Liver Flashcards
1
Q
What is the normal colour of the liver?
A
Typically a reddish-brown, but may be brown in animals, such as cattle, sheep and pigs, that have been bled out
2
Q
Why might a liver be yellow-brownish in colour?
A
Accumulation of fats in the liver can cause it to have a yellowish-brown appearance
3
Q
Why might a liver be greenish/yellow?
A
Post-mortem changes can cause areas of pallor or darkening or greenish-yellow discolouration, especially adjacent to the gall bladder
4
Q
What is the weight of the liver dependent on?
A
The weight of the liver as a proportion of body wieght can vary depending on factors includin the species (higher in carnoviores comapred to herbivores), nutritional status (hepatic storage of glycogen and fat) and age (liver weight decreases with age).
5
Q
What is the percentage of body weight of the liver?
A
Dog = 3-4%
Horse = 1-1.5%
6
Q
What blood vessels deliver blood to the liver?
A
Portal vein – provides 70-80% of the blood inflow
Hepatic artery
7
Q
From which organs does the blood in the portal vein come from?
A
Collects blood from the spleen, pancreas, stomach and intestines
8
Q
From what blood vessel does the hepatic artery originate from?
A
From the ceoliac artery, which arises from the aorta
9
Q
What blood vessels drain blood from the liver?
A
Hepatic vein to the caudal vena cava
10
Q
After blood enters the liver from the portal vein and hepatic artery, what structures for sit flow through before arriving in the hepatic veins?
A
Portal vein and hepatic artery > hepatic sinusoids > across hepatic lobule > central vein > interlobualr veins > hepatic veins
11
Q
Within the functional unit, the hepatic acinus, what are the 3 zones?
A
Zone 1 – periportal region. The area that recievs the blood frm the portal vein and hepatic artery first
Zone 2 – midzonal region. Receives blood next
Zone 3 – centtilobular region. Recives the blood last before it drains into the central vein
12
Q
What are the metabolic differences between the 3 zones of the hepatic acinus?
A
Zone 1 – periportal will receive blood with the highest oxygen and nutrient content
Zone 3 – centrilobualr will receive blood with lower oxygen and nutrient content. Hepatocytes in zone 3 also have higher levels of metabolic enzymes. These factors make this zone the most sensitive to injury by toxic compounds
13
Q
Name 3 circulatory disorders affecting the liver.
A
- Congenital portosystemic shunts
- Post-hepatic conditions affecting outflow of blood from the liver
- Intra-hepatic or pre-hepatic conditions associated with abnormal portal vein inflow
14
Q
How can portosystemic shunts be classified?
A
Whether the anomlous blood vessel is within the liver or not
15
Q
How does an intra-hepatic portosystemic shunt form?
A
Large blood vessel connects the portal vein directly to the hepatic vein, which is a lower resistance path than through the lobule and smaller sinusoides, so a significant portion of blood flow is through this shunt and bypasses the functional part of the liver
16
Q
How does an extrahepatic portosystemic shunt form?
A
Large blood vessel connect the portal vein/tributaries of the portal vein, bypassing the liver and through extra-hepatic anomalous vein to connect to the systemic circulation (caudal vena cava or hepatic vein).
17
Q
Distinguish which breeds are affected by which type of portosystemic shunt.
A
Extrahepatic – small (wEe) dog breeds
Intra-hepatic – large (bIg) dog breeds
18
Q
Distinguish intra and extrahepatic CPSS.
A
Intrahepatic CPSS – left or right portal vein branch to hepatic vein or directly with caudal vena cava
Extra-hepatic CPSS – left or right gastric vein or splenic vein to the caudal vena cava or azygous vein
19
Q
What are the functional consequences of congenital portosystemic shunts?
A
- Reduced hepatic perfusion
- Small liver due to underperfusion – microhepatica
- Poor growth due to less liver and so less functional capacity
- Hepatic encephalopathy, as the liver is unable to detoxify waste products and these build up and affect the central nervous system
20
Q
Will congenital portosystemic shunts result in increased blood pressure in the portal venous system – portal hypertension?
A
No – offer a lower resistance route
21
Q
How does heart disease affect outflow from the liver?
A
Especially right sided CHF, which will increase pressure in the caudal vena cava which can be referred back through the hepatic vein to the liver and impair outflow of blood from the liver
22
Q
How does hepatic vein/vena cava obstruction affect outflow from the liver?
A
Luminal obstruction (thrombus), vessle wall thickening (neoplasia, inflammation), external compression (by a mass, such as an abscess or tumour)
23
Q
What are the consequences of impairment of post-hepatic outflow?
A
- Hepatic passive venous congestion – dilation of the sinusoids and central vein and becoming packed full of the blood, can extend to portal vein
- Hepatomegaly – blood pools and congest in the liver may make it appear larger so there is some degree of hepatomegaly
- Chronic passive congestion may develop an enhanced lobular or reticular pattern on the sectioned surface of the liver (nutmeg liver). Reddening due to congestion and the yellowish colour caused by accumulation of fat, create enhanced lobular pattern
24
Q
Could post-hepatic conditions causing passive congestion of the liver cause an increased blood pressure in the portal venous system (portal hypertension)?
A
Yes
25
Name 3 intra-hepatic and pre-hepatic conditions associated with abnormal portal vein inflow.
- Advanced chronic liver disease with fibrosis
- Portal vein obstruction – thrombosis, inflammation, abscess, neoplasia
- Portal vein hypoplasia – portal vein is smaller than normal
26
Could intra-hepatic conditions, such as diffuse liver fibrosis or pre-hepatic conditions, such as portal vein hypoplasia, be a cause of portal hypertension?
Yes
27
What are the potential causes of portal hypertension?
- Post-hepatic conditions affecting outflow of blood from the liver
- Intra-hepatic or pre-hepatic conditions associated with abnormal portal vein inflow
28
What are the potential consequences of portal hypertension?
