What is Dr. Zubair Khalid's research focus?

Dr. Zubair Khalid specializes in molecular virology, mRNA vaccine development, and computational biology, with a focus on avian pathogens like IBDV and Avian Reovirus.

Where is Dr. Zubair Khalid currently working?

Dr. Zubair Khalid is a Postdoctoral Research Associate at the University of Maryland (UMD), specifically within the Department of Animal and Avian Sciences.

Bubbling Gut: Why Stomachs Growl and Rumble

Name: Bubbling Gut: Why Stomachs Growl and Rumble
Creator: Dr. Zubair Khalid

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-09-20

A stomach growl is the sound of gas and fluid being pushed through the intestines by muscular waves called peristalsis. The medical term is borborygmi, and in dogs and cats these noises are usually normal, especially when the gut is empty.

That explanation covers most of what owners hear. A bubbling gut after a meal, a rumbly tummy at 3 a.m., a growling belly during a car ride: these are mechanical events, not messages from the body about hunger or illness. The tricky part is telling a noisy but healthy gut apart from a noisy gut that is trying to move past a blockage. This guide explains the physiology behind borborygmi, describes what veterinarians listen for during abdominal auscultation, and gives a practical decision table for when a grumble stomach is worth a phone call and when it is worth a trip to the emergency clinic.

What Borborygmi Actually Are

Borborygmi are audible bowel sounds. They are not produced by the stomach alone. The stomach, small intestine, and large intestine all generate them, and the loudest ones often come from the small intestine, where a narrow tube, a mix of liquid and gas, and rhythmic muscular squeezing combine to make noise.

The gut is never truly still in a healthy animal. Even between meals, the digestive tract runs a housekeeping program. Smooth muscle in the intestinal wall contracts in coordinated waves, and those waves move contents forward. When the moving contents are mostly gas and thin fluid, the result is a gurgle, a rumble, or a series of clicks. When the contents are thicker, the sound is duller and harder to hear.

Two patterns of motility matter most for understanding gut sounds.

Peristalsis and Segmentation

Peristalsis is the propulsive wave. A ring of muscle contracts behind a bolus of content while the muscle ahead relaxes, and the bolus moves forward. Segmentation is different. It is a mixing pattern in which short segments of intestine contract and relax in alternating fashion, chopping and churning chyme rather than pushing it steadily down the tract.

Both patterns move fluid, and both create sound. Computational modeling of intestinal motility shows that segmentation and peristalsis produce very different patterns of fluid movement inside the lumen, with segmentation generating more local mixing and peristalsis generating more forward transport [1]. For an owner listening with a stethoscope or an ear pressed to the flank, these differences show up as changes in the character and rhythm of the sounds rather than as distinct noises.

The Migrating Motor Complex

The migrating motor complex, or MMC, is the gut's fasting housekeeping rhythm. It is a cyclical pattern of electrical and mechanical activity that sweeps from the stomach down the small intestine during periods without food [2]. The MMC has three classic phases. Phase I is quiet. Phase II has irregular contractions. Phase III is a burst of strong, rhythmic contractions that propagate down the tract and clear residual debris, bacteria, and secretions.

Phase III is the loudest phase for most animals. Plasma motilin concentrations rise during spontaneous phase III contractions of the MMC, and motilin is the hormone that drives this fasting pattern in species that produce it, including dogs and humans [3]. The MMC is present across many species and is a standard target of gastrointestinal motility testing in both human and veterinary medicine [4]. When a dog's stomach growls loudly at night, the most likely explanation is a phase III burst moving through an empty stomach and small intestine.

Why an Empty Gut Is Louder

A full gut absorbs sound. Food, liquid, and thick chyme dampen vibrations and reduce the resonance of the intestinal wall. An empty gut has less material to muffle the noise, and the gas and fluid that remain are free to slosh against the walls. That is why borborygmi are loudest when the stomach is empty, and why owners often describe a growling belly first thing in the morning or late at night. The old idea that a growling stomach means hunger is partly right, but the mechanism is motility, not a hunger signal from the stomach itself.

What Normal Gut Sounds Sound Like in Dogs and Cats

Normal borborygmi are intermittent. They come in short bursts, then fade. They vary in pitch and intensity from one minute to the next. They are usually louder after a meal, quieter during deep sleep, and more noticeable when the animal is excited, stressed, or hungry.

