Dogs have an extraordinarily developed vision. They are highly perceptive of quick movements and able to see in conditions of extreme darkness and light.
When we think of our dogs, we see spoiled couch potatoes. However, deep down, our modern dogs are true to their wild heritage. Their wild ancestor was a primal predator and needed a keen sense of vision.
Several evolutionary steps forward and our modern domestic dogs inherited that keen sense of sight. Sadly, eye problems and vision problems occur even in species with such a remarkable sense of vision.
Namely, the complex ocular structure makes the eye prone to developmental defects. One of those developmental defects affecting the lens is the juvenile cataract.
The Lens – A Lesson In Embryology, Anatomy, And Physiology
The lens is a flexible, crystal-clear biconvex structure in the eye. It is contained in an eggshell-type of a protective capsule. The lens is a living tissue, which means it grows and changes, needs continuous nutrition, and is susceptible to damage and disease.
The lens’s role is to focus the light rays that enter the eye onto the retina at the back of the eye. The lens changes its shape to focus the light rays on the exact place on the retina, thus changing its refractive power.
The lens form early during embryologic development and orchestrates the entire eye development. Namely, the lens’ development is pivotal for developing other eye structures.
Therefore, if a set of defective genes affect the lens formation, the faulty-developing lens will affect the construction of other eye components vital for healthy eyes and vision. A puppy born with a cataract will likely have accompanying eye problems.
Ultimately, it is worth mentioning that puppies are born with immature eyes. Several critical eyes maturing and developing processes take place after birth.
That is the reason why puppies are born with closed eyelids and do not open them until around two weeks of age. However, even when the eyelids open, the puppy’s eyes are not fully developed.
The maturing and developing processes continue for some time after the eyelids opening. To be more accurate, in most dog breeds, the eyes are fully developed at around 12 weeks of age. At this point, the puppy will have a reasonably good visual acuity.
What Is A Cataract?
A cataract is an intraocular lesion (a lesion inside the eye) that changes the lens’s opacity and appears as mildly foggy or completely white, cloud-like discoloration.
The lesion causes the fragile lens to become deformed. Once deformed, the lens cannot correctly direct the light onto the retina, which affects the eyesight.
The cataract has a progressive and non-reversible nature, which means once the lens changes start, they cannot be stopped, nor can their consequences be repaired.
Based on the condition’s advancement, the consequences range from decreased visual acuity to complete blindness.
Cataracts can affect one or both eyes. It can also affect only part of the lens or fill it completely.
If the affected part is the center of the lens, the cataract interferes with the light path and impairs the visual acuity. If the affected part is in the lens’ periphery, the vision is mildly disturbed by the presence of foggy shades. Ultimately, if the cataract fills the entire lens, the vision is completely impaired.
Another, final cataract classification considers the cataract’s developmental stage. Based on this classification, the cataract can be:
- Immature – if it in its early developmental stages and usually affecting only a small portion of the lens.
- Mature – if it is in its more advanced developmental stages and usually affecting more extensive parts of the lens or the entire lens.
The Different Types Of Cataracts
When someone mentions cataracts, the first thing that comes to mind is that the sufferer is old. This applies to both humans and canines. We directly associate cataracts with old age.
This is mainly because the age-related cataract is the most common type.
However, there are several other types. For example, a metabolic cataract occurs due to a metabolic condition, more often than not, diabetes.
There is also a so-called “acquired” cataract that develops due to trauma, injury, or chemical damage to the eye.
Finally, there is a juvenile cataract. A juvenile cataract develops before birth or shortly after birth. The juvenile cataract’s origin is associated with problems affecting the pregnant mother and defective genes.
What Is A Juvenile Cataract?
We already explained that the term “cataracts” means clouding the lens’s proteins, which causes the lens to lose its transparency and become foggy or completely white. The word “juvenile” means young.
In a nutshell, the diagnosis of juvenile cataract translates to clouding of the lens in young individuals, or in our case, in puppies less than six months of age.
The Different Types Of Juvenile Cataract
There are two types of juvenile cataract:
- Congenital juvenile cataract – develops before birth while the puppy is still inside the mother’s womb
- Developmental juvenile cataract – develops shortly after birth while the puppy’s eyes are maturing.
What Causes Juvenile Cataracts?
Acquired Juvenile Cataract
If it is caused by problems affecting the pregnant mother or the newborn puppy, the condition is referred to as an acquired juvenile cataract.
Viral infections of the mother or the newborn puppy are a common cause of acquired juvenile cataracts. Other common causes are physical injuries and inadequate nutrition.
Hereditary/Congenital Juvenile Cataract
The condition can be caused by a complex mix of faulty genes passed from the parents to the offspring via complex modes of inheritance.
If the underlying cause is faulty genes, the condition is referred to as hereditary or congenital juvenile cataract.
Breeds Predisposed To Juvenile Cataract
Occurring in over 80 dog breeds, hereditary juvenile cataract is among the most frequently reported genetic diseases in dogs.
