Dog & Cat HospitalCalabasas

Patient Education

Vomiting & Diarrhea

Vomiting and diarrhea are among the most common reasons dogs and cats visit the vet — and the most common reason owners underestimate what's driving them. Finding the root cause is what separates short-term relief from lasting resolution.

Gastrointestinal (GI) disease covers a wide spectrum — from a single vomiting episode after eating grass to months of weight loss from inflammatory bowel disease or a hidden intestinal tumor. The GI tract includes the esophagus, stomach, small intestine, and large intestine, and disease at any point produces overlapping signs. That overlap is exactly why a thorough diagnostic workup matters: treating symptoms without finding the cause usually provides only temporary relief. Our internal medicine team at Dog & Cat Hospital Calabasas uses in-house lab testing, digital radiography, abdominal ultrasound, and on-site endoscopy to move from signs to diagnosis efficiently, often in a single visit.

Signs & Symptoms

The pattern of signs often points toward where in the GI tract the problem lives and whether it's acute (sudden) or chronic (ongoing).

Upper GI (stomach / small intestine):

  • Vomiting — with or without blood or bile
  • Regurgitation of undigested food (suggests esophageal involvement)
  • Decreased appetite or complete refusal to eat
  • Abdominal pain or a hunched posture
  • Large-volume watery diarrhea

Lower GI (large intestine / colon):

  • Frequent, urgent trips outdoors or to the litter box
  • Small amounts of soft stool, sometimes with mucus or fresh blood
  • Straining or discomfort during defecation

Systemic or chronic signs:

  • Progressive weight loss despite a maintained or even increased appetite
  • Protein loss causing fluid accumulation (pot-bellied appearance)
  • Dull coat, muscle wasting, lethargy

A single vomiting episode in an otherwise bright pet is usually minor. Repeated vomiting, blood, significant lethargy, or any sign lasting more than 24–48 hours calls for an evaluation.

Causes & Risk Factors

GI disease has a long differential list — which is why systematic diagnosis matters so much. Common causes include:

  • Dietary indiscretion: eating garbage, table scraps, a new food introduced too quickly, or a food sensitivity/allergy
  • Parasites: roundworms, hookworms, Giardia, and Tritrichomonas foetus (in cats) all cause diarrhea; regular fecal testing catches these early
  • Infectious disease: parvovirus in unvaccinated dogs, panleukopenia in cats, Salmonella, Campylobacter
  • Foreign bodies: swallowed toys, bones, socks, or string — a common cause of acute obstruction
  • Pancreatitis: frequently triggers vomiting and diarrhea alongside abdominal pain
  • Inflammatory bowel disease (IBD): immune-mediated infiltration of the intestinal wall causing chronic, recurrent GI signs
  • Intestinal lymphoma: the most common gastrointestinal tumor in cats, often clinically indistinguishable from IBD without biopsy
  • Exocrine pancreatic insufficiency (EPI): the pancreas fails to produce enough digestive enzymes, causing malabsorption and large volumes of soft, fatty stool
  • Toxin ingestion: certain plants, medications, and household chemicals damage the GI lining directly

GI symptoms that keep coming back deserve real answers.

Book an Appointment

How We Diagnose It

The workup scales with how sick the pet is and how long the signs have persisted. A first acute episode in an otherwise healthy dog might need only a fecal exam and dietary change; a cat with a month of weight loss needs a full panel. Our in-house capabilities let us move through the diagnostic ladder in one visit when needed.

  • Fecal examination and PCR testing: checks for parasites, Giardia, and intestinal pathogens
  • Complete blood count and chemistry panel: evaluates protein levels, liver and kidney function, inflammation markers, and evidence of blood loss
  • Cobalamin (B12) and folate levels: abnormal levels suggest where in the small intestine absorption is failing
  • Trypsin-like immunoreactivity (TLI): diagnoses exocrine pancreatic insufficiency
  • Digital radiographs: detect gas patterns suggesting obstruction, free fluid, or foreign objects
  • Abdominal ultrasound: evaluates intestinal wall thickness and layering, lymph nodes, and mesentery — critical for distinguishing IBD from lymphoma
  • Endoscopy: our on-site upper and lower endoscopy capability allows direct visualization and biopsy of the esophagus, stomach, small intestine, and colon without surgery

Treatment Options

Treatment is targeted at the confirmed cause — which is why diagnosis first is always the right approach. Common treatments include:

