cat's mouth open and tongue out
Questions About Cats

Why Do Cats Hold Their Mouth Slightly Open?

Cats rarely open their mouths unless eating, drinking, or verbalizing. Despite this, some cats hold their mouths open for minutes at a time.

A cat with an open mouth may be processing a new scent using its vomeronasal organ (Jacobson’s organ). Dental problems may mean that a cat is reluctant to close its mouth due to discomfort. It may also be that your cat is preparing to bite, or trying unsuccessfully to meow.

A cat occasionally holding its mouth open is perfectly natural. However, this should not be its default expression. If your cat never closes its mouth, a health problem is likely preventing your cat from doing so.

Why Do Cats Keep Their Mouth Open Sometimes?

Cats hold their mouth open for many reasons. This can range from assessing a new scent to a health issue. Explanations include:

Unique Scents

The most common explanation for a cat holding its mouth open is a new scent. Cats have an additional scent gland in the roof of the mouth, called the vomeronasal organ or, more commonly, the Jacobson’s organ.

Cats have an excellent sense of smell. When a cat picks up the scent, it demonstrates what is known as the flehmen response. This looks like the cat is grimacing. In reality, it is trying to better understand the new scent. The flehmen response works as follows:

  1. An unfamiliar scent is detected.
  2. The cat opens its mouth and sticks out its tongue.
  3. The tongue is flicked back into the cat’s mouth.
  4. The pheromones of this scent will reach the Jacobson’s organ.
  5. The cat curls back its top lip while assessing the new scent.

The cat then memorizes this smell for future reference. Any unfamiliar aroma can spark the flehmen response. As explained by Applied Animal Behavior Science, it is often used to detect urine scents. Outdoor cats can determine who is a friend or foe by marking territory.

Dental Pain

When a cat closes its mouth, its upper and lower teeth should align. If this is not the case, it is known as a malocclusion. You may have heard of a malocclusion being referred to as an overbite or underbite.

A malocclusion will make it painful for your cat to close its mouth. An overbite will see the upper jaw stretch beyond the lower. A cat with an underbite will have a longer lower jaw. Either way, teeth will pierce the soft tissue in a cat’s mouth when closed. This will be painful, so the cat will understandably be reluctant to close its mouth.

As per the BMJ’s In Practice journal, malocclusions are often hereditary. Older cats can develop malocclusions through trauma to the jaw, though. These concerns will require dental surgery to resolve.

If your cat’s jaws are aligned, it may still be experiencing dental pain. Gum disease impacts most cats at some point. If your cat is holding its mouth open regularly, try to touch its teeth. If the cat shies away or reacts aggressively, gum disease is likely. Symptoms include:

  • Black gums
  • Yellow staining of the teeth
  • Pawing at the face and mouth
  • Swelling around the mouth
  • Refusing food and water
  • Foul breath
cat keeps mouth open after meowing

Trouble Breathing

Cats are obligate nasal breathers, which means that they always breathe through the nose. If a cat is breathing through its mouth heavily, it’s likely due to dyspnea or panting.


Dyspnea is the act of a cat breathing heavily, especially through the mouth. It is not a condition in and of itself. Rather, it is a symptom of a different medical concern.

Most senior cats will breathe heavily on occasion. The older a cat is, the more physical exercise will take its toll. The cat may need to rest for a few moments while it catches its breath before nasal breathing can resume.

A cat breathing heavily through its mouth for a prolonged period of time suggests dyspnea. Explanations include:

  • Nasal blockages or nosebleeds
  • Issues with the trachea (aka windpipe)
  • Asthma
  • Bloated stomach
  • Impact injuries to the chest
  • Pneumonia
  • Liver difficulties

If your cat regularly breathes heavily through its mouth while at rest, this is clearly a problem that needs to be addressed.


Panting is a more serious form of dyspnea. The European Journal of Physiology defines panting as taking over 100 breaths per minute. A panting cat will hold its mouth open.

Panting can be caused by physical pain or the side-effects of medication. Most often, cats pant because their body temperature is too high.

A cat’s preoptic anterior hypothalamus constantly monitors body temperature. If above 103 degrees Fahrenheit, the cat is at risk of overheating. The brain recognizes this as a problem and sends messages to the body. The cat will pant to cool off.

