Lizard Respiratory Infection: Early Signs and the Husbandry Behind Them

Quick answer

Respiratory infection is one of the most common serious illnesses in captive lizards, and in most cases it is a husbandry problem before it is an infection. The temperature gradient, the humidity and the ventilation decide whether the bacteria that are always present get an opportunity.

Reptiles are also poorly equipped to clear an infection once it starts. There is no diaphragm, no effective cough, and the pus a reptile produces is thick and solid rather than liquid, so it does not drain. That is why a lizard with a chest infection needs weeks of veterinary treatment rather than a few days, and why catching it early changes the outcome so much.

The enclosure is the case history. Almost every respiratory infection in a captive lizard is traceable to something measurable in it.

• Open-mouth breathing at the basking spot in a bright, alert lizard is normal thermoregulation.
• Open-mouth breathing away from the heat, at rest, with noise or mucus, is not.
• Immune function in a reptile is temperature-dependent, so a cool lizard cannot fight an infection.
• Never raise humidity for a desert species, and never use a steamy bathroom as treatment.
• White crusty deposits around the nostrils in iguanas and some agamids are excreted salt, not discharge.

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A lizard that is holding its head and neck elevated, breathing with its mouth open at rest, and making audible clicks or bubbles needs veterinary care immediately.

Reptile lungs are simple sacs with a poor ability to clear secretions, and there is no cough reflex worth the name. Exudate accumulates in the lower parts of the lung and the animal cannot shift it. Raising the head is an attempt to keep the airway above the fluid, and animals that have reached this stage deteriorate quickly. This is not a condition to treat by adjusting the enclosure and waiting a week.
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Decide in 60 seconds

Why husbandry decides the outcome

Temperature runs the immune system.

A lizard is ectothermic. Every enzyme reaction in its body, including the ones that produce and mobilise immune cells, runs at a rate set by its body temperature. Each species has a preferred range within which those systems work properly, and below it they simply do not.

That is why a lizard kept a few degrees too cool for months is not merely sluggish. It is immunosuppressed. Bacteria that a correctly warmed animal clears without any sign establish themselves instead. It is also why correcting the gradient is part of the treatment rather than a suggestion to follow afterwards: antibiotics given to a cold reptile are absorbed, distributed and eliminated at rates the dose was never calculated for.

The gradient matters as much as the peak. A lizard needs a genuine range of temperatures within the enclosure so that it can choose. A single hot spot in an otherwise cold tank, or a uniformly warm enclosure with nowhere cool, both remove that choice.

Humidity has to match the species, not the shop's habit.

A desert species kept in high humidity cannot dry its skin or its airway properly, and the warm damp environment favours bacterial and fungal growth. A tropical species kept dry has a damaged airway lining and retained shed. The same enclosure humidity is right for one animal and wrong for another, so the target is the species, not a general figure.

Screen-sided enclosures for chameleons illustrate the trap neatly. They ventilate well, which is good, but they also make it very difficult to hold either heat or humidity, so keepers compensate by misting heavily and adding heat at the top. The result is often a warm wet upper zone and a cold lower one.

Ventilation and air quality.

Stale air over damp substrate accumulates ammonia from waste, which damages the airway lining directly. Fine dusty substrates are inhaled. Both make infection easier.

Nutrition.

Vitamin A maintains the epithelial lining of the airway. Deficiency, common in insectivorous species fed unsupplemented feeder insects, produces a fragile lining that infects readily, along with the swollen eyelids that often appear first.

Stress.

Cohabitation with a dominant animal, excessive handling, an enclosure without cover, a new environment, transport, or an enclosure in a busy noisy room. Chronic stress suppresses immune function in reptiles as it does in mammals.

Recognising it

Cover at both the warm and the cool end lets a lizard choose its temperature. Without it, the animal picks safety over thermoregulation and stays cold.

Early.

A faster resting breathing rate. Slightly reduced appetite. Spending unusually long at the basking site, or unusually little time there. A small amount of clear fluid or a bubble at a nostril. Reduced activity. These are the signs that make treatment straightforward, and they are also the ones most easily explained away.

Established.

Visible mucus at the nostrils or in the mouth, sometimes as strands between the jaws when the mouth opens. Audible breathing: clicking, popping, wheezing or a wet sound. Forced exhalation, where the animal puffs the throat and body to push air out. Open-mouth breathing at rest, away from the heat source. Weight loss.

Late.

Head and neck held elevated. Continuous gaping. Pale or bluish mouth lining. Weakness, unwillingness to right itself, sitting in the water bowl. At this point the lungs are substantially filled and the prognosis worsens sharply.

By species.

Bearded dragons often show mucus at the nares and gaping away from the basking spot, and their normal basking gape is the thing owners must learn to exclude. Leopard geckos are easily kept too cool and too damp and present with clicking and lethargy. Chameleons show mouth gaping, a puffed throat, closed eyes and bubbles at the mouth, and are prone to being treated too late because their normal gular movement looks similar. Crested geckos are often over-misted in poorly ventilated enclosures. Larger monitors and tegus show the same picture at a larger scale, with obvious body wall effort.

