Why does a cat open mouth? – Understanding a cat with mouth open

Many times, you must have wondered that why does your cat open mouth at weird times. The opened mouth is accompanied by strange facial expressions including a wrinkled nose and back curled lips. As adorable as the cat’s face might look, you would be intrigued to know that there exist many scientific reasons behind your cat making that face, and it not a usual thing that they do despite being natural.

A cat with mouth open can only be seen when it’s drinking, eating, or making any sound. However, for all the other times that they open their mouth, there can be more than one reason for it. It is to make you aware of all of them that we write this article where we would be telling you all the causes and what to do in those cases.


Cats opening mouth after smelling

cat open mouth

The most commonly believed reason for cats opening their mouth for some time is that they do so after smelling different types of scent. We all know that the sensory organs of the felines remain most active all the time and in the case of cats, they open their mouths accompanied by the sniffing to identify any scent more closely.

That was the answer to the question that why do cats open their mouth after smelling. Now the process entails the use of the Jacobson’s organ or Vomeronasal sac present in the cat’s mouth at the upper portion behind the teeth. When the cat opens the mouth, it sucks in the scent which is then transferred to this organ for processing and understanding via the signals sent to the brain.

This whole process is known as the Flehmen reaction which is a common behavioral response found in particular mammals, cats being one of them. The most common scents that trigger this reaction are the pheromones like urine marks of other cats, female cat heat, and other regular smells like that of food, catnip, etc.

So, if your cat opens its mouth after smelling something, that’s not anything to worry about since there is no harm being caused to the cat. You might also come across them doing so during grooming or just observing something enticing.

Cats opening mouth for breathing…

This can be another reason why your cat open mouth more frequently and leaves it open for longer than usual.  Anything can cause open mouth breathing in cats like excessive playing or any health issue. Let us give you some of the reasons why cats might open their mouth to breathe.


This is very normal as the cat might happen to pant after playing too much, just like humans do after physically exerting activities. The symptoms subside after some time.


Your cat might have a cold due to any viral or bacterial infection in the upper respiratory system. This can be confirmed by looking for accompanying symptoms like coughing, excessive sneezing, nasal or eye discharge, dehydration, appetite loss, or fever.


This condition can both be genetic or develop later in the cat, making it difficult to breathe and even cough or wheeze. If your cat is open mouth breathing due to asthma, it may also develop darker gums and tongue.


It’s a condition of the cat breathing heavily through their mouth and if your cat does so frequently, you must take closer care of them. Older cats usually mouth-breathe heavily but it shouldn’t be frequent in any cat. This may be caused due to anything like nasal blockages, bloated stomach, blocked windpipe, pneumonia, liver issues, chest injuries, etc.


If the open mouth breathing in your cat looks like panting, it’s a signal for immediate action. A panting cat gets at the risk of overheating and may suffer serious repercussions. Watch what to do when the cat starts panting.

Severe health conditions

This includes your cat suffering from medical issues like Pulmonary Edema and Lung Cancer. P. Edema is a heart disease in felines that has symptoms like dry cough, wheezing, lethargy, appetite loss, etc. As for cancer, weight loss, frequent fever, blood coughing, etc. might accompany the open mouth breathing.

Cats opening their mouth for vocalizing…

Felines make various sounds and it’s obvious that they do so with their mouth open. However, you might see that your cat with mouth open is not able to make any sound. This hints at a probable chance of voice loss in your cat which can be either temporary or more severe due to causes like sore throat, respiratory tract infection, high fever, etc.

Throat blockage

Your cat’s throat may be lodged with any item like a furball or any other foreign object causing an interruption in verbalization. Also, check for any tumor growth in the throat.


This condition causes the swelling of the lymph nodes in cats and occurs due to bacterial infections.

Laryngeal paralysis

This involved the paralyzing of the voice box of the cat due to nerve damage in the larynx. However, it’s a very rare occurrence in cats.

Cats opening their mouth due to mouth issues…

cat open mouth

This usually involves two painful conditions of the cat’s mouth due to which they prefer not to close their mouth to avoid the pain.


Also known as underbite or overbite, it’s a condition involving the misalignment of lower and upper jaws where they overlap. This causes the piercing of the teeth in soft tissues and the cat suffers severe pain while closing the mouth.

Dental pain

This is caused by various gum diseases and includes symptoms like discoloration, teeth staining, mouth swelling, foul breath, inability to ingest food, etc.

Cats opening their mouth to bite…

This involves the cat hanging their mouth open for a bit longer as they decide the best way and time to strike. Signals like ears flattening, fidgeting, body tensing, tail flicks, pupil dilation, and other verbal cues can be observed to know if the cat is going to launch an attack due to any discomfort. This may happen upon excessive petting of the cat or them being engaged in any fight with other animals.

Final words

This was all about the reasons for understanding why would a cat open mouth other than for the usual purposes. You must relax if you have been thinking that why do cats open their mouth after smelling as that’s the most natural flex cats display. However, if you see prolonged mouth opening by the cats, you must look for the signs we discussed as there might be any serious problem on the way.

The best way out would be to contact a vet immediately if you are unsure of what is happening to your cat. We wish good health for your feline friend!

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Luna Tran

My name is Luna and I am a great cat lover and a cat owner of three lovely cats. I have owned many cats till now and have dedicated many years to nurturing and caring cats. Through this blog, I am here to share my knowledge and experience about cats.