  • Dietary modification: a novel-protein or hydrolyzed diet trial (8–12 weeks) for food-responsive disease; highly digestible diets for recovery from acute episodes
  • Antiparasitic medications: metronidazole, fenbendazole, and related drugs for confirmed parasites or Giardia
  • Immunosuppressive therapy: corticosteroids (prednisolone) or combination protocols (chlorambucil + prednisolone in cats) for IBD or low-grade intestinal lymphoma
  • Enzyme supplementation: powdered pancreatic enzymes added to every meal for EPI, with reliable and often dramatic improvement
  • Cobalamin injections: for pets with confirmed deficiency, injectable B12 improves intestinal cell health and appetite
  • Supportive care: anti-nausea medications, probiotics, and fluid support during acute flares
  • Surgery: for foreign-body obstructions, intestinal masses, or intussusception (bowel telescoping on itself)

When to See Our Team in Calabasas

Occasional mild vomiting or a brief loose stool is normal. But vomiting or diarrhea that persists more than 24–48 hours, includes blood, or comes with lethargy, pain, or weight loss needs evaluation — don't wait to see if it resolves on its own. Chronic intermittent signs that come and go over weeks are just as important to investigate as a sudden crisis. Our team in Calabasas can image, scope, and lab-test in the same building, which means fewer referral trips and faster answers. Book an appointment and let us find what's behind the signs.

Frequently Asked Questions

1When should I take my dog to the vet for vomiting?
Vomiting once or twice in an otherwise bright, playful dog is usually not an emergency. Seek same-day care if your dog vomits more than two or three times in a few hours, shows lethargy or pain, has blood in the vomit, or hasn't eaten in more than 24 hours — these patterns suggest something more serious is going on.
2What causes chronic diarrhea in cats?
Chronic diarrhea in cats is most commonly caused by dietary sensitivity, parasites (especially Giardia or Tritrichomonas), inflammatory bowel disease, or low-grade intestinal lymphoma. Because IBD and lymphoma look very similar clinically, endoscopic biopsy is often needed to tell them apart — which matters because their treatments differ.
3Can I give my dog Pepto-Bismol or Pepcid for an upset stomach?
Some human antacids are used in dogs at veterinarian-guided doses, but Pepto-Bismol contains salicylate, which is toxic to cats and risky in dogs on certain medications. It's best to call your vet before giving any human GI medication to your pet — and to investigate the cause rather than just treat the symptom.
4What is inflammatory bowel disease in dogs and cats?
IBD is a chronic immune-mediated condition where inflammatory cells infiltrate the intestinal wall and disrupt normal digestion and absorption. It causes intermittent or persistent vomiting, diarrhea, and weight loss, and is diagnosed by intestinal biopsy. Most pets are managed long-term with a combination of diet and immunosuppressive medication.
5How do I know if my pet swallowed something and has an obstruction?
Signs of a GI obstruction include repeated vomiting (especially of bile without food), complete loss of appetite, abdominal pain or bloating, and sudden profound lethargy. If you suspect your pet swallowed a toy, sock, bone, or other object, treat it as an emergency — obstructions can become life-threatening within hours.
6What is EPI and can it be cured?
Exocrine pancreatic insufficiency (EPI) means the pancreas fails to produce enough digestive enzymes, so food passes through largely undigested. Affected dogs — especially German Shepherds — often eat ravenously but still lose weight and produce large, soft, fatty stools. EPI is managed lifelong with enzyme powder added to every meal; most dogs thrive with consistent treatment.
7Is a bland diet enough to treat my pet's diarrhea?
A bland diet (boiled chicken and rice) can help calm a simple, short-lived episode of diarrhea, but it doesn't treat the underlying cause. If diarrhea recurs, lasts more than 48 hours, or is accompanied by other signs, a veterinary workup is needed to avoid prolonged discomfort and missing a treatable condition.
8Can stress cause diarrhea in dogs and cats?
Yes — stress colitis from a change in routine, travel, boarding, or a new pet in the home is a real and common trigger, particularly in dogs. It typically causes urgent, mucus-tinged diarrhea that resolves within a few days. However, other causes should be ruled out if the diarrhea doesn't improve promptly or keeps recurring.

Related

ProceduresEndoscopy

GI symptoms that keep coming back deserve real answers.

Our team combines in-house lab testing, ultrasound, and endoscopy to find the cause of your pet's vomiting or diarrhea — often in a single visit.

Book an Appointment