Differential Diagnosis in Small Animal Medicine....pdf

Differential Diagnosis in Small Animal Medicine - A. Gough



Format pdf
484 Pages
Published 2007
1st Edition
ISBN: 978-1-4051-3252-7
Fully bookmarked and Indexed
Size 3.05 MB

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INDEX



Brief Introduction

This book was written to fill what I felt was a gap in the market. While working up
difficult medical cases, I have often wanted a single ready reference to help me formulate
a differential list from the clinical information I have available. Unfortunately, I
found myself frequently having to consult multiple textbooks to bring all the information
I needed together. I decided therefore to write a book that would serve as a ready
reference for differential diagnoses of the majority of presentations that are encountered
in practice, including both common and uncommon conditions. This text should be of
use to veterinary students, general practitioners, university interns, residents and anyone
who, like me, cannot fully carry these lists around in their heads. I hope other clinicians
find it as useful as I do.
The differential diagnosis list is one of the most important aspects of the problemoriented
approach to clinical diagnosis. For those who are not familiar with the problemoriented
approach, a brief outline follows.
As the name implies, problem-oriented medical management (POMM), concentrates
on the individual problems of a patient. A differential diagnosis list should be made for
each and every problem that is found in a patient, whether in the history, the physical
examination, imaging or clinicopathological tests. Although superficially this may not
sound very ‘holistic’, in fact, if all the patient’s problems are considered individually, the
whole patient will have been evaluated, without falling into the trap of presuming that
all of the findings are caused by a single condition.
The problem-oriented approach starts with a detailed history, and it is important to
discover what the owners perceive to be the main problems – after all, they usually know
their animal better than the clinician does. However, there may be relevant historical
signs that the owners had not considered significant, so failing to systematically ask all
the questions which could be of importance in a case can lead to overlooking important
information. Using a checklist or form, such as the one in Appendix A can be useful
as an aide-memoire.
In every case, a detailed physical examination should be carried out, including body
systems that are not apparently of immediate concern. Again, a checklist or form, such
as the one in Appendix B, can help ensure a systematic approach.
Once the history has been taken and the physical examination has been completed,
the clinician should list every problem that has been discovered. Problems may include
such findings as exercise intolerance, pruritus, pyrexia or a heart murmur. A differential
diagnosis list should then be created for every problem. The list should be appropriate
to that animal. There is no point listing feline leukaemia virus as a likely diagnosis
in a dog!
An attempt should also be made to categorise the conditions in order of likelihood,
or at least into common and uncommon. Although the more common conditions have
been indicated in this book with an asterisk (*), there are few objective data regarding
the true incidence of conditions, and the estimate of incidence is largely subjective and
influenced by the author’s geographical location and caseload. Familiarity with how
common conditions are and their local incidence will help prioritise differential lists.
The clinician can then select diagnostic tests in a rough order of probability, although
rarer but life-threatening conditions, such as hypoadrenocorticism, should also be ruled
out early in the course of investigations. Some authorities rightly point out that emphasis
should be placed on historical and physical signs, and that ‘over-investigating’ can
be expensive and potentially detrimental to the patient (Chesney, 2003).
It is this author’s opinion, however, that it is possible to place too much importance
on probabilities and how commonly a condition occurs. The newly-qualified veterinary
surgeon will often look for the rare but exciting and memorable condition they learned
about at college, while the experienced practitioner will often remind them that
‘common things are common’, and suggest they restrict their investigations only to
commonly-encountered conditions. The ideal approach is probably somewhere in
between.................................................and more