- Ascites
- Acquired portosystemic shunts – intra-hepatic and re-hepatic causes of portal hypertension (not by passive hepatic congestion, such as heart failure). Allow portal blood to flow directly to the systemic venous system bypassing the liver
29
What are the possible responses to hepatic injury?
- Hepatocellular vacuolation
- Necrosis
- Hepatocellular regeneration
- Inflammation
- End stage liver (cirrhosis)
- Hyperplastic and neoplastic changes
30
What are the possible hepatocellular vacuolar changes?
- Vacuoles may contain lipid (fatty change), water (hydropic change) and glycogen
- Potential gross changes – enlargement, altered colour change (pallor or yellow-brown), or altered consistency (greasy if lipid accumulation, increased fragility)
31
Why do cats' livers appear more brown than dogs' livers?
Cats can store more fat in their livers so can end up naturally appearing more brown than dogs
32
What are the 2 mechanisms of lipid accumulation in the liver?
There is excess delivery of free fatty acids to hepatocytes, causing negative energy balance and metabolic/endocrine disease
Reduced hepatocellular capacity to metabolise fats often due to hepatocellular injury – hypoxia, toxins, dietary deficiencies lipotropes for lipid metabolism
33
What are the causes of water accumulation/hydropic change in the liver?
Various toxins
Metabolic insults
Hypoxia
34
What are the causes of glycogen accumulation?
Associated with hyperadrenocorticism or corticosteroid administration – ‘steroid induced hepatopathy’
35
What is a property of the liver on PME if there is significant fat present?
It can cause the liver to be bouyant in water
36
What does a focal/random pattern of necrosis suggest of the cause?
Scattered, randomonly distributed foci of necrosis. Typical of some infectious agents, such as bacteria, viruses, protozoa, migrating parasites. May be of little functional significance to the liver
37
What is the appearance of focal/random necrosis?
Area of necrosis in hepatocytes and there is variable amounts of erythrocytes in necrosis. So typical gross appearance is one or more white/grey or reddish foci (if lots of blood associated with them).
38
What does a zonal pattern of necrosis suggest of the cause?
Zone 3/certrilobular/periacinar most commonly affected as it is more prone to hypoxia as it receives blood last and also the hepatocytes in zone 3 contain a lot of metabolic enzymes and so may activate toxins
39
What are some typical causes of zonal necrosis?
- Hypoxia/ischaemia
- Exposure to some toxins
- Some severe viral infections, such as canine adenovirus 1
40
Describe the appearance of zonal necrosis.
Multiple areas of necrosis, paler pink, surrounding central veins. In some areas, these join, known as bridging necrosis. This results in a gross pattern of mottled appearance, with colour intensity perhaps dictated by amount of haemorrhage. Microscopy needed to identify necrotic areas. Pattern sometimes called enhanced lobular pattern/enhanced reticular pattern.
41
What are the causes of massive necrosis?
- Severe toxic injury
- Vitamin E/selenium deficiency in pigs/hepatosis dietetica
42
Describe the appearance of massive necrosis.
Red appearance due to red blood cell snow filling the spaces left by the necrotic hepatocytes. There is a fine rim of surviving hepatocytes along the edge of the lobules but most have died and been replaced with blood
43
You submit a liver biopsy in formalin for histopathology. The pathology report report indicates a vacuolar hepatopathy. What type of material could be present in the vacuoles?
Lipid, water or glycogen – intracellular accumulation of lipid, water or glycogen can all create cytoplasmic vacuolation. Sometimes some features of the vacuolated hepatocytes may allow the pathologist to suggest the most likely material.
44
A 6 month old frenhc bulldog has severe jaundice and rasied liver enzymes. Severe centrilobular necrosis is rpeorted on a liver biopsy submitted for histopathology. Of the aetiologies, which should you include as the potential cause of the hepatic necrosis?
Recent hepatotoxin ingestion and severe hypoxia
45
What are the vague clinical signs of liver disease?
Inappetence
Lethargy
Weight loss
Vomiting
Diarrhoea
Polyuria/polydipsia
46
What are the specific clinical signs of liver disease?
- Jaundice/icterus) - hyperbilirubinaemia – normal is 10-1 umol/L, 10-35umol/L high but not appear yellow, so significantly high to appear yellow
- Ascites
- Hepatic encephalopathy
- Coagulopathy
47
Summarise the cycle of bilirubin.
Bilirubin from senescent RBC, macrophages break down these in liver, spleen and bone marrow. Bilirubin bound to albumin and uptaken into liver cells. Stored in gall bladder and excreted when gall bladder contracts and is released when eating
48
Distinguish pre-hepatic, hepatic and post-hepatic jaundice.
- Pre-hepatic for a process prior to the liver, such as increased breakdown of RBC, so patients would be anaemic
- Hepatic would be inherent liver disease, as we can’t convert these
- Post hepatic is something wrong with the pancreas or gall bladder
49
Why do effusions in liver disease occur?
From either increased hydrostatic pressure or low albumin
50
What is hepatic encephalopathy?
Toxins that accumulate in bloodstream such as ammonia due to liver disease affects rain function. With extreme hepatic dysfunction or portosystemic shunting
51
What are the clinical signs of hepatic encephalopathy?
Obtunded
Lethargic
More vague forebrain signs seizures
Comas or death in more severe cases
High ammonia in the blood or other evidence of liver disease
52
What is the hepatic link to coagulopathy?
Liver dysfunction may mean not enough clotting factors
53
What is hepatocutaneous syndrome?
Hyperkeratotic footpads, skin biopsy specific diagnostic. Ultrasound looks like Swiss cheese
54
Describe the severity-time graph for differentials of liver disease.
