Anatomy of the Male Cat
There are several anatomical differences between male and female cats related to their reproductive systems.
Male cats have external genitalia including the penis and scrotum (sac containing the testicles). The main reproductive organs of male cats include:
- Testicles – Located inside the scrotum, the testicles produce sperm and testosterone. The scrotum helps regulate the temperature needed for sperm production.
- Penis – Located near the anus, the penis transports sperm and urine outside the body during mating and urination.
- Prostate gland – Located near the neck of the bladder, this gland produces fluid that nourishes and protects sperm.
- Bulbourethral glands – Pea-sized glands that secrete fluid during mating to lubricate the urethra for sperm passage.
Female cats lack external genitalia. Their main reproductive organs are internal and include the ovaries, uterus, cervix, and vagina.
Unlike female cats, the external location of the testicles and scrotum makes them vulnerable to injury in male cats. The scrotum protects the testes and provides temperature regulation critical for normal sperm development (cite: https://www.merckvetmanual.com/cat-owners/reproductive-disorders-of-cats/the-gonads-and-genital-tract-of-cats).
Testosterone Effects
Testosterone is the primary male sex hormone and it plays a major role in the anatomy and behavior of male cats. Testosterone levels are highest in intact (unneutered) male cats and act on many parts of the body.
Studies have found that intact male cats generally have higher testosterone levels than neutered males. One study measured testosterone levels ranging from 0-23.5 ng/ml in intact male cats, with seasonal variations [1]. After neutering, testosterone levels decrease significantly.
Higher testosterone levels lead to increased muscle mass and bone density in male cats [2]. Testosterone also influences male cat behavior. Intact males tend to be more territorial, roam farther from home, fight more with other males, and urine mark more frequently.
So in summary, testosterone is responsible for many of the anatomical and behavioral differences between male and female cats. Neutering reduces testosterone levels and thus impacts muscle mass, territoriality, and other traits influenced by this hormone.
Neutering Effects
Neutering or castration involves surgically removing a male cat’s testicles to eliminate testosterone production. This reduction in testosterone often leads to noticeable changes in a male cat’s behavior and metabolism.
According to the VCA Animal Hospital, neutered male cats tend to be less aggressive, roam less, spray urine less often, and show less sexual behavior compared to intact tomcats. These behavioral changes are attributed to the drastic decrease in testosterone levels after neutering [1].
The lack of testosterone also slows down a neutered cat’s metabolism and activity levels. With less testosterone, neutered males often gain weight more easily and struggle to burn fat and calories as before. This can lead to weight gain around the belly. According to Quora, the slower metabolism of neutered male cats is the primary reason for their “hanging belly” appearance post-neutering [2].
So in summary, neutering reduces testosterone levels which commonly leads to less aggression and roaming but also slower metabolism and potential weight gain in male cats. The weight gain tends to accumulate around the belly, causing a saggy or “hanging belly” look.
Diet and Exercise
Obesity is one of the most common health issues affecting house cats today. Studies show that over 50% of domestic cats are considered overweight or obese. This epidemic is largely attributed to indoor cats leading sedentary lifestyles and overeating. To maintain a healthy weight, male cats require scheduled feedings of a nutritionally balanced cat food and daily exercise through play and activity.
When it comes to diet, it’s important to feed an age-appropriate cat food in the proper portions. Male cats that have been neutered require 25% fewer calories than intact males. Consult with your veterinarian to determine the ideal daily caloric intake and feeding schedule. Portion control is key – don’t free-feed. To encourage activity, engage your cat in at least two 15-20 minute play sessions per day with interactive toys like feather wands and laser pointers. Provide puzzle feeders and food dispensing toys to make them “work” for their food. Place cat trees, perches, and scratching posts around your home to promote movement and exercise. With the right diet and exercise routine, male cats can maintain a healthy weight and live full, active lives.
Medical Conditions
There are several diseases and medical issues that can cause an enlarged or swollen belly in male cats:[1] Some of the more common ones include:
- Heart Failure – Fluid can build up in the abdomen due to heart disease or heart failure. This is called ascites. Symptoms include fatigue, coughing, and trouble breathing.[2]
- Liver Disease – The liver helps regulate fluid levels in the body. Liver damage or disease can cause fluid buildup and swelling in the abdomen. Symptoms include vomiting, diarrhea, loss of appetite.[1]
- Kidney Disease – Kidney disease leads to an accumulation of toxins in the blood which in turn leads to fluid retention and swelling. Symptoms include increased thirst and urination, weight loss.[2]
- Cancer – Lymphoma, leukemia and other cancers can cause swollen lymph nodes or tumors in the abdomen. Symptoms depend on the type and severity of cancer.[1]
- FIP – Feline infectious peritonitis (FIP) is caused by a mutation of the feline coronavirus. It leads to fluid accumulation in the abdomen. Symptoms include fever, weight loss, lethargy.[2]
Treatment depends on the underlying cause but may include diuretics, chemotherapy, antiviral drugs, or immunosuppressants. In many cases, treatment aims to manage symptoms and make the cat comfortable.[1] Working closely with your veterinarian is important for accurately diagnosing and developing a treatment plan for your cat.
