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WSV18-0218
SVA FELINE
GI ENDOSCOPY: A MINIMALLY INVASIVE OPTION FOR THE MINIMALLY INVASIVE CAT OWNER
E. Robertson1
1American Board Certified Diplomate Feline Practice, Feline Vet and Endoscopy Vet Referrals, Brighton, East Sussex, United Kingdom
Feline gastrointestinal (GI) endoscopy is in high demand, particularly by cat owners already aware of the clinical benefits and availability of this procedure within the human heathcare system. This lecture will provide a basic introduction to GI flexible endoscopy including important aspects of endoscope selection, clinical indications, and basic techniques required to perform a thorough and diagnostically meaningful examination in the cat.
or chemotherapy without delay after the procedure.3 Unfortunately, endoscopy has some limitations in that it rarely diagnoses functional diseases (e.g. dysmotility, dietary hyper- sensitivity, antibiotic-responsive disease, etc.), lesions outside the GI tract (liver, pancreas, etc.) nor allows for full evaluation of the entire jejunum.3 Other clinical challenges associated with implementing endoscopy into a GIT investigation include lack of appropriate/suitably-sized equipment to perform a thorough examination, insufficient operator training/understanding how to ‘drive the ‘scope’ through the gastrointestinal tract, and/ or confidence with identifying normal from abnormal. The endoscopist performing procedure should also have a high level of proficiency, as GI endoscopy in cats is more demanding in skill than in dogs, due to the small size of the animal and the decreased tolerance to anaesthesia.
Theoretical risks which should be communicated with the owner include: 1) general anaesthesia 2) bowel perforation 3) bleeding 4) non-diagnostic samples (depth of sample and length of endo- scope in relation to lesion). Saying that, these risks are consid- ered rare.
Equipment:
A flexible endoscope suitable for performing an upper and low- er GI examination in cats should be no greater than 8.0mm in diameter, at least 100cm in length and must have four-way tip deflection. In Oriental lines, where the antral canal, pylorus and ileocolic sphincter are seemingly more narrow compared to oth- er breeds will benefit from the use of a smaller diameter endo- scope (<6.0mm).4
To obtain adequately sized biopsies, the instrumentation chan- nel should be at least 2.2mm, preferably ≥ 2.5mm. The latest model of endoscopes specifically designed for veterinary use, and suitable for most cats, is a 7.9mm outer diameter x 1.40m videoendoscope with an instrumentation channel of 2.8mm in diameter.4
Anaesthesia:
General anaesthesia is required for GI endoscopy and intuba- tion with a cuffed endotracheal tube is mandatory because of the risk of gastro-oesophageal reflux. Some anaesthetic agents affect intestinal motility and sphincter function making the pas- sage of the cardia and pylorus potentially more difficult.5 Atro- pine and other anticholinergic drugs should not be used unless necessary to increase heart rate, as these drugs may alter gastric motility patterns and increase pyloric tone. Pure opioid agonists may also increase pyloric tone and should ideally be avoided. Fluid support should be given during anaesthesia; dehydrated animals need to be rehydrated before anaesthesia unless en- doscopy needs to be performed as an emergency procedure. In hypoproteinaemic patients colloid administration should be considered to ensure reasonable oncotic pressure. Anaesthesia monitoring during upper GI endoscopy includes at minimum assessment of heart rate, respiration, blood pressure and pulse oximetry. Overdistension of the stomach during insuf- flation can cause cardiorespiratory.
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  Introduction:
Gastrointestinal endoscopy offers a minimally invasive method for obtaining a relatively thorough examination of the GI. Pro- curement of biopsy samples is often necessary in achieving a diagnosis in patients presenting with chronic or recurrent gas- trointestinal tract signs (>2 weeks). In addition, endoscopy also offers a minimally invasive option for foreign body retrieval, oe- sophageal stricture dilation therapy and percutaneous gastros- tomy tube placement.
Endoscopy should be considered the next logical step when investigating those patients where haematology, biochemistry, electrolytes, anthelmintic therapy, B12 assessment/supplemen- tation, fPLI/TLI, and abdominal imaging have failed to provide an explanation for presenting clinical signs. In cats, oesophagosco- py, gastroduodenoscopy, proximal jejunoscopy, distal jejunos- copy, illeoscopy and colonoscopy should always be considered in those cases presenting chronic weight loss, polyphagia, hyp- orexia/anorexia or chronic hypocobalaminemia. This is especial- ly true for cases with confirmed hypocobalaminemia where sig- nificant distal small intestinal evaluation/biopsies are required. The World Small Animal Veterinary Association (WSAVA) Inter- national GI Standardisation Group and the American College of Veterinary Internal Medicine (ACVIM) have published multiple statements to provide guidance and standards for performance and interpretation of various diagnostic tests in dogs and cats presenting with gastrointestinal signs, including treatment tri- als, patient response, and outcome.1,2 Interestingly, inflammato- ry bowel disease (IBD) and lymphosarcoma (LSA) are often the remaining differential diagnoses in these patients. The clinical history and findings up to this critical point seems to present a clinical conundrum for the practitioner resulting in either poly- pharmacy or offering invasive interventions (e.g. exploratory lap- arotomy). It’s not unsurprisingly that both of these options are often met with resistance by both patient and cat owners.
For most practitioners, the most challenging question associat- ed with obtaining biopsies is how to obtain tissue samples of adequate depth and at the correct anatomic location. Whether to obtain full thickness biopsies or endoscopic biopsy samples has been a subject of discussion over the past 10-15 years. Ben- efits of endoscopic biopsies include the ability to directly visual- ise and document mucosal changes and lesions, enabling direct access and biosies of these changes, to collect multiple tissue samples from each anatomic site, and to begin antiinflammatory
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