TL;DR: Alternating diarrhea and constipation in cats indicates a gastrointestinal disruption that should be evaluated within 24–48 hours, though symptoms like vomiting or unproductive straining require immediate emergency care.
What does it mean if my cat is alternating between diarrhea and constipation?
When a cat experiences a cycle of loose stools followed by difficulty defecating, it typically indicates a disruption in the gastrointestinal tract. This can sometimes be 'paradoxical diarrhea,' where liquid waste leaks around a hard fecal impaction, or it may be a symptom of chronic conditions such as Inflammatory Bowel Disease (IBD), food sensitivities, or early-stage megacolon.
When should I seek emergency care for my cat's bowel issues?
- The urgency level for alternating bowel movements is generally Medium, meaning your cat should be evaluated by a veterinarian within 24 to 48 hours.
- Seek Immediate emergency care if your cat is also vomiting, lethargic, or refusing to eat.
- Seek emergency care immediately if your cat is straining painfully in the litter box without producing anything, as this could indicate a total obstruction.
How can a photo of my cat's stool help the veterinarian?
- Taking a clear photo of both diarrhea and constipated portions helps the vet assess stool color and texture.
- Images allow the team to check for mucus or blood, which helps determine whether the issue is located in the small or large intestine.
- Visual evidence helps your veterinarian narrow down potential causes much faster.
Clinical Context (Merck Veterinary Manual)
Alternating diarrhea and constipation in cats can be attributed to several underlying causes. Colonic or rectal compression from a narrowed pelvic inlet post-fracture, enlarged sublumbar lymph nodes, or an enlarged prostate gland should be considered. Colonic stricture due to trauma or neoplasia is another possibility. Cats with chronic constipation or obstipation may develop megacolon, potentially caused by a neuromuscular lesion of the colon, though the etiology often remains undiagnosed. Other diseases affecting neuromuscular control, such as hypothyroidism, dysautonomia, and spinal cord lesions, as well as electrolyte imbalances like hypokalemia and hypercalcemia, can also contribute. Additionally, certain drugs including opioids, diuretics, antihistamines, anticholinergics, sucralfate, aluminum hydroxide, potassium bromide, and calcium channel-blocking agents can promote constipation.
Chapter: Gastroenterology
Source: The Merck Veterinary Manual, 11th Edition (Page 381)