- Vascular, trauma, toxin = 2-6 hours
- Inflammatory (infectious/sterile) = acute over hours to a few days – main challenge is owners not noticing clinical signs in first stages so appears more acute than actually is
- Metabolic quiet insidious, but progressively worsen with wax and wane, more chronic in terms of months, owners may not notice
- Neoplastic often chronic, can be acute, as insidious part at the beginning is progressive,
- Degenerative months to years, vague clinical signs reported over months and years
55
What is done next after a differential list for liver disease is made?
Use hepatic enzyme elevations to determine whether predominantly hepatocellular or cholestatic
56
Which are the hepatocellular enzymes in dogs and cats?
ALT and AST in cats and dogs (and/or GGT)
57
Which are the cholestatic enzymes in dogs and cats?
ALP and/or GGT (> ALT and/or AST) with/without other features of cholestasis – hypercholesterolaemia with/without hyperbilirubinaemia with/without overt jaundice
58
How do liver enzymes differ between cats and dogs?
Be aware of limitations, especially in cats, as short half-life. Dog half life is 3-4 days and cats is 4-6 hours, so can miss window of opportunity for cats – may have normal blood ranges on cats with liver disease.
59
What are some acute toxic causes of hepatobiliary disease with hepatocellular patterns?
- Drugs – antimicrobials like TMPS and doxycycline, immunosuppressants like azathioprine, anti-thyroidals like methimazole
- Toxins like blue-green algae, aflatoxins
- Amantia species (mushrooms)
- Xylitol
60
What are some chronic toxic causes of hepatobiliary disease with hepatocellular patterns?
Chronic, low-level exposure, such as phenobarbitone (seizure medication, can give accumulative toxic injury if wrong dose over time)
61
What are some acute traumatic causes of hepatobiliary disease with hepatocellular patterns?
Blunt trauma – hepatic contusions
62
What are some acute inflammatory causes of hepatobiliary disease with hepatocellular patterns?
Infections – neutrophilic cholangitis (cats)/cholangiohepatitis (dogs), leptospirosis (dogs), CAV-1 in unvaccinated dogs
63
What are some chronic inflammatory causes of hepatobiliary disease with hepatocellular patterns?
Sterile – lymphocytic cholangitis (cats), chronic hepatitis (dogs)
64
What are some metabolic and neoplastic causes of hepatobiliary disease with hepatocellular patterns?
Metabolic - reactive hepatopathies
Neoplastic - hepatocellular adeno/carcinoma, lymphoma – metastasise to liver
65
What are some acute toxic causes of hepatobiliary disease with cholestatic patterns?
Drugs/toxins – some can cause an idiosyncratic cholestatic pattern
66
What are some chronic toxic causes of hepatobiliary disease with cholestatic patterns?
Chronic, low-level exposure, such as phenobarbitone
67
What are some acute traumatic causes of hepatobiliary disease with cholestatic patterns?
Biliary rupture – typically secondary to underlying disease, such as trauma
68
What are some acute inflammatory causes of hepatobiliary disease with cholestatic patterns?
- Infections – neutrophilic cholangitis (cats)/cholangiohepatitis (dogs, cholecystitis, FIP (cats), toxoplasma
- Sterile – acute pancreatitis, not hepatobiliary but critical differential
69
What are some chronic inflammatory causes of hepatobiliary disease with cholestatic patterns?
Sterile – lymphocytic cholangitis (cats), chronic hepatitis (dogs), chronic pancreatitis
70
What are some acute metabolic causes of hepatobiliary disease with cholestatic patterns?
Hepatic lipidosis, gall bladder mucocele, obstructive choleliths
71
What are some chronic metabolic causes of hepatobiliary disease with cholestatic patterns?
Vacuolar hepatopathies, including steroid/metabolic, gall bladder mucocele
72
What are some neoplastic causes of hepatobiliary disease with cholestatic patterns?
Hepatocellular adeno/carcinoma – sometimes just cause isolated ALP elevation, primarily biliary neoplasia
73
What are the other possible origins of ALP not specific to liver disease?
As well as cholestatic, there are steroid (dogs) and bone isoenzymes, so in growing cats and dogs. Commonly induced by some drugs (steroid in dogs, phenobarbitone)
73
What are the other possible origins of GGT not specific to liver disease?
Cholestatic and steroid induction in dogs, can be induced by some drugs (steroid in dogs, phenobarbitone)
74
What are the other possible origins of AST not specific to liver disease?
Found in muscle, concurrent creatine kinase will help evaluate for myopathy
75
What are the other possible origins of ALT not specific to liver disease?
Found in muscle – needs to be very severe myopathy to increase ALT
76
What are some possible conditions causing secondary liver disease?
- Liver as an immune organ – any systemic inflammatory disease
- Drugs causing enzyme induction (glucocorticoids, phenobarbitone)
- Metabolic diseases causing vacuolar hepatic change (hyperadrenocorticism, diabetes mellitus) or a toxic hepatopathy (hyperthyroidism)
- Hepatic hypoxaemia, anaemia, hypovolaemia, heart failure
77
What may magnitude of enzyme elevation indicate about liver disease?
- May be low with end stage liver disease or in cats
- Often low-moderate with secondary/reactive – can be markedly increased with steroid induction
- Can be anything (low-high) with primary liver disease
- May fluctuate – re-assess if not sure of significance and animal clinically well
78
What is the evidence of multisystemic disease with liver disease?
- Renal – leptospirosis, toxins
- Lymphadenomegaly, multiple organs – lymphoma
- Ocular – canine adenovirus 1 (CAV-1)
79
What does structural hepatic disease suggest on ultrasound?
Structural hepatic disease indicates hepatic pathology is present, regardless of enzyme elevations (such as nodular regeneration)
80
81
Is the size of the gall bladder on ultrasound significant?
Size of gall bladder never significant, only when ducts are dilated indicates back pressure and obstruction
82
What is sludge on the gall bladder?
Normal in dogs and much less normal in cats. Majority of cats with sludge probably have biliary disease. Biliary mucocele looks like kiwi in cross section (border terriers prone to), mucus overproduction in wall of gall bladder and produces very solid gall bladder, can get bigger over time and cause pressure necrosis and may rupture.
