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Flashcards in Icterus in horses Deck (36):
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

20

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

22

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

27

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

30

cholelithiasis - treatment + prognosis

treat - Antimicrobials: long term (weeks – months) Supportive care
prognosis - Depends on fibrosis, number and extent of choleliths, severity of clinical signs

31

hyperlipaemia

mostly in miniature breeds
incr risk of obese
due to -ve energy balance - disease, stress, pregnancy, lactation

32

hyperlipaemia - clinical signs

Lethargy
Anorexia
Weakness
Icterus
Mild colic, diarrhoea
Recumbency
+/- more severe signs of liver disease

33

hyperlipaemia - diagnosis

Breed
History
Clinical signs
Measure Tg in serum - Hyperlipidaemia, Hyperlipaemia
+/- liver biopsy

34

hyperlipaemia - treatment

reverse -ve energy balabnce
treat hepatic disease
eliminate stress/treat disease
inhibit further fat mobilization - insulin
incr triglyceride uptake by peripheral tissue - heparin

35

hyperlipaemia - prognosis

poor once clinical signs seen

36

hyperlipaemia - prevention

monitor at risk animals
measure Tg level in sick ponies
prevent obesity