In dogs, normal gut sounds are common and are not diagnostic of anything on their own. The same is true in cats. A veterinarian who hears active borborygmi in an otherwise bright, eating, drinking, and defecating pet usually treats that finding as normal.

Auscultation technique matters. Listening for a few seconds over one spot is not enough. A proper abdominal auscultation covers all four quadrants and lasts at least one to two minutes per quadrant, because motility is cyclical and a quiet moment can be followed by a burst of activity. A veterinarian who hears nothing in one quadrant may simply have listened during a quiet phase. Listening longer and moving the stethoscope across the abdomen gives a much more reliable picture.

General anesthesia affects gut sounds. In horses undergoing non-abdominal surgery, gut sounds were significantly decreased during the first two post-anesthetic evaluations, and jejunal diameter and visualization frequency increased on ultrasound [5]. Those changes were mild and short-lived, and none of the horses developed colic or reduced fecal output. The lesson for small animal owners is that a quiet gut after anesthesia or sedation is expected and does not by itself indicate a problem.

Why the Gut Makes Noise: A Step-by-Step View

The pathway from a quiet gut to an audible rumble follows a predictable sequence.

The enteric nervous system and interstitial cells of Cajal generate rhythmic electrical activity in the gut wall.
Smooth muscle contracts in coordinated waves, either as peristalsis or as segmentation.
The contractions push gas and fluid against the intestinal wall.
The wall vibrates, and the vibration travels through the abdominal cavity.
The vibration reaches the body surface, where it is heard as a gurgle, rumble, or click.

The enteric nervous system is the gut's own brain. It develops early in life and takes over motility control as the animal matures. In the chicken embryo, the first contractile events are circular smooth muscle calcium waves, and the enteric nervous system begins controlling motility later, coupling longitudinal and circular contractions through inhibitory neurotransmission [6]. That sequence gives rise to the migrating motor complex and to the polarized pressure response known as the law of the intestine. The same general developmental logic applies to mammals.

Hormones modulate the pattern. Motilin drives phase III of the MMC and stimulates food intake in species that produce it [3]. Cholecystokinin can induce phase II-like contractions in the small intestine, and those contractions are blocked by a CCK1 receptor antagonist [2]. Spexin, another gut peptide, can disrupt the MMC pattern in the rat small intestine through galanin-2 receptors [7]. These findings come from laboratory species, but they illustrate a general principle: gut motility is a tightly regulated rhythm, and many signals can speed it up, slow it down, or break its normal pattern.

The brain also influences the gut. The locus coeruleus, a brainstem nucleus, is involved in regulating colonic motility, and noradrenergic signaling from this region affects the frequency of giant migrating contractions in the colon [8]. Stress, pain, and excitement can all change gut sounds through pathways like this. That is why a nervous dog may have a loud, active gut during a vet visit and a quiet one at home.

The Decision Table: When Noisy Gut Sounds Need a Vet

The character of the sound matters less than what comes with it. A loud gut in a happy, eating pet is usually normal. A quiet gut in a vomiting, painful pet is a red flag. The table below summarizes the main combinations.

Sound character	Accompanying signs	Likely interpretation	Urgency
Normal intermittent gurgles	None, pet is bright and eating	Normal borborygmi	No visit needed
Loud, frequent rumbles	Hunger, recent meal, excitement	Normal fasting or postprandial motility	No visit needed
Quiet or absent sounds	Vomiting, bloating, no feces, lethargy	Possible ileus or obstruction	Same-day veterinary visit
High-pitched, tinkling sounds	Pain, vomiting, bloating, no feces	Possible mechanical obstruction	Emergency visit
Loud sounds with diarrhea	Soft stool, normal appetite	Increased motility, often dietary or stress-related	Monitor, call if it persists
Loud sounds with vomiting	Repeated vomiting, not eating	Possible gastroenteritis or obstruction	Same-day veterinary visit
Any sound with a distended, painful abdomen	Bloating, restlessness, unproductive retching	Possible bloat or torsion	Emergency visit
Any sound with blood in stool or vomit	Weakness, pale gums	Possible bleeding or severe inflammation	Emergency visit

The table is a guide, not a diagnosis. A veterinarian needs to examine the pet, palpate the abdomen, and listen to all four quadrants before deciding what the sounds mean.