83
What is the problem with colour ultrasound imaging the bile ducts?
Vessels are coloured, bile ducts are non-coloured. Previous obstruction – bile ducts may never go back to normal, so may not be an active problem
84
Why are cats with liver disease hard to diagnose?
- Every cat with hyperthyroidism has increased liver enzymes
- Short enzyme half-lives
- Commonly have non-specific signs
- Commonly have multiple comorbidities
- Older cats, elevated hepatic enzymes, normal function
85
What are the functions of the liver?
- Protein metabolism
- Carbohydrate metabolism – synthesis, storage and release of glucose
- Lipid metabolism
- Excretion of bile – no gall bladder so continuous flow
- Detoxification – biotransformation of endogenous and exogenous compounds
- Mononuclear – phagocyte system
- Miscellaneous – storage of vitamins
86
How does the liver do protein metabolism?
- Protein synthesis, including factors involved in coagulation
- Gluconeogenesis from amino acids
- Eliminating ammonia the major toxic byproduct of amino acid catabolism
87
When are hepatic functions impaired in horses?
Most hepatic functions not impaired until greater than 80% of the hepatic mass is lost
88
What are the common clinical signs of hepatic insufficiency in horses?
Depression
Anorexia
Colic
Hepatic encephalopathy
Weight loss
Icterus
89
What are the less common clinical signs of hepatic insufficiency in horses?
Photosensitization
Diarrhoea
Bilateral laryngeal paralysis
Bleeding
Ascites
Dependent oedema
90
What is stage 1 hepatic encephalopathy in horses?
Probably missed in most equine patients. Subtle impairment of intellect
91
What is stage 2 hepatic encephalopathy in horses?
Motor function, intellectual ability and consciousness impaired:
Depression
Head pressing
Circling
Ataxia
Aimless walking
Yawning
92
What is stage 3 hepatic encephalopathy in horses?
Aggressive
Periods of stupor
Recumbent
Coma
93
What is the cause of hepatic encephalopathy in horses?
Insufficient hepatocellular function, irrespective of the cause of the liver disease
94
What is the pathogenesis of hepatic encephalopathy in horses?
- Accumulation of toxins in the blood (including ammonia)
- Augmented activity of inhibitory neurotransmitters
95
How is hepatic encephalopathy diagnosed in horses?
- Presence of neurologic signs of cerebral dysfunction
- With physical examination and laboratory findings compatible with liver disease
96
What are the disease states resulting in hyperbilirubinaemia in horses?
- Increased production of bilirubin – haemolysis, intracorporeal haemorrhage
- Impaired uptake and conjugation of bilirubin – liver disease, anorexia, prematurity
- Impaired excretion of bilirubin into biliary tract = regurgitation icterus
97
Why might there be impaired excretion into the biliary tract in horses?
- Blockage of bile with cholangitis, hepatitis, cholelithisasis, neoplasia, fibrosis
- If congested bilirubin more than 30% greater than normal, indicative cholestasis
98
What is hepatogenic photosensitisation in horses?
- Abnormally heightened reactivity of the skin to UV
- Increased blood concentration of a photodynamic agent phylloerythrin if hepatogenic
- UV + phylloerythrin = free radicals = cell membrane damage and necrosis
99
Distinguish conjugated and unconjugated bilirubin in horses.
Conjugated (direct) + unconjugated (indirect) = total bilirubin
Increase in unconjugated bilirubin seen in hepatic disease – usually acute hepatocellular. But also anorexia, haemolysis, others
100
How is bile acid concentration indicative of disease in horses?
- Enterohepatic circulation normally removes greater than 90% bile acids
- Blood concentration increases with liver disease
- Quantitation is an excellent screen of liver failure
101
How is protein synthesis tested in horses?
- Hypoalbuminaemia – non-specific
- Evaluation of haemostasis – non-specific
- Liver removes ammonia from circulation, converts to urea – increase in ammonia, decrease in BUN, not specific
102
Why are increased liver enzymes indicative of disease in horses?
- Hepatocellular necrosis results in the release of enzymes
- So increased serum activity may be indicative of active hepatic disease
103
What is the indication of increased SDH, ARG and GLDH in horses?
- Liver specific and not inducible
- Specific for hepatocellular disease but not type of disease
- All usually better for acute disease
- SDH would be the best test but doesn’t survive in a tube
104
What is the indication of increased ALT in horses?
- Also found in other tissues
- So low specificity
105
What is the indication of increased GGT in horses?
- Specific for hepatic disease in horses
- The most sensitive indicator of hepatic disease
- Hepatocellular damage
- Continues to rise for 1-2 weeks after liver improving
- May not increase in chronic disease
- Higher in young foals
106
What are the first line lab tests investigating liver disease in horses?
- GGT – damage
- Bile acids – function
107
How is the liver biopsied in horses?
- Ultrasound guided
- Check they can clot first
- But usually low risk
- Not if hepatic lipidosis
108
What is the treatment for hepatic insufficiency in horses?
- Therapy for hepatic insufficiency largely supportive
- Maintain until enough liver regenerates to provide adequate function
- If severe hepatic fibrosis, adequate regeneration often not possible
- Care with sedation – low dose xylazine
- Correct fluid deficit, acid-base, electrolyte imbalances – IV fluids spiked appropriately. If anorexic, spike fluids to be 5% glucose
109
How can hepatic insufficiency in horses be managed with diet?
- High carbohydrate, low in (good quality) protein
- Multiple small feeds as impaired gluconeogenesis
110
How can absorption and production of toxins by enteric bacteria be reduced?
Reduce absorption – paraffin/magnesium sulphate by nasogastric tube
Reduce production – neomycin, metronidazole, lactulose
111
What may chronic hepatic disease in horses show?
