This picture is humourous but the reason for a cat crying is probably serious.
What is cat crying? ANS: A cat that meows continuously. REASON: The cat is probably in pain1. There are other reasons, however.
When this happens a trip to the veterinarian is usually called for and as quickly as possible, it seems to me. Although sometimes a crying cat can simply be seeking attention for one reason or another. But in my experience these are rarely continuous.
Cat crying for long periods can strain the voice - cause laryngitis.
Some examples when cat crying occurs:
Cat in Heat The cat is not in pain. During estrus the second stage in the heat cycle and when the queen is sexually receptive, she makes more noise and the meows are louder and more frequent. See Cat heat behavior
A kitten crying indicates that he or she is cold, sick, hungry or perhaps in pain. A kitten that is distressed for these reasons might crawl about and move away from the mother. The crying meow may continue for 20 minutes or more. The mother may reject the kitten. This situation can be reversed if the cause it treated.
Pseudorabies: This disease has symptoms that look like those of rabies. It is caused by a herpes virus. It can be acquired by eating infected uncooked beef or pork or an infected rat. It is 'highly fatal'1. The cat suffers intense pain and cries. It drools excessively and scratches the head and shoulders where there is intense itching. Collapse and coma follow.
Dilated Cardiomyopathy is rapid onset. It progresses over 2-3 days as the heart fails. There is laboured breathing. The cat strains for air. The pulse is rapid. There is weight loss, weakness and cat crying. See Cat heart murmur symptoms
Feline Lower Urinary Tract Disease is the most common lower urinary tract disorder in cats. The symptoms are prolonged squatting and straining when urinating. Cats pass bloody urine and urinate in strange places. Cats cry out when voiding.
Cognitive Dysfunction Syndrome commonly known as cat senility. Very old cats tend to cry at night. My lady cat does. She looks confused and I think it is this that makes her cry out.
Feline Hyperthyroidism a disorder of the glands tending to affect older cats. Read about it here.
There are obviously other reasons why cat crying occurs. The advice as mentioned is immediate veterinary care if pain is suspected. Other signs will firm up the diagnosis.
1. Cat Owner's Home Veterinary Handbook by Drs Carslon and Giffin.