Chinchilla watery and crusted eyes: what the tears are telling you

Quick answer

A wet, crusted or half-closed eye in a chinchilla is almost never a simple eye problem. In this species the most common reason for a weeping eye is dental: the cheek teeth and incisors grow for life, and when their roots elongate into the bone of the upper jaw they press on the tear duct that drains the eye into the nose.

That is why wiping the eye clean makes no lasting difference, and why an eye that keeps weeping needs skull imaging rather than more eye drops. The other real causes are a scratched cornea from hay, conjunctival irritation from dust or ammonia, and a respiratory infection draining forward.

Look at the eyes from the side and from the front in good daylight, before you touch anything.

• A chinchilla holding one eye shut is in pain. Treat it as a same-week appointment at worst, and sooner if it is not eating.
• Weeping eyes plus any change in eating are a dental problem until an exotics vet proves otherwise.
• Never put leftover eye drops from another animal into a chinchilla's eye. Steroid drops on a scratched cornea can perforate it.
• A chinchilla that has stopped eating for a day is an emergency regardless of what its eyes look like.
• Photograph both eyes in daylight before you clean them. The vet needs to see what you saw.

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A chinchilla that stops eating needs help within hours, not days.

The chinchilla gut depends on constant fibre moving through it. When intake stops, gut motility slows, gas-producing bacteria overgrow, and the animal goes into gut stasis, which is painful and can be fatal within a day or two. Eye pain and dental pain both stop a chinchilla eating. If the droppings have got smaller, fewer or have stopped altogether while an eye has been weeping, the eye is no longer the urgent problem.
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Decide in 60 seconds

Why chinchilla eyes weep from the teeth

A chinchilla's teeth are open-rooted and grow throughout life. In the wild that growth is matched by the abrasion of chewing tough, silica-rich grasses for most of the waking day. In a home, a chinchilla eating a bowl of pellets and a handful of hay chews for a fraction of that time, and the teeth grow faster than they wear.

Growth has to go somewhere. The crown, the part you would see, overgrows into spurs that cut the tongue and cheek. The root, the part you cannot see, elongates backwards into the bone. In the upper jaw the elongating roots push into the space occupied by the nasolacrimal duct, which is the drain that carries tears from the inner corner of the eye down through the maxilla and into the nose.

Once that drain is compressed, tears that should disappear down the nose instead spill over the lower lid. The fur below the eye stays permanently damp, then becomes matted and stained, then becomes inflamed and infected because damp fur is a good place for bacteria. The eye itself is often entirely normal. The problem is plumbing.

This is why the pattern is so distinctive: the eye keeps weeping, wiping helps for an hour, drops do nothing lasting, and the chinchilla is otherwise slowly changing the way it eats.

What to look for in the mouth end of the problem

Chinchillas with dental disease rarely stop eating suddenly. They change what they eat and how they eat it, and the changes are easy to miss.

They select pellets and abandon hay, because hay demands the sideways grinding that hurts. They take a piece of food, chew on one side, drop it, and pick it up again. They eat more slowly and spend longer at the bowl for less food. They may drool, which shows as damp fur under the chin and on the front of the chest, and on the forepaws they use to wipe.

The droppings follow the mouth. Smaller, drier, fewer, or more irregular pellets in the cage mean less fibre is going through. This is the single most useful thing an owner can monitor, and it changes before the weight does.

Weight change comes later. By the time a chinchilla has lost noticeable condition under that dense coat, the dental disease is advanced. This is why weekly weighing on a gram scale is worth more in this species than almost any other observation.

A weekly weight and a note on droppings turn a vague worry into a trend a vet can act on.

The other causes and how they differ

Corneal ulcer or scratch.

Usually one eye. The chinchilla holds it shut or blinks hard, avoids light, and may rub the eye with a forepaw. The classic source is a hay stalk, particularly stalky, coarse hay presented in a way that puts the face into it. It can also follow a scuffle between cage mates. A vet confirms it with a fluorescein stain, which shows damaged cornea as a green patch under blue light. This is the diagnosis that makes borrowed eye drops dangerous, because steroids applied to an ulcer suppress healing and can allow the cornea to melt through.

Conjunctivitis from dust and ammonia.

Usually both eyes, with reddened lid margins and a mucoid rather than watery discharge. Ask what changed. A new bag of bath dust of a different grade, a bath left in the cage all day so the chinchilla lies in it, a cage cleaned less often over a busy fortnight, or a switch to pine or cedar shavings, whose aromatic phenols irritate eyes and airways. Ammonia from urine collecting under bedding is not something you have to smell for it to be affecting an animal whose face sits centimetres above it.

