The Overlooked Place Pet Parents Shouldn't Forget to Check
A quick belly check could save your cat's life. Discover the often-overlooked spot every pet parent should be examining.
Reviewed by Dr. Elizabeth Hardoon
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STORY AT-A-GLANCE
- Mammary tumors are one of the most common feline cancers, accounting for about one-third of all cases, and they often go unnoticed until they’ve already begun to spread
- Most tumors start as small, firm lumps under or near a nipple that aren’t painful at first — making regular at-home checks essential for early detection
- Certain cats face higher risks, including older females, Siamese and Persian breeds, overweight cats, and those given hormone-based medications
- Tumor size predicts outcome — cats with lumps smaller than 2 centimeters (cm) often live years longer than those with larger or more advanced growths
- A quick belly check can be lifesaving — feeling along your cat’s underside once a week helps you spot subtle changes before they become serious
When it comes to caring for your cat, you probably think about the basics first — feeding them a healthy diet, providing fresh water, and brushing their teeth or grooming their coat. But there’s one part of your cat’s body that often gets overlooked; and checking it regularly could actually save their life — the mammary glands (breast tissue).
Yes, just like humans, cats can be prone to breast lumps, and regular checks are vital to their health. All cats have mammary glands, but they don’t have just two — they have eight of them. They are arranged in two neat rows running along their belly. And while it may sound surprising, mammary tumors (or “breast tumors”) are one of the most common types of cancer in cats. The good news? When caught early, these tumors are far easier to treat, and your cat’s chances of a long, healthy life increase dramatically.
What Are Mammary Tumors?
Mammary tumors develop when the cells in your cat’s mammary glands start growing abnormally. Instead of dividing in an orderly, controlled way, they multiply out of control, forming a lump or mass under the skin. These growths can be either benign (non-cancerous) or malignant (cancerous).1
Unfortunately, in cats, the vast majority of mammary tumors are malignant — around 85% to 96% according to several veterinary studies.2 Adenocarcinoma is the most common type, and it starts in the milk-producing or ductal tissue and often spreads to other parts of the body.
While it can happen in both male and female cats, this disease overwhelmingly affects females. Tumors can occur in any of the mammary glands, from the ones near the chest to those closer to the hind legs, and may appear on one or both sides of the body.
Why Should You Care About Your Cat’s Mammary Glands?
Mammary cancer in cats is not a rare occurrence — it accounts for about one-third of all feline cancers and is the third most common type overall, after lymphoma and skin cancer. Most affected cats are older (around 10 to 12 years old), but younger cats can also develop it, especially certain breeds like Siamese and Persian cats, who appear more prone to early and aggressive forms of the disease.3
The danger lies in how quickly these tumors can spread. Once a mammary tumor becomes malignant, it often travels first to the nearby lymph nodes, and from there to vital organs such as the lungs, liver, or kidneys. By the time a tumor is large enough to be easily noticed, it may already be spreading inside the body. That’s why early detection, ideally before the tumor grows beyond 2 centimeters (about the size of a grape), is absolutely critical.
Risk Factors of Mammary Tumors
There are several conditions that can also raise your cat’s chances of developing mammary tumors. These include:4
- Breed — As mentioned, Siamese and Persian cats are more prone to developing this type of cancer; it often occurs at a younger age and triggers more aggressive tumors.
- Age — Most cases occur in middle-aged or older cats (around 10 to 12 years old).
- Obesity — Overweight cats appear to be at higher risk, possibly due to the influence of body fat on hormone metabolism.
- Hormonal medications — Giving synthetic hormone-based medications (such as those used to prevent heat cycles) can triple the risk of developing mammary cancer later. Female cats that are not spayed or that are spayed later in life also have a higher risk due to naturally circulating hormones.
Male cats can develop mammary tumors too, but it’s extremely rare. When it does happen, it’s usually malignant and aggressive.
The Subtle Early Signs
In the early stages, mammary tumors can be almost impossible to detect without careful inspection. They often start as small, firm or hard, pea-size lumps, sometimes no bigger than a BB pellet, beneath or next to a nipple. At this stage, the lump isn’t painful, and your cat will likely act completely normal.5 Acting quickly at this stage can save your pet future troubles.
In the beginning there is no redness, swelling, or change in appetite. That’s what makes these tumors so dangerous — by the time they’re visible or causing discomfort, they’ve often been growing for weeks or months. As the tumor develops, you might notice:6,7
- One or more lumps or nodules along your cat’s belly, near or around the nipples.
- The skin over the lump may become ulcerated (open or scabbed) and oozing.
- The area might feel warm, tender, or painful to the touch.
- Your cat may lick or groom the area excessively.
In advanced cases, your cat may lose weight, eat less, become lethargic, or even have trouble breathing if the cancer spreads to the lungs. Because cats are so skilled at hiding discomfort, it’s up to you to look for these signs before they worsen.
