FELINE MEDICINE NUTRITION to be involved in the pathogenesis include : 1 ) increased breakdown of peripheral fat stores with resultant increased fatty acid delivery to the liver . As a result , oxidation of fatty acids in the liver by mitochondria is overwhelmed ( i . e ., decreased oxidation of fatty acids ; leads to lipid accumulation ), 2 ) impaired removal of triglycerides ( as VLDL ) from the liver .
History and physical exam
Patients typically present with prolonged anorexia , gastrointestinal signs , weight loss ( often > 25 % of body weight ), and lethargy . Icterus is frequently present on initial examination (> 70 % of cases ). Other findings include hepatomegaly , dehydration , and muscle wasting .
Preliminary diagnostics
Initial CBC may be normal or reveal a mild nonregenerative anemia ( 22 % of cases ) and poikilocytosis . A declining haematocrit is a common finding during treatment and is influenced by a number of factors including repeated blood draws , haemolysis ( due to Heinz bodies or severe hypophosphaetemia ), and / or blood loss . Care should be taken to limit the amount drawn during daily blood sampling to the absolute minimal amount needed to run the desired test , to avoid exacerbation of anaemia . Approximately 25 to 40 % of HL cats will require blood products during hospitalisation .
Biochemical abnormalities include moderate increases in ALP , mild to moderate increases in ALT , and increases in AST . In contrast to other feline hepatobiliary diseases where GGT is typically increased , GGT is often normal or only mildly elevated in patients with hepatic lipidosis . Hypokalaemia ( 30 %), hypophosphataemia ( 17 %), and hypomagnesaemia ( 28 %) may develop during the course of the disease , particularly during the refeeding period . When present , hypoalbuminaemia , hyperammonaemia , and hypoglycaemia , are indicators of severe hepatic dysfunction .
In a study of 22 cats with naturally occurring liver disease , coagulation abnormalities were found in 82 % of cats . Vitamin K deficiency was the most common abnormality detected . Coagulopathy in HL cats can result from deficiency of active vitamin K ( due to cholestasis ) and from reduced production of clotting factors . Routine coagulation testing such as PT and PTT are appropriate , but proteins-induced-by-vitamin K absence ( PIVKA ) may be a more sensitive test to detect vitamin K dependent coagulopathies .
On abdominal ultrasonography the liver is diffusely hyperechoic and may also be enlarged . Ultrasound eamination also assists with documentation of concurrent diseases such as pancreatitis or other intra-abdominal conditions that may have led to the anorexia . All HL patients should be screened for the presence of concurrent or underlying diseases . One study found a decreased recovery rate in HL cats that had concurrent pancreatitis compared to those in whom HL was the only diagnosis .
Diagnosis
Definitive diagnosis of HL is established by histologic examination of the liver , which reveals severe intrahepatic lipid accumulation . Hepatic lipidosis may be suggested on fine-needle aspiration of the liver , and many clinicians prefer this test during the initial phase of treatment to support a presumptive diagnosis of HL , and may postpone biopsy of the liver until the hospitalised patient is more stable .
Fine-needle aspiration of the liver can easily reach a diagnosis of HL by demonstration of a predominance of heavily vacuolated hepatocytes . It has the advantage of being much less invasive and may be a more appropriate means of arriving at a preliminary diagnosis during the early phase of treatment in the fragile liver cat . However , it has significant drawbacks , in that it may miss concurrent hepatic disorders and may on occasion incorrectly classified as primary .
EDITORS NOTE : Liver FNA may show lipid accumulation in the hepatocytes of normal cats .
Liver biopsy is required for definitive diagnosis and to rule out other concurrent hepatic conditions , and is usually obtained with ultrasound-guidance . Because of the high lipid content , biopsy specimens of HL cats may float when placed in formalin . Obtaining a biopsy is particularly important if suspicion for another primary hepatopathy exists . Aerobic and anaerobic bile or liver cultures are also obtained at this time .
Histologic examination of biopsy specimens demonstrates severe vacuolisation in the majority of hepatocytes . Inflammation and necrosis are absent unless another concurrent hepatic disorder is present . Vitamin K1 ( 0.5 mg / kg SC q 12h ) is administered in an attempt to improve coagulation abnormalities prior to liver biopsy . This may resolve abnormalities resulting from vitamin K 1 deficiency .
All clotting factor deficiencies will not correct with this therapy . Therefore if coagulation parameters remain abnormal , fresh frozen plasma or fresh whole blood may be required before liver biopsy to provide necessary clotting factors . Risk of complications is also increased if the platelet count is below 80,000 . Haemorrhagic complications from liver biopsy can be reduced to 10 % or less by careful patient selection . Most post-biopsy bleeding complications occur within the first 5 hours after biopsy but can be delayed up to 18 hours . Cats should be closely monitored for significant post-biopsy bleeding during this time . vet360
Issue 02 | MAY 2018 | 36