Let's talk about cat jaundice today.
Jaundice is not a disease, but a term used to describe the clinical manifestations of hyperbilirubinemia. Although reference values may vary, in most cases it can be assumed that serum bilirubin > 1 mg/dl is abnormal, and in general, the clinical symptoms of jaundice occur only after bilirubin > 3 mg/dl.
Bilirubin is broken down from hemoglobin (the main source), myoglobin, and other proteins that contain porphyrins. The mononuclear phagocytic system in the spleen, liver, and bone marrow engulfs damaged red blood cells. Erythrocytes are broken down and release hemoglobin. Hemoglobin is broken down into heme and globulins, in which globulins are converted into amino acids and heme is broken down into iron and protoporphyrin. Protoporphyrin is first converted to bilirubin and then to bilirubin.
Bilirubin is released from phagocytes, attaches to transport proteins, and is transferred to liver cells through a saturated membrane transport system. Once inside the liver cells, bilirubin binds to the protein ligand, thus preventing blood reflux. This bilirubin is then combined and most of it is excreted into the bile tubules and rarely enters the bloodstream. Some of the bilirubin in the blood is still unbound and enters the urine, but some bind proteins in the circulation, so both bound and unbound bilirubin can be found in the circulation. The binding bilirubin in the bile is excreted from the small intestine, and bacteria convert it into urine biliaryogen. Almost all pro-urocholinin is excreted into the feces in the form of steroidal proteins, and only a small amount is absorbed by the liver or excreted into the kidneys.
Hyperbilirubinemia can be caused by hypersecretion of bilirubin (prehepatic), impaired hepatic uptake/binding (hepatic), or decreased excretion (posterior hepatic). The most common cause of excessive bilirubin secretion is hemolysis, but extensive internal bleeding and damage to red blood cells can also occur. With extravascular hemolysis, bilirubin is produced, but with intravascular hemolysis, hemoglobin is freely complexed with globin in circulation and removed by hepatocytes when hemoglobin breakdown occurs.
Hepatocyte dysfunction due to hypohepatocyte function, poor perfusion, or uptake or binding defects can also lead to hyperbilirubinemia and jaundice. This is associated with inflammatory, infiltrative and necrotic diseases of the liver.
Decreased bilirubin excretion is due to impaired extrahepatic bile flow. Inflammatory, infectious, neoplastic, and obstructive diseases affecting the gallbladder duct, gallbladder, common bile duct, or duodenum can affect bile flow.
As we said earlier, hyperbilirubinemia can be caused by excessive bilirubin secretion (prehepatic), impaired liver uptake/binding (liver), or decreased excretion (posterior hepatic). One by one to see Ha:
Medical history and life history
The medical history can provide information related to a history of possible exposure to drugs or a history of disease that has the potential to predispose the cat to cholangitis, such as pancreatitis and inflammatory bowel disease. Overweight cats with anorexia and jaundice are likely to develop fatty liver. Fleas are associated with Mycoplasma blood cats. Fever may be accompanied by inflammation and infectious diseases. Fatty liver or hepatobiliary tumors can lead to hepatomegaly. Lymphoma may involve the intestines and present as a palpable abdominal mass. Purulent cholangitis, hepatitis, pancreatitis, and biliary peritonitis can cause abdominal pain.
Basic checks
Initial laboratory evaluation of patients with jaundice includes blood routine, biochemical, and urinalysis. There are two things to watch out for first: anemia and liver problems. If moderate to severe anaemia is found, a reticulocyte count should be performed. Aplastic anemia should pay attention to the prehepatic causes of jaundice. Cats with chronic diseases and fatty liver may become moderate to severe anemia. Cats with fatty liver disease also develop microcytosis. However, these diseases can lead to non-aplastic anemia.
Infectious disease surveillance and parasite testing
If aplastic anemia is found, feline leukemia virus, feline immunodeficiency virus, and appropriate parasite testing should be performed. Mycoplasma is the most common bloodthirsty parasite and can cause severe hemolysis and immune-mediated hemolytic anemia. Parasitaemia can be intermittent, so what is shown in cats is a polymerase chain reaction, where the organism on the blood smear is not obviously visible. Diagnosis is usually done through the identification of organisms on a blood smear or tissue aspiration. Primary immune-mediated hemolytic anemia is rare in cats, but the diagnostic method is to rule out the cause of secondary immune-mediated hemolytic anemia, look for hemocoagulation, or perform a coombs test. Cats deficient in pyruvate kinase recurrent strongly aplastic hemolytic anemia, jaundice, and elevated liver enzymes from an early age. Heinz is the result of oxidative damage to red blood cells. Small amounts of Hein's body are normal in cats. More Heinz's body can be seen in cats with hyperthyroidism, diabetes and lymphoma, but their effect on anemia is unclear in these diseases. Amphetamine phenol toxicity can lead to Heinz anemia in cats, but jaundice in these cats can also be caused by liver damage.