When Gut Sounds Become a Warning Sign

The absence of gut sounds is often more concerning than their presence. A quiet abdomen in a vomiting, painful, or bloated pet raises concern for ileus, which is a functional shutdown of motility, or for mechanical obstruction, in which a physical blockage prevents contents from moving forward. In both cases, the gut may be contracting against a closed segment, or it may have stopped contracting altogether.

High-pitched, tinkling sounds are a classic description of mechanical obstruction. They occur when gas and fluid are trapped in a dilated segment of bowel and are pushed against a tight narrowing. The sound is sharper and more musical than a normal rumble. When those sounds are paired with vomiting, abdominal pain, and the absence of feces, the situation is urgent.

Chronic intestinal pseudo-obstruction, or CIPO, is a related but different problem. It is a severe motility disorder in which the gut behaves as if it is obstructed even when no physical blockage is present. In children with CIPO, ileal manometry shows abnormal motility patterns, including absent or abnormal phase III of the MMC, while children with defecation disorders tend to have normal ileal motility [9]. Antroduodenal manometry in children with upper gastrointestinal symptoms shows that a normal phase III of the MMC is associated with idiopathic etiology and with overall successful response to treatment [10]. These findings come from pediatric human medicine, but they illustrate why veterinarians take absent or abnormal MMC activity seriously.

Gastroparesis is another motility disorder that can change gut sounds. In adults with gastroparesis, the number and duration of phase III contractions and the number of MMCs are lower in idiopathic and diabetic patients than in post-surgical patients [11]. In children with delayed gastric emptying, postprandial antral motility is reduced compared with children with normal gastric emptying [12]. A pet with gastroparesis may have a quiet or abnormally patterned gut rather than a loud one.

Disorders of gut-brain interaction, which include irritable bowel syndrome and functional dyspepsia in humans, are associated with measurable changes in antroduodenal motility. Patients with severe disorders of gut-brain interaction have a lower frequency and amplitude of phase II duodenal contractions and fewer propagated antroduodenal contractions than healthy volunteers [13]. The clinical relevance for veterinary patients is that chronic gut symptoms can reflect real motility changes even when standard tests look normal.

What Owners Can Do at Home

Most episodes of a bubbling gut do not need treatment. If the pet is eating, drinking, urinating, defecating, and behaving normally, the sounds are almost certainly normal borborygmi.

A few practical steps help owners decide what to do next.

Note the timing. Sounds that occur before meals or late at night are usually fasting MMC activity.
Check the stool. Normal stool and normal appetite are reassuring.
Watch for vomiting. One episode after dietary indiscretion is common. Repeated vomiting is not.
Feel the abdomen gently. A soft, non-painful abdomen is reassuring. A tense, distended, or painful abdomen needs a vet.
Record a video. A short phone video of the abdomen and the pet's behavior gives the veterinarian useful information.
Do not withhold food or water unless a veterinarian tells you to. Fasting changes motility and can make assessment harder.

Owners should not give human medications for gas, bloating, or diarrhea without veterinary guidance. Many human products are unsafe for pets, and some can worsen the underlying problem.

How Veterinarians Evaluate a Noisy Gut

The physical examination starts with history: appetite, water intake, stool quality, vomiting, weight change, and any recent dietary or medication changes. The veterinarian then palpates the abdomen and auscultates all four quadrants for at least one to two minutes each.

If the history and examination suggest a motility problem, further testing may include blood work, abdominal imaging, and in some cases motility studies. Antroduodenal manometry measures antral and small bowel motility and is used in human and veterinary medicine to evaluate upper gastrointestinal symptoms [10]. High-resolution antroduodenal manometry can characterize motor alterations in patients with severe disorders of gut-brain interaction [13]. Wireless motility capsules offer a noninvasive way to collect motility data and have been used to study fasting gastrointestinal motility in larger cohorts [14]. Balloon-based recording systems have been developed for in vivo measurement of gastrointestinal motor function in mice [4].

