How I approach... The cat with chronic diarrhea

Clinicians will be all-too-familiar with the cat that has recurrent diarrhea; dealing with these patients can be frustrating for both the veterinarian and the owner, but Craig Webb offers his thoughts on how best to approach these cats with a case-based article that illustrates the key pointers for a successful outcome.

Craig B. Webb
PhD, DVM, Dipl. ACVIM
 

Introduction

Endoscopy is a versatile and minimally invasive technique used to visualize the gastrointestinal (GI) lumen, perform biopsies for further analysis such as histopathology or bacterial analysis, and to deliver treatment for problems such as strictures, polyps or foreign body removal. Although complications of routine endoscopic procedures are rare (1), endoscopy must be performed after a thorough work-up and should never be a substitute for a complete history, physical examination, appropriate laboratory procedures and other diagnostic imaging. It is especially important to note that endoscopy and endoscopic biopsy are not always indicated, especially in animals with chronic GI dis-ease, without appropriate therapeutic trials (e.g., deworming, dietary modification, antimicrobial trial). In conjunction with other diagnostic modalities, endoscopy can be both a powerful diagnostic tool for many GI disorders in dogs and an invaluable therapeutic tool, particularly for the retrieval of gastric or esophageal foreign bodies. This article will consider the benefits of endoscopy in dogs using five case studies. Interventional endoscopy and laparoscopy are beyond the scope of this paper.

The approach

My approach to a cat with chronic diarrhea – which is defined as continuous or intermittent diarrhea (reduced consistency, increased volume, or increased frequency) of greater than 3 weeks’ duration – may actually come from a variety of different directions. Consider the following options:

• I like to start with the cat and the owner together. I use the history of the cat, the history of the clinical sign(s), and a physical examination to rank-order, from most likely to least likely, my list of differentials for feline chronic diarrhea. From that list, I prioritize the diagnostic test(s) that seems best suited to confirm or refute my number one differential. Additional diagnostic testing will move a possible diagnosis either up or down my rank-ordered list until I identify the differential that sticks to the top. This is known as the Clinical Reasoning Approach, where one moves logically from a presumptive to a definitive diagnosis.
• The next approach is much less involved. Again I start by looking at the cat and listening to the owner. Then I look at the case presentation, or “illness script”, and simply go with what my instinct tells me. This is known as the Script Recognition Approach and is based very strongly on “gut feeling”.
• As I review the medical history and perform the physical examination, I pay special attention to aspects of the case that do not make sense or do not seem to fit; these incongruities often turn out to be important clues. I will also run a “Cine Loop” of the case through my head, from start to finish, attempting to describe the case more completely and accurately each time, in search of any missing piece of the puzzle. These are components of the Key Features Approach, which separates critical notes from background noise.
• Finally, despite the eloquence of the argument for a committed work-up, and often as a result of financial constraints, the owner may opt to begin a “trial treatment”. So I prescribe treatment X and schedule a recheck in 2 weeks. This is known as the Ready-Fire-Aim Approach, and frequently evolves into the Ready-Fire- Fire-Fire Approach.

Many variables can influence the way I approach a case; some in a positive manner, some in a way that results in a (somewhat predictable) error of medical judgement. The above methods are not mutually exclusive – in many cases one approach can complement another. I strongly encourage you to “think about how you think about cases” ( 1 ) and this is best illustrated by considering some case presentations. [...]