Cats do not start to pant unless absolutely necessary. Move your cat to a cool location and encourage hydration. If your cat will not drink water, give it a meat-flavored ice cube to lick.

why does my cat open its mouth after I pet it?

Attempting to Verbalize

Your cat could be performing the action associated with vocalization, but not making a sound. Cats can lose their voice for various reasons.

Oftentimes, cats are unable to vocalize due to a sore associated with an upper respiratory tract infection. A respiratory infection will cause a high fever, but will usually run its course in a few days.

A cat without a fever will rarely have a respiratory infection. Other explanations for a cat’s loss of voice include:

Throat Obstructions

Your cat may have a throat obstruction that is preventing verbalization. If your cat is also reluctant to eat or drink, this becomes likelier. Your cat may have swallowed a substantial furball.

Drizzle some olive oil over your cat’s food. If it will not eat, offer the olive oil on a teaspoon. This will act as a lubricant in your cat’s throat. The oil will soothe the passage of the furball, and help it pass through the digestion.

If the obstruction is caused by a foreign object, removal may be more difficult. Some things are too big to pass through a cat’s throat, no matter how well lubricated. A vet may need to remove the item with a laryngoscope. This must never be attempted at home.

It’s rare for the obstruction to be organic, but it can happen. Ensure that your cat does not have a growth in its throat. Do not panic – this does not automatically equal cancer. Cats develop growths in a range of places and they are often benign. All the same, arrange a scan.


Check your cat’s lymph nodes for signs of swelling. These are found beneath the jaw. Your cat may have a condition called lymphadenopathy. This is an inflammation of the lymph nodes. This will make swallowing and verbalizing difficult,

Lymphadenopathy is often caused by a bacterial infection. Microbiology and Immunology link the condition to Bartonella henselae, aka cat scratch disease. Be mindful of this if your cat has scratched you and the wound itches.

It is also possible for allergies to spark lymphadenopathy. The condition is caused by an excess of white blood cells. If a cat undergoes an allergic reaction, it will create more white blood cells. Essentially, your cat’s body is overreacting to a threat.

Determining the cause of lymphadenopathy is key to treatment. Ordinarily, it is comparatively straightforward. A course of antibiotics of an anti-inflammatory will right the problem.

Laryngeal Paralysis

Laryngeal paralysis is a medical condition in which a cat’s voice box becomes paralyzed. The issue is caused by nerve damage to the larynx. It is an idiopathic concern, meaning that no root cause has been established. Thankfully, laryngeal paralysis is rare in cats.

The Journal of the American Veterinary Medical Association surveyed 16 cases of feline laryngeal paralysis over ten years. 7 of the cats required surgery, with 6 surviving. The remaining 9 cats were treated with medication.

With treatment and appropriate care, most cats with laryngeal paralysis regain their voice. Fast action is key. Be wary of a verbal cat suddenly becoming silent, especially if it holds its mouth open. The cat may be struggling to meow.

cat breathing with an open mouth

Preparing to Bite

Some cats keep their mouths open so they can bite. The cat is weighing up options and deciding when best to strike. You will most often see this while petting or grooming a cat. The cat is gearing up to bite or nip your hands to cease the contact.

While cats being petted, the experience can quickly turn from pleasure to pain. Petting to excess can overstimulate a cat’s sensitive skin. This will feel like sandpaper being rubbed against the cat’s back. Understandably, the cat will react.

Watch out for your cat holding its mouth open during this time. A contented cat will keep its mouth closed and purr. When it starts to grow more uncomfortable, the cat will display warning signs. These include:

  • Fidgeting
  • Flattening of the ears
  • Moving the head to watch hand movements
  • Tensing of the body
  • Drastic tail flicks
  • Dilation of the pupils
  • Verbal cues (growling or hissing)

If your cat is no longer enjoying petting, let it go. Do not toss the cat from your lap. Just lift your hands out of reach and allow the cat to walk away. Most cats will only bite as a last resort. Once the mouth starts to hang open, you are on your final warning.

In most cases, cats hold their mouths open to gain access to the Jacobson’s organ. If your cat shows no signs of ill health or distress, this almost certainly the answer. Be vigilant about any other warning signs. New scents are exciting for cats, but anything else is troublesome.