GI part 2 small animal

Megacolon in Cats

• Mostly seen in obese cats; obesity is a common risk factor.
• Presentation: constipation with large fecal material; may mimic diarrhea because only liquid stool passes around hard chunks; vomiting, hyporexia or anorexia; vocalizing/straining; constipation with backed-up stool.
• Diagnosis
  • Abdominal palpation limited in fat cats; obtain at least one view radiograph to assess fecal material and obstruction. $1$ view radiograph commonly used.
• Treatment
  • Enema after sedation when possible; warm water + lubricant enema using a red rubber catheter; flush while withdrawing, then digital evacuation to expand the colon.
  • Fluids: IV or subcutaneous fluids as needed for dehydration.
  • Manage clinical signs: antiemetic for vomiting.
  • If enema cannot relieve obstruction: abdominal surgery to remove stool.
• Medical management for ongoing cases
  • MiraLAX dosing for obese cats: $\frac{1}{8}\text{ tsp}$ sprinkled on food daily; lifelong therapy.
• Prognosis and notes
  • Once the obstacle is removed, the colon often returns toward normal size because the colon can shrink after relief of the obstruction.
  • Megacolon differs from megaesophagus in that the colon can physically shrink after removing the blockage; esophagus issues are more often neural/genetic.

Constipation in Dogs

• Key idea: differentiate diarrhea from constipation; owners notice squatting more often.
• Differentials for squatting/straining: increased urinary output (polyuria), straining, constipation, or diarrhea (especially large-bowel types).
• Diagnostics
  • Thorough exam and possibly X-rays.
  • In dogs, constipation is less common than in cats and is often due to external factors (e.g., foreign body, rectal tumor) that block stool.
• Clinical signs: straining, dehydration, anorexia; vomiting if severe.

Liver and Hepatobiliary System

• Common hepatotoxicities/toxins
  • Acetaminophen: major risk in cats; some dogs on chronic pain regimens; cats cannot have acetaminophen at all.
  • Antifungals and NSAIDs can cause liver disease/toxicity.
• Clinical signs of liver disease
  • Jaundice (yellow gums, mucous membranes, sclera), vomiting, depression, anorexia; dehydration.
• Diagnostics
  • Chemistry panel: liver-specific enzyme ALT; nonliver enzyme ALP; bilirubin.
  • Abdominal ultrasound; biopsy often needed for definitive diagnosis.
• Liver enzymes
  • ALT: liver-specific; elevation indicates hepatocyte injury.
  • ALP: nonliver-specific; elevation can occur with liver disease or other chronic inflammatory conditions.
• Liver supplements and therapies
  • Ursodiol (ursodeoxycholic acid) for biliary issues and bilirubin management.
  • Denamarin (S-adenosylmethionine-based supplement) for hepatoprotection.
• Diagnostic imaging and biopsy
  • Abdominal ultrasound followed by biopsy to identify etiology.
• Infections and hepatitis
  • If WBCs (neutrophils) elevated or other signs of infection: broad-spectrum antibiotics (e.g., Clavamox + enrofloxacin).
• Canine infectious hepatitis and leptospirosis
  • Leptospirosis is zoonotic; vaccination recommended in many regions; not core in all guidelines but increasingly advocated.
  • Diagnosis often requires isolation; isolate with PPE in suspected cases.
  • Clinical signs: jaundice, dehydration, anorexia; severe cases may involve kidney failure.
  • Leptospirosis vaccine is often given with distemper/parvovirus vaccines; consider based on risk and local prevalence.
• Cholangiolitis / cholangitis
  • Inflammation of bile ducts; biliary mucocele and tumors to rule out with ultrasound.
  • Treatment: Ursodiol + Denamarin; antibiotics if infection; adjust based on WBC and clinical status.
• Hepatic lipidosis (cats)
  • Triggered by prolonged anorexia; liver fills with fat; very high risk in cats; requires hospitalization and nutrition support.
  • Feeding via nasogastric or oral gastric tube is common; small, frequent, bland meals preferred over prolonged fasting.
• Hepatic neoplasia
  • Primary liver tumors or metastatic disease (most often secondary to other sites via blood).
  • Hemangiosarcoma is a common liver-associated tumor; prognosis poor when liver is involved.
  • Treatments may include splenectomy with chemotherapy or hepatic resection; prognosis guarded to grave with liver involvement.
• Portosystemic shunt (PSS)
  • Congenital shunt bypassing the liver; toxins bypass detoxification, causing hepatic encephalopathy in young animals.
  • Neuro signs: vomiting, failure to thrive, head pressing, circling, seizures.
  • Treatment: surgical correction is preferred; high-protein diets can worsen encephalopathy.

Pancreas

• Pancreatitis
  • Dogs: typically acute pancreatitis; cats: often chronic pancreatitis.
  • Common triggers: fatty meals; abdominal pain; vomiting; diarrhea.
  • Diagnostics: canine pancreatic lipase (cPL) or feline pancreatic lipase (fPL).
  • Treatment
  • Historically NPO; now small, frequent, bland meals to support pancreas healing.
  • Hospitalization for severe cases; may require feeding tube to maintain nutrition.
  • Exocrine pancreatic insufficiency (EPI)
  • Chronic pancreatitis can lead to EPI in some patients (especially dogs like German Shepherds).
  • Signs: poor weight gain, greasy/mucoid stools, poor digestion.
  • Pancreatic enzyme supplementation
  • Pancreatic enzyme powder sprinkled on food daily; lifelong therapy.

Perianal and Anal Region

• Perianal hernia

  • Often requires neuter at the time of repair to reduce recurrence risk.
  • If surgery is not feasible, use stool softeners like MiraLAX to ease defecation and reduce protrusion.

• Perianal fistulas

  • Usually secondary to ulcerative disease; very painful.
  • Treatment of choice: cyclosporine with antibiotics; e-collar to prevent licking/chewing.
  • Surgical repair is challenging due to nerves and high infection risk; surgery can jeopardize continence.

• Perianal adenomas (perianal gland tumors)

  • Typically firm, red, raised masses near the anus; often not ulcerated.
  • Left-sided masses may be monitored if asymptomatic; right-sided masses more likely to be removed if obstructive or ulcerating.
  • If a lesion ruptures or becomes chronically infected, antibiotics are used first; recurrent rupture suggests surgical removal.

• General note on external masses

  • External lesions are generally easier to manage surgically than internal ones due to anatomy and infection risk.

End of notes: Quick takeaway

• Obesity is a common driver in feline megacolon and lipid-related hepatic disease.
• Early imaging (radiographs, ultrasound) guides treatment across GI, liver, and pancreatic diseases.
• Small, frequent meals and appropriate enzyme or supplement therapies are central to chronic GI conditions.
• Vaccination and zoonotic disease awareness (e.g., leptospirosis) are important in hepatic cases.