Page 10 - Problem-Based Feline Medicine

2 HOW TO MAKE A PROBLEM-BASED DIAGNOSIS

It is important to only list the problem at the level “WHERE?” for an abdominal mass includes liver,
that it is understood. For example, if the cat has an GIT, spleen, urinary tract, omentum, reproductive tract,
abdominal mass, the problem is initially listed as an etc. “WHERE?” for alopecia is skin; “WHERE?” for
abdominal mass and not a neoplasm, because it may be PU/PD is kidney, which is the end organ influencing
caused by a number of other conditions including reac- water intake and urine output. It is usually better to
tive lymphadenomegaly, feces, abscess, etc. simplify the answer in this way, rather than listing all
Characterize each problem listed based on duration, the organs that can cause polyuria/polydipsia, although
character and severity. this can also be done, e.g. kidney, liver, brain, kidney,
Characterize each problem by the 3 Cs: adrenal, bladder, etc.
● Chronicity (duration) To answer “WHERE?”, you may have to answer the
● Character question what is the “MECHANISM?” that results in
● Concern (severity/frequency/size). this problem, and use your knowledge of pathophysio-
– For example, the problem “sneezing and nasal logic principles to answer “WHERE”?
discharge” may be characterized as 2 months ● For example, abdominal effusion can be due to:
duration (chronicity), purulent (character), – Decreased oncotic pressure as a consequence of
occurring approximately six times/day (i.e. mod- hypoalbuminemia resulting from liver, GIT or
erate severity). kidney dysfunction.
– Increased hydrostatic pressure resulting from
Select the problem/s to consider first. Choose those
cardiac disease or vascular obstruction.
that are most likely to provide a diagnosis.
– Increased permeability of blood vessel walls.
Choose problems for consideration first that are:
– Lymphatic obstruction involving abdominal
● Severe or frequent problems. Problems that are
lymphatics.
infrequent or mild may not lead to the main definitive
diagnosis as quickly, or may be independent problems. If the answer to “WHERE?” is more than one organ
● Represent the problem the owner was concerned system, then diagnostic tests are usually required to
about. localize the problem. For example, for an abdominal
● Problems that are most specific for an organ or mass, results of diagnostic tests such as a serum bio-
body system. Avoid using non-specific problems chemistry profile (showing increased liver enzymes),
such as lethargy or anorexia. These problems indi- radiography (indicating hepatomegaly), and/or ultra-
cate severity of the problem, but are not organ-spe- sound (revealing a mass in area of liver), may be
cific and can be caused by almost any disease in the required to answer the question WHERE? (liver).
body. They are not useful diagnostically because
Once the organ systems involved have been identified,
they require a wide range of diagnostic tests to be
you can move on to answering the question
performed in an attempt to detect an organ-specific
“WHAT?”. That is, for each organ or body system
abnormality.
identified as potentially being involved, what diseases
are potential causes of the problem?
3. List the differential diagnoses (likely diseases)
for each problem. To formulate a list of differen- ● To assist in listing the diseases that can cause
tials, it helps to ask two questions, “WHERE?” and the problem, it helps to use an acronym such
“WHAT?”. as DAMNPIT to aid the memory.
To answer “WHERE?”, ask yourself which organs
or body systems can cause the problem? D : * degenerative
If possible, try to first categorize the answer to
A : * anomaly (congenital)
“WHERE?” into sub-headings. For example, for
* accident (e.g. volvulus, intussusception)
seizures, the problem could have extra-cranial or intra-
M : * metabolic (e.g. electrolyte, hormonal)
cranial causes. Similarly, for vomiting, there could be
* mechanical (e.g. foreign body, urolith)
extra-gastrointestinal or gastrointestinal causes; and for
jaundice, the sub-headings pre-hepatic, hepatic, and N : * neoplastic
post-hepatic are appropriate. * nutritional