Hyperglobulinaemia
Hypoalbuminaemia
Fibrosis
112
What is theiler's disease in horses?
- ‘Serum associated hepatitis’
- Usually received an equine origin antiserum 4-10 weeks before
- Supportive treatment
113
Describe bacterial hepatitis in horses.
- Primary is rare
- Secondary more common – after cholelithisasis, intestinal obstruction, anterior enteritis
- Liver biopsy for histology and culture
- Supportive therapy
- Appropriate antibiotics 4-6 weeks
114
How is acute lipidosis treated in horses?
- Secondary to hyperlipidaemia
- Supportive
- Treat hyperlipidaemia
115
What are the causes of chronic meagolocytic hepatopathy in horses?
- Ingestion of pyrrolizidine alkaloid containing plants
- Ragwort
- Cumulative toxicity
116
What is the pathogenesis of chronic megalocytic hepatopathy in horses?
- Toxin stops cell division – hepatocytes enlarge ‘megalocytes’
- When megalocytes die, get fibrosis
- Extensive fibrosis results in the liver shrinking > failure
117
What are the clinical signs of chronic megalocytic hepatopathy?
- Clinical signs 4 weeks – 12 months after ingestion
- Abrupt onset of H.E. and photosensitisation late in disease
- Earlier, anorexia, weight loss, icterus
118
What is the prognosis of chronic megalocytic hepatopathy?
Generally poor prognosis as fibrosis limits regeneration
119
What are the clinical signs of cholelithiasis in horses?
Icterus
Colic
Pyrexia
Weight loss
Often intermittent signs
Conjugated bilirubin more than 30% increased often
Many have dilated bile ducts on ultrasound
120
How is cholelithiasis in horses treated?
- May have underlying bacterial cause so long term antibiotics (culture biopsy)
- Surgery
121
What is non-septic hepatitis in horses?
- Lymphoplasmacytic
- Inflammatory infiltrate without infection
122
How is non-septic hepatitis in horses treated?
- Corticosteroids, azathioprine
- Monitor with biopsies
123
You see a horse which has been losing weight and has some sunburn on his white patches. There is a tight budget. What test(s) do you take?
GGT and bile acids
124
Increased serum activity of GGT but bile acids are borderline OK. What next?
Liver panel, clotting and biopsy
125
Non-infectious hepatitis. What next?
Treat horse and test other horses there
126
Describe normal abdominal palpation of the liver.
Normal to not feel liver on palpation, should be very tucked up in costal arch
127
How might cholestatic and hepatocellular hepatopathy be presented?
ALT and ALP both raised
128
What is the normal cut off point for bile acids on biochemistry?
30-35 cut off for normal). Can do bile acid stimulation test but with bile acids that are so persistently high, no point in doing this test.
129
What are the characteristics of chronic hepatitis?
Small liver so such as vascular compromise, such as portosystemic shunts, or if losing liver cells over time due to fibrosis and scarring from chronic hepatitis.
130
What do characteristics of abdominal effusion analysis indicate?
- Transudate – hypoalbuminaemia
- Modified transudate – portal hypertension
- Bile – biliary rupture
131
What are 2 other specific infectious disease tests that can be used in chronic hepatopathy cases?
Leptospirosis – serology, PCR
Feline Infectious Peritonitis – PCR, immunocyto/histochemistry, can sample admonial fluids to diagnose, will often have liver changes
132
When is hepatic sampling required?
- Required for definitive diagnosis of many diseases – neoplasia cannot be diagnosed on appearance alone. Never put an animal to sleep based on imaging of the liver, always sample
- Rarely used in the acute or toxic setting
133
What are the indications for hepatic sampling?
- Persistent/progressive enzyme elevations – exclude extra-hepatic causes first
- Structural parenchymal pathology
- Monitoring response to therapy
- Breed screening – Bedlington terriers prone to copper storage in the liver
134
Describe liver cytology as a way of hepatic sampling.
Normal gauge needle but longer to get FNA from liver – works well in small number of cases, such as round cell tumours, hepatic lipidosis. Does not perform well in sterile inflammatory disease as you can’t see architecture of the liver and does not perform well for hepatic masses/primary tumours of the liver as these are often not discernible on cytology.
135
Describe liver histology as a way of hepatic sampling.
Percutaneous (‘tru-cut’) biopsy needles to take a core of the liver, biopsy on both sides as you can have different disease processes on different lobes/sides.
136
Describe cholecystocentesis as a way of hepatic sampling.
Bile cytology (EDTA), culture (plain). Sample of bile, empty gallbladder as much as possible as this will leak if left full after this
137
Describe laparoscopy as a method liver sampling.
Larger and can access more, minimally invasive, more expensive, specialist equipment
138
Describe laparotomy as a method liver sampling.
More likely to be done if being taken to surgery and likely to be sampling multiple organs
139
What can be done before liver sampling?
Check platelets, PT, aPTT first with/without pre-treat with vitamin K
140
What are the possible complications of liver sampling?
- Haemorrhage
- Ascites
- Bile peritonitis
- Clinical deterioration
- Unnecessary sample
- Non-diagnostic sample
141
When can't hepatic sample be cultured?
If fixed in formalin
142
What are the 3 most common feline liver diseases in the UK?
Neutrophilic cholangitis
Lymphocytic cholangitis
Hepatic lipidosis
143
Why might cats be jaundiced?
- FIP is a common and important cause of jaundice in cats
- Septic cats can become jaundiced
144
Which multisystemic diseases can the liver be involved with?
Lymphoma
Toxoplasma
FIP
145
Describe neutrophilic cholangitis.
- Ascending bacterial biliary infection
- Acute disease
- Often sick/pyrexic
- Diagnosis - bile cytology/culture
- Chronic/mixed cholangitis possible
- May accompany pancreatitis and/or inflammatory enteropathies 'triaditis'
146
Describe lymphocytic cholangitis.
