Changes

Any hepatic injury of a moderate degree or more, is going to cause a degree of fibrosis when the lesion has resolved. Fibrosis occurs due to proliferation of the supportive connective tissue in the liver. Fibrosis isolates the [[Liver - Anatomy & Physiology|liver]] cells by effectively changing the sinusoids into capillaries and when a certain amount of fibrosis occurs, it can be self-perpetuating, the end result is a small scarred liver with functional failure.

Any hepatic injury of a moderate degree or more, is going to cause a degree of fibrosis when the lesion has resolved. Fibrosis occurs due to proliferation of the supportive connective tissue in the liver. Fibrosis isolates the [[Liver - Anatomy & Physiology|liver]] cells by effectively changing the sinusoids into capillaries and when a certain amount of fibrosis occurs, it can be self-perpetuating, the end result is a small scarred liver with functional failure.

== Types of Fibrosis ==

==Patterns of Fibrosis ==

=====Periacinar Fibrosis=====

===Centrilobular (periacinar) Fibrosis===

In this type of fibrosis, the fibrous area surrounds the hepatic venule (centrilobular vein). This can be seen when there is chronic passive congestion with atrophy of the surrounding periacinar hepatocytes and condensation of the remaining connective tissue.

This involves fibrosis around  the hepatic venule (centrilobular vein). It is associated with chronic toxic injury since hepatocytes in this region are involved in drug metabolism. It is also associated with chronic passive congestion due to long-term [[Hear Failure, Right-Sided|right sided congestive heart failure]].

This involves fibrosis that is mostly confined to the portal region, and is associated with chronic inflammatory conditions that lead to inflammation in the portal triads.

=====Biliary Fibrosis=====

===Post-Necrotic Scarring===

This usually occurs along with another type of fibrosis and will accompany inflammation centered on the portal triads.

This occurs following massive hepatic necrosis where  large areas of parenchyma are lost and replaced by fibrosis.  

=====Post-Necrotic Scarring=====

===Bridging (diffuse) Fibrosis===

This type of fibrosis occurs following massive necrosis where the necrotic cells are removed and the defect is repaired by fibrosis. It is seen histopathologically as bands of fibrous tissue.

This is the sequel to chronic parenchymal injury, such as prolonged inflammation or numerous episodes of zonal necrosis. Fibrosis occurs throughout lobules and leads to bridging between portal areas, or between portal regions and central veins, causing pseudolobulation.

Although all types of fibrosis can lead to hepatic dysfunction if severe enough, bridging fibrosis is more likely to impair hepatic function than any of the other types.

This occurs after repeated damage to one or more zones. The fibrosis generated proliferates throughout to involve all the tissue.

== References ==

== References ==

Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary''' (2nd Edition), ''Elsevier Science''.

Blood, D.C. and Studdert, V. P. (1999) '''Saunders Comprehensive Veterinary Dictionary''' (2nd Edition), ''Elsevier Science''.

 

Ettinger, S.J. and Feldman, E. C. (2000) '''Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat''' Volume 2 (Fifth Edition),'' W.B. Saunders Company.''

Ettinger, S.J. and Feldman, E. C. (2000) '''Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat''' Volume 2 (Fifth Edition),'' W.B. Saunders Company.''

 

 

 

Smyth, B (2008) ''' Alimentary System Study Guide, ''''' Royal Veterinary College.''

Smyth, B (2008) ''' Alimentary System Study Guide, ''''' Royal Veterinary College.''