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Urgent care is for pets who are unwell, in discomfort, are in urgent situation or are not acting like themselves and should be assessed within 24 hours.
Wellness, routine, or general care is for pets needing vaccines, preventive care, or ongoing monitoring who can safely wait at least 24 hours.
This page focuses on urgent assessment. Routine wellness exams, preventive care, and monitoring of stable conditions are provided through scheduled general wellness appointments.
Cat Has Diarrhea – When to Seek Urgent Care
Diarrhea can range from mild and self-limiting to life-threatening, depending on the cause and your pet’s hydration status.
Definition
Diarrhea is an increase in the frequency, fluidity, or volume of bowel movements. It is a clinical sign, not a diagnosis.
It occurs when the intestinal tract cannot properly absorb water and nutrients, or
when intestinal movement is accelerated and contents pass through too quickly. This can lead to dehydration, electrolyte imbalance, and systemic illness.
In dogs and cats seen in the Stittsville-Kanata area, diarrhea is one of the most
common reasons for urgent veterinary visits and may signal anything from dietary upset to serious metabolic or infectious disease.
Who This Page Is For
Sudden, watery, explosive, or foul-smelling stools
Blood, black/tarry stool, or excess mucus
Straining to defecate or accidents in the house
Diarrhea without a clear cause
Who This Page Is Not For
A single soft stool that resolved immediately and your pet is otherwise eating, drinking, and acting completely normal
If you are unsure whether your pet's diarrhea is significant, that uncertainty warrants a veterinary assessment.
Related Urgent Symptoms
Dog vomiting blood
Dog lethargic and weak
Dog not eating for 24 hours
Dog bloated stomach but still active
Cat not eating for 24 hours
Cat open mouth breathing
What This Can Look Like at Home
Diarrhea may range from “soft-serve” consistency to complete liquid, with pets
needing to go outside or to the litter box much more frequently.
Large bowel diarrhea: frequent straining, small amounts, mucus or blood
Small bowel diarrhea: larger volume, higher risk of dehydration
Puppies, kittens, small dogs, and senior pets are especially vulnerable to rapid fluid
loss.
Why This Can Be Hard to Judge
Pets often compensate and appear outwardly stable while losing significant fluids.
This early misleading normalcy can mask dehydration and electrolyte imbalance.
Diarrhea is frequently dismissed as “just a food issue,” when it may be the first visible sign of infection, inflammation, toxin exposure, or metabolic disease.
The Improvement Trap
Diarrhea commonly fluctuates. Stools may firm up briefly, leading owners to believe the issue has resolved.
Temporary improvement does not equal resolution. Conditions such as Giardia,
inflammatory bowel disease, food hypersensitivity, or hormonal disorders often cycle — improving before returning with greater severity. Waiting for prolonged consistency can allow diarrhea to become chronic and harder to treat.
What Is Easy to Miss at Home
Reduced thirst or appetite
Mild lethargy or weakness
Abdominal discomfort
Dull hair coat or pale gums
Focusing only on stool appearance can miss the more important indicators: hydration status, energy level, and overall comfort.
When This Can Be an Emergency
Diarrhea should be treated as urgent or emergent if any of the following are present:
Blood or black/tarry stool
Vomiting occurring alongside diarrhea
Lethargy, weakness, or collapse ( pets not themselves or are a bit off )
Puppies, kittens, or very small pets
Known toxin exposure
Signs of dehydration (dry gums, sunken eyes)
How Veterinarians Assess This
Diarrhea that looks similar at home can represent very different internal disease
processes. Clinical signs alone cannot reliably determine severity.
Veterinarians use diagnostic testing to determine severity, identify the underlying
cause, and guide appropriate treatment while avoiding both under- and over-
treatment.
Testing may include:
Fecal analysis to identify parasites such as Giardia or Coccidia
Full bloodwork and electrolytes to assess hydration, inflammation, metabolic stress, and organ involvement
Blood glucose testing when shock or endocrine disease is suspected
Abdominal ultrasound to evaluate intestinal wall thickness, motility, and masses
Veterinary Differentials - Serious / Must-Rule-Out First
Acute Hemorrhagic Diarrhea Syndrome (AHDS / HGE)
Sudden, severe bloody diarrhea that can cause rapid dehydration and circulatory
collapse. Testing may include bloodwork, electrolytes, and abdominal imaging.
