CONDITION
Cataracts in Dogs
A cataract is an opacity that forms in the lens of the eye. The lens normally sits behind the pupil and is transparent, allowing light to pass through to the retina at the back of the eye. When the lens becomes cloudy, vision is affected to varying degrees, from small areas of haze that may go unnoticed to complete whiteness that can lead to blindness. Owners often first notice a cloudiness or white appearance in one or both eyes, or they may observe that their dog is bumping into objects, hesitating on stairs, or becoming more cautious in dim light or unfamiliar places. Cataracts can appear at any age, from puppies to older dogs, and may develop rapidly or progress slowly over months or years. Not all cloudiness in the eye is a cataract: a normal age-related change called nuclear sclerosis can also cause a greyish haze but does not typically interfere with vision. This page explores what cataracts look like and how they may be identified, what causes them to form, how they are investigated, and the range of approaches available depending on the extent of cloudiness and how the dog is affected.
Why this matters now
Cataracts can develop at any age in dogs, though the timing and cause vary considerably. Hereditary cataracts, which have a strong genetic basis in many breeds, may appear in young dogs from a few months to several years of age, with the specific age of onset often characteristic of the breed involved. Diabetic cataracts develop in most diabetic dogs, even when the diabetes is well regulated: in one study of 200 diabetic dogs, half had cataracts by 170 days after diagnosis and 75% by 370 days. Once they start, the osmotic effects of high glucose levels on the lens can make them progress very quickly. Age-related cataracts tend to develop gradually in older dogs and may not become visually significant for some time. It is important to distinguish cataracts from nuclear sclerosis, a normal age-related hardening and bluish hazing of the lens nucleus that develops in dogs from about seven years of age and does not significantly impair vision. This distinction matters because nuclear sclerosis does not typically require intervention.
The progression of cataracts varies depending on the type and underlying cause. Hereditary cataracts may progress from incipient (affecting less than 15% of the lens) to immature, mature, and eventually hypermature stages over months to years. Some hereditary cataracts stabilise at an immature stage and remain visually manageable, while others progress to complete opacity. Diabetic cataracts often progress very rapidly, sometimes reaching maturity within weeks. As a cataract matures, lens proteins can leak out through the lens capsule and trigger lens-induced uveitis, inflammation within the eye caused by the immune system reacting to those proteins. This uveitis can cause secondary complications including glaucoma and retinal detachment if left unmanaged. In the hypermature stage, the lens may begin to resorb, sometimes allowing partial return of some light perception, though the visual quality is typically poor and the risk of complications remains.
Signals & patterns
Early signals
Subtle cloudiness visible in the eye
In the earliest stages, a small area of whitish or hazy opacity may be visible within the pupil, sometimes only noticeable under certain lighting conditions or when the pupil is dilated. This cloudiness is located within the lens itself, behind the iris, and differs from the surface cloudiness seen with corneal disease.
Difficulty catching treats or tracking objects
As cataracts in both eyes grow beyond the earliest (incipient) stage, dogs may show subtle changes in their ability to track moving objects or catch treats tossed to them. Very early cataracts do not usually cause any noticeable change in vision.
Hesitation in unfamiliar environments
While dogs often navigate their familiar home environment well even with developing cataracts, unfamiliar settings may reveal visual difficulty earlier. Dogs may hesitate at unfamiliar doorways, show reluctance to navigate new spaces, or appear less confident in environments where they cannot rely on spatial memory.
Increased reliance on smell and hearing
Dogs with gradually developing cataracts may subtly shift their orientation strategy, using their nose more actively and responding more attentively to sounds. This compensatory behaviour can be so effective that owners may not recognise the visual decline until the cataracts are quite advanced.
Later signals
Obviously white or opaque lens visible through the pupil
As cataracts mature, the opacity becomes clearly visible as a white or bluish-white structure behind the pupil. In mature cataracts, the entire lens is opaque and the pupil appears uniformly white rather than black. This change is usually unmistakeable and may affect one or both eyes.