Liver enzyme testing
Liver enzymes should also be evaluated when anaemia is evaluated. If there is no prehepatic component and elevated alkaline phosphatase, alanine aminotransferase, and γ-glutamyltransferase, liver problems should be suspected. However, diseases of many other body systems affect the liver and can lead to elevated liver enzymes. Elevated liver enzymes have patterns that may suggest different hepatobiliary disorders. For example, in patients with hepatic lipid degeneration, an increase in alanine aminotransferase (alp) is most pronounced with elevations in alanine aminotransferase (alt) and normal alanine aminotransferase (ggt). With cholangitis, the increase in alt and ggt is greater than that of alp. Elevated bilirubin alone may be seen in cholestasis secondary to sepsis. The most pronounced or severe elevation of bilirubin is biliary obstruction.
Other diagnostic modalities
Other diagnoses to evaluate liver disease may include bile acids, abdominal ultrasound, bile cytology/culture, and liver aspiration/biopsy. A large, high-echo liver suggests fatty liver. In cholangitis, the appearance of the liver parenchyma varies, but the gallbladder wall may thicken. Lymphoma can also have a variable appearance, but is usually heterogeneous and nodular. Primary liver tumors may present as mass lesions. Biliary tract tumors may be cystic in cats. Intrahepatic and extrahepatic biliary trees can assess dilation and obstruction. It is worth noting that some older cats will have manifestations of bile duct dilation, which is a normal physiological change. Intrahepatic ductal dilation is more like biliary obstruction. Cholelithiasis is actually rare and rarely causes obstruction of the common bile duct. Biliary tract tumors, cysts, inflammatory tissues, and stenosis are common causes of obstruction. It is very common that the source of the obstruction cannot be identified, in which case surgery may be required to diagnose and treat the case. Ascites may be found and caused by primary hepatobiliary disorders such as cholangitis, hepatitis, liver tumors, and biliary rupture. Intra-abdominal effusions may also occur in some conditions outside the liver that can lead to jaundice, such as inflammatory bowel disease and pancreatitis. Ultrasound is a great way to assess the state of other abdominal organs (eg, intestines, pancreas, lymph nodes).
When a tumor and hepatic lipidosis are suspected, liver aspiration is performed. Patients with cholangitis may have bile extraction for cytology and culture. Cytology helps to distinguish between purulent and lymphocytic cholangitis. A positive bile culture is common in purulent cholangitis. Care should be taken when considering that the biliary tract aspiration of cats may be blocked due to biliary tree rupture and subsequent biliary peritonitis or abnormal gallbladder walls.
Liver biopsy is necessary for certain diseases such as cholangitis, hepatitis, necrosis, infectious peritonitis in cats, and occasionally with tumors. Biopsy also provides prognostic information. Biopsies can be performed under ultrasound guidance, laparoscopy or surgery. Care should be taken when obtaining a tru-cut liver biopsy from a cat. There are concerns about using a fully automatic tru-cut biopsy gun on cats. Contact with the biliary epithelium is suspected to result in vagus nerve irritation, bradycardia, shock, and, in some cases, death. Biopsy tissues can submit histology and culture. A normal coagulation test should be performed prior to biopsy. Inadequate synthesis of coagulation factors, inability to activate coagulation factors, and vitamin K deficiency due to cholestasis can lead to liver disease. Therefore, coagulation should be assessed prior to biopsy. Severe bleeding can occur even if blood clotts normally.
Treatment is both a solution to the primary disease and supportive care. Supportive care may include fluid therapy to correct fluid deficiencies, maintain hydration, and correct electrolyte and metabolic disorders.
Antiemetics are used to help control vomiting. Severe anemia requires blood transfusions. Fatty liver is recommended for enteral nutrition, amino acids, antioxidants and gallstone drugs. Antioxidants and biliary tract compounds are used for inflammatory liver disease and liver necrosis. Hemolytic mycoplasma, purulent cholangitis, and sepsis require antimicrobial agents. Glucocorticoids (and other immunosuppressants) are used for immunosuppression, immune-mediated hemolytic anemia, lymphocytic cholangitis, and inflammatory bowel disease. Chemotherapy is recommended for lymphoma using a chop-based regimen. Biliary obstruction may require surgery. Biliary stents or metastases may be required. Biliary peritonitis also requires surgery. Surgery can also be used to remove focal tumors.