Page 912 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Liver disease 887

VetBooks.ir Table 5.2 Biopsy scoring system

VARIABLE ABSENT MILD MODERATE SEVERE
Fibrosis 0 0 2 4
Irreversible cytopathology 0 1 2 2
Inflammatory infiltrate 0 0 1 2
Haemosiderin accumulation 0 0 0 2
Biliary hyperplasia 0 0 2 4
Scores are attributed to the presence and severity of five pathological changes. Minimum score = 0, maximum score = 14. (Irreversible
cytopathology = necrosis or megalocytosis.) (From Durham et al. 2003a.)

finding in liver biopsy specimens. However, long- selection of therapeutic choices can be made in the
term survival of cases with severe periportal and absence of biopsy examination.
bridging fibrosis is sometimes seen suggesting other When faced with an initial diagnosis of liver
factors are also important. A prognostic liver biopsy disease based on clinical suspicions and serum bio-
scoring system has been applied to liver specimens for chemistry, the clinician may choose to employ an
many years and appears to offer reasonably accurate empirical approach to treatment or may seek fur-
prognostic guidance. The score is based on a broad ther clinical information from hepatic ultrasound
comparative index of histopathological severity and biopsy. Although this choice might be markedly
with weighted attribution of scores to five different influenced by client wishes and budget, it must be
pathological findings, comprising: fibrosis, biliary realised that a logical therapeutic and management
hyperplasia, inflammation, haemosiderosis and irre- approach to hepatopathy cases can only be made on
versible cytopathology (necrosis and/or megalocy- the basis of biopsy results. Liver biopsy is the only
tosis) (Table 5.2). The total score may range from 0 procedure likely to confirm that liver disease is
to 14 with a good prognosis associated with scores genuinely present, to indicate the prognosis of the
<3 and a very poor prognosis being offered to cases disease and to allow an informed selection of appro-
with scores >7. The practical benefits of establish- priate therapy based on the pattern of pathology
ing the biopsy score include informing a concerned identified. The alternative approach of administer-
owner of the likelihood of successful resolution of ing empirical courses of drugs such as antimicrobi-
the condition as well as influencing how important als, anti-inflammatories and feed supplements in the
and aggressive therapeutic interventions should be. absence of biopsy results is speculative at best and
Indeed, specific therapy for liver disease can only is not a good example of responsible medicine given
be logically applied following examination of liver the potential adverse consequences of some of these
biopsy specimens as it is very unlikely that informed drugs (especially if they are not indicated!).

SPECIFIC DISEASE ENTITIES

HEPATIC INSUFFICIENCY overwhelming challenge to the liver is less com-
mon than a slow and insidious progressive loss
Definition/overview of hepatic function. Thus, cases presenting with
It is suggested that the liver will fail to adequately hepatic insufficiency will generally represent
perform its normal functions when more than only a small proportion of cases compared with
60–70% of its metabolic capacity is lost. Acute those suffering a subcritical extent (e.g. 1–60%) of
hepatic insufficiency in the face of an abrupt and hepatic damage.