Hepatobiliary investigations, acute & infectious Flashcards
Investigations, acute and infectious
What zones or the liver are effected by metabolic/toxic damage? Are they different to the zones affected by hypoxic damage?
Metabolic/toxic damage in zone 1
Hypoxic damage in zone 3
What clinical signs are addociated with liver disease?
- portal hypertension
- jaundice
- drug intolerances
- hepatic encephalopathy
- ascites
- coagulopathy
- lethargy
- anorexia
- weight loss
- PUPD
- V+/D+
How is portal hypertension linked to fluid retention/ascites?
- blood pools in spleen and GIT
- this reduces the circulating volume
- RAAS is then activated to retain fluid
- ascites develops
Why do we see vomiting and diarrhoea with liver disease?
- Can be due to metabolic derangements or due to portal hypertension.
- Portal hypertension leads to vascular stasis and venous congestion and oedema -> adverse effect on GI tract.
- Increases the risk of GI ulceration.
Why does PUPD occur with liver disease?
- Decreseased urea production -> decreased medullary solute gradient -> impaired renal concentrating mechanism -> dilute urine & compensatory polydipsia
- Psychogenic component? Linked to hepatic encephalopathy
- Reduced hormone metabolism e.g. cortisol
What is the pathophysiology of hepatic encephalopathy? What clinical signs are associated?
Encephalopathic detoxification fails for several reasons:
- Congenital portosystemic shunts (cPSS) - toxins bypass the processing plant of the liver
- Acute liver disease - detoxification processes in the liver are compromised and overwhelmed
- Acquired portosystemic shunts - chronic fibrotic/cirrhotic liver disease leads to multiple tortuous anastomotic vessels opening up to divert blood from the hepatic portal vein to bypass the liver
Clinical signs
- Waxing and waning; non-localising on neuro exam
* May be associated with feeding
* Hyperactive &/or depressed/dull/clumsy
* Circling, pacing, central blindness
* Salivation, especially cats
* Seizures —> coma
How do we diagnose hepatobiliary disease?
Diagnosis
- ALT, AST, GLDH
- ALP and GGT
- albumin, urea, glucose, cholesterol, coag factors, bilirubin, bile acids, ammonia
- imaging
- sampling
- urinalysis
How is urinalysis useful to diagnose hepatobiliary disease?
Urine specific gravity
Often decreased due to various mechanisms causing PU/PD
Bilirubinuria
Normal to find some bilirubin in dog urine but can be increased.
Always abnormal in cat urine
Sediment analysis
Ammonium biurate crystals sometimes seen with PSS.
Identifies dogs at risk of urate urolithiasis
Is radiography helpful to diagnose hepatobiliary disease?
No
- poor sensitivity for detection of liver disease
- some information about liver size
- could see choleliths or mineralisation
Is ultrasound helpful to diagnose liver disease? What should you look for?
Poor sensitivity for detection of liver disease unless:
* mass lesion
* nodular disease
* significant change in echotexture
Gives some information about liver ie normal if:
* moderately and uniformly echoic
* less echoic than spleen (“kidney, liver, spleen”)
* coarsely granular parenchyma
* uniform texture
Things to look for:
Ascites
Parenchyma
- focal/diffuse change?
- is the margin irregular?
- can we do a guided biopsy?
Biliary tract
- dilation of bile ducts?
- abnormal gall bladder wall and/or contents?
- can we get a guided aspirate?
Vasculature (Doppler)
- congenital portosystemic shunt?
- acquired portosystemic shunts?
What are positive indicators of liver malignancy in dogs when using CT?
- Size (>4.5cm)
- Postcontrast enhancement pattern
How can we differentiate primary from secondary liver diseases?
- Careful interpretation of signalment, history, physical exam and results of initial diagnostic investigations
- Avoiding unnecessary testing if the evidence suggests secondary hepatopathy
- Assessing response to treatment: secondary disease should resolve with management of the underlying disease.
What are examples of secondary hepatopathies?
- GI disease
- Pancreatitis
- Endocrine disease
- hyperadrenocorticism (very rare in cats)
- diabetes mellitus
- hypothyroidism (dogs)/hyperthyroidism (cats)
- Right-sided congestive heart failure
- Hypoxia e.g. secondary to shock, trauma, anaemia
- Toxaemia
- Sepsis/bacteraemia
- Drug induced in dogs e.g corticosteroids, phenobarbitone*
What are examples of acute primary hepatopathies?
Idiopathic
**Toxin/ drug – induced **
“Acute toxic hepatitis”
* Phenobarbitone
* NSAID eg carprofen
* TMPS
* Azathioprine
* Paracetamol
* Xylitol
* Environmental toxins e.g. blue green algae, mushrooms
**Infection; “Infectious hepatitis” **
* Leptospirosis
* Viruses: CAV-1 ; neonatal canine herpes virus
* Bacteria from the GI tract
* Tyzzer’s disease (clostridium piliformis)
Congenital
* Portosystemic shunt
* Primary portal vein hypoplasia
Metabolic
* Glycogen storage disease
* Hepatic amyloidosis
Sepsis/ endotoxaemia
May be part of progression of sepsis to SIRS and MODS
What should you make sure you do before sampling liver using ultrasound guided FNA?
coagulation profile
