Liver Disease Diagnosis Quiz

Equine Liver Disease

• Investigating equine liver disease is presented by Andy E Durham, Liphook Equine Hospital, UK.
• Learning objectives include recognizing presentations, clinical signs, diagnostic approaches, prognostic indicators, and therapeutic options for treating horses with liver disease.

Key Points

• Differentiating hepatic disease from hepatic insufficiency is important.
• Subclinical liver disease frequently affects horses.
• Elevated liver enzymes are common in horses.
• Outbreaks of subclinical liver disease are prevalent.
• Liver biopsy is often necessary to investigate liver disease fully.

Clinical Signs of Hepatic Insufficiency

• Lethargy and lack of appetite
• Weight loss
• Colic
• Photosensitivity
• Encephalopathy
• Diarrhea
• Jaundice
• Edema
• Coagulopathy

Clinical Signs of Hepatic Encephalopathy

• Depression
• Circling
• Aimless wandering
• Head pressing
• Blindness
• Yawning
• Coma
• Bilateral laryngeal paralysis

Pathophysiology of Hepatic Encephalopathy

• Neurotoxic substances from the gut cause issues.
• Ammonia, glutamine, osmotic astrocyte/neuron swelling, and mercaptans/phenols contribute to this.
• Neurotransmitters are impacted (e.g., reduced excitatory dopamine, increased inhibitory GABA).
• Endogenous benzodiazepine-like substances increase in concentrations.
• Other factors such as hypoxia, electrolyte imbalances, acid-base problems, and hypoglycemia play a role.

Clinical Signs - Hepatic Insufficiency

• Assessing if over 70% of the functional liver mass is affected determines prognosis and suggests biopsy is more risky and adverse outcomes are likely.

Clinical Signs - Subclinical/Mild

• If less than 70% of the functional liver mass is affected, the outlook for the horse is better and biopsy is generally deemed safe.

Clinical Scoring

• Scoring system categorizes horses into normal or with varying degrees of hepatic issues (mild, moderate, severe).
• Data (61 horses) from a 2003 study shows distributions for different categories (normal, mild, moderate, severe).

Survival Rates

• Survival rates at six months differ according to the clinical score, with lower scores (0-1) associated with significantly higher survival than those with higher scores (2-3).

Clinical Signs - Implication

• Clinically normal horses can have significant liver disease.
• If signs of hepatic insufficiency are present, the prognosis is poor.

Serum Biochemistry

• Liver damage releases enzymes (e.g., alkaline phosphatase, AST, GGT, GLDH).
• Serum biochemistry tests on liver function including albumin, globulin, bile acids, bilirubin, and urea can provide more clues.
• GGT, AST, GLDH, and AP are helpful for diagnostic purposes, but can be misleading at times.

Case Monitoring

• Normalization of liver enzymes improves outcomes.
• Persistent enzyme elevation (> 2-3 months) suggests persistent liver damage.
• Assessing for treatment failure is important.

Epidemiological Clues

• Potential causes of liver disease include hepatotoxicity, septic cholangitis, cholelithiasis, viral infection, parasitic infections, neoplasia, and immune-mediated conditions.

Possible Causes - Hepatopathy Outbreaks

• Toxicity (e.g., pyrrolizidine alkaloids, iron, mycotoxins)
• Infectious disease (e.g., Fasciola hepatica, viral hepatitis)
• Viral infections (e.g., equine hepacivirus, equine parvovirus)

Infectious Hepatitis Outbreaks

• Liver fluke (Fasciola hepatica) is a rare but significant concern, especially in areas with cattle or sheep.
• Diagnosis is often challenging post-mortem.
• Coproantigen analysis is unreliable and serology is variable.

Viral Hepatitis

• Acute and chronic infections are observed in young horses, potentially linked to non-primate hepaciviruses.
• Viruses such as equine hepacivirus and equine parvovirus have been identified as common causes.

Ultrasonography

• Ultrasound is potentially helpful in identifying areas relevant for biopsy, minimizing risk.
• Significant liver disease can still be present with unremarkable images.

Biopsy Procedure

• Procedure includes sedation, ultrasound-guided site identification, biopsy depth/angle determination, clipping, scrubbing, local anesthesia, incision, instrument insertion and biopsy removal.
• Biopsies are then placed in formalin or other preserving solutions and possibly antimicrobial agent, for effective analysis.

Purpose of Liver Biopsy

• Confirms liver disease existence.
• Helps determine the cause, guiding therapy.
• Aids in prognosis determination.
• Guides appropriate therapy.

Biopsy Findings

• Several conditions are observed through biopsy, like pyrrolizidine alkaloids, hemosiderosis, septic cholangitis, and neoplasia are possible causes.
• Most biopsies, however, do not indicate a specific cause.

Prognostic Biopsy Score

• Scoring system categorizes biopsy findings based on severity of liver damage.
• The scoring system can help predict the outcome or prognosis of diseases based on biopsy.

Prognostic Value of Biopsy

• Biopsy score correlates with survival time, demonstrating a predictive value in determining prognosis.

Treatments

• Empiric treatments for liver disease are not recommended.
• Specific therapies are based on the precise findings of a liver biopsy, given there are varied pathological areas.
• Antimicrobials, steroids, and other drugs may have detrimental impacts.

Specific Therapies

• Based on finding of the biopsy.
• Options include corticosteroids, immunosuppressants, anti-parasitic therapies, and supporting treatments.
• Consider underlying factors.

Adverse Effects of Liver Biopsy

• High risk of liver disease is associated with a poor prognosis anyway.
• Focusing on early diagnosis is recommended to avoid serious outcomes and improve outcomes.

Overall Approach to Equine Liver Disease

• Initial tentative diagnosis based on blood tests helps determine if herd mates have problems.
• If there are concerns, consider common toxins, viral, parasitic causes, and if appropriate a liver biopsy to confirm, determine the cause and prognosis based on the findings.
• Maintaining enzyme levels, along with considering other aspects, can aid in the treatment and prognosis of the disease.

Test your knowledge on the causes and diagnoses of liver diseases. This quiz includes questions on toxic substances, infectious diseases, and diagnostic tools like hepatic ultrasound. Challenge yourself with questions that explore the complexities of liver dysfunction.