Changes

==Causes of Icterus==

==Causes of Icterus==

===Pre-hepatic Jaundice===

===Pre-hepatic Jaundice===

This condition results from increased red blood cell destruction, overwhelming the capacity of the [[Liver - Anatomy & Physiology|liver]] to conjugate and excrete the bilirubin which is released into the plasma.  The majority of the bilirubin is therefore unconjugated and, unlike the conjugated form, this cannot be excreted by the [[Urinary System Overview - Anatomy & Physiology|kidney]].  Possible causes of haemolysis and prehepatic jaundice include:

Also sometimes called '''Haemolytic Icterus'''. This condition results from increased red blood cell destruction, overwhelming the capacity of the [[Liver - Anatomy & Physiology|liver]] to conjugate and excrete the bilirubin which is released into the plasma.  The majority of the bilirubin is therefore '''unconjugated''' and, unlike the conjugated form, this cannot be excreted by the [[Urinary System Overview - Anatomy & Physiology|kidney]].  Possible causes of haemolysis and prehepatic jaundice include:

*'''Haemolytic bacteria''', including ''[[Clostridium haemolyticum]]'' in cattle and [[Leptospira|'''Leptospires''']] in various species.

*'''Haemolytic bacteria''', including ''[[Clostridium haemolyticum]]'' in cattle and [[Leptospira|'''Leptospires''']] in various species.

*'''Haemolytic parasites''', including '''[[Babesia|Babesiosis]]''' in cattle and dogs and ''[[Feline Infectious Anaemia|Mycoplasma haemofelis]]'' in cats.

*'''Haemolytic parasites''', including '''[[Babesia|Babesiosis]]''' in cattle and dogs and ''[[Feline Infectious Anaemia|Mycoplasma haemofelis]]'' in cats.

*'''Inherited defects of red blood cell enzymes''', including phosphofructokinase and pyruvate kinase.

*'''Inherited defects of red blood cell enzymes''', including phosphofructokinase and pyruvate kinase.

*'''Microangiopathic damage''' to red blood cells as they pass through narrow or damaged blood vessels, as in '''haemangiosarcomata''', [[Disseminated Intravascular Coagulation|'''disseminated intravascular coagulation (DIC)''']] or '''[[Vasculitis|vasculitis]]'''.

*'''Microangiopathic damage''' to red blood cells as they pass through narrow or damaged blood vessels, as in '''haemangiosarcomata''', [[Disseminated Intravascular Coagulation|'''disseminated intravascular coagulation (DIC)''']] or '''[[Vasculitis|vasculitis]]'''.

*'''Oxidative damage''' to red blood cells, caused by '''paracetamol''' in cats, '''onion poisoning''' in dogs and '''copper toxicity''' in many species.  Ingestion of red maple leaves may also cause haemolysis in horses, as may brassicas (such as rape and kale) in cattle and sheep.

*'''Oxidative damage''' to red blood cells, caused by '''paracetamol''' in cats, '''onion poisoning''' in dogs and [[Copper Toxicity|'''copper toxicity''']] in many species.  Ingestion of red maple leaves may also cause haemolysis in horses, as may brassicas (such as rape and kale) in cattle and sheep.

Haemolysis which is sufficiently severe to cause icterus is likely to be life-threatening due to the reduction in oxygen-carrying capacity of the blood.  Animals affected acutely may require transfusions of whole blood, packed red blood cells or synthetic bovine haemoglobin and it may be advisable to provide oxygen by nasal catheter, flow-by or mask.  In addition, the presence of large amounts of haemoglobin may cause acute intrinsic renal failure (in addition to the pre-renal failure caused by reduced oxygen delivery to the kidneys) and neonates may suffer from kernicterus, direct damage to the central nervous system caused by bilirubin.

Haemolysis which is sufficiently severe to cause icterus is likely to be life-threatening due to the reduction in oxygen-carrying capacity of the blood.  Animals affected acutely may require transfusions of whole blood, packed red blood cells or synthetic bovine haemoglobin and it may be advisable to provide oxygen by nasal catheter, flow-by or mask.  In addition, the presence of large amounts of haemoglobin may cause acute intrinsic renal failure (in addition to the pre-renal failure caused by reduced oxygen delivery to the kidneys) and neonates may suffer from kernicterus, direct damage to the central nervous system caused by bilirubin.

=====Hepatic (Toxic) Icterus=====

=====Hepatic (Toxic) Icterus=====