A little lump, bump or bubble under the skin in your cat's lower abdomen or groin is cause for concern, but as long as your cat isn't in pain there's no reason to panic. If it's soft and you can push it in and out, it's probably an inguinal hernia.
What Is It
To put it simply, a hernia is internal tissue pushing through the outer muscle wall. For example, a portion of the large intestine may slip through a tear in the muscle, creating a bubble that's palpable through the skin. "Inguinal" describes the location of the hernia. An inguinal hernia occurs in the lower abdomen, near the groin. This type of hernia is not common in cats, but when it does occur it is more often seen in females, particularly pregnant females, than in males.
A weak muscle wall is to blame for an inguinal hernia. The muscle wall should be strong enough to hold inner tissue in place, but some cats are born with thin muscle walls and others are injured or succumb to constant pressure on the muscles. Straining from constipation, constant bloating or pregnancy can cause an inguinal hernia. If the muscle wall is genetically thin, it doesn't take much pressure at all to create a hernia.
An inguinal hernia will usually look like a bubble or lump under the skin near the groin. Most of the time it is soft and can be pushed back in only to pop back out again. If the lump is hard, it may be something other than a hernia or it may be a strangulated inguinal hernia, which is a serious medical emergency. The size of a hernia can vary from a very small lump to a large balloonlike formation.
Most of the time, an inguinal hernia presents only a small health risk and your veterinarian can schedule surgery whenever it is convenient. Sometimes, though, an inguinal hernia can turn into a serious life-threatening emergency. If the muscle clamps off the blood supply to the tissue, or if a portion of intestine trapped in the muscle twists, the hernia must be treated right away. This is a strangulated hernia -- the part of the tissue caught in the muscle is literally being strangled. If not treated, the tissue caught in the muscle will die, releasing toxins into your cat's body. Your cat could die within 24 to 48 hours if the hernia is not treated right away. A strangulated hernia will be extremely tender, swollen and hard. Your cat will also be in pain, hunched up and protecting his abdomen.
Surgery is the only way to treat an inguinal hernia. The procedure involves pushing the tissue back through the muscle wall and stitching the muscles together to prevent the breach from happening again. A surgeon might also attach a piece of medical mesh to the muscle to help strengthen it. There is a risk that the protruding tissue will be damaged during surgery or a blood vessel cut or pinched, but the risk of the hernia eventually strangulating is much higher.