Guinea pig eye problems: hay pokes, the tear duct the teeth block, and what discharge means

Quick answer

Most guinea pig eye injuries happen at the hay rack, and most of the rest are prevented by keeping the coat and the cage clean.

A guinea pig with a suddenly closed, weepy, painful eye almost always has a corneal ulcer, and the usual cause is a stem of hay. Those eyes sit on the side of the head for a wide field of view, which means the animal has a blind spot directly in front of its nose, which is exactly where it puts its face when it eats.

A guinea pig with a persistently wet face and no pain is a different problem. The tear duct runs past the roots of the upper incisors, and when those roots elongate they compress it. That is a dental diagnosis presenting as an eye complaint, and drops will not touch it.

• A squinting or held-shut eye is painful and needs a same-day appointment.
• Ask specifically for the eye to be stained. An ulcer is not reliably visible without it.
• Never put any human eye drop into a guinea pig's eye, and never a steroid drop into a painful one.
• A milky white secretion appearing briefly while the guinea pig washes its face is normal.
• Eye pain stops a guinea pig eating, and a guinea pig that stops eating develops gut stasis within hours.

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Never use a steroid-containing eye drop, or any drop prescribed for another animal or person, on a guinea pig's eye.

If there is an ulcer, a steroid suppresses the local response that is holding the cornea together and can turn a superficial ulcer into a perforating one within a day. Because you cannot see most ulcers without a fluorescein stain, the only safe rule is that nothing goes into a guinea pig's eye unless a vet has examined it and prescribed it for that eye, on that day.
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Decide in 60 seconds

Why guinea pigs damage their eyes so often

The eyes are in the wrong place for the way they eat.

Lateral eye placement gives a prey animal a wide field of view, which is exactly what it needs. The cost is that the guinea pig has poor vision directly ahead and little depth perception at close range. It navigates the last few centimetres by whisker and smell.

So when it pushes its face into a hay rack or a pile of hay, it is doing so effectively blind, several times an hour, every day of its life.

Hay is not soft.

Good grass hay contains stiff stems with cut ends. A stem that catches the cornea scratches it. That scratch is a corneal ulcer, and the cornea is one of the most densely innervated tissues in the body, which is why the pig immediately closes the eye.

Bedding and dust do the rest.

Fine shavings, dusty substrates and sawdust irritate the conjunctiva. Ammonia rising from a cage that is overdue for cleaning does the same, and it does it to both eyes at once.

Long coats add a second route.

In Peruvian, Sheltie, Texel and other long-coated breeds, hair falls across the eye and carries bedding and hay with it. Every blink drags that debris across the cornea.

Cage mates.

A scuffle over food or space produces scratches. Eye injuries in a group are worth reading as a signal about resources as well as treating as an injury.

The eye sits well back on the side of the head. From this position the guinea pig can see almost all the way behind itself, and almost nothing directly in front of its nose.

Corneal ulcer: the one that needs today

What you see

The eye is held shut or half shut. There is watering, often running down the face. The pig rubs the eye with a forepaw or scrubs the side of its face along the bedding. It avoids bright light. It becomes quiet and stops eating.

On the eye itself you may see a dull, cloudy, or blue-grey area, or nothing at all. Most early ulcers are invisible to the naked eye, which is the point of the stain.

How it progresses

A superficial ulcer involves only the outermost layer and can heal in days with the right treatment. If it deepens, it involves the supporting layer, and if that continues, the cornea can thin down to its innermost membrane. That stage is a step away from perforating, and a perforated eye is usually lost.

Infection accelerates all of this. So does a steroid drop, which is why the danger box above exists.

Why it is a whole-body problem

Corneal pain is severe. A guinea pig in that much pain stops eating, and a hindgut fermenter that stops eating slides into gut stasis within hours. A significant proportion of the risk in a guinea pig eye case has nothing to do with the eye.

That is also why pain relief prescribed by a vet is not optional comfort. It is what keeps the gut moving while the eye heals.

What the vet does

A drop of fluorescein dye, which pools in any area where the surface layer is missing and glows under a blue light. This takes seconds, is not painful, and is the difference between a diagnosis and a guess. If your guinea pig has a painful eye and this has not been done, ask for it.

The watery eye that is really a tooth

This is the presentation that gets treated wrongly for months.

Tears drain from the eye through the nasolacrimal duct into the nose. In a guinea pig that duct runs close to the roots of the upper incisors.

Guinea pig teeth grow continuously. When wear falls behind growth, the crowns overgrow and the roots elongate in the opposite direction, up into the skull. An elongated incisor root presses on the tear duct and narrows it.

What that looks like

A persistently wet eye, usually on one side, with a stained track down the face and crusting in the fur. The eye itself looks comfortable. There is no squinting and no rubbing. Drops make no difference, because nothing is wrong with the surface of the eye.

What goes with it

Often nothing obvious at first. Later, the usual dental picture: hay refusal while soft food is still accepted, dropping food, a damp chin, and a slow fall in weight.

