Histiocytic Ulcerative Colitis in Dogs & Cats: Chronic Diarrhea, Colonoscopy & Long-Term Care [2025]
Histiocytic ulcerative colitis is a distinctive intestinal inflammation that causes chronic diarrhea. Diagnosis requires endoscopy and biopsy, and antibiotic treatment often produces a good response.
When to See a Vet
Seek immediate veterinary care (emergency)
- •Persistent large amounts of bloody stool with lethargy and inability to stand
- •Obvious dehydration, dry mouth, poor skin elasticity, and low activity level
- •Repeated vomiting with weakness, drowsiness, and inability to eat on their own
Schedule a veterinary appointment soon (within 24-72 hours)
- •Diarrhea lasting more than two days while overall energy remains acceptable
- •Intermittent blood in the stool or passage of large amounts of mucus
- •Marked decrease in appetite or continued weight loss
01What symptoms indicate a problem?
The main presentation is chronic or intermittent diarrhea with appetite changes, often accompanied by mucus or blood in the stool and weight loss.
- Poor appetite or noticeably reduced food intake
- Chronic or intermittent diarrhea, often with mucus or blood in the stool
- Gradual weight loss or inability to maintain body weight
- Frequent tenesmus or discomfort during defecation
- Decreased energy and reduced activity levels
- Early referral to a gastroenterology specialist is recommended
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02How to monitor at home? Key observations and emergency warning signs
Key things to observe and record at home to help your vet assess the condition and plan diagnostics.
- Record your pet's appetite and actual food intake at each meal daily
- Weigh your pet weekly and track any changes in trend
- Take photos or videos of the stool and bowel movements to save for your vet
- Note when diarrhea started, its frequency, and how many days it has lasted
- If blood appears in the stool or vomiting occurs, record the exact time immediately
- Bring all records and photos to the specialist appointment for review
03How does the vet reach a diagnosis? Common diagnostic tests
Your vet will combine clinical signs with test results, using colonoscopy and biopsy when necessary to confirm the diagnosis.
Full physical examination
assessing hydration, abdominal pain, and overall condition
Complete blood count
checking inflammation markers, signs of anemia, or infection
Serum biochemistry and electrolytes
evaluating liver, kidney, and metabolic status
Urinalysis
helping assess kidney function and concentrating ability
Abdominal ultrasound
evaluating intestinal wall thickening and surrounding tissues
Advanced imaging (CT scan)
used for complex or challenging cases
Colonoscopy and tissue biopsy
taken when needed for histopathological confirmation
A referral to a fully equipped specialty hospital is recommended for a complete workup
04How is the condition treated and managed? Medications, dietary changes, and care guide
Treatment typically requires individualized adjustment and long-term follow-up; regular check-ups and tests are essential for monitoring response.
- Drug therapy requires regular recheck appointments and monitoring of blood work and clinical response
- Use a prescription or hypoallergenic diet and observe its effect
- Home care priorities include ensuring adequate hydration and keeping a stool diary
- Schedule follow-up blood work and imaging as directed by your vet
- Weigh your pet regularly to assess nutritional status and treatment efficacy
- If symptoms recur or worsen, consider referral to a specialist or revision of the treatment plan
05What to prepare before the vet visit? Key information to help your vet diagnose quickly
This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.