The most reliable sign that internal stitches have failed after a spay is a soft swelling near the incision that you can push back into the abdomen with gentle pressure. Unlike a normal post-surgical lump, which stays in place when you press on it, a lump that disappears inward suggests a gap has opened in the muscle wall. Other warning signs range from subtle changes in your pet’s energy level to visible bulging along the incision line.
Internal suture failure, called dehiscence, is one of the most serious complications of a spay. Catching it early makes a significant difference in outcome, so knowing what to look for in the days after surgery matters.
What Normal Healing Looks Like
Before you can spot a problem, it helps to know what’s expected. A healthy spay incision has edges that touch neatly together. The skin will be a normal or slightly pinkish-red color, especially in the first few days. You may notice a slightly rippled texture along the incision line. That rippling is normal and comes from the layer of internal stitches sitting just beneath the skin surface.
Some mild swelling directly around the incision is common in the first 48 to 72 hours. A small, firm lump may form under the skin and even grow slightly over the first couple of days. The key test: if you gently press on that lump with your hand, it should stay put. It should not slide or sink deeper into the body. You should check the incision daily for the first 7 to 10 days after surgery to track how healing is progressing.
Signs the Internal Layer Has Opened
A spay involves stitching closed multiple layers: the abdominal wall muscle, the tissue just under the skin, and sometimes the skin itself. When the internal muscle layer tears open, the signs can be different from what you’d see with a simple skin wound opening up.
The most telling sign is a swelling near the incision that can be pushed back into the abdomen. This means tissue or organs are poking through a gap in the muscle wall, forming what’s called an incisional hernia. These hernias can feel soft or firm, and they tend to grow larger over time rather than shrinking. Unlike a seroma (a harmless pocket of fluid that sometimes collects after surgery), a hernia won’t resolve on its own and needs surgical repair.
Other signs to watch for:
- A lump that keeps growing after the first two or three days, rather than stabilizing or shrinking
- A visible bulge along the incision that changes size when your pet shifts position, stands up, or lies down
- Pain or reluctance to move normally, such as difficulty jumping onto furniture, walking stiffly, or flinching when the belly area is touched
- Skin incision edges pulling apart, which can sometimes indicate the deeper layers have also separated
How to Tell a Seroma From a Hernia
Not every lump after a spay means the stitches have failed. Seromas are one of the most common post-surgical findings, and they’re usually harmless. A seroma is a pocket of fluid that collects under the skin near the incision. It feels soft and squishy, fluctuates slightly when you touch it, and typically shows up within the first few days after surgery.
The critical difference is what happens when you press on it. A seroma stays in place under the skin. It doesn’t disappear into the abdomen. A hernia, on the other hand, may partially reduce (push back in) when you apply gentle pressure, then reappear when your pet moves. Hernias also tend to get bigger over time, while seromas usually stay the same size or gradually shrink as the body reabsorbs the fluid. If you’re unsure which you’re dealing with, the safest move is to have your vet feel it. They can often tell the difference with a quick physical exam, and an ultrasound can confirm it if there’s any doubt.
Emergency Warning Signs
Internal suture failure becomes dangerous when it leads to infection inside the abdomen, a condition called septic peritonitis. If bacteria or contents from internal organs leak into the abdominal cavity, your pet can become critically ill quickly. The warning signs are systemic, meaning they affect the whole body rather than just the incision area.
Lethargy is the most consistent early sign. Your pet may seem exhausted beyond normal post-surgery tiredness, refusing to get up or showing no interest in food. Loss of appetite that lasts more than a day after surgery, or appetite that returns briefly then disappears again, is concerning. Vomiting, a swollen or tense abdomen, and increased drinking or urination can also point to an internal problem.
Fever is present in nearly all cases of abdominal infection. You may not be able to measure your pet’s temperature at home, but you can check their gums. Healthy gums are pink and moist. Gums that look pale, white, brick red, or tacky and dry suggest a circulation problem that needs immediate attention. A belly that looks bloated or feels tighter than it did the day before, combined with any of these signs, warrants an emergency vet visit rather than waiting for a scheduled appointment.
What Increases the Risk
Dehiscence after a routine spay is uncommon, but certain factors raise the odds. The biggest risk is too much activity too soon. Running, jumping, roughhousing with other pets, or climbing stairs aggressively can all put strain on internal stitches before the tissue has healed enough to hold on its own. Standard veterinary guidelines call for restricting your pet’s activity for 7 to 10 days after surgery, and in some cases up to two weeks.
Licking or chewing at the incision is another major cause. Saliva introduces bacteria, and persistent licking can weaken both the skin closure and the layers underneath. An e-collar (cone) is annoying for your pet but genuinely protective during this window. Swimming and baths should also be avoided during recovery, since moisture helps bacteria reach the wound.
Overweight pets face higher risk because there’s more tension on the suture line from abdominal fat pressing outward. Pets who are very active by nature, young dogs especially, are also more prone simply because they’re harder to keep calm during recovery.
How Your Vet Confirms the Problem
If you suspect the internal stitches have failed, your vet will start with a physical exam, feeling along the incision for gaps in the muscle wall. In many cases, they can identify a hernia or dehiscence just by palpation. For less obvious cases, abdominal ultrasound is the most commonly used imaging tool in veterinary medicine for this type of problem. It can reveal fluid pockets, tissue pushing through the abdominal wall, or free fluid in the abdomen that shouldn’t be there. X-rays may also be taken to check for signs of organ displacement or fluid accumulation.
If the internal stitches have opened significantly, surgical repair is typically needed. The vet will reopen the incision, assess the internal layers, and re-close the muscle wall. If caught before infection sets in, the repair is usually straightforward. If peritonitis has developed, treatment becomes more intensive and the recovery period longer. This is why acting on early signs, rather than waiting to see if things improve, makes a real difference in how smoothly things go.
The First 10 Days: What to Watch For
Days 1 through 3 are when your pet is most groggy and the incision looks its freshest. Mild redness and slight swelling are expected. By days 3 through 5, the redness should be fading rather than intensifying. Any new swelling appearing after day 3, or existing swelling that suddenly increases, deserves a closer look.
Days 5 through 10 are when healing should be visibly progressing. The incision edges should look like they’re knitting together, and your pet should be returning to a more normal energy level and appetite. Continuous dripping or seeping of blood, fluid with a foul smell, or discharge from the incision at any point during recovery is abnormal. If your pet manages to pull out visible skin sutures, contact your vet even if the incision looks okay on the surface, because the deeper layers may also be compromised.