Diagnostic approach for infiltrative enteropathies and liver dysfunction Flashcards
Initial exam - clinical history
- Age and activity
- Perceived length of weight loss
- Diet: amount and frequency is important
- Worming history
- Dental care
- Episodes of diarrhoea, soft manure, inappetence, colic…
Initial exam - environmental management
- Type of pasture: size, grass coverage and species, weeds, trees..
- Sharing pasture with other horses (how many)
- Living with other animal species
Physical exam
- Body score
- Muscle waste: pay attention to head muscles, cervical and epaxial
- Presence of oedema: ventral, distal limbs
- Faecal staining on hindquarters
- HR, abnormal lung sounds, GI motility
- Dental exam
- Type and quality of faeces, presence of parasites, sand, gravel, long-stem fibre
Blood work
- White blood cells: leukopenia/cytosis
– Low WBCs commonly seen, but mild elevations can be seen with parasitism or IBD - Anaemia (RBC and HB)
- Protein concentration: hypoalbuminemia, hyperglobulinemia
- Fibrinogen, SAA, Globulins
– Acute phase proteins can be elevated, esp with parasitism, bacterial infections and some neoplasias - Liver values: SDH, GGT, AST, Bile acids
– can be mild elevated in cases of chronic enteropathy, but moderate-marked elevations are consistent with a liver aetiology - Creatinine, Na, K, Ca (+/-Phosphorus)
Ultrasound evaluation
SI wall thickness:
- inguinal area, cranioventral abdomen, next to R-Kidney
- Abnormal >4mm
LI wall thickness:
- right dorsal colon (11-13th ICS), left ventral abdomen
- Abnormal >6mm
Liver: right and left lobules:
- sharpness of edges, echogenicity, masses, gas shadowing structures
Peritoneal fluid:
- anechoic viscous
Masses:
- round, lobulated, variable echogenicity
Only ~50% & 30% of LI & SI (respectively) can be examined using US
Rectal examination - looking/feeling for:
- masses
- mesenteric lymphadenopathies
- faecal samples
Abdominocentesis
Colour: Turbid, serosanguinous, green-dark
Protein (refractometer): abnormal if >30g/L: Inflammation/infection
Lactate: Abnormal if >2.5mmol/L
– intestinal ischemia= >double systemic
– bacteria production
WBC: Abnormal if >5000cells/ul; likely infection if >10 000cells/ul
– >90% neutrophils
– Features of degeneration
– Intra and extracellular bacteria
– Abdominal glucose>2.8mmol/L blood glucose
– bacterial production
Helps rule out other causes of weight loss, e.g. peritonitis
Intestinal function test
= Glucose absorption Test
- Sn=45%; Sp=90-100%
- Dextrose/glucose readily available as fluid/powder 1g/kg
- Less reliable in patients with hyperglycaemia or stress response
- IV catheter, nasogastric tube placement and serial blood test
- To; T90min: T150min:
– >85% increase from baseline: NORMAL
– 15-85% increase from baseline: Partial malabsorption
– <15% increase from baseline: Total malabsorption
Intestinal biopsies
Main confirmatory diagnostic tool for IBD in horses, but requires a segment of the affected tissue
- Histopathology and culture/PCR (L. intracellularis & Salmonella)
- Relies on diffuse disease vs localized disease: 18m of SI and 4m LI
Rectal: 50% of Granulomatous enteritis and MEED
– little diagnostic value on lymphocytic-plasmacytic and eosinophilic
Duodenal: 20% cases: Lymphocytic-plasmacytic and eosinophilic
Full-thickness: Eosinophilic enteritis, Lymphoma and Grass sickness (ileum)
– Gold standard but only done under GA with laparoscopy or laparotomy
Granulomatous enteritis (albumin, blood work, glucose absorption test, biopsies)
Albumin:
- Low
Blood work:
- Anaemia
Glucose absorption test:
- Abnormal
Biopsies:
- Good correlation with rectal biopsy
Lymphocytic enterocolitis (albumin, blood work, glucose absorption test, biopsies)
Albumin:
- ± low
Blood work:
- Normal
Glucose absorption test:
- Abnormal
Biopsies:
- Unreliable
Focal eosinophilic enteritis (albumin, blood work, glucose absorption test, biopsies)
Albumin:
- Normal
Blood work:
- Normal
Glucose absorption test:
±
Biopsies:
- Focal full thickness
- Not rectal biopsy
MEED (albumin, blood work, glucose absorption test, biopsies)
Albumin:
- Normal initially
- Low in advanced cases
Blood work:
- Normal (± eosinophilia)
- Anaemia
- High GGT
Glucose absorption test:
- Normal (LI»_space; SI)
Biopsies:
- 50% with rectal biopsy
Intestinal lymphoma (albumin, blood work, glucose absorption test, biopsies)
