How to Know When Your Pet Is Really Sick

Pets can't tell us when they're hurting. As a responsible owner, learning to read the signs of illness early can be the difference between a simple treatment and a serious health crisis. Here are ten warning signs that should prompt a call — or trip — to your veterinarian.

10 Warning Signs to Watch For

1. Sudden Changes in Appetite or Thirst

If your pet stops eating for more than 24–48 hours, or suddenly begins drinking far more water than usual, something is off. Increased thirst can signal kidney disease or diabetes, while loss of appetite may indicate infection, dental pain, or organ problems.

2. Unexplained Lethargy

All pets have lazy days, but if yours is consistently unresponsive, reluctant to move, or shows no interest in activities they normally love, that's a red flag. Lethargy is one of the most common early signs of illness across nearly every condition.

3. Vomiting or Diarrhea That Won't Stop

Occasional digestive upset happens. But vomiting or diarrhea that persists longer than 24 hours — or contains blood — warrants immediate veterinary attention. Dehydration can set in quickly, especially in small animals.

4. Difficulty Breathing

Labored breathing, wheezing, persistent coughing, or open-mouth breathing in cats is always an emergency. Don't wait to see if it resolves on its own.

5. Swollen or Distended Abdomen

A bloated belly can signal anything from gas to a life-threatening condition called gastric dilatation-volvulus (GDV) in dogs. If the abdomen looks unusually large or your pet seems uncomfortable, act fast.

6. Limping or Difficulty Moving

Occasional stiffness after rest is common in older pets, but sudden limping — especially if your pet refuses to bear weight on a limb — may indicate a fracture, ligament tear, or joint disease.

7. Eye or Nasal Discharge

Clear discharge may not be serious, but yellow, green, or bloody discharge from the eyes or nose often points to infection that needs treatment.

8. Skin and Coat Changes

Excessive scratching, bald patches, flaky skin, or a dull coat can signal allergies, parasites, hormonal imbalances, or nutritional deficiencies. Don't dismiss skin issues as minor — they're often a window into your pet's overall health.

9. Straining to Urinate or Defecate

This is especially urgent in male cats, who can develop urinary blockages that become fatal within hours. Any straining to use the bathroom — particularly with little to no output — is an emergency.

10. Sudden Behavioral Changes

Aggression in a normally gentle pet, hiding, disorientation, or sudden fearfulness can all point to pain, neurological issues, or other medical problems that need professional evaluation.

When It's a True Emergency

Certain situations require emergency veterinary care immediately — don't wait for a regular appointment:

  • Seizures or collapse
  • Suspected poisoning or ingestion of a toxin
  • Severe trauma (hit by a car, fall from height)
  • Inability to breathe
  • Uncontrolled bleeding

Prevention: The Best Medicine

Regular annual (or bi-annual for senior pets) wellness exams are the single most effective way to catch problems early. Keep up with vaccinations, parasite prevention, and dental cleanings. Building a relationship with a trusted vet before a crisis hits means faster, better care when it matters most.

Bottom line: You know your pet best. If something feels wrong, trust your instincts and make that call. A quick phone consultation with your vet is always better than waiting and wondering.