What it needs

Imaging of the skull, because root elongation cannot be seen by looking in the mouth. The tear duct can sometimes be flushed, which helps temporarily, but the answer is managing the dental disease and getting hay intake back up.

Why it matters that you know this

A chronically wet eye that is repeatedly treated as conjunctivitis is a dental problem progressing unaddressed. If your guinea pig has had three courses of eye treatment and the eye is still wet, ask about the teeth.

The white discharge that is normal

Guinea pigs produce a milky white secretion from the eye, spread it over the forepaws, and wash their face with it.

This alarms owners regularly. It is normal grooming behaviour.

How to tell it from a problem

It appears briefly, during or just before a face-washing session, usually from both eyes, and disappears once the pig has finished. The eyes are wide open, the pig is comfortable, and it is behaving normally.

A discharge that persists between grooming sessions, that is coloured or thick, that sticks the lids together, or that comes with squinting is not this.

The rest of the differential

Conjunctivitis

Red, swollen lids, discharge, both eyes or one. Often secondary to dust, ammonia from a dirty cage, or an underlying infection. In a group, an outbreak affecting several pigs points at the environment or at an infectious cause rather than at an injury.

Pea eye

A smooth, semicircular fold of conjunctiva bulging at the lower lid, usually on both sides, looking like a small pea under the lid margin. It is painless, does not affect vision, is thought to have an inherited component, and generally needs nothing. It is worth having identified once so that you can stop worrying about it.

Heterotopic bone, sometimes called an osseous choristoma

A small, firm, white nodule on the surface of the eye. It is a discrete lump rather than a fold, and it needs a veterinary assessment because it can irritate the cornea.

Entropion

The eyelid rolls inward so the hair rubs on the cornea. Seen in young pigs, and it causes chronic irritation and repeated ulcers until it is corrected.

Cataract

A whiteness within the lens rather than on the surface. Seen in older animals and associated with diabetes in guinea pigs. It develops slowly and is not painful.

Uveitis, and pus inside the eye

Inflammation inside the eye, sometimes with a visible layer of white material settling at the bottom of the front chamber. This usually reflects infection elsewhere in the body and is a systemic problem, not a local one.

Proptosis

The eye displaced forward out of its socket, after trauma or after being restrained too firmly around the head. An emergency. Keep the eye moist with saline or clean water on a soaked pad and go immediately. Do not attempt to push it back.

Vitamin C deficiency

Does not cause a specific eye disease, but it impairs collagen production, so a deficient guinea pig heals a corneal injury slowly and is more prone to conjunctival problems. Any pig recovering from an eye injury should have its vitamin C intake confirmed.

What to do while you wait for the appointment

Keep it eating.

This is the priority. Offer hay at floor level in a pile rather than in a rack, plus its usual food, and watch that something is going in. Record weight and droppings.

Reduce the light.

A pig with a corneal ulcer is genuinely photophobic. Move the cage out of bright light or cover part of it.

Remove the mechanism.

Take hay racks that require the pig to push its face upward out of use for now. Switch to a dust-free bedding. If the coat is long, clip the hair around the eyes.

Do not put anything in the eye.

No drops, no ointment, no breast milk, no tea, no saline flush as a substitute for examination. If the eye is visibly dirty you may rinse gently with sterile saline, but that is a cleaning step, not a treatment, and it does not replace the appointment.

Do not let a cage mate groom it.

If the companion is persistently licking at the eye, separate with visual and scent contact rather than fully.

In long-coated breeds, regular grooming and keeping the hair short around the face is genuine eye disease prevention rather than tidiness.

Preventing the next one

What the vet will want to know

What never to do

Do not use human eye drops. Many contain preservatives or active ingredients that are inappropriate, and some contain steroids that are dangerous on an ulcer.

Do not use drops left over from another animal, or from a previous episode. The same eye can have a different problem this time.

Do not apply ointment or cream around the eye to soothe it. Anything greasy traps debris against the cornea.

Do not try to flush an eye forcefully. Gentle rinsing with sterile saline is the limit, and it is not a treatment.

Do not pull at crusted discharge stuck to the fur. Soften it with warm water on a pad and lift it away.

Do not restrain a guinea pig by gripping around the head or neck. Pressure there is one of the ways an eye is displaced from its socket.

Do not assume a chronically wet eye is just how that pig is. Chronic tearing on one side with no pain is a dental problem until imaging says otherwise.

Do not wait through a weekend on a squinting eye. A superficial ulcer treated promptly usually heals well. A deep one may cost the eye.

A comfortable guinea pig holds both eyes wide open and equally. Any difference between the two sides is worth a proper look.

When to get help

Go immediately for an eye that is protruding from the socket, for any penetrating injury, and for a guinea pig with an eye problem that has stopped eating.

Contact a vet the same day for an eye held shut, squinting, rubbing at the face, any cloudiness or blue-grey area on the eye, or a sudden thick discharge.

Book within the week for a chronically watery eye with no pain, for a new lump or nodule on or around the eye, and for repeated eye irritation in a young pig, which may mean the lid is rolling inward and will keep causing ulcers until it is corrected.