Bumping into furniture or objects
With advanced bilateral cataracts, dogs may walk into familiar objects, misjudge distances, or appear startled by obstacles they cannot see. This is particularly noticeable in dim lighting, rearranged environments, or when objects are moved from their usual positions.
Red or painful-appearing eyes
Lens-induced uveitis, inflammation triggered by leaking lens proteins, can produce visible redness, squinting, excessive tearing, or a change in the appearance of the eye. It may develop as cataracts mature and can lead on to glaucoma. A red, painful eye with a hazy blue cornea or a widely dilated pupil can mean acute glaucoma or a lens that has moved forward, and the pressure inside the eye cannot be judged at home. Vision can be lost within hours to days. In acute glaucoma the pressure inside the eye is typically above 40 to 60 mmHg, against a normal average of about 19 mmHg in dogs, and once vision has gone the prospect of it returning is guarded.
Behavioural changes related to vision loss
Dogs with significant bilateral cataracts may become more cautious, startle more easily when approached from their blind side, show reluctance to navigate stairs or jump onto furniture, or become more dependent on their owners for navigational cues. Some dogs may display increased anxiety, particularly in unfamiliar settings.
Click to read about the biological mechanisms
How this is usually investigated
Investigation of cataracts involves confirming the diagnosis, distinguishing cataracts from other causes of lens opacity, assessing the stage of cataract development, evaluating the health of the rest of the eye, and determining whether the retina is likely to be functional, which is critical for assessing whether surgical intervention could restore useful vision. Breed history, age of onset, and the presence of systemic conditions such as diabetes mellitus provide important context for understanding the type and cause of cataract formation.
Ophthalmic examination with slit lamp biomicroscopy
Electroretinography (ERG)
Ocular ultrasound
Tonometry (intraocular pressure measurement)
Blood work and metabolic screening
Options & trade-offs
Management of cataracts ranges from monitoring and supportive care for early or slowly progressing cataracts to surgical intervention for cataracts that significantly impair vision. The decision about whether and when to pursue surgery involves considering the stage of the cataract, the health of the rest of the eye, the dog's overall health and temperament, and the practical implications of surgical aftercare. Not all cataracts require or are suitable for surgical intervention.
Monitoring and medical management
For incipient or immature cataracts that are not significantly affecting vision, regular monitoring by a veterinary ophthalmologist can track progression and identify any secondary changes such as uveitis or glaucoma early. Topical anti-inflammatory eye drops may be used to manage lens-induced uveitis and protect the internal structures of the eye, even when surgery is not being pursued.
Trade-offs: Monitoring alone does not halt cataract progression, and there is a risk that secondary complications may develop between check-ups. The frequency of monitoring and the cost of ongoing ophthalmological assessment need to be weighed against the benefits of early detection of changes. Dogs may adapt well to gradual vision loss, but sudden changes in cataract maturity or the development of complications may shift the clinical picture.
Phacoemulsification (cataract surgery)
Phacoemulsification is the standard surgical technique for cataract removal in dogs, involving the use of ultrasonic energy to fragment and aspirate the opaque lens material through a small incision. An artificial intraocular lens is typically implanted to restore focusing ability. The procedure is performed under general anaesthesia using an operating microscope and specialised equipment, and is carried out by veterinary ophthalmologists.
Trade-offs: Cataract surgery has a high success rate in appropriate candidates: the MSD Veterinary Manual reports it as 90 to 95 per cent successful within the first one to two years, with better results when it is done before the cataract is fully mature and before lens-induced uveitis is established. However, the procedure requires general anaesthesia, meticulous postoperative care including several eye drops four to six times a day in the early weeks, strict activity restriction during healing, and usually at least one eye medication and regular eye examinations for life. Complications can include postoperative uveitis, glaucoma, retinal detachment, and posterior capsule opacification, though these occur in a minority of cases. The financial investment is significant, and the aftercare commitment is substantial.
Management of secondary complications
Even when cataract surgery is not pursued, managing the secondary effects of cataracts, particularly lens-induced uveitis and secondary glaucoma, is important for maintaining the comfort and health of the eye. Topical anti-inflammatory medications can help control uveitis, while glaucoma may require specific pressure-lowering medications.