- Immune-mediated biliary disease
- Chronic disease
- May have hepatomegaly, abdominal effusion, jaundice and hyperglobulinaemia (FIP differential diagnosis)
- Diagnose with a liver biopsy
- Chronic/mixed cholangitis possible
- May accompany pancreatitis and/or inflammatory enteropathies 'triaditis'
147
Describe hepatic lipidosis.
- Triglyceride deposition within hepatocytes, due to fat mobilisation in times of starvation
- Look for underlying disease
- Often sick with significant hepatic dysfunction - coagulopathy, encephalopathy
- Diagnosis - liver FNA
148
How do cats with liver disease appear on bloods and on imaging?
Hepatocellular on bloods and then cholestatic on imaging
149
When is cholecystocentesis not done?
Don’t do this if gallbladder wall is very thickened, makes this very risky of leaking
150
When is surgery indicated in liver disease?
- Abdominal free fluid – if bile peritonitis, if haemoabdomen secondary to hepatic pathology
- Hepatic mass lesion
- As a diagnostic/therapeutic procedure, where minimally invasive sampling is contraindicated
- Gall bladder compromise
- Symptomatic gall bladder mucocele
- Obstructive biliary disease – exemption is pancreatitis
151
How is dietary modification used to address liver disease?
- To avoid exacerbating hepatic dysfunction
- With/without copper restriction
152
What are the complications of liver disease management?
- Hepatic encephalopathy
- Portal hypertension
153
List the ways of managing liver disease?
- Anti-inflammatory/immunosuppressive therapies
- Specific – copper chelation, treatment of infectious agents, neoplastic disease
- Hepatoprotective therapies – antioxidants, choleretics
- Various supportive – fluids, nutrition, anti-emetics
154
What is the characteristic of congenital shunting?
1 abnormal vessel not multiple
155
What are the clinical problems in congenital portosystemic shunt patients?
- Hepatic encephalopathy
- Inappetence
- Gastrointestinal signs
- Urolithiasis – ammonium biurate. High excretion of ammonia and concentrated in ammonia and crystals form and crystals aggregate to form stones
- Urinary tract infections
- Coagulopathies/gastrointestinal haemorrhage
156
How can congenital portosystemic shunts be medically managed?
- Normalise macroscopic vascular anatomy to prevent further shunting
- Requires period of pre-operative medical stabilisation
157
How can congenital portosystemic shunts be surgically managed?
- As a precursor to intended surgical management
- As a long-term option where surgery is declined/not possible
158
What dietary modification can be used for hepatic encephalopathy?
- Transition to plant based protein diets > produce fewer aromatic amino acids > less likely to get encephalopathy
- Protein modification to minimise encephalopathy
- Vegetable based protein vs. protein restriction
- With/without cottage cheese as this doesn’t produce aromatic amino acids and helps with palatability
159
How can lactulose be used to medically manage hepatic encepahlopathy?
Human laxative that can work in cats and dogs but not used as a laxative in animals, smaller dose but laxative traps ammonia in colon in ionised form to prevent going into the blood
160
How is hepatic encephalopathy crisis managed?
- Ensure euhydrated, normokalaemic – IV fluids
- Dietary/protein modification/GI haemorrhage – if owner gives a very high protein meal with PSS, such as a steak, they can become comatose quickly
- Lactulose retention enema
- Check blood glucose
- Anti-epileptic therapy – Levetiracetam vs. phenobarbitone
- Mannitol? Controls cerebral oedema
161
What are the medical considerations in portosystemic shunt patients?
- Inappetence – palatability considerations vs. medical management
- Gastrointestinal signs – avoid fluid deficit
- Urolithiasis – may dissolve post-op/may need intervention/surgery
- Urinary tract infections – indication for antibiotics
- Check coagulation times (PT/aPTT)
- Gastric ulceration/haemorrhage especially in intrahepatic shunts
162
What is done when you suspect leptospirosis?
- Amoxicillin-clavulanate/penicillins – IV/pending results
- Doxycycline – 2 weeks oral to clear carrier state
163
What is done when you suspect hepatic abscesses?
Surgery + antibiotics - amoxicillin-clavulanate, then guided by culture/sensitivity
164
What is done if you suspect toxoplasmosis?
- Clindamycin
- Protozoa – but some antimicrobials have efficacy
165
What are choleretics?
- Ursodeoxycholic acid (UDCA)
- Hydrophilic, 'beneficial' bile acid
- Synthetically derived
166
What is the mechanism of choleretics?
- Alters bile composition
- Stimulates bile flow
- Modulates inflammatory response in liver
- Modifies apoptosis
167
When are choleretics indicated and contraindicated?
Indicated if cholestatic disease
Not safe in rabbits
168
What are some antioxidants that can be used in liver disease management?
- N-Acetyl-Cystine (IV option)
- Milk thistle extracts/isolates. Naturally occurring antioxidant
- S-Adenosyl-L-methionine (SAMe) – naturally occurring antioxidant
- Vitamin E
- Vitamin C?
169
When might steroids be used in liver disease?
- Anti-inflammatory vs. immunosuppressive
- Chronic hepatitis (some cases), lymphocytic cholangitis
170
When might immunosuppressants used in liver disease and how?
- Diseases benefitting from immunosuppression – lymphocytic cholangitis, chronic hepatitis
- Start with steroids
- May need adjuncts
171
What are the complications of liver disease?
- Hepatic encephalopathy
- Portal hypertension
- Coagulopathies
- Hypoglycaemia
172
What are the consequences of portal hypertension?
- Secondary shunting
- Splanchnic bed oedema > impairs GI perfusion and health, GI haemorrhage
- Ascites
173
How is portal hypertension managed?
- Treat cause of portal hypertension (if possible)
- Spironolactone with/without Na+ restriction
- Avoid GI toxic drugs
174
How is chronic hepatitis characterised?
