Bella and her liver Flashcards
Current History:
Bella presents with a three day history of refusing to eat. She has vomited several times over the last 48 hours and has passed small amounts of loose, greyish stool. Mrs Statham thinks Bella seems anxious. Bella has lost some weight recently and also might be drinking a bit more since she’s been off colour. She will go for walks but is less active than usual. Mrs Statham hasn’t noticed any breathing problems with Bella and she doesn’t cough.
Sly and Tyson are well.
Previous medical history:
Bella is very often pruritic in the summer; this can lead to a secondary bacterial pyoderma. She has seen a specialist veterinary dermatologist and has been diagnosed with an allergy to a variety of pollens and grasses. Her pruritus is managed with anti-histamine treatment, and if particularly severe she is given a short course of corticosteroids (prednisolone). She stopped treatment with prednisolone two months ago.
Clinical examination
Bella weighs 27kg (BCS 2.5/5).
Her rectal temperature is 37.6oC
Heart and pulse rate: 140 bpm and regular, peripheral pulses fine.
Respiratory rate was difficult to assess because she was panting.
On examination her oral mucous membranes and sclera appear yellow.
Examination of the head and thorax were otherwise unremarkable.
Palpation of her abdomen was challenging because Bella was very tense, but there was no evidence of hepatic enlargement and no foci of obvious abdominal pain.
No other abnormalities were noted.
What clinical signs might you expect to be exhibited by animals with abdominal pain, are there any species differences?
Distention, anorexia, lethargy, vomit, diarrhoea, various stages of shock, reluctant to move, a stilted gait, tense when palpated, vocalisation, increased respiration rate, increased salivation (nausea) or a praying posture
Non specific visceral pain – pace and restless
What broad categories of disease could be causing the yellow discolouration of Bella’s mucous membranes and sclera?
Destruction of RBC
Liver disease
Obstruction of bile duct
A venous blood sample was taken from Bella’s jugular vein and submitted for a full haematological and clinical biochemistry profile. You submit a fresh blood smear with the samples.
Bella was walked outside the practice and a urine sample obtained by free catch.
Billirubin high
Blood smear: no abnormal cells identified, automated platelet count seems to be correct
Biochem: ALT (specific to liver) Raised, AST raised, ALP (specific to bileduct) rasied, bilirubin raised and fasting bile acids raised.
What is the difference between sensitivity and specificity with respect to a biochemical blood test?
- Sensitivity how low it can pick it up – so sensitive if it is low it will still pick up. RULE OUT – can’t detect it so isn’t there
- Specificity – detecting the right thing. So if you detect it it is there. RULE IN.
- Test sensitivity is the ability of a test to correctly identify those with the disease (true positive rate), whereas test specificity is the ability of the test to correctly identify those without the disease (true negative rate).
How are the “reference ranges” quoted by laboratories for different tests in different species generated?
The short answer to this question is by testing a large number of people who have key similarities and observing what appears to be “typical” for them.
To determine ranges, labs may conduct their own studies for the tests they perform, they may adopt reference ranges from test manufacturers or other labs, or they may derive reference ranges from existing patient data
Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Alkaline phosphatase (ALKP)
Creatine kinase (CK)
These are all enzymes released from cells into the circulation. A “normal” level of activity of these enzymes is found in the circulation in normal animals, damage to the cells which contain these enzymes results in an increase in the level of these enzymes in the circulation.
Which of these enzymes is released only from hepatocytes?
ALT
Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Alkaline phosphatase (ALKP)
Creatine kinase (CK)
These are all enzymes released from cells into the circulation. A “normal” level of activity of these enzymes is found in the circulation in normal animals, damage to the cells which contain these enzymes results in an increase in the level of these enzymes in the circulation.
When we refer to “liver enzymes” are we suggesting they are specific indicators of primary liver disease?
No – they can be raised in other conditions e.g. muscle atrophy
Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Alkaline phosphatase (ALKP)
Creatine kinase (CK)
These are all enzymes released from cells into the circulation. A “normal” level of activity of these enzymes is found in the circulation in normal animals, damage to the cells which contain these enzymes results in an increase in the level of these enzymes in the circulation.