Upper respiratory infection.

Eye discharge with a wet or crusted nose, sneezing, and matted fur on the inside of the forelegs where the chinchilla wipes its face. Chinchillas have narrow airways and hide respiratory disease well, so a chinchilla that is visibly snuffly is often further along than it looks. This needs a same-day appointment.

Retrobulbar abscess or mass.

The eye protrudes, sits more prominently than the other, or the lids no longer meet. Often a consequence of a tooth root abscess tracking backwards. This is urgent and it is surgical territory.

Heat.

Chinchillas overheat easily because of their extraordinarily dense coat. Heat stress produces red, hot ears, drooling, lying flat and rapid breathing rather than a weeping eye, but a chinchilla found in a hot room with any of those signs needs cooling and a vet before anyone looks at its eyes.

A healthy chinchilla eye is clear, wide and dry, with dry fur right up to the lid margin.

Where the popular advice fails

"Bathe the eye with cooled tea or salt water and it will settle."

Cleaning damp fur is reasonable supportive care and it does reduce secondary skin infection. It is not treatment. The common harm is not the tea; it is the six weeks of wiping that pass before anyone images the skull, during which tooth roots keep elongating and the chinchilla keeps eating less.

"It is just dust in the eye."

Sometimes it is, and that resolves in a day or two once the source is removed. A weep that is still there a week later is not dust.

"Take the dust bath away for good."

Removing dust bathing permanently causes its own problems. Chinchilla fur is too dense to dry properly if it gets wet or greasy, and animals denied dust develop matted, oily coats and skin disease. The fix is the right grade of dust, offered for a short period and then removed, not abolished.

"Any small-animal vet can check the teeth."

An awake oral examination sees the crowns and misses the roots entirely. Root elongation, which is the cause of most chinchilla eye discharge, is only visible on radiographs or CT. If you are told the teeth look fine but the eye keeps running, ask for imaging.

The routine that catches this early

Weigh weekly on a gram scale, at the same time of day, and write the number down. A slow downward drift is the earliest reliable warning of dental disease in a chinchilla.

Look at the face daily under a real light. You are checking that the fur below both eyes is dry, the nose is dry, the chin is dry, and both eyes are equally wide open.

Watch the droppings, not just the food bowl. Count roughly, look at size, and notice any change in shape or dryness.

Keep hay unlimited and make it the largest part of the diet by far. Chewing long fibre is the only thing that wears the teeth, and no chew stick or mineral block substitutes for it.

Keep the cage dry. Spot-clean the wet corner daily, and change bedding often enough that you never smell ammonia when you put your face near the cage.

Use a fine, clean bath dust, offer the bath for a short session rather than leaving it in, and replace the dust rather than reusing it once it is soiled.

What never to do

Do not use eye drops or ointment prescribed for another animal, or bought without a diagnosis. Steroid-containing drops on an ulcerated cornea can cost the eye.

Do not attempt to trim or file a chinchilla's teeth yourself, or let anyone do it without anaesthesia and proper instruments. Nail clippers on incisors shatter them lengthways and expose the pulp.

Do not bathe a chinchilla in water to clean a stained face. The coat holds water, dries very slowly, and a wet chinchilla chills and develops fungal skin disease.

Do not pull or pick at matted, crusted fur under the eye. Chinchilla skin is thin and tears easily, and the animal will fur-slip a patch away rather than let you.

Do not treat a weeping eye as cosmetic. It is a window onto the teeth, and the teeth determine whether this animal keeps eating.

Do not wait for weight loss before acting. Under that coat, weight loss is late.

The goal is a dry face, a stable weight and a chinchilla that still prefers hay to pellets.

When to get help

Go the same day for an eye held shut, a cloudy or discoloured cornea, a bulging eye, thick coloured discharge with a wet nose, or any chinchilla that has stopped eating or is producing fewer droppings.

Book within the week for any watery eye that persists beyond a couple of days, any staining down the cheek, any drooling or wet chin, and any downward drift in weight.

Ask specifically for an exotics or small-mammal vet, and ask when you book whether they can image the skull. Not every practice can, and knowing before you arrive saves a second appointment.

Bring the weight record, photographs of both eyes taken before cleaning, a description of exactly what the chinchilla is and is not eating, a note of dropping size and number, the brand and grade of bath dust, the bedding type, and the age of the animal. If there is more than one chinchilla, say whether the others are affected and whether they share a bath.