Mixed inflammatory infiltrate, with/without fibrosis and regenerative nodules. Is an end/alter stage liver disease and is a reaction to a previous hepatic insult, perhaps years previously. So as a result, progressive loss means can be subclinical until end stage
175
What are the causes of chronic hepatitis?
- Idiopathic – most cases, diagnosis of exclusion
- Copper associated
- Breed/genetic basis – Bedlington Terriers, Labrador Retrievers
- Infectious – CAV-1, leptospirosis
- Previous toxin exposure
- Previous acute hepatitis insult
- Immune-mediated - Dobermans and cocker spaniels
176
What is copper analysis in copper associated chronic hepatitis?
Qualitative/stain for copper and quantitative/quantity proportion of liver biopsy that is copper
With/without genetic testing (COMMD1/MURR1) in breeds that are predisposed (homozygous) or in breeding programmes
177
What is decoppering therapy for copper associated hepatitis?
Converted and excreted renally, takes 6-9 months to extract copper from the liver
178
Which agents are used for decoppering therapy of copper associated chronic hepatitis?
- D-penicillamine chelator – for those with copper over 1000
- Dietary copper restriction – avoid red meat/offal/eggs, cereals – for those with copper 400-1000
- Zinc supplementation/maintenance – different substrate for liver to uptake, not with decoppering agents – for those with lower than 400 copper
179
Name a hepatoprotective therapeutic agent that can be used in copper associated chronic hepatitis.
SAMe
180
How is copper associated chronic hepatitis managed longer term?
- Monitor liver enzymes q1-2 months
- Re-biopsy 1 month after normalisation – re-quantify copper
- Copper remains elevated = continue and re-evaluate
- Copper normal = stop D-pen, maintain on copper restricted diet and/or transition to zinc), continue hepatoprotective therapies
181
What is indicated to be imaged on ultrasound if hepatopathy is cholestatic?
Renal, liver, pancreatic and duodenal abdominal ultrasound
182
What is characteristic about cat kidneys on ultrasound?
Cats have fat in renal pelvis that can be seen on ultrasound
183
What is the characteristic of pyelonephritis on ultrasound?
Obstruction to urine flow will expand space between pelvis and cortex with urine, typical for pyelonephritis
184
How is hepatic lipidosis confirmed?
Cholecystocentesis and hepatic FNA after checking coagulation function
185
What are the consequences of feline hepatic lipidosis?
- Lead to biliary stasis
- Liver failure – encephalopathy, coagulopathy
- Death
186
Why does obesity predispose hepatic lipidosis?
Clog up hepatocytes with fat and cannot move fatty acids through the liver and obstructs small bile ducts between the liver cells
187
What is the most important management aspect in feline hepatic lipidosis?
Nutritional support
188
Why should you never syringe/force feed a cat with hepatic lipidosis?
If nauseous this is disastrous, bad food aversion
189
How is feline hepatic lipidosis treated?
- Treat the underlying disease
- Nutritional support - tube feeding – 2-3 weeks, 40-60kcal/kg/day (titrate up), appropriate protein content
- Antioxidants, SAMe/silybin with/without vitamin E
- UDCA – little evidence
- L-carnitine? Might help cycling of fatty acids through mitochondria where energy block is, little evidence
190
Could you introduce antiemetics and appetite stimulants when treating feline hepatic lipidosis?
May introduce anti-emetics and appetite stimulants if biochemically and clinically think should be improving and perhaps starting to eat and start to offer food, careful of food aversion
191
What supportive management is used for feline hepatic lipidosis?
- Fluids (+ supplemental K+)
- Manage nausea – maropitant
- Manage pain (if present) – opioids
- HE management – lactulose
- B12?
- Vitamin K?
192
Which breed is predisposed to gall bladder mucoceles?
Border terrier
193
What is the clinical significant of gall bladder mucoceles?
- Can be asymptomatic/incidental findings at PME
- Acute biliary rupture due to pressure necrosis
- Bile peritonitis
194
What are the predisposing factors for gall bladder mucoceles?
Breed related
Dyslipidaemias
Endocrinopathies - hypothyroidism, hyperadrenocorticism
195
How are gall bladder mucoceles treated if symptomatic?
Cholecystectomy
196
How are gall bladder mucoceles treated if asymptomatic?
Screen/monitor vs. medical (choleretics/manage predisposing disease)
Or elective cholecystectomy - if incidental finding, track over 3 months and then decide whether to remove or not based on any changes, but owner may choose to do this before they get to this stage if breeding them
197
The pre-anaesthetic bloods for a dog undergoing a dental has very high ALP and ALT, but otherwise normal. What do you do next?
Suggest postponing the dental and do cheaper bile acid stimulation test or more expensive hepatic ultrasound. But based on the rest of biochemistry, could go ahead if owner refuses.
198
The pre-anaesthetic bloods for a dog undergoing a dental has very high ALP and ALT, but otherwise normal. Post dental, hepatic enzymes are normal 4-6 weeks later. What is the likely cause of the previous elevations?
Reactive hepatopathy
199
What are ameroid constrictor and cellophane used for in hepatic surgery?
Gradually close portosystemic shunt
200
What are cholecysto-enterostomy, cholecysto-duodenostomy and cholecysto-jejunostomy?
Cholecysto-enterostomy = anastomosing the GB to the small intestine
Cholecysto-duodenostomy = biliary diversion, GB to duodenum
Cholecysto-jejunostomy = biliary diversion, GB to jejunum
201
How are bile acid stimulation tests done?
Bile acid level taken from a starved patient, patient fed. 2nd bile acid level taken 2-3 hours after feeding. High difference between the 2 confirms hepatopathy.
202
When are silk sutures used in hepatic surgery? What is the advantage and disadvantage of silk sutures?
- Used for PSS and PDA occlusion as an organic, on-absorbable, braided multifilament
- Easy to handle and good knot security
- Thought to cause sufficient inflammatory reaction that progressive vascular occlusion is possible
203
What are the indications for liver biopsy?