[1] https://vcahospitals.com/know-your-pet/testing-for-abdominal-enlargement-in-cats
[2] https://www.hillspet.com/cat-care/healthcare/cat-and-kitten-swollen-belly
Parasites
Internal parasites like roundworms, hookworms, and tapeworms are common causes of a bloated or enlarged belly in male cats. These intestinal worms live inside a cat’s digestive tract and can cause a distended or pot-bellied appearance when present in large numbers (1).
Kittens are especially prone to getting worms, usually by ingesting parasite eggs or larvae from contaminated soil, feces, or rodents. Adult cats can also pick up worms through exposure to feces or by eating infected rodents or birds. Some worms like tapeworms are transmitted by fleas (2).
Preventing worms involves keeping your cat indoors, promptly removing feces from the litter box, controlling fleas, and not feeding raw meat or prey animals. Deworming medication clears out intestinal worms and helps reduce belly size. Kittens should be dewormed regularly starting at 2 weeks old. Adult cats should be dewormed 1-4 times per year based on risk factors (2).
If your male cat has a persistently enlarged belly despite deworming, additional testing and treatment may be needed. Contact your veterinarian, as certain worms can cause serious health problems if left untreated.
Normal Variation
It is actually quite normal for male cats to have larger bellies than female cats. This is due to natural variations in body shape between the sexes. Male cats tend to have broader chests and more barrel-shaped bodies, while females are usually more petite and slender in build.
According to the Cat Size-O-Meter from UK Pet Foods, the average weight for a neutered male cat ranges from 9-11 lbs, while for a spayed female it is typically 6.5-9 lbs. So on average, male cats do tend to weigh more and have larger frames than females (https://www.ukpetfood.org/resource/cat-size-o-meter.html).
The size and shape of a cat’s belly can vary quite a bit within the normal weight range, regardless of sex. For instance, some male cats may naturally have a very rounded belly even at an optimal weight, while others remain more lean. There is no single “normal” belly size for all male cats.
So some fullness in a male cat’s belly region is to be expected. As long as your cat is active, eating well, and within a healthy weight range, a somewhat prominent belly is likely just his normal body type.
Breed Differences
There is significant variation in belly size between cat breeds. Some breeds are known for having very large, saggy bellies compared to other breeds.
For example, the primordial pouch – the saggy abdominal skin and fat between the hind legs – is especially prominent in breeds like the Egyptian Mau, Japanese Bobtail, and Bengal. The loose skin helps these active, athletic breeds move freely. In contrast, breeds like the Siamese and Russian Blue tend to have much tighter, firmer bellies.
Some male cat breeds are also prone to developing larger stomachs due to genetics and body type. For instance, Maine Coon cats are a larger breed overall with broad chests and sizable bellies. Ragdoll cats often become broad-chested as adults. Neutered Persians and Himalayans are also known for weight gain and protruding bellies.
When to See a Vet
An enlarged or bloated belly in cats can sometimes indicate a medical issue that requires veterinary attention. Here are some warning signs that warrant a trip to the vet:
- Rapid abdominal swelling over a few days
- Loss of appetite or vomiting
- Difficulty breathing or open-mouth breathing
- Abdominal pain or sensitivity
- Lethargy or reduced activity
- Straining to urinate or defecate
- Weight loss
- Fever
According to veterinarians, any sudden or abnormal swelling of the abdomen should be evaluated promptly by a vet to determine the underlying cause (1). An examination and diagnostic tests like blood work, imaging, or ultrasound can help identify conditions like infections, organ disease, cancer, fluid buildup, or intestinal obstructions.
It’s also recommended to have senior cats evaluated annually for diseases that can cause abdominal enlargement as part of their wellness checkup (2). Contact your vet whenever you notice any unusual changes in your cat’s belly, as early treatment can help manage many conditions effectively.
(1) https://vcahospitals.com/know-your-pet/testing-for-abdominal-enlargement-in-cats
(2) https://www.hillspet.com/cat-care/healthcare/cat-and-kitten-swollen-belly
Caring for Your Male Cat
To keep your male cat healthy and happy, there are some tips you can follow for enrichment, exercise, and preventative care.
Be sure to get your cat neutered, as this can help prevent diseases later in life like prostate cancer according to the ASPCA. Neutering also reduces roaming, fighting, and spraying behaviors.
Providing enrichment is important to keep your cat mentally and physically stimulated. Rotate different types of toys to prevent boredom and consider puzzles like food-dispensing balls. Allowing access to areas with a view outdoors can provide entertainment. Set up climbing areas, scratching posts, and “kitty jungle gyms” to encourage activity.
Play interactive games like chasing toys or lasers daily. Consider adopting a companion cat as cats can enjoy social enrichment with other cats. Try food enrichment techniques like hiding kibble around the home for them to hunt and forage.
Maintain a consistent routine and set up litter boxes on each level of the home. Keep the litter box clean and scoop daily. Brush your cat weekly and trim nails as needed. Feed a balanced diet and monitor weight, adjusting food if needed. Take your cat to regular vet checkups.