If your cat is suddenly behaving differently, it may be that it's feeling unhappy or even suffering from depression. There are many signs that can tell you if your cat is not doing well.

Similar to dogs, cats signal their well-being through their body language, voice, and behavior.

While some cats never change their behavior, there are others that are very sensitive to changes, such as a place to live or a new person in the home.

Here's a look at the tell-tale signs that may indicate tour four-legged friend is feeling blue.

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As always, being vigilant and keeping a close eye on small but revealing developments pays off.

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Normally you come home and your cat is eagerly awaiting your arrival, but has it suddenly stopped showing its face? Creating little nests or hiding in unusual places may indicate that something is wrong.

Try to find the cat without forcing it out of its hiding place. If it crawls out, take a close look at how it reacts to you. Does it hiss, seem run-down, or hide again immediately? If you can rule out medical reasons or increasing age, try to deal with your pet carefully and gently.

A cat's language also tells you a lot about whether they are comfortable or not. Cats are able to make different sounds for different situations, such as chattering when they hunt or simple mewing when they want food.

If the cat's tone of voice changes and it starts to scream or hiss when looking at you, it may be that the bond between you and your pet has been damaged. Either way, your cat is not comfortable with the current arrangements.

It's normal for cats to go wild every once in a while – after all, they sleep up to 17 hours a day, so especially indoor cats need to let off a little steam.

It's a different story when your cat stops running around and starts attacking people.

This can manifest in various ways: if your cat bites more often and with more force, purposefully scratches people, or arches its back with a bristled tail, this is a pretty clear signal that it's unhappy.

A cat's body language is a good indicator of its mood: does it run away from you permanently, tense up, or is it huddled in a corner when it sees you?

Both are signs that your cat is stressed by you or the atmosphere at home. Give it some space to relax again.

When your cat over-grooms or doesn't groom at all, there may be something wrong. Over-grooming may be an indication that the feline is bored and it may even start to pull out its fur.

If bald patches appear on your pet, it's time to act quickly. First try to rule out a parasite. Once you've made sure this isn't the source of the problem, it's important to change something about the environment so that the cat can feel relaxed again.

After your pet stops grooming itself, it'll start looking shaggy and even smell, which both indicate a genral lack of well-being.

Cats are very particular about their diets. Sometimes they find the food great, other times they suddenly give established favorites the side eye. Nevertheless, it's important that your cat always eats enough. Unlike dogs, their digestive system is not designed for long-term storage of food, so a cat should always have food in its stomach.

A sudden refusal of food can be the first sign of illness, so take your cat to the vet as soon as possible to rule out anything serious.

If the reasons for this change in eating habits are more psychological than physical, try to find out what is making your cat unhappy. Felines generally give you fewer clues than dogs. Have there been any recent changes? Have you moved house, or maybe your home life has changed? Is there a new partner or baby in the picture. Maybe something changed in the cat's life, like the death of a pet companion.

Always check if the cat's basic needs are met: a clean litter box, clean drinking water, and fresh food.

Remember: when in doubt, or you have a gut feeling something might be wrong, visit a veterinarian.