- Hepatic insufficiency
- Anaemia/haemoabdomen
- Hypoglycaemia
204
What are the considerations for liver biopsy?
- Pre-op clotting and blood typing critical
- Blood products if APTT and/or PT raised
205
How is a laparoscopic lung biopsy at the edge of the lobe taken?
- Apply lap punch biopsy to selected lobe
- Close firmly and pull back (cup has sharp edges for cutting)
206
Describe the risk of laparoscopic technique for liver biopsy.
- Risk of haemorrhage but small sample
- Does not penetrate far into the tissue
- Edge of lobes easy to access and contain relatively small vessels, so serious haemorrhage is unlikely
207
How is an open biopsy using crushing haemostats/forceps done?
1. Artery forceps across tip of lobe
2. Excise sample with scalpel
3. Leave forceps 5 mins before removal
208
How is an open biopsy using crushing guillotine done?
1. Place an encircling ligature of synthetic absorbable suture material (2/0 or 3/0) around piece of liver selected for biopsy
2. Can do with/without forceps
209
How is an open liver biopsy done using punch biopsy?
- Central tissue of a lobe
- Use 6mm skin biopsy punch to sharply excise into liver lobe in selected area
- Dissect gently away with scissors/blade
- Take care not to damage sample/cause xs bleeding
- Fill defect with a haemostatic agent
210
What are the indications for liver lobectomy?
- Primary neoplasia
- Abscess
- Torsion
- Diaphragm rupture
211
What are the peri-surgical considerations for liver lobectomies?
- Manage hepatic insufficiency
- Care if using drugs that are metabolised in the liver
- Assess for anaemia, clotting and need for blood transfusion
- Samples – before or after antibiotics?
212
How much liver can you remove in a liver lobectomy?
Up to 70% in total as liver will regenerate. Partial for peripheral lesions or where hilum inaccessible
213
Why is the left of the liver easier to remove in a liver lobectomy than the right?
Caudal vena cava runs through the RHS
214
How is the finger fractures technique used for a partial liver lobectomy?
- Peripheral of lobe
- Individual/mass ligation
- Blunt dissect the liver tissue with fingers
- Ligate individual vessels as they are encountered
215
How is the overlapping mattress suture technique used for a partial liver lobectomy?
- Periphery of lobe
- Place overlapping sutures across tissue to be resected
- Control haemorrhage with electrosurgery, pressure or ligation of individual vessels
216
Name 3 techniques for complete liver lobectomy.
- Ligation at hilus
- Linear staplers
- Advanced vessel sealing devices
217
How is the difficulty of lobectomy determined by which lobe you are removing?
Left lateral and medial do not require very much dissection due to more defined pedicle. Right side requires more dissection and risks damaging caudal vena cava as it passes through the liver.
218
What is the path of bile acids through the body?
1. Bile formed in liver
2. Runs down hepatic ducts in common bile duct
3. Bile runs in to gallbladder via cystic duct for storage and concentration or duodenum
219
What is the difference between cat and dog cystic ducts and common bile duct?
In cats, cystic duct appearance in long and tortuous and common bile duct joins pancreatic duct and together enter duodenum
In dogs, cystic duct is short and straight and common bile duct enters duodenum near the pancreatic duct
220
What are 2 indications for biliary tract surgery?
Extra-hepatic biliary tract obstruction
Biliary tract rupture and bile peritonitis
221
What are the causes of extra-hepatic biliary tract obstruction?
Cholelithiasis (gallstones)
Gall bladder mucocele
Pancreatitis (cats)
Neoplasia
222
What may be present in extrahepatic biliary obstruction?
Vitamin K deficiency may be present due to fat malabsorption
223
What are the possible causes of biliary tract rupture and bile peritonitis?
- Trauma
- Inflammatory disease, such as cholecystitis
224
How is bile peritonitis managed?
- Aggressive stabilisation
- Exploratory laparotomy
- Aggressive post-op care with targeted antibiotics
225
What are the indications for a cholecystectomy?
Primary gallbladder disease
Secondary disease
Trauma
226
When is a cholecystectomy contraindicated?
If CBD is blocked, so patency must be confirmed by squeezing the gallbladder/flushing the CBD via the duodenum
227
What are the indications for common bile duct stenting?
- Extraluminal obstruction
- Rupture
- To avoid biliary diversion
228
What are the possible techniques for common bile duct stenting?
- Duodenotomy
- Catheter into CBD, sutured in place with absorbable sutures
- Stent will either pass once sutures dissolve/can be removed endoscopically
229
What are the indications and contraindications for a cholecysto-enterostomy?
- Complete/irreversible CBD blockage
- Severe CBD trauma
Contraindications – unhealthy gallbladder
230
What are the possible complications for extrahepatic biliary tract surgery?
- Bleeding from liver with cholecystectomy
- Bile peritonitis (bile leakage)
- Peritonitis (where intestines opened)
- Pancreatitis
- Ascending cholangiohepatitis
- Sepsis/MODS/SIRS
- Antibiotics and vitamin K strongly recommended
231
Distinguish an intrahepatic and an extrahepatic portosystemic shunt.
IPSS - abnormal blood vessel within the liver diverting blood in portal vein from being metabolised as it should in the liver
EPSS - abnormal blood vessel diverting blood in portal vein around the liver and so stopping it from being metabolised as it should in the liver
232
What are the intraoperative complications of portosystemic surgery?
- Haemorrhage
- Failure associated with technique
- Portal hypertension – the intestines will become congested due to the back pressure from the blood, turn purple. Pain/ascites/diarrhoea cause death
233
What are the possible complications of portosystemic surgery before discharge?
- Portal hypertension > pain, ascites and diarrhoea
- Neurological
- Hypoglycaemia
234
What are the possible complications of portosystemic surgery after discharge?
- Acquired PSS
- Recanalisation
- Typically multiple new vessels are formed
