Reptile coelomic swelling: what bloat actually means

Quick answer

Reptiles do not get bloat in the way the word is normally used. There is no canine-style stomach torsion in a lizard or a snake. What owners see and call bloat is coelomic distension, meaning the single body cavity has become fuller than it should be, and the list of things that fill it is long and mostly serious.

The reason it matters more in a reptile than in a mammal is anatomical. Reptiles have no diaphragm, so there is no partition between the gut and the lungs. Anything that takes up space in the body cavity presses directly on the lungs, and a swollen reptile is a reptile that is also struggling to breathe.

A quiet, unhurried look at body shape in good light, from above and from the side, is how this is caught early.

• Never press hard on a swollen reptile. Eggs, follicles and a distended bladder all rupture under pressure.
• A rounded, symmetrical, gradual swelling in a female of breeding age is eggs or follicles until proven otherwise.
• A shell hides everything, so in tortoises and turtles the signs are indirect rather than visible.
• Weight and a photograph from directly above, taken weekly, catch this weeks before the shape becomes obvious.
• Swelling plus laboured breathing is an emergency, not a wait-and-see.

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Do not squeeze, massage, palpate firmly, or attempt to express anything from a swollen reptile.

Female lizards commonly develop enlarged ovarian follicles, and those follicles are thin-walled sacs of yolk. Pressure ruptures them, yolk spills into the body cavity, and the result is yolk coelomitis, a severe inflammatory condition that is frequently fatal. The same applies to eggs, to a distended bladder in species that have one, and to a fluid-filled organ. Look, photograph and describe. Let a vet do the palpating.
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Decide in 60 seconds

Why the anatomy makes this urgent

A mammal has a diaphragm. A dog with a hugely distended stomach is uncomfortable and eventually compromised, but there is a muscular sheet doing the work of breathing and a physical partition between the two compartments.

Reptiles have neither. The lungs, heart, liver, gut, kidneys and reproductive organs share one cavity. Breathing is done by moving the ribs and body wall, and in chelonians by a set of muscles that pull the limb pockets in and out because the shell cannot expand at all.

That means anything occupying space in the coelom does three things at once. It reduces the volume available for the lungs to inflate into, it increases the effort required to move the body wall, and it presses on the large blood vessels returning blood to the heart.

This is why a reptile that has been quietly swelling for weeks can decompensate suddenly. The system tolerates the encroachment until it cannot, and then the animal is in respiratory trouble.

For chelonians it is starker still. There is no give at all. A tortoise with a bladder full of stones or a coelom full of eggs has nowhere for that volume to go except into the space its lungs need.

What is actually filling the cavity

Eggs and follicles.

The most common cause in female lizards, and it happens without a male present. Ovarian follicles enlarge on a seasonal cycle. Normally they are either reabsorbed or ovulated and laid. When they enlarge and then stall, the condition is called pre-ovulatory follicular stasis, and it is common in bearded dragons, leopard geckos and veiled chameleons.

The picture is a female of breeding age with a rounded, often visibly lumpy body, who goes off food, becomes restless, digs, and loses condition in the limbs and tail base while the middle gets bigger. Post-ovulatory egg stasis, where formed eggs cannot be laid, looks similar and is equally serious.

Yolk coelomitis.

The complication of the above. A follicle ruptures, either on its own or because someone squeezed the animal, and yolk enters the body cavity. Yolk is intensely inflammatory. The animal becomes rapidly unwell, the swelling worsens, and this is a surgical emergency.

Coelomic effusion.

Free fluid in the cavity. It follows liver disease, kidney disease, heart failure, sepsis, tumours and coelomitis. The swelling is usually soft, symmetrical, and moves as the animal moves. The underlying disease has usually been progressing for some time.

Organ enlargement.

An enlarged liver, most often from hepatic lipidosis in an obese or previously anorexic animal, or enlarged kidneys, which are common in older lizards and in dehydrated animals with gout. In many lizards the kidneys sit within the pelvis, and enlarged kidneys can obstruct the passage of faeces, which produces constipation on top of the swelling.

Impaction and constipation.

Firm, sometimes lumpy, with reduced or absent droppings. Causes include ingested substrate, dehydration, low enclosure temperature slowing transit, oversized prey, and a diet with the wrong fibre balance for the species.

Bladder distension and cystic calculi.

Chelonians and most lizards have a urinary bladder. Urate sludge and bladder stones can build up until the bladder occupies a large part of the coelom, and in tortoises this is a common and easily missed cause of a big, quiet, poorly animal.

Obesity.

Fat bodies within the coelom and fat stored at the tail base and in the jowls. The animal is smoothly and symmetrically rounded, is eating well, and is otherwise behaving normally. Obesity matters because it predisposes to hepatic lipidosis and to follicular problems, so it is a real finding rather than a reassuring one.

Gas.

Genuine gas accumulation happens with gastrointestinal infection, with obstruction, with gut stasis in a cold animal, and after force-feeding or syringe feeding that introduces air. In aquatic turtles, gas in the gut or asymmetric lung disease shows up as a tilted float.