Trade-offs: Medical management of complications does not address the visual impairment caused by the cataract itself but can preserve the health of the eye and prevent painful secondary conditions. This approach requires ongoing medication compliance and regular monitoring to assess the effectiveness of treatment and detect any changes in intraocular pressure or retinal health.
Environmental adaptation for vision-impaired dogs
Dogs with bilateral cataracts that are not candidates for surgery, or whose owners choose not to pursue surgical intervention, can often adapt remarkably well to reduced vision with environmental support. Maintaining consistent furniture placement, using textured mats or runners to mark pathways, providing verbal cues before approaching, and avoiding rearranging the home environment can all support a vision-impaired dog's quality of life.
Trade-offs: While dogs can adapt well to gradual vision loss, sudden complete vision loss may be more challenging. Environmental adaptation addresses the practical impact of vision impairment but does not address the underlying condition or its potential complications. Dogs with bilateral cataracts and no surgical intervention still require monitoring for secondary conditions that could cause pain.
Common misconceptions
"The bluish haze in older dogs' eyes is always a cataract"
Nuclear sclerosis, a normal age-related change in the lens, is frequently mistaken for cataracts. Nuclear sclerosis produces a symmetrical, bluish-grey haze in both eyes that develops gradually with age and typically does not significantly impair vision. True cataracts produce a whiter, denser opacity and may affect vision substantially. An ophthalmic examination can readily distinguish between these two conditions, and the distinction is clinically important because nuclear sclerosis generally does not require intervention.
"Cataracts can be treated with eye drops"
Despite ongoing research, there are currently no eye drops that have been proven to dissolve or reverse cataracts in dogs. Phacoemulsification surgery is the standard method for removing a cataractous lens and restoring vision. Eye drops may be used to manage secondary inflammation (uveitis) associated with cataracts, but these treat the complication rather than the cataract itself.
"Dogs with cataracts are in pain"
The cataract itself does not cause pain: it produces visual impairment by blocking the passage of light through the lens. However, secondary complications of cataracts, particularly lens-induced uveitis and glaucoma, can be painful. This is why monitoring for these complications is important even when the cataract itself is not being surgically addressed. A dog with a cataract that is not causing secondary inflammation or pressure changes is typically comfortable despite the visual impairment.
Related conditions
Nuclear Sclerosis
Nuclear sclerosis is often mistaken for cataract formation because both can cause a greyish or cloudy appearance in the pupil, but nuclear sclerosis is a normal age-related change that typically does not impair vision in the way cataracts can.
Diabetic Cataracts
Diabetic cataracts describe a specific pattern of lens clouding that develops in dogs with diabetes mellitus, and they tend to progress more rapidly than cataracts from other causes. They develop in most diabetic dogs, even when the diabetes is well regulated.
Lens Luxation
Lens luxation can occur as a complication of advanced cataract formation, because the swelling and structural changes in a cataractous lens may put strain on the fibres that hold it in place, though luxation can also arise independently. A lens that moves forward into the front of the eye often brings on acute glaucoma.
The page on this condition is being checked again and is offline for now.
Glaucoma in Dogs
Glaucoma may develop as a secondary complication in eyes with advanced cataracts, particularly if inflammation or changes in lens position interfere with the normal drainage of fluid inside the eye, and acute glaucoma can cost the eye its vision within hours to days.
Understanding the distinction between normal age-related lens changes and true cataracts is a useful starting point for families noticing changes in their dog's eyes. Recognising that cataracts can develop at different rates depending on their cause, from the very rapid progression seen with diabetes to the slow development of age-related changes, can help frame expectations about how the condition may evolve. Being aware of the signs of secondary complications matters: an eye with a cataract that turns red or painful, makes the dog squint, or develops a hazy blue cornea may have uveitis, glaucoma or a lens that has moved. Glaucoma and a moved lens can cost vision within hours to days. For dogs adapting to vision loss, understanding that their other senses can compensate remarkably well, and that environmental consistency supports their confidence, may help families navigate the adjustment.
Last reviewed: 10 October 2026 · Dr Alastair Greenway MRCVS