How to Check Your Cat’s Mammary Glands
Checking your cat’s mammary glands doesn’t take long, and doing it regularly can make all the difference. Think of it like a monthly “wellness scan” you can do right at home. Here’s how:
- Find a quiet moment — Pick a time when your cat is relaxed, such as during grooming or cuddling.
- Gently run your hands along her belly — Start from the chest and move toward the back legs. You should feel two rows of four glands on each side.
- Use light pressure — Move your fingers in small circles as you go, feeling for any lumps, firm spots, or swelling.
- Check both sides — It’s possible for tumors to appear on one side only, but they can also develop in multiple glands.
- Look for changes — If you notice any lumps, no matter how small, or areas that seem sore or different from usual, make an appointment with your veterinarian right away.
Even if it turns out to be something harmless, early evaluation is key. Never wait to “see if it goes away.” Small tumors are much easier to remove and treat successfully than large or spreading ones.8
Getting a Diagnosis
If your vet suspects a mammary tumor, they’ll start with a physical exam and then perform diagnostic tests to determine what’s going on. These may include:9,10
- Fine-needle aspiration (FNA) — Using a thin needle to collect cells from the lump for microscopic examination.
- Biopsy — Removing a small section (or the whole lump) for a detailed analysis (histopathology) to determine if it’s cancerous and how aggressive it is.
- Staging tests — To check if the cancer has spread, your vet might recommend chest X-rays, abdominal ultrasound, blood tests, or sampling lymph nodes near the mammary glands.
Together, these tests help your veterinarian determine how advanced the cancer is and what treatment options will offer the best outcome.
Treatment Options
Once a mammary tumor is diagnosed, your vet will discuss the best treatment plan for your cat. This depends on factors like tumor size, whether it has spread, and your cat’s overall health. The main options are surgery, chemotherapy, and palliative care.
If surgery or chemotherapy aren’t possible, perhaps because the cancer has spread too far or your cat has other health problems, your vet can still help manage pain and maintain quality of life. Palliative care might include:
- Pain relief and anti-inflammatory medication
- Partial tumor removal to ease discomfort
- Antibiotics and wound care for ulcerated or infected tumors
- Herbal therapy and acupuncture
- Nutritional and emotional support to keep your cat comfortable
Even when a cure isn’t possible, thoughtful care can make your cat’s remaining months or years peaceful and pain-free.
Prognosis — What to Expect
The outcome for a cat with a mammary tumor depends on several key factors, mainly the size of the tumor, whether it has spread, and how aggressive the cancer is.11,12
- Tumors smaller than 2 cm — Best prognosis; many cats live three years or longer after surgery.
- Tumors between 2 to 3 cm — Moderate prognosis; average survival is about two years.
- Tumors over 3 cm — More serious; average survival drops to about six months.
Early detection is the single most important factor. Cats with small, localized tumors have a far better chance of full recovery than those whose cancer has already spread.
What You Can Do to Prevent Mammary Tumors
The encouraging news is that there’s a lot you can do to protect your cat from mammary cancer. Most prevention steps are simple and highly effective.
- Avoid hormonal medications — Some medications used to control heat cycles or modify behavior contain synthetic hormones that can increase the risk of mammary cancer. Also, exposure to any human hormonal medication — such as topical creams — should be avoided. Always talk to your vet before using these treatments, and explore safer alternatives whenever possible.
- Maintain a healthy weight — Obesity has been linked to several types of cancer, including mammary tumors. Keeping your cat at a healthy weight with a balanced diet and regular activity can help lower overall cancer risk. Cats benefit from a fresh, raw or moist diet. Kibble diets can contribute to weight gain and should be avoided.
- Perform regular home checks — Make a habit of gently feeling along your cat’s underside once a week — especially during grooming. It takes less than a minute and can help you detect small lumps before they grow large or spread.
- Schedule regular vet visits — Your veterinarian can often spot subtle changes long before they become obvious at home. Routine check-ups are especially important for middle-aged and older cats, as well as for breeds with a known higher risk. Your holistic vet can also recommend any supplements or treatments such as acupuncture to help your aging cat’s immune system and keep their body in balance.
What if You Find a Lump?
If you discover a lump on your cat’s belly or near a nipple, don’t panic — but don’t delay. Schedule a veterinary appointment immediately. Your vet can quickly determine whether the lump is minor or a potential tumor. If it’s cancerous, the sooner it’s removed, the better your cat’s chances of recovery.
Remember, you are your cat’s first line of defense. By simply being observant and proactive, you can detect problems early, when they’re most treatable.
The Takeaway — Don’t Forget to Check
Cats are experts at hiding illness. They can have serious health issues brewing beneath the surface while seeming perfectly fine on the outside. But by taking just a few moments to check your cat’s belly every week, you could catch a dangerous disease before it has a chance to take hold.
So the next time you’re giving your cat a cuddle or brushing their coat, take a minute to gently feel along that “overlooked place” — the mammary area. If you ever find anything unusual, don’t wait. Call your veterinarian. It could be the difference between a minor surgery and a life-threatening illness.
By being proactive, informed, and attentive, you can help ensure your cat enjoys many more years of purrs, play, and companionship.
