There are several signs that can indicate that a pet needs medical attention. When these signs are recognized, it is important to consult a veterinarian as soon as possible. Here are some signs to look out for:

physical signs
Change in appetite:

Loss of appetite or sudden overeating can indicate medical problems.
Weight change:

Rapid weight loss or gain may indicate health problems.
Change in drinking:

Drinking more or less than usual can be a sign of kidney problems, diabetes or other problems.

Vomiting or diarrhea:

Frequent vomiting or diarrhea can indicate problems with the digestive system.
Cough or difficulty breathing:

Persistent coughing, wheezing or difficulty breathing are signs that require immediate attention.
Skin or fur changes:

Itching, rashes, sudden hair loss or other signs on the skin can indicate allergic reactions or other skin problems.
pain:

If the pet does not want to touch a certain area of ​​its body, displays apprehensive behavior or appears to be in pain, this could indicate a medical problem.

behavioral signs
Change in behavior:

A pet that shows signs of fatigue, lack of interest in daily activities, or mood swings may be ill.
Excessive shedding:

More shedding than usual can indicate stress or health problems.
Concealments:

If the pet seems to be hiding more than usual, this may be a sign that it is not feeling well.
Aggression or anxiety:

A sudden change in behavior, such as aggression or anxiety, may indicate pain or discomfort.

Additional signs
Change in urination:

A change in the amount or color of urine (such as dark or blood-like urine) can indicate kidney or urinary tract problems.
High body temperature:

If the pet is warm to the touch, it may have a fever or an infection.
Unusual reactions:

If the pet does not react as it normally does (for example, if it does not recognize its owner), this can indicate a neurological problem.
Summary
When these changes occur, it is important to consult a veterinarian as soon as possible. Preventive medicine and timely medical care can prevent serious complications and improve the pet's quality of life.