These tests are not routine for a pet with a noisy but otherwise normal gut. They are reserved for animals with persistent vomiting, chronic weight loss, suspected CIPO, or other signs that point to a serious motility disorder.

The Role of Diet and Stress

Diet changes motility. A large meal slows gastric emptying and increases postprandial contractions. A fatty meal triggers cholecystokinin release, which affects small intestinal contractions [2]. A sudden diet change can alter the gut microbiome and the motility pattern, which is one reason bland diets are often recommended during episodes of gastroenteritis.

Stress changes motility too. The locus coeruleus and noradrenergic signaling influence colonic motility, and stress can shift the pattern of giant migrating contractions [8]. A dog with separation anxiety may have a loud, active gut during stressful periods. A cat with a recent household change may develop diarrhea or constipation along with changes in gut sounds.

Aging affects motility. In mice, aging reduces the force of contraction of the distal colon mucosal reflex and the frequency and force of colonic migrating motor complexes, and these changes are linked to reduced NK2-mediated signaling [15]. Older pets may have quieter or less organized gut sounds for reasons related to normal aging rather than disease.

What Is Still Uncertain

The physiological role of the MMC is not completely understood [4]. Researchers know it clears the gut between meals, but the full set of functions and the reasons for individual variation remain active areas of study. The relationship between specific gut sounds and specific motility patterns is also not fully mapped. A veterinarian can hear that the gut is active or quiet, but cannot reliably tell from sound alone whether the activity is normal peristalsis, segmentation, or an abnormal pattern.

Species differences add another layer of uncertainty. Motilin regulates gastric motility in humans, dogs, monkeys, and house musk shrews, but it does not regulate gastrointestinal motility in fish, where motilin receptors are limited to the intestinal mucosa [16]. Findings from one species do not always translate to another, which is why veterinary motility research continues.

Limitations and When to Contact a Veterinarian

This article is educational and is not a substitute for veterinary diagnosis or treatment. Individual pets need individual assessment, and a veterinarian who examines your pet can weigh the history, physical findings, and diagnostic results together.

Contact a veterinarian the same day if your pet has repeated vomiting, a distended or painful abdomen, no stool for more than 24 hours, lethargy, or a sudden change in appetite. Go to an emergency clinic immediately if your pet has unproductive retching, a hard or swollen abdomen, pale gums, collapse, or severe pain. A quiet abdomen in a sick pet is an emergency until proven otherwise. A loud abdomen in a bright, eating pet is usually normal, but if you are unsure, a phone call costs nothing and can prevent a delay in care.

Frequently Asked Questions

Why does my dog's stomach growl so loudly?

A dog's stomach growls when gas and fluid move through the gut during peristalsis or the migrating motor complex. The sound is loudest when the stomach is empty because there is less material to muffle the vibrations.

Is a growling belly always a sign of hunger?

No. A growling belly usually reflects fasting motility, which is why it happens between meals, but it can also occur after eating, during stress, or with gastrointestinal illness. Hunger is one trigger among several.

When should I worry about my cat's rumbly tummy?

Worry if the rumbly tummy comes with vomiting, diarrhea, not eating, weight loss, or a painful abdomen. A rumbly tummy in a cat that is eating and behaving normally is usually not a concern.

Can a bubbling gut mean a blockage?

A bubbling gut can occur with a blockage, especially if the sounds are high-pitched and tinkling and come with vomiting, pain, and no stool. A blockage can also cause a quiet abdomen. Imaging is needed to tell the difference.

Why does my pet's stomach make noise at night?

Fasting motility is active overnight, and the migrating motor complex produces strong phase III contractions that move gas and fluid through an empty gut. That is why nighttime stomach grumbles are common.

Do gut sounds change after anesthesia?

Yes. Gut sounds can decrease after general anesthesia and return to normal within a day. A quiet gut right after surgery is expected and does not by itself indicate a problem.

Are loud gut sounds a sign of diarrhea?

Loud gut sounds can accompany diarrhea because increased motility moves fluid and gas faster than usual. Diarrhea has many causes, and a veterinarian can help identify the specific one.

Should I fast my pet to stop the growling?

No. Fasting changes motility and can make assessment harder. Unless a veterinarian tells you to withhold food, keep feeding your pet normally and monitor for other signs.