Albumin:
- Low
Blood work:
- Anaemia
Glucose absorption test:
- Generally abnormal
Biopsies:
- Full thickness
- Rectal or duodenal if diffuse
Intestinal weight loss - faecal analysis
- Faecal egg counts
- Faecal cultures and PCR
Faecal egg counts for intestinal weight loss
- Limitations of faecal egg counts
- Adult vs larvae
- Encysted forms: do not produce eggs
- Ultrasound might help to determine Ascarids burden in weaning, yearling horses
Faecal cultures and PCR for intestinal weight loss
- Proliferative enteropathy (L.intracellularis): Faecal PCR
– Chronic cases»Biopsy, PCR and histo staining, Silver staining - Chronic Salmonella: PCR and enriched culture
Faecal analysis for sand enteropathy
- sedimentation test> low sensitivity, false negatives - Radiography and ultrasound
Biochem
- SDH
- AST
- GGT
- ALP
- Bile acids
- Bilirubin
SDH (description, location within liver, other organs, considerations, other comments)
= sorbitol dehydrogenase
Location within liver:
- Hepatocellular
Other organs:
- Liver specific
- but increases might occur with GI obstruction or enteritis
Considerations:
- Low stability for testing 4h> frozen plasma
Other comments:
- Probably the most sensitive marker of hepatocyte damage but has the lowest stability in plasma
– Makes its use in practice more complicated
AST (description, location within liver, other organs, considerations, other comments)
= aspartate transferase
Location within liver:
- Hepatocellular
Other organs:
- Muscle (+++)
- RBC
- Kidney
Considerations:
- Needs interpretation with both muscle and liver enzymes
Other comments:
- Good for hepatocyte damage but also released by muscle during muscle damage, so isolated elevations should be interpreted in conjunction with other muscle markers
GGT (description, location within liver, other organs, considerations, other comments)
= gamma-glutamyl transferase
Location within liver:
- Billiary ducts
Other organs:
- Reproductive, urinary, mammary gland, pancreas: Local elevation but no systemic
Considerations:
- Takes longer to come down after insult
- Normal elevation foals and TB
Other comments:
- Released by several organs as a result of insult, but this released is local and has minimal impact on plasma concentration
- Therefore, the enzyme is a good marker of liver dz, particularly biliary dz
ALP (description, location within liver, other organs, considerations)
= alkaline phosphatase
Location within liver:
- Billiary ducts
Other organs:
- 80% Liver
- 20% bone
Considerations:
- Non-specific in horse
- Normal elevation growing foals and horses with fractures
Bile acids (other organs, considerations)
- Function test
Other organs:
- Liver specific: higher in hepatobilliary than hepatocellular
Considerations:
- Normally: moderate to severe dysfunction needed
Bilirubin (other organs, considerations, other comments)
- Function test
Other organs:
- Liver specific: Total of little value: Anorexia, haemolysis, liver disease
Considerations:
- Liver driven in acute cases>170umol/L
- Chronic=mild elevation
Other comments:
- Not a reliable marker of liver dz in horses
– Only tends to elevate in chronic stages and moderate elevations are produced as a result of anorexia in horses
US
➢ Rarely diagnostic
– But can be useful for masses, dilated biliary ducts or stones, and changes in echogenicity might be suggestive of fat infiltration or fibrosis
➢ Right: larger window: 6th-17th ICS
➢ Left: 7th to 9th ICS
➢ Normal echogenicity : branching vasculature, echogenic portal vein walls, medium echogenicity parenchyma
– more echogenic than kidney tissue
– less echogenic than spleen
Liver biopsy (what it’s needed for, histopath, bacterial culture, virus PCR)
Biopsy: required for definitive diagnosis (14-15 ICS right side)
Histopathology:
- Toxic: pyrrolizidine (megalocytosis, hyperplasia and fibrosis)
– Mycotoxins: severe hepatic necrosis
– Iron supplements: hepatic necrosis, haemochromatosis
- Bacterial: acute suppurative and diffuse
- Viral: hepatic necrosis with acidophilic inclusions - FIBROSIS: Prognostic scoring
Bacterial culture:
- Clostridium piliforme (foals 1w-2months),
- Ascending cholangiohepatitis: Klebsiella, E. coli, Salmonella
Virus PCR:
- Equine Parvovirus-Hepatitis Virus (EqPV-H)
Which liver values are most important in horses?
- SDH, AST, GGT & bile acids