Intestinal Obstruction
Foreign material may allow only liquid to pass, mimicking diarrhea. Diagnostics often include abdominal X-rays, ultrasound, and bloodwork.
Parvovirus (Dogs)
A highly contagious viral infection causing severe diarrhea, vomiting, and immune
suppression. Testing may include SNAP parvo testing, CBC, and electrolytes.
Sepsis
Systemic infection that may initially present as gastrointestinal upset. Bloodwork,
lactate levels, and imaging are commonly considered.
Addisonian Crisis
A life-threatening hormonal failure that frequently appears as “simple diarrhea.”
Electrolytes, blood glucose, baseline cortisol, and ACTH stimulation testing may be
required.
Veterinary Differentials - Common / More Typical
Giardia or Other Protozoa
Common in dogs and cats and frequently under-diagnosed. Fecal testing or antigen testing is often needed.
Dietary Indiscretion (“Garbage Gut”)
Sudden bacterial overgrowth following ingestion of inappropriate food. Bloodwork
and fecal testing may still be recommended to rule out complications.
Adverse Food Reaction
Immune-mediated response to specific ingredients. Diagnosis often involves dietary trials after infectious causes are excluded.
Inflammatory Bowel Disease (IBD)
Chronic immune-mediated irritation of the gut lining. Bloodwork, ultrasound, fecal
testing, and sometimes biopsy may be considered.
Exocrine Pancreatic Insufficiency
Failure to produce digestive enzymes, leading to malabsorption and chronic diarrhea. Blood testing is commonly used.
Safety, Psychology, & Peace of Mind
Waiting for diarrhea to “run its course” is high-risk, particularly for young, small, or senior pets. Fluid and electrolyte imbalance can progress quickly, even when a pet appears outwardly stable.
Veterinary assessment provides peace of mind by confirming whether the issue is self-limiting or a signal of a more serious underlying problem. Early diagnosis is the most effective way to restore comfort and prevent complications.
Frequently Asked Questions
Can I give my pet Imodium?
No. Imodium (loperamide) is not routinely safe for dogs or cats and should not be given without veterinary guidance. In some pets, it can cause serious neurologic side effects, including sedation, disorientation, or agitation. In others, it can slow intestinal movement and trap bacteria, toxins, or inflammation inside the gut, which may worsen the underlying condition. Diarrhea has many possible causes, and medication choice depends on identifying the trigger rather than suppressing the symptom.
Should I fast my pet for 24 hours?
Routine fasting is no longer universally recommended. While short periods of intestinal rest were once standard advice, current veterinary approaches focus on supporting hydration and addressing the underlying cause of diarrhea. Prolonged fasting—especially in puppies, kittens, small dogs, or senior pets—can worsen weakness, dehydration, or low blood sugar. Whether dietary modification is appropriate depends on the reason for the diarrhea, which cannot be determined by stool appearance alone.
What does blood in the stool mean?
Blood in the stool indicates significant irritation or injury to the intestinal lining and should always be taken seriously. Bright red blood may suggest large bowel inflammation, while dark or tarry stool can indicate bleeding higher in the digestive tract. Even small streaks or specks of blood can be clinically important. Blood in the stool can be associated with infections, parasites, inflammatory disease, toxin exposure, or more serious systemic conditions, and warrants veterinary assessment.
My pet is still acting fine - do they need a vet?
Yes, often they do. Pets are biologically skilled at appearing normal despite internal illness, especially in the early stages. Diarrhea, appetite changes, or subtle lethargy may be the first visible signs of dehydration, electrolyte imbalance, infection, or organ stress. By the time a pet appears obviously unwell, internal changes may already be advanced. Acting “mostly normal” does not reliably indicate that a condition is mild or self-limiting.
Is diarrhea always caused by a food change?
No. While dietary changes are a common trigger, diarrhea frequently reflects parasites, infections, inflammation, metabolic disease, or systemic illness. Assuming food is the cause can delay diagnosis of more serious problems. Some conditions may temporarily improve before recurring or worsening. Identifying whether diarrhea is dietary, infectious, inflammatory, or metabolic requires veterinary assessment and, in many cases, diagnostic testing.