year Residency Programme and became an ACVIM Diplomate shortly before joining NEH in 2019. She has lectured internationally and published in peer reviewed publications.

Other Services

Our hospital veterinary surgeons are consultants in their field, holding specialist qualifications endorsed with extensive clinical experience.