Flashcards in Icterus in horses Deck (36)
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1
pre-hepatic icterus
problem with the rbc breakdown-haemoglabin-unconjugated bilirubin part of bile production
haemolysis - incr bilirubin production
primarily unconjugated bilirubin
2
haemolysis in horses
Neonatal isoerythrolysis - immunocompatibility between foeal + mothers RBCs
Infections eg EIA
Drugs eg penicillin
Toxins eg onion
Autoimmune HA – relatively rare in horses
3
hepatic icterus
Impaired hepatic uptake or conjugation
Increased unconjugated bilirubin
Common causes in horses : anorexia, acute hepatocellular disease
4
anorexia + icterus
anorexia is most common cause of icterus in horses
10-15% horses look mildly icteric
may be due to ligandin shortage - protein needed for uptake of unconjugated bilirubin into liver
5
post-hepatic icterus
Impaired excretion of bilirubin
Cholangitis, cholangiohepatitis etc
Cholestasis if conjugated bilirubin >30% of total bilirubin shunts very uncommon
6
common clinical signs of liver dysfunction
depression
anorexia
colic
abnormal behaviour
weight loss
icterus
7
less common clinical signs of liver dysfunction
photosensitization
diarrhoea
bilateral laryngeal paralysis
haemorrhagic diathesis
ascites
dependant oedema
8
colic - suggests which hepatic dysfunction
hepatocellular swelling
biliary obstruction
9
weight loss - suggests which hepatic dysfunction
Chronic disease
Decreased intake
Metabolic dysfunction
10
hepatic encephalopathy
Severe hepatic dysfunction
clinical signs of cerebral disease vary - mild depression–head pressing
11
hepatic encephalopathy - pathogenesis
decr ammonia clearance
amino acid alterations - creates false neurotransmitters
12
photosensitisation
Phylloerythrin - photodynamic, made by bacteria in gut + excreted by liver
liver dysfunction = more phylloerythrin
UV exposure causes cell membrane damage + necrosis
13
liver specific components of blood test
bile acids
SDH
GGT
14
what to look for on a hepatic ultrasound
size
Changes in echogenicity
Dilated bile ducts, choleliths, abscesses, neoplasia
15
hepatic biopsy can provide info for ___
diagnosis
prognosis
treatment options
16
treatment of HE
Sedation – care
Mannitol/hypertonic saline: cerebral oedema
Oral lactulose: limit ammonia absorption
Oral BCAA (branched chain amino acids): no evidence that this is beneficial
17
dietary modification
High carbohydrate, limited protein – protein source rich in BCAA
18
anti-inflammatories
NSAIDS - Flunixin meglumine
DMSO
Corticosteroids - dexamethasone, prednisolone
19
pyrrolizide alkaloid toxicity - aetiology
Ingestion of plants containing pyrrolizidine alkaloids - Ragwort
Usually unpalatable
Long term ingestion (cumulative) – 4-12 weeks
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pyrrolizide alkaloid toxicity - pathogenesis
Pyrrolizidine alkaloids metabolized by liver to toxic pyrrole derivatives
Pyrroles are antimitotic: cross link DNA + bind to nucleic acid and proteins within hepatocytes
Cells can't divide - megalocyte production (large RBC) - megalocyte death - fibrosis
21
pyrrolizide alkaloid toxicity - clinical signs + diagnosis
non-specific clinical signs
diagnosis - History of ingestion, Blood work, Biopsy - megalocytosis
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pyrrolizide alkaloid toxicity - treatment + prognosis
no specific treatment
Poor prognosis
Typically death within 10 days of clinical signs of liver failure
Regeneration not possible if fibrosis present + megalocytosis extensive
23
theiller's disease a.k.a
serum sickness
acute necrotic hepatitis
serum associated heptitis
24
theiller's disease
unknown cause
widespread hepatic necrosis
small liver at post mortem
no specific treatment
prognosis - poor if severe HE
25
tyzzers disease - cause by which bacteria
Clostridium piliformis
26
tyzzers disease - clinical signs
May be none – found dead
Non-specific
Loss of suckle, depression, recumbency
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tyzzer's - diagnosis
antemortem – difficult
Definitive diagnosis – post mortem identification of organism
Multifocal hepatitis and enteritis
28
tyzzer's - treatment + prognosis
treat - antibiotics + supportive, only 1 ever successful case
prognosis - grave
29
cholelithiasis - diagnosis
Liver enzyme activity: GGT, SDH, AST
Ultrasound: ? Dilated bile ducts, cholelith
Biopsy: histopathology, culture
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