Why does my cat smell bad?
Cats are meticulous groomers, so a persistent bad smell is usually a sign that something specific is going on rather than simple dirtiness — most often the mouth, skin, litter tray habits, or reduced grooming from an older or overweight cat struggling to reach everywhere. Working out where the smell is coming from is the first step to sorting it properly.
Usually not urgent
This is common and often manageable at home — but see a vet if it persists, gets worse, or comes with other changes.
Where the smell is likely coming from
Get close and check systematically: sniff near the mouth, the coat generally, and underneath the tail. Bad breath points squarely at the mouth and teeth, a greasy or matted coat with an unusual smell often means grooming has dropped off or there is a skin issue underneath, and a strong smell around the back end can mean anal gland problems or, less commonly, urinary issues.
A cat that has recently reduced how much it grooms itself is worth watching for other changes too, since reduced grooming is often one of the first visible signs that an older cat is developing arthritis and finding it physically harder to reach around to clean themselves properly.
The common causes
Dental disease is extremely common in cats and produces a distinctive, persistent bad breath that gets steadily worse as it progresses, often alongside drooling, pawing at the mouth, or a reluctance to eat harder food. Skin infections and allergies can cause a musty or greasy smell along with excess licking at specific areas, while obesity or arthritis commonly reduce a cat's ability to groom the harder-to-reach areas, particularly around the base of the tail and lower back.
Litter tray issues are worth ruling out too — a cat that is stepping in soiled litter, or struggling to fully clean themselves after using the tray because of weight or joint problems, can carry a persistent smell that has nothing to do with the coat or skin itself. Urinary tract infections occasionally cause a noticeable smell as well, usually alongside more frequent trips to the tray or visible discomfort while using it.
When it is worth a vet visit
Book an appointment if bad breath is persistent or worsening, if you notice drooling, pawing at the mouth, or reluctance to eat, if the coat looks greasy, matted or the cat seems to be grooming less than usual, or if there is any change in litter tray habits alongside the smell. A vet can check the teeth and gums properly, assess joint mobility in an older cat, and rule out infection where needed, which is far more reliable than guessing at home.
A smell that clears up after cleaning the litter tray and giving the cat a gentle check-over, with no other changes present, is far less concerning, but it is still worth keeping an eye on a cat who seems to be grooming noticeably less than they used to, particularly if that cat is older or carrying extra weight already.
What helps day to day
Regular tooth brushing, where a cat will tolerate it, and dental-specific treats or food can genuinely slow the build-up of the plaque that drives most bad breath, alongside a yearly dental check at the vet. Keeping the litter tray clean and easily accessible — including a lower-sided tray for a cat with stiff joints — removes one common source of lingering smell entirely.
For an older or overweight cat struggling to groom, a soft brush used regularly by an owner helps keep the coat clean in the areas a cat can no longer reach comfortably themselves. None of this replaces a vet's opinion where dental disease, infection or reduced mobility is the actual underlying cause — think of home care as maintenance between check-ups rather than a substitute for one.
What can help
Things we stock that owners commonly use alongside a vet’s advice — not a substitute for it.
Plastic Cat Litter Tray — Large & XL
A sturdy plastic litter tray in two generous sizes — practical, no-fuss, and easy to clean.
From£11.49
NanoSanitas Advanced No-Brush Dental Gel for Dogs & Cats
A brush-free dental gel for dogs and cats, formulated with silver nanoparticles and papaya extract to help reduce plaque and freshen breath.
£14.99
Plastic Cat Litter Scoop
A no-nonsense plastic litter scoop for daily tray maintenance — comes in assorted colours.
£4.99
Enclosed Cat Litter Box with Carbon Filter
A roomy enclosed litter box with a carbon filter that helps keep household odours in check.
From£28.99
Common questions
- Why does my cat's breath smell so strong all of a sudden?
- Sudden or worsening bad breath is most often dental — a build-up of plaque, gum disease, or occasionally an abscess or broken tooth. This tends to get worse rather than better on its own, so it is worth a vet check rather than masking it with treats alone.
- Can weight affect how a cat smells?
- Yes, an overweight cat often struggles to reach and clean certain areas properly, particularly around the base of the tail, which can lead to a persistent smell that has nothing to do with illness directly but is still worth addressing with your vet.
- Is a strong smell from my cat's back end always anal glands?
- Anal gland issues are a common cause of a strong smell from that area, but litter tray hygiene, obesity affecting self-cleaning, and occasionally a urinary infection can also be responsible. A vet can work out which one it is rather than guessing.
- My older cat has started grooming less — is that linked to the smell?
- Very possibly. Reduced grooming in an older cat is a common early sign of arthritis or joint discomfort making it physically harder to reach certain areas, and this often shows up first as a coat that seems greasier or a persistent smell rather than an obvious mobility problem.
- What can I do at home before booking a vet visit?
- Check and clean the litter tray, have a gentle look at the teeth and gums for redness or visible tartar, and brush the coat if your cat will tolerate it. If the smell persists despite this, or you notice any other change, that is the point to book a proper vet check.
Related
Sources
Written against guidance published by UK veterinary and welfare organisations. Always confirm specifics with your own vet.
Written by Matt Garnett, who runs Giddy Pets and is a lifelong pet owner — not a vet. This is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your animal. How we write these guides.