Changes

*[[Toxoplasmosis - Cat and Dog|Toxoplasmosis]] in dogs and cats

*[[Toxoplasmosis - Cat and Dog|Toxoplasmosis]] in dogs and cats

 

== Zonal Necrosis ==

== Zonal Necrosis ==

Zonal necrosis is necrosis occurring mainly in a part of the lobule and further subdivided according to whether the lesions are situated centrally, peripherally, or in the mid-zone of the lobule:

This type of change affects hepatocytes in defined anatomic regions of the liver lobule:

===Periacinar (Centrilobular)===

'''Periacinar (Centrilobular)'''<br>

This is the most common type of zonal necrosis and occurs mainly due to the fact that the hepatocytes in this zone are furthest away from the incoming blood supply and are therefore less oxygenated and relatively anoxic. They are reported to contain the greatest number of enzymes responsible for metabolising substances to more toxic metabolites capable of killing the hepatocytes. Therefore hypoxic states and toxic substances predominate in this type of necrosis, although some viral conditions also are the cause, such as '''[[Infectious Canine Hepatitis]] (ICH)'''. This is a highly infectious disease of young dogs which is spread by urine. It is now rare due to vaccination in the UK.

This is the most common type of zonal necrosis and occurs mainly due to the fact that hepatocytes in this central zone are furthest away from the incoming blood supply. They are therefore more susceptible to hypoxia. Additionally, they contain the greatest concentration of cytochrome p450 enzymes that metabolise substances into more reactive metabolites capable of killing the hepatocytes. Therefore toxic insults and conditions leasing to hypoxia commonly produce this pattern of necrosis. Some viral conditions, however, also result in centrilobular necrosis, such as '''[[Infectious Canine Hepatitis]] (ICH)'''. This is a highly infectious disease of young dogs caused by canine adenovirus-1. It is now rare in the UK and US due to effective vaccination protocols.

===Midzonal===

===Midzonal===