Gastrointestinal bleeding would be hard to miss in its most dramatic form with voluminous hematemesis being a clear give away sign. The majority of our patients, however, do not present this way and may only show vague non specific clinical signs. Last week’s webinar led by Jonathan Lidbury BVMS MRCVS PhD DCVIM DECVIM-CA demonstrated how to navigate a sometimes challenging path toward determining the presence of gastrointestinal (GI) bleeding, diagnosing  its underlying cause and ultimately offering the most suitable treatment for our patients.

The classic signs of GI bleeding include hematemesis and melena but even these need to be considered with caution. You would think it would be easy to spot a dog vomiting blood but unfortunately it can be a clinical sign sometimes confused for hemoptysis. For this reason it’s imperative to differentiate between hematemesis and hemoptysis. Jonathan explained that fluid produced from hemoptysis would be bright red, contain sputum and may be frothy with blood clots. Whereas fluid from hematemesis would  be dark red/brown, may contain gastric contents and have a coffee ground appearance. The pH can also be tested using a urine dipstick with the fluid from hemoptysis having a pH greater than 7 and the fluid from hematemesis having a pH less than 7. Jonathan also explained that the lack of melena does not rule out the presence of GI bleeding. Studies have shown there needs to be a blood loss of around 2.5-3.5mls/kg before signs of meleana are noted explaining why it’s often not present in many patients with GI bleeding.

There will be several patients which show no gastrointestinal signs at all and often present with non specific signs such as anorexia, behavioural changes and signs consistent with anaemia. GI bleeding may not even be considered until blood work has been evaluated in a patient  which usually shows  regenerative anaemia,  panhypoproteinamia and an increase in the urea to creatinine ratio. However over time these patients will become iron deficient causing  variable reticulocyte counts and a microcytic hypochromic anaemia. Jonathan also reminded us that with peracute blood loss a patient’s PCV may initially not decrease at all due to the presence of hypovolaemic shock.

Jonathan also discussed the use of a number of  diagnostic tools to aid in determining the root cause of a GI bleeding including ultrasound, endoscopy and exploratory laparotomy. There was however one technique discussed by Jonathan which I was completely unaware of despite it being used extensively in the field of human medicine, ‘capsular endoscopy’. This involves the patient swallowing a capsule encompassing a 360 degree camera which can take 16-18 hours worth of still images as it passes its way through the intestinal tract. This capsule can then be retrieved from a patient’s motions and sent to a company  who will then analyse the images for any abnormalities. Although this is not commonly utilised in veterinary medicine Jonathan states it can be very useful when all other diagnostic methods have failed in identifying the offending lesion. It can be particularly effective at imaging the lumen of the mid sections on the intestines where endoscopy cannot reach. However Jonathan also demonstrated another method which can be used to visualise this awkward section of intestines. It involves performing an exploratory laparotomy where the mid section of intestines can be manually fed over an endoscope being controlled by a clinician at the head of a patient. The lumen of the mid section of intestines can then be visualised via endoscopy.

Once the reason for GI bleeding has been established Jonathan advises that treatment usually centres around addressing the underlying cause. This could, for example, involve the resection of an intestinal mass or the treatment of a clotting disorder. Treatment of conditions such as gastric ulcers, however, usually involve the use of specific drugs. Histamine 2 receptor antagonists can be helpful with famotidine being the most effective out of all the standard use H2 antagonists (ranitidine and cimetidine). They do not however match up to  proton pump inhibitors (omeprazole) which have been shown to be far more effective at reducing levels of gastric acid. Studies have also looked at using H2 antagonists and PPI’s in combination but these have shown that a combination is no more effective than a PPI being used alone. Twice daily administration of omeprazole has also been shown to offer maximum efficiency in patients. Sucralfate can also be useful as it forms a protective coat over the gastric mucosa and Jonathan tends to use this alongside twice daily omeprazole as his standard treatment for gastric ulceration.

Further Discussions

There were further discussions within this webinar about the underlying causes of GI bleeding as well as the additional diagnostic processes deemed necessary such as checking clotting function, looking for faecal occult blood, history taking and physical examination. Jonathan delivers this plethora of information in an engaging and practical way which will not only remind you of what you have learnt in the past but will also keep you bang up to date on all the advances made in diagnostics and therapeutics relevant to this challenging condition.