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Melena

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Introduction

  • Cause: gastritis (bacterial/viral/parasitic, eg coccidiosis), gastric ulcers, gastroenteritis, foreign body, pancreatitis, dysbiosis, long term use of ulcerogenic medication, rodenticide poisoning.
  • Signs: lethargy, anorexia, abdominal distension, bruxism, bloating, dark, digested blood originating from the small intestine.
  • Diagnosis: clinical history, fecal examination.
  • Treatment: dependent on the cause, can range from antibiotics, fluid, and nutritional support to euthanasia.
  • Prognosis: guarded.

Presenting signs

  • Lethargy.
  • Anorexia.
  • Weakness.
  • Nausea.
  • Bruxism.
  • Signs consistent with dehydration
  • Black, tarry feces on presentation.
  • Pyrexia.
  • Collapse.
  • Vomiting/regurgitation.
  • Hypersalivation.
  • Abdominal pain.
  • Tachycardia.
  • Shock.

Acute presentation

  • Lethargy.
  • Anorexia.
  • Weakness.
  • Nausea.
  • Bruxism.
  • Pale mucous membranes.
  • Dehydration.
  • Hypovolemia.
  • Shock.
  • Black, tarry feces.

Geographic incidence

  • Worldwide.

Public health considerations

  • Until fecal analysis has been performed, care should be taken when handling affected animals.

Cost considerations

  • Initial stabilization with hospitalization and analgesia may be expensive especially when the patient presents out of hours.
  • Investigations into the cause of the melena may be expensive involving blood sampling, diagnostic imaging, endoscopy, PCR and repeat testing.
  • Cost of ongoing medication for management of possible underlying ulceration and repeat visits need to be considered.

Special risks

  • Patients affected by acute hemorrhage may require aggressive stabilization before investigations can be carried out.
  • Anemic animals suffering from chronic blood loss may not be suitable for anesthesia until stabilized.

Pathogenesis

Etiology

Predisposing factors

General

Specific

  • Long-term use of non-steroidal anti-inflammatory medication such as meloxicam Meloxicam without the use of gastroprotectants and whilst using higher doses.
  • Chronic azotemia due to kidney disease Renal disease.

Pathophysiology

  • Long-term use of anti-inflammatory medication and inhibition of cyclo-oxygenase-1 (COX-1) receptors in the gastrointestinal tract reduces prostaglandin secretion. Prostaglandins have a cytoprotective effect on the gastric mucosa. This increases the risk of mucosal injury and development of ulceration.

Timecourse

  • Ulceration may develop acutely following rodenticide toxicity or gastrointestinal surgery.

Epidemiology

  • Young, stressed, and immunocompromised animals will be more predisposed to infectious causes of gastrointestinal ulceration.
  • Geriatric animals will be more predisposed to gastrointestinal ulceration as they will often have coexisting conditions such as kidney and heart disease as well as neoplasia.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Mans C (2013) Clinical update on diagnosis and management of disorders of the digestive system of reptiles. J Exotic Pet Med 22 (2), 141-162 SciDirect.
  • Buker M, Foldenauer U, Simova-Curd S et al (2010) Gastrointestinal obstruction caused by a radiolucent foreign body in a green iguana (Iguana Iguana). Can Vet J 51 (5), 511-514 PubMed.
  • Chia M Y, Jeng C R, Hsiao S H et al (2009) Entamoeba invadens myositis in a common water monitor lizard (Varanus salvator). Vet Pathol 46 (4), 673-676 PubMed.
  • Kubisch U, Fischer I & Hatt J M (2006) Gastric ulcer in green iguanas (Iguana iguana). Tierärztliche Praxis. Ausgabe K, Kleintiere/Heimtiere 34 (1), 50-53 VetMedResource.
  • Goldberg S R & Bursey C (1989) Physaloptera retusa (Nematoda, Physalopteridae) in naturally infected sagebrush lizards, Sceloporus graciosus (Iguanidae). J Wildl Dis 25 (3), 425-9 PubMed.