If you pay attention to your cat, it’s not too hard to tell when she’s sick. A lot of it is obvious. But sometimes even subtle symptoms indicate a serious problem. Here’s a good rule of thumb: if you notice any symptom for more than a few days, consult your vet for testing.

Symptoms include:

Bloody Urine (Hematuria): May indicate a urinary infection of problem, like stones, Cancer, parasites, or clotting.

Bloody Vomit (Hematemesis): Causes include clotting disorders, gastrointestinal tract ulcerations, bleeding tumors in the stomach, irritating medications, and ingestion of poisonous materials.

Blue skin or gums (Cyanosis): A bluish coloration might be a sign of congenital heart disease, respiratory diseases, or exposure to chemicals.

Chronic coughing: Causes include bronchitis, pneumonia, heartworm disease, lung tumors, obstruction in the windpipe, and heart failure.

Constipation: There could be a dietary cause, such as a change in food. Other possible causes include medications, physical blockages, neurologic disease, metabolic problems, and endocrine disease. Look for straining, infrequent defecation, and hard, dry feces.

Dehydration: This occurs when your cat’s lost fluids and electrolytes—minerals like sodium, chloride, and potassium. It could be a result of fever or other illness.

Diarrhea: Can be acute (lasting less than a few weeks) or acute (lasting longer). It could be a sign of parasites, bacteria, or even pancreatic or liver disease. See your vet if it persists beyond a few days—especially if you notice worms in it.

Distended abdomen: Weight gain could be to blame, in which case you need to consider a healthier diet for your cat.

Ear discharge: Cats are prone to ear problems, and discharge is often the first sign. Either ear mites or an ear infection could be the cause. (This is why it’s important to clean your cat’s ears regularly!)

Fast breathing (Tachypnea): Any number of problems could be to blame, including upper respiratory disorders (problems with the nostrils, sinuses, larynx, or windpipe) and lower respiratory problems (including bronchitis, asthma, and chest tumors). The problem could also be non-respiratory, like cancer or heart disease.

Fever: A fever could indicate an infection, or something more serious like inflammation, cancer, or an immune system disease. A persistent temperature over 103 requires veterinary assistance.

Hair loss: Could be caused by scratching or chewing, or may indicate a hair follicle disease.

Lethargy: Chronic drowsiness can indicate any number of problems, including anemia, cancer, an electrolyte abnormality, a neurological disorder, or a skeletal disease.

Licking the genitals: Your cat may lick his or her genitals excessively because there is some type of discharge caused by a disorder or infection. Discharge could suggest a mild, serious, or even life-threatening problem.

Lost appetite: Could signal a disease of the digestive system—the esophagus, intestine, liver, pancreas and stomach. Pain in general and problems with other organs can also affect appetite.

Loss of vision: Causes include cataracts, corneal disease, diseases of the occipital cortex, optic nerve disease, glaucoma, and retinal inflammation.

Nasal discharge: Slight nasal discharge isn’t a cause for alarm, but severe bouts of discharge and sneezing could represent a more serious illness, like nasal mites, a fungal disease, or an inflammatory disease in the nasal cavity.

Overeating (Polyphagia): There could be a physical problem, like Cushing’s syndrome, diabetes, or intestinal cancer, or a psychological problem could be to blame—like a change in environment.

Problems urinating: If your cat is urinating more often than usual or straining at the litter box, lower urinary tract disease may be to blame. Although more common in males, urinary inflammation can happen to any cat. Other causes include bacterial urinary infection, bladder stones or tumors, or behavioral problems.

Red eyes: May indicate inflammation, infection, or glaucoma.

Swollen face: Causes include cellulitis, an allergic reaction, cancer, and muscle inflammation.