7 Warning Signs in Dogs and Cats You Should Never Ignore

By Dr. Jivitesh Singh, B.V.Sc. & A.H.

As a veterinarian, the most heartbreaking conversations I have are the ones that start with: “I noticed something a few days ago but thought it would go away on its own.”

Pet owners love their animals deeply — but animals are experts at hiding pain. By the time symptoms become obvious, a treatable condition can turn into an emergency. Knowing what to watch for can make all the difference.

Here are seven warning signs in dogs and cats that should prompt a vet visit — sooner rather than later.

1. Not eating for more than 24–48 hours

A skipped meal here and there is not unusual. But if your dog or cat refuses food for more than 24 hours (cats) or 48 hours (dogs), something is wrong.

In cats especially, not eating is an emergency. A condition called hepatic lipidosis — or fatty liver disease — can develop within just 2–3 days of not eating, particularly in overweight cats. It is serious, but completely preventable if caught early.

What to do: If your pet skips more than one meal and seems lethargic or uninterested in their surroundings, call your vet the same day.

2. Drinking much more water than usual

You fill the water bowl and it is empty again an hour later. Your pet is asking to go outside more often to urinate. This combination — increased thirst and increased urination — is a classic sign of several serious conditions, including:

• Diabetes mellitus (common in both dogs and cats)
• Kidney disease
• Cushing’s disease (dogs)
• Hyperthyroidism (cats over 8 years old)

All of these are manageable when diagnosed early. A simple blood and urine test at your vet clinic can identify the cause.

What to do: Track how much your pet is drinking over 24 hours and mention it to your vet. Do not wait — these conditions progress quietly.

3. Sudden change in breathing

Normal resting breathing for dogs and cats is 15–30 breaths per minute. If you notice any of the following, treat it as an emergency:

• Open-mouth breathing in cats (almost always abnormal)
• Breathing with visible effort — ribs moving dramatically, belly pumping
• Blue or pale gums
• Breathing that is noisy, wheezy, or labored

Respiratory distress can be caused by heart failure, fluid around the lungs, asthma (in cats), or airway obstruction. These conditions can deteriorate within hours.

What to do: Go to a vet or emergency clinic immediately. Do not wait for a scheduled appointment.

4. Vomiting or diarrhoea more than twice in 24 hours

Occasional vomiting — like eating grass or eating too fast — is common. But repeated vomiting or diarrhoea, especially if it contains blood, is a red flag.

Watch for these combinations that indicate something more serious:

• Vomiting + lethargy + not eating = possible obstruction or infection
• Diarrhoea + blood + weakness = possible parvovirus (dogs), panleukopenia (cats), or intestinal bleeding
• Vomiting + bloated or painful belly = possible bloat in large breed dogs (a life-threatening emergency)

What to do: One or two episodes — monitor at home and offer water. More than that, or any blood — call your vet.

5. Limping or reluctance to move

Animals do not complain about pain the way humans do. If your pet is limping, holding up a paw, hesitating to jump, or suddenly unwilling to climb stairs — they are in significant discomfort.

Common causes include:

• Joint pain or arthritis (especially older pets)
• Injury or fracture
• Tick-borne diseases like Lyme disease (dogs)
• Bone infections or, in serious cases, bone tumors

Do not assume it will pass. Many pets suffer in silence for months before owners realize the problem.

What to do: If limping persists more than 24 hours or is accompanied by swelling, visit your vet for an examination and X-ray if needed.

6. Lumps or bumps that appear suddenly or grow quickly

Not every lump is cancer — many are harmless fatty deposits called lipomas, especially in older dogs. But some lumps are not harmless, and the only way to know is to have them checked.

See a vet promptly if a lump:

• Appears suddenly and grows within days or weeks
• Is hard, irregular in shape, or fixed to underlying tissue
• Bleeds, oozes, or causes your pet pain when touched
• Appears on the mammary glands of unspayed females

Early detection dramatically improves outcomes for pet cancers.

What to do: Any new lump should be noted. If it changes size or shape, get it checked. A fine needle aspirate is a quick, low-stress test that gives a lot of information.

7. Changes in behaviour or sudden aggression

Animals communicate through behaviour. A friendly dog that suddenly snaps when touched, or a social cat that hides under the bed for days — these are not personality quirks. They are often signs of pain, neurological issues, or illness.

Other behavioral changes worth noting:

• Confusion, disorientation, or getting “lost” in familiar spaces (can indicate neurological disease or cognitive decline in older pets)
• Sudden house soiling after being well-trained
• Excessive vocalization, especially at night (common in hyperthyroid cats)
• Staring blankly or apparent seizure-like episodes

What to do: Trust your instincts. You know your pet’s normal behavior better than anyone. A sudden shift is worth a vet call, even if you are not sure.

The bottom line

You do not need to be a veterinarian to protect your pet’s health. You just need to pay attention. Animals rely entirely on us to notice when something is wrong and act on it.

When in doubt — call your vet. A quick phone consultation is almost always free, and peace of mind is worth it.

Dr. Jivitesh Singh is a qualified veterinarian (BVSc) with a passion for making animal health information accessible to every pet owner. For more evidence-based pet health content, follow this page.