What else looks like a respiratory infection

Normal basking gape. At the hot spot, in a bright alert lizard that closes its mouth when it moves away. Not accompanied by noise or mucus.

Salt gland secretion. Green iguanas and some agamids excrete excess salt through glands in the nose, sneezing out a fine white crust that dries on the snout and on the glass. This is normal excretion and needs no treatment.

Retained shed over the nostrils. A ring of old skin partially blocking a nare produces noisy breathing and looks alarming. Correct the humidity for the species and it resolves.

Substrate in the nostril. Fine sand or dust lodged in a nare, causing sneezing and one-sided discharge.

Stomatitis. Infection of the mouth spreading upward. Look for redness, swelling, pinpoint haemorrhages or cheesy material along the gum line.

Hypovitaminosis A. Swollen eyelids, discharge, and secondary respiratory disease. Diet-driven and correctable.

A gravid female or a coelomic mass. Anything filling the body cavity presses on the lungs, because the lungs have no diaphragm protecting them. A female with a body full of eggs breathes with effort and it is not an infection.

Aspiration. After forced feeding, syringe feeding, or an unsupervised soak in water that was too deep.

Correcting the enclosure

This is the part you can start today, and it must be done with measurements rather than impressions.

Measure, do not estimate.

An infrared thermometer for surface temperatures, particularly the basking surface. A probe or digital thermometer with the sensor at animal height for ambient warm and cool ends. A separate reading for night. Stick-on dial thermometers and guesses are not adequate.

Check the gradient across the whole enclosure.

Record the basking surface, the warm ambient, the cool ambient and the night low. Compare each to the published requirements for your specific species, and adjust one variable at a time.

Measure humidity where the animal sits, not at the top of a screen cage, and match it to the species rather than to a generic reptile figure.

Look at ventilation.

Air should move. A sealed enclosure with damp substrate is the classic setup for this disease.

Change the substrate if it is dusty or damp.

Kitchen paper or paper towel during treatment removes both the dust and the humidity variable and lets you see droppings.

Check the UVB.

Type, age and distance. Lamps lose output long before they stop emitting visible light, and a lizard without functional UVB is a lizard with wider health problems.

Reduce handling and stress. Provide cover at both ends of the gradient. Separate cohabiting animals during treatment.

Do not simply crank up the heat. Overheating is its own emergency, and a hot spot above the species range causes burns and dehydration. Use a thermostat.

Readings taken at the animal's level, at several points, are what a reptile vet will ask for. Wall-mounted dials are not.

What treatment involves

Expect a physical examination, radiographs taken in more than one projection to see how much lung is affected, and often a wash of the trachea or lung to obtain a sample for culture and cytology.

Culture matters here more than in many species. The bacteria involved are frequently Gram-negative organisms with unpredictable sensitivities, and treating blind commonly fails. Fungal infection is a real possibility in chronic cases and is treated completely differently.

Treatment is usually injectable rather than oral, often for several weeks, sometimes with nebulisation. Fluids and assisted feeding are common. Throughout, the animal needs to be held in its correct thermal range for the drugs to work as intended, which is why a hospital enclosure or a corrected home enclosure is part of the prescription.

Rechecks and repeat imaging are normal. Stopping when the animal looks better is the commonest route to a relapse that is harder to treat than the original.

Quarantine any new or affected animal away from others, with separate equipment and hand washing between, since several of the organisms involved transmit between reptiles.

What never to do

Do not raise humidity for a desert species in the hope of easing the breathing.

Do not use steam, vaporisers or a hot shower room.

Do not soak a weak lizard in deep water.

Do not use leftover antibiotics from another animal, or reptile products sold without prescription for respiratory problems.

Do not add heat without a thermostat, or use a heat rock.

Do not house an affected animal with others during treatment.

Do not stop a prescribed course early because the animal is eating again.

Do not assume gaping is always abnormal, or that a lizard with no visible discharge cannot have pneumonia.

When to get help

Go the same day for open-mouth breathing at rest, audible clicking or wheezing, mucus at the nose or in the mouth, forced exhalation, or a head held persistently raised.

Go immediately for a lizard that is weak, cannot right itself, has pale or dusky mouth lining, or is sitting in the water bowl and not moving.

Book promptly for a slightly increased breathing rate with reduced appetite, for a single nostril bubble, or for any lizard whose enclosure temperatures turn out to be well below the species range.

Basking deliberately, moving between temperatures and breathing silently is the endpoint, and the enclosure is what maintains it.

Bring written temperature readings for the basking surface, the warm end, the cool end and overnight, with a note of how each was measured, the humidity at animal height, the UVB lamp type and its installation date and distance, the enclosure dimensions and ventilation, the substrate, the diet and supplementation routine, whether the animal lives with others, the weight trend, and your healthy baseline video. Expect radiographs and a sample taken for culture, and expect treatment to be measured in weeks.