Lumps and swellings on a lizard: abscess, tumour, fat pad or gout

Quick answer

Compare left with right. Most lumps on a lizard are diagnosed first by whether the same structure exists on the other side.

A lump on a lizard does not behave like a lump on a mammal. Reptile pus sets solid rather than staying liquid, so an abscess becomes a firm capsule that antibiotics cannot penetrate and that will never burst and drain on its own.

That single fact decides most of what follows. A swelling that is not normal anatomy needs to be identified, and the ones that need surgery need it sooner rather than after months of waiting.

• Check the other side first. Fat pads, hemipenal bulges and femoral pores are symmetrical. Disease is usually not.
• Photograph the lump next to a ruler or a coin, and date the photo. Growth rate is diagnostic information.
• Never squeeze, lance, or hot-compress a lump on a reptile.
• A firm swelling on the jaw of a bearded dragon or a chameleon is not a fat pad. Consider infection of the jaw bone.
• Older bearded dragons develop tumours often enough that any new, growing mass in an adult deserves sampling rather than observation.

Decide in 60 seconds

The examination that answers most of it

Examine on a towel on a flat surface at chest height, in daylight or under a bright neutral lamp, with the lizard warm and settled after basking.

Handle the lizard when it is warm. A cold reptile is stiff, defensive and hard to assess, and warm animals tolerate handling better.

Work through the body in the same order every time so that you are comparing like with like: head and jaw, ear openings, neck, each front limb and each foot, flanks, belly, thighs and femoral pores, tail base, tail.

For each finding, note four things.

Position. Is it over a joint, over a bone, in the skin, or deeper in the body wall? Skin lumps move with the skin. Deeper ones do not.

Symmetry. Does the same thing exist on the other side? Almost all normal anatomy is paired.

Consistency. Firm, hard, soft, fluid, or gritty. A reptile abscess is firm and does not fluctuate under a finger.

Change. Photograph it with a ruler or a coin in the shot, in the same light and from the same angle, and repeat weekly. Growth over days means something different from a lump that has been identical for a year.

What it usually turns out to be

Where species and sex change the answer

Bearded dragons are the species most often presented with lumps, for two reasons. They have prominent normal fat pads that owners mistake for masses, and they have a genuine, well recognised tendency to develop tumours as they age.

In bearded dragons and chameleons, and in other lizards whose teeth are fused to the crest of the jaw rather than sitting in sockets, a jaw swelling has a specific and serious meaning. Plaque and gum infection in these species track down into the jaw bone. A firm, warm, asymmetrical jaw swelling with reddened gums or a change in how the lizard takes food needs dental assessment under anaesthesia, not observation.

Leopard geckos store fat in the tail, so tail thickness is your body condition score. A leopard gecko that develops a thin, pointed tail while remaining hungry needs investigation for chronic intestinal infection, and that is a wasting problem rather than a lump problem.

Male lizards of every species carry two structures that are routinely reported as lumps: the hemipenal bulges at the tail base and the femoral pore row on the thighs. Both are normal. Both can also become abnormal: a hemipenal plug or infection makes one side larger than the other, and a blocked, hardened femoral pore can inflame and abscess.

Females change through the season. Follicles develop and are visible or palpable as multiple rounded swellings low in the body, and this is normal until it stops progressing. A female that develops these swellings and then becomes lethargic, stops eating, strains or digs frantically has moved into a reproductive emergency.

Older animals of any species shift the odds toward neoplasia. Young ones shift them toward trauma, infection and husbandry disease.

How the lump got there

Most abscesses in captive lizards start with a break in the skin. The common sources are cage mate bites, especially between males or where two animals compete for the basking site, and crickets or locusts left in the enclosure overnight, which chew on a sleeping lizard.

Burns from heat mats and heat rocks are the next source, because burnt skin is dead skin and it becomes infected.

Injections and blood samples occasionally leave a reaction, which is why any lump appearing at a recent injection site should be mentioned to the vet who gave it.

Behind all of them sits the same amplifier: temperature. A reptile that cannot reach its species-appropriate body temperature cannot mount a normal immune response, so infections that a well-kept animal would contain instead progress. When an abscess turns up, check the enclosure temperatures with a probe before you conclude anything about the lizard.

Humidity and hygiene matter for the same reason. A wet, dirty substrate keeps skin damaged and bacterial numbers high.

Staging: what early, established and late look like

Early. A small firm swelling, skin and scales normal over it, the lizard eating, basking and behaving normally. This is the stage at which surgery is small and recovery is quick, and it is the stage owners almost always watch rather than act on.

Established. The lump is larger, the scales over it are stretched, paler or separated, and the lizard may favour that side or use the limb less. Appetite is often still normal.

Late. The skin ulcerates, the mass discharges dry crumbly material, or the infection reaches bone underneath. The lizard loses weight, stops basking and stops eating. Treatment is now much bigger surgery on a much weaker patient.

Tumours run the same course but with an additional feature: they keep growing, they can recur after removal, and some spread internally, which is why a growing mass is imaged as well as sampled.

What the vet will do, and why it is not just antibiotics

Expect a fine needle sample of the lump, examined under the microscope. That one test separates abscess from tumour from fat from gout in most cases, and it is quick.

Expect radiographs if the lump is on a limb, over the jaw, or if the lizard is unwell, because bone involvement and internal masses change the plan completely.

Expect culture from any abscess, taken at surgery, because the bacteria involved in reptiles are frequently ones that do not respond to the antibiotic that would be chosen by guesswork.

Expect the recommendation to remove an abscess whole, with its capsule, under anaesthesia, rather than to lance it. Lancing leaves the capsule, and the capsule is where the infection lives.

Expect blood tests if gout is suspected, because gout is a kidney disease with a joint sign, and treating the nodules without addressing hydration, diet and renal function does nothing.

What the vet will want to know

What never to do

Never squeeze, pop or cut a lump on a reptile. The contents are solid, the capsule stays behind, and you introduce infection into tissue that heals slowly.

Never apply hot compresses or soak in the hope that it will burst. It will not, and heat on infected tissue in a reptile risks a burn as well.

Never apply human antiseptic creams, essential oils, tea tree preparations or wound powders to a reptile without veterinary advice.

Never give leftover antibiotics from another animal, and never expect antibiotics alone to resolve an abscess.

Never assume symmetry means safe without looking properly. Bilateral swellings occur in gout, in reproductive activity and in fluid retention.

Never leave uneaten live insects in the enclosure overnight. This is the single easiest source of bite wounds to eliminate.

Never watch a jaw swelling. Of all the lumps on this list, that is the one where delay costs bone.

A weekly handling session in good light, on a towel, is how lumps get found while they are still small.

When to get help

Get same-day or next-day reptile veterinary care for a lump with weight loss or appetite loss, for chalky joint nodules, for tissue swelling beyond a ring of retained shed, for a discharging or ulcerated mass, and for generalised puffiness in a lizard that has stopped basking.

Book within the week for any new firm lump, for a swelling at the ear opening, for a jaw swelling, and for any mass in an adult that is growing.

Book a routine appointment, but still book one, for a stable swelling in a well animal, so that a sample settles what it is while it is still small.

Take dated photographs with a scale object, your temperature and UVB details, the weight record, and the lizard itself in a secure, warm transport container. In reptile medicine the husbandry history is not background information. It is usually half the diagnosis.