Understanding Chronic Diarrhea in Dogs
A Comprehensive Guide for Pet Owners
Chronic diarrhea in dogs can be a challenging condition for pet owners to navigate. This guide aims to explain the big-picture approach to diagnosing and managing chronic diarrhea, helping you understand the steps your veterinarian may take to identify and treat the underlying cause.
Topics Covered
What is Chronic Diarrhea?
Chronic diarrhea is defined as diarrhea lasting longer than three weeks. Chronic diarrhea in dogs can stem from various causes, which I categorize into two main groups to simplify diagnosis and treatment:
1. Primary Gastrointestinal Causes (arising from the GI tract itself)
2. Secondary Causes (arising outside the GI tract), such as:
• Pancreatitis
• Exocrine pancreatic insufficiency (EPI)
• Addison’s disease
• Liver or gallbladder disease
Understanding Primary Gastrointestinal (GI) Causes
When focusing specifically on primary GI causes, we can further classify the diarrhea based on its origin in the digestive tract:
Small Bowel Diarrhea (small intestines): Larger volumes, less frequent, weight loss, sometimes vomiting.
Large Bowel Diarrhea (colon): Smaller volumes, more frequent, straining, mucus, or blood.
Mixed Diarrhea: A combination of the above signs.
This classification system helps veterinarians narrow down potential causes and develop targeted treatment plans. But you might be wondering…
How Does This Translate to Actual Treatment?
With so many possible causes, how do we determine the best approach? The key lies in assessing your dog’s specific situation through what we call the Canine Chronic Enteropathy Clinical Activity Index (CCECAI). This evaluation considers:
1. Attitude/activity levels
2. Appetite changes
3. Vomiting frequency
4. Stool consistency
5. Stool frequency
6. Weight loss
7. Albumin levels (when available)
8. Breed predispositions (especially important for breeds like Boxers or French Bulldogs)
Dogs showing multiple concerning signs typically need more aggressive diagnostic work, while stable cases may benefit from a step-by-step approach.
Primary GI Causes of Chronic Diarrhea
So for stable dogs, where do we begin? If your dog appears otherwise healthy, we start by examining the most common primary GI causes, which fall into three main categories…
Food-responsive enteropathies (64%)
The majority of dogs respond remarkably well to dietary management. Effective diet options include:
Fiber-rich formulas
Low-fat diets
Hypoallergenic options
Steroid-responsive enteropathies (20%)
These conditions that require immunosuppressive therapy (similar to conditions like IBS, Crohn’s or Ulcerative Colitis in humans).
Microbiota-related modulation-responsive enteropathies (16%)
Previously called “antibiotic-responsive diarrhea” – though we now know antibiotics are rarely the solution. Very VERY VERY few cases of chronic diarrhea need antibiotics. In fact patients treated with antibiotics can often become more complicated and more difficult to treat.
64% of dogs with chronic diarrhea will improve with diet management.
Step 1: The Diet Trial Approach
Dietary changes are often the safest and most cost-effective way to address chronic diarrhea. Here’s how it works:
Diet Trail Part 1 : Mixed Fiber Diet (1 month trial)
• Especially useful for large bowel diarrhea.
• Examples: Hill’s Biome.
If poor response (little to no improvement) then move to Part 2
Diet Trail Part 2: Hydrolyzed Diet with Fat Restriction (1 month trial)
• Designed for sensitive digestive systems
• Examples include: Purina HA Vegetarian, Hill’s z/d Low Fat, or Royal Canin GI Low Fat + Hydrolyzed Protein.
Important Note
Diet trials are not recommended for unstable pets with severe signs such as weight loss, vomiting, fever, extreme lethargy, or loss of appetite. These pets require diagnostic testing before starting treatment.
If dietary changes don’t help or if your dog shows concerning CCECAI signs, we escalate to:
Step 2: Diagnostic Testing
As with all medical conditions, testing can help identify the underlying cause of the diarrhea and help us to target therapy.
1. Fecal Exam: to check for parasites. This is especially important in young dogs, dogs that spend a lot of time outdoors or families with immunocompromised family members.
2. Bloodwork: to screen for systemic diseases. These may include things like Addison’s disease, liver / gallbladder disease low protein levels
3. Imaging: Imaging like abdominal ultrasounds and/or X-rays help your veterinary team assess the size, shape and consistency of the GI tract and the abdominal organs.
4. GI-Specific Lab Tests
• Cobalamin (Vitamin B12): Low levels can signal malabsorption and benefit from supplementation.
• Folate: Low levels suggest upper small intestine issues, while high levels may indicate bacterial imbalance.
•TLI (Trypsin-like Immunoreactivity): Diagnoses exocrine pancreatic insufficiency.
•PLI (Pancreatic Lipase Immunoreactivity): Screens for pancreatitis.
5. Dysbiosis Index: Measures gut microbiota imbalances and bile acid metabolism. This is especially important in dogs that have received antibiotics like metronidazole or tylosin in the past to treat their diarrhea.
Advanced Diagnostics: When More Information is Needed
6. GI Biopsies: These are recommended if the previous tests don’t give clear answers or if severe disease is suspected. Biopsies can be done via endoscopy or surgery, each with its own pros and cons that your veterinary team will review with you. Biopsies can help diagnose conditions like steroid-responsive disease, intestinal cancer, or deep intestinal infections.
Putting It All Together: Your Action Plan
1. Assess severity using CCECAI criteria
• Mild/moderate signs → Begin diet trials
• Severe signs → Immediate diagnostics
2. Diet Trial Protocol
• Phase 1 (Fiber diet) → Monitor response
• No improvement? → Phase 2 (Hydrolyzed/low-fat)
3. Diagnostic Escalation
• Basic tests if diet fails
• GI-specific tests as needed
• Advanced imaging/biopsies for unresolved cases
Chronic diarrhea can be stressful, but there’s hope – most dogs respond beautifully to the right treatment plan. Remember, you’re not alone in this. Our team at Yonge Sheppard Animal Hospital is here to guide you through every step, from diet trials to advanced diagnostics.
If you have any questions or concerns about your dog’s digestive health, don’t hesitate to reach out. Give us a call at 647-260-8387 or email yonge.sheppard.vets@gmail.com – we’re happy to help your furry friend feel their best again.
– The Yonge Sheppard Animal Hospital Team 🐾💚