A meal, in snakes.

A prey bulge is normal, sits where the meal has reached, moves caudally over the following days, and shrinks. A lump that does not move, does not shrink, or appears without a meal is not food.

Free air under the skin.

After trauma, particularly in chelonians hit by a vehicle or dropped, air can escape a torn lung into the tissues. The animal looks inflated and crackles under gentle touch. This is an emergency.

How it looks in each group

Lizards.

Look from directly above. A healthy lizard has a visible narrowing behind the ribcage and in front of the hips. Loss of that waist, or fullness that bulges out beyond the line of the ribs, is the first change. Compare the two flanks: asymmetry points towards a mass or a single enlarged organ, while symmetry points towards fluid, fat or bilateral follicles.

Watch the limbs and tail base. Follicular stasis produces a fat middle on a thin animal, which is a very different picture from obesity, where the tail base and limbs are also fat.

Snakes.

Look at the cross-sectional shape along the body. A healthy snake in good condition is rounded to slightly triangular in cross-section depending on species. A swelling that raises the body wall on one side, or a segment that has become noticeably wider than the rest, needs explaining. Track it: photograph against a fixed reference such as a ruler or a tile line so you can tell whether it has moved between days.

Chelonians.

The shell hides the swelling completely, so the signs are all indirect. Limbs that no longer retract fully into the shell, a head that stays extended, a change in how the animal breathes with more visible movement at the limb pockets, a heavier feel when lifted, and in aquatic species a change in how the animal floats.

Weight is disproportionately useful in this group precisely because you cannot see anything. A tortoise gaining weight without eating more is retaining fluid, urates or eggs.

Feeding from tongs or a dish keeps substrate out of the gut. Ingested substrate is one of the commonest causes of a firm, impacted coelom.

Catching it early

Weigh weekly and write it down.

A trend is far more informative than a single number, and it is the only way to detect fluid or eggs in a shelled species.

Photograph from directly above and from the side, monthly.

Same distance, same light, same surface. Reptiles change shape slowly and the human eye adapts to gradual change. A photograph from three months ago does not.

Learn the waist.

For lizards, the narrowing behind the ribs. For snakes, the cross-sectional shape. Check it every time you handle the animal.

Track droppings.

Note when droppings and urates are passed. A reptile that is passing less, or nothing, while getting bigger is the clearest early warning there is.

Know your females.

Record the age, the season, and the dates of any previous laying or digging behaviour. A female of breeding age is in a different risk category, and vets will ask.

While you arrange the appointment

Check and correct the temperature gradient first. Digestion, gut motility and drug metabolism are all temperature dependent, and a reptile kept below its preferred range cannot move anything through. Measure with a probe or infrared thermometer rather than trusting a dial.

Offer water in the form the species uses, and ask the vet whether a shallow warm soak is appropriate for your animal. Soaking helps some cases of constipation and is unhelpful or risky in others, particularly if there is respiratory compromise.

Remove particulate substrate and house on paper towel for now.

Do not feed. Adding bulk to a cavity that is already full is not helpful, and a reptile that may need anaesthesia should not have a full stomach.

Move the animal into a container that limits climbing and falling, especially if it is unsteady.

Take photographs from above and from the side with something for scale, and take a short video of the breathing at rest.

What never to do

Do not press, squeeze or attempt to feel what is inside.

Do not attempt to make the animal pass anything with mineral oil, an enema, a laxative, or a human antacid or anti-gas product.

Do not force-feed or syringe feed on your own initiative. It introduces air and it can cause aspiration in an animal whose lungs are already compressed.

Do not soak an animal that is breathing with effort. Water pressure on the body wall makes breathing harder.

Do not assume obesity because the animal is eating. Females with follicular stasis often eat well for a while.

Do not wait for a female to lay. Once a female is off food and losing condition, the window in which medical management works is closing.

Do not treat a snake lump as a meal that will pass if the snake did not eat, or if the lump has not moved over several days.

When to get help

Go immediately for swelling with laboured breathing, open-mouth breathing at rest, a raised or stretched neck used to breathe, sudden swelling over hours, collapse, or a female that was gravid and is now dull and deteriorating.

Go within a day or two for a female of breeding age who is rounded, off food and digging, for any firm swelling with reduced or absent droppings, for a tortoise whose limbs no longer retract, and for an aquatic turtle floating at an angle.

Book an appointment for any gradual change in body shape, any unexplained weight gain, and any snake lump that has not moved or reduced.

Bring photographs from above and from the side with something for scale, a weight history, measured temperatures, the substrate type, the diet, the date of the last droppings and last meal, and for females the breeding history. Expect radiographs and possibly ultrasound, because most of this list cannot be separated from the outside.

A settled animal with an even body outline, a visible waist, quiet breathing and regular droppings is the baseline to compare against.

A smooth-sided transport container lined with paper towel, prepared before you need it, avoids a scramble on the day.