Why Does My Cat Have Bad Breath? Causes and What to Do

You lean in for a cuddle, your cat yawns, and the smell makes you recoil. It is easy to shrug off as "just cat breath", but a healthy cat's breath should not smell offensive at all. Bad breath, or halitosis, is one of the most useful early warning signs your cat can give you, and it is almost always worth a closer look. Here is what it really means and what to do about it.

What normal cat breath smells like

Mostly, of nothing much. A cat with a healthy mouth has clean, off-white teeth, light pink gums and breath you would barely notice. A faint whiff after a meal of fishy food is one thing. A smell that lingers, or one strong enough to make you pull away, is your cat telling you something is wrong. As Cornell's Feline Health Center puts it plainly, a healthy cat's breath should not be offensive.

The key word is persistent. One bad yawn is not a crisis. Day-after-day bad breath is.

The most common cause: dental disease

Roughly 50 to 90% of cats over the age of four have some form of dental disease, so if your cat's breath has turned, this is the first place to look. It starts with plaque, a soft film of saliva, food and bacteria that builds up on the teeth every day. Left alone, it hardens into tartar and inflames the gums, and the bacteria produce that distinctive rotten smell.

Dental disease in cats usually shows up as one of three problems:

• Gingivitis – inflammation of the gums, which go red, swollen and sore. Caught early, it is reversible.
• Periodontitis – when gingivitis is left to progress and starts destroying the tissue and bone anchoring the teeth. This cannot be reversed and can lead to tooth loss.
• Tooth resorption – where the tooth structure breaks down from the inside out. It is the single most common cause of tooth loss in cats, thought to affect somewhere between 30 and 70% of them, and it is painful.

The hard part is that cats are experts at hiding pain. Many carry on eating with genuinely sore mouths, which is exactly why owners often notice the smell before anything else. Other signs to watch for, listed by PDSA and Cats Protection, include drooling, red or bleeding gums, visible tartar, pawing at the mouth, dropping food, eating on one side, reduced appetite and weight loss.

Vets often say cats seem years younger and far happier after dental treatment. That is because they were quietly putting up with pain the whole time. Bad breath can be the only clue you get.

When the smell is a clue to something bigger

Sometimes the mouth is only the messenger. Certain illnesses change how a cat's breath smells, and knowing the difference can help you and your vet get to the answer faster. PDSA breaks it down like this:

| What the breath smells like | What it can point to | |---|---| | Rotten, foul, with tartar or sore gums | Dental disease (gum disease, tooth resorption, infection) | | Ammonia or bleach, like urine | Kidney disease – toxins building up in the blood | | Sweet, like pear drops or nail varnish remover | Diabetes, possibly diabetic ketoacidosis | | Foul, sweet and musty | Liver disease | | Strong and decaying from one spot | Something stuck in the mouth, or, rarely, a mouth tumour |

This is why bad breath deserves attention rather than a breath mint. Kidney disease is common in older cats, and an ammonia-like smell can be one of its signs. A sweet, pear-drop smell alongside a cat that is suddenly drinking and weeing more, or losing weight, needs a prompt vet visit, as it can point to diabetes. None of these are things to sit on.

Other everyday causes

Not every case is sinister. Bad breath in cats can also come from:

• Diet – some strongly flavoured wet foods simply leave a smell for a while. If it clears quickly and the mouth looks healthy, this is usually harmless.
• Something lodged in the mouth – a splinter of bone, a grass blade or a fragment of a toy can wedge between teeth, decay and cause both smell and infection.
• Airway or sinus infections – cat flu and other upper respiratory infections often cause bad breath.
• Gut problems – less common, but tummy issues can affect the breath, usually alongside vomiting or diarrhoea.

The trouble is you cannot reliably tell these apart at home, and a cat's mouth is difficult and risky to examine yourself. That is a job for your vet, who can look safely and properly.

When to see the vet

PDSA is clear that bad breath is not normal, even in an older cat, and that you should contact your vet if your cat has it. Book a routine appointment for persistent bad breath on its own. Treat it as more urgent if it comes with any of these:

• Drooling, or blood-tinged saliva
• Not eating, or struggling and crying when they try
• Noticeable weight loss
• Increased thirst and urination
• Lethargy, hiding or a general sense they are unwell
• Pawing at the face or a swelling around the jaw

A quick tip for the appointment: try to describe the smell, whether it is more rotten, ammonia-like or sweet. It is a genuinely useful clue that helps your vet decide what to check first.

What the vet will do

Expect a proper look in the mouth, and often a recommendation for a dental under general anaesthetic. That is not vets being cautious for the sake of it. Much of the disease, and the pain, sits below the gumline where it cannot be seen or cleaned in a wriggling, conscious cat. Under anaesthetic they can scale and polish the teeth, take dental X-rays, and remove any teeth that are damaged or resorbing. If they suspect kidney disease, diabetes or a liver problem, they will usually run blood and urine tests too. Yes, it costs, but a healthy mouth is one of the best investments in a long, comfortable life, and untreated dental disease only gets more expensive and more painful the longer it is left.

Keeping your cat's breath fresh

Once any existing problem is sorted, prevention is largely down to you at home. The single most effective thing is brushing.

• Brush the teeth. Daily is ideal, but even three to four times a week makes a real difference. Focus gently on the line where tooth meets gum, where plaque gathers.
• Only ever use cat toothpaste. Human toothpaste is not safe for cats – it is too frothy and can contain fluoride, and some human dental and food products contain xylitol, which is toxic. Cat pastes come in flavours like fish or poultry that cats will actually tolerate.
• Start slow and kind. Let your cat lick the paste, build up to a finger or a soft cat toothbrush over a couple of weeks, and pair it with a treat. If the gums bleed or your cat is clearly in pain, stop and speak to your vet, as brushing an already-sore mouth hurts.
• Use extras, not replacements. Dental diets, cat dental treats, water additives and gels can help, but they support brushing rather than replace it. Choose dental chews large and tough enough that your cat has to actually chew.
• Book a yearly dental check. Most cats benefit from having their teeth looked at once a year, usually at their booster appointment. Some, especially those prone to tooth resorption, need checking more often.

A sensible routine to remember: brush little and often, feed well, and get a professional check every year. Larger breeds such as the Maine Coon are no more immune than a moggy, so build the habit whatever cat you share your home with.

Bad breath is one of the kindest early warnings your cat will ever give you. Whether it turns out to be tartar or something that needs treating sooner, the smell has done its job by getting you to the vet. Do not wait for it to "settle" on its own, because with cats, it rarely does.

Sources

• PDSA – Bad breath in cats
• PDSA – Dental disease in cats
• Cats Protection – Cat dental care
• Cornell Feline Health Center – Bad breath: sign of illness?
• Cornell Feline Health Center – Feline dental disease