In general terms, what is the specificity and sensitivity of circulating enzymes with respect to liver disease?
Aren’t specific … but are sensitive
Of the clinical biochemistry parameters listed for Bella, which ones are indicators of liver damage and which are indicators of liver function?
Liver damage – ALT, AST, CK
Liver function – ALP, bilirubin, albumin
What might happen to urea levels in hepatic failure and why?
In the case of hepatic insufficiency (e.g., due to liver atrophy caused by a portosystemic shunt, PSS), urea levels may be reduced, as the liver cells are no longer capable of producing sufficient urea. A reduced urea value, however, is not specific to liver disease, as several other factors also influence the blood urea content. A low-protein diet and polyuria/polydipsia, in particular, may result in reduced urea values. Animals with liver disease exhibit a tendency towards gastrointestinal haemorrhages and these patients may therefore also exhibit raised urea levels.
Why are circulating bile acids such a useful test of liver function?
Is the fasting bile acid in Bella’s table of results useful and if not, why not?
IF the liver is functioning properly the BA are removed from the blood to the GB until they are needed again.
Two qualifying points must be considered in the interpretation of BA values. Firstly, different hepatobiliary diseases cannot be distinguished from one another based on BA determinations. Secondly, there is a very poor correlation between the severity of histological lesions or the degree of a PSS, and the magnitude of increase in BA values. The only reliable indicator for clinical remission is a return to normal values, following several BA determinations conducted in a patient in order to assess disease progression or therapeutic response.
Two qualifying points must be considered in the interpretation of BA values.
Bile is secreted by the liver and aids in digestion. When animals (as well as humans) eat, they need the bile (along with other digestive elements secreted by the pancreas) to help break down foods, especially fats. The gallbladder, where the bile is stored, contracts to release bile into the small intestine as needed for digestion. From there, the bile acids do their work breaking down fats during the process of digestion.
The bile acids are then absorbed by the intestine into the liver (portal) bloodstream and returned back to the liver. If the liver is functioning properly, the bile acids are removed from the bloodstream and returned to the gallbladder until they are needed again. This is called Enterohepatic Circulation and is the body’s way of “recycling” the bile acids.
How Is a Bile Acid Test Performed?
In order to conduct a bile acid test, your dog will need to fast. Then blood is drawn and the dog is fed a fatty meal. Two hours later, the blood is drawn again. The blood tests measure pre- and post- meal levels of bile acids. If the levels are high, there may be a problem with the liver or hepatic vasculature (the liver’s blood flow).
What Do the Test Results Mean?
Comparing the two blood levels (pre- and post-meal) allows the veterinarian to see how well the liver, bile ducts, and blood flow to the liver are functioning. Bile acids are removed from the liver (portal) blood by the liver cells (hepatocytes). If the liver cells are not functioning well, the bile acids remain in circulation and enter the body (systemic) blood supply where the elevated levels are measured by this test.
If post-meal (or even in some cases, fasting) blood levels of bile acids are high, this means that the liver isn’t doing its job of removing the bile acids from the blood as it should. The actual numbers that are considered “normal” vary with the laboratory used, so please discuss numerical lab findings with your vet.
Fasting – is overnight or just before a meal. But she hasn’t eaten. However is the normal dog you would expect these to plummit so you know these are high.
Should not use in V+ or D+
Comment on bellas ultrasounds?
BD= common bile duct
The ultrasound scan of the liver was normal but a dilated, rather tortuous common bile duct and moderately large gall bladder were seen.
Ultrasound examination of the region of the pancreas revealed an abnormal area of variable echogenicity.
What could be causing this ultrasound appearance?
Pancreatic adenocarcinoma
Pancreatic inflammation
Pacnreatic infection
Pancreatic necrosis
Fatty changes of the pancreas with age
What would you recommend next for Bella?
Exploratory laparotomy
Thoarcic radiographs
Offer euthanasia
CPLI (canine pancreatic lipase) And coagulation times
Fluids