A hereditary juvenile cataract occurs in the following breeds:
- German Shepherds (age of onset: +8 months)
- Belgian Shepherds
- Afghan Hound (age of onset: 6-12 months)
- Staffordshire Bull Terrier (age of onset: +6 months)
- Bichon Frise
- Boston Terriers (congenital)
- English Cocker Spaniels
- American Cocker Spaniels (age of onset: +6 months)
- Cavalier King Charles Spaniels
- English Springer Spaniels
- Welsh Springer Spaniels (congenital)
- Swedish Lapland Dogs
- Finnish Lapland Dogs
- Norwegian Buhunds
- Alaskan Malamutes
- Siberian Huskies (age of onset: +6 months)
- Tibetan Terriers
- West Highland White Terrier (congenital)
- Old English Sheepdog (congenital)
- Poodles (age of onset: +1 year)
- Miniature Schnauzers (congenital or +6 months)
- Standard Schnauzers
- Giant Schnauzer
- Labrador Retrievers (age of onset: +6 months)
- Golden Retrievers (age of onset: +6 months)
- Chesapeake Bay Retriever (age of onset: +1 year)
- Newfoundland Dogs
Signs And Symptoms Of Juvenile Cataract
The two most strikingly noticeable signs that a puppy or dog has cataracts are:
- Presence of white or faintly yellow-casted, opaque spot or spots on the eye with no distinctive shape and size
- Failing vision
In addition to the eye clouding, a puppy/dog with cataract can also manifest the following signs:
- Eye color changes
- Pupil shape, size and color changes
- Watery eyes due to frequent eye rubbing and pawing at the eyes
- Squinting (if instead of focusing, the damaged lens shatters the light rays)
A puppy or dog with failing vision will likely:
- Bump into walls, doors, furniture or basically, anything in its path
- Seem as overly shy because are reluctant to move
- Be afraid of exploring darkened rooms and areas
- Be reluctant to go in new and not very well-known environments
- Avoid jumping on and off furniture
- Avoid going up and down stairs
- Disobey commands given by hand signals while obeying the same commands when given by vocal signals
- Misjudge distances
- Have unsure footing or walk in an unusual high-stepping pattern
Diagnosing Juvenile Cataract
A vet can confirm the presence of a cataract by conducting an ophthalmic examination. Although the disease can be diagnosed simply and without the need for specific tests and procedures, the general vet will likely recommend seeing a veterinary ophthalmologist.
The veterinary ophthalmologist will perform a specific diagnostic test called an electroretinogram (ERG). Performing the ERG involves placing a prosthetic lens over the dog’s eye and several sensors around the dog’s eye and head.
The sensors are linked with a light source producing variably pulsed light rays. The concept is to stimulate the visual pathways and test the dog’s overall vision system. The procedure is performed on a sedated dog.
Basically, the test’s goal is not conclusively confirming the presence of a cataract but determining whether the cataract is the only vision impairment culprit.
This is important for setting up a treatment strategy. If the dog has additional problems affecting its vision, eye surgery will not significantly improve vision.
On the other hand, if the cataract is the only ocular problem, the vet will recommend surgical cataract removal.
Surgical Treatment Of Juvenile Cataract
Over the past few decades, cataract surgery techniques improved significantly. Although there are several frequently used techniques, the concept is similar in all of them.
First, the lens is removed (either physically or ultrasonically liquefied) through a small incision. A prosthetic lens is then implanted, and the incision is closed with an extremely fine suture.
Several prosthetic lens options are made of different materials, such as silicone acryl foldable and polymethylmethacrylate (PMMA). Each type has its pros and cons.
Alternatively, with the owners’ previous agreement, the surgeon may simply remove the diseased lens and close the incision without implanting a prosthetic lens. In such cases, based on the light/dark variations, the dog will be able to see vague patterns. This limited vision is something most dogs cope with really well.
Finally, as with any other surgical procedure, complications are possible. The most common complications following a cataract removal surgery are:
- Pain and infection
- Retinal detachment
To minimize the risk of complications, the vet will:
- Bandage the eye or even temporarily suture the eyelids
- Prescribe oral drugs and topical drops and lubricants
- Recommend using the “cone of shame” (Elizabethan collar) for at least two weeks post-surgery
- Recommend restricted movement and excitement avoidance during the first week after the surgery
- Schedule frequent follow-ups and examinations
The prognosis for dogs with surgically removed cataracts depends on the cataract’s stage at the time of removal and the presence/absence of co-existing eye problems.
Early removal in dogs with no co-existing eye issues ensures excellent visual acuity return in over 90% of the cases.
Juvenile Cataracts – Expectations
When a puppy or dog is diagnosed with a juvenile cataract, dog parents often ask what to expect and when to expect further changes? Sadly, there are no straightforward answers to these questions.
That is mostly because the onset of juvenile cataracts varies among individuals. Although it often occurs before or shortly after birth, the first signs of hereditary juvenile cataract may not appear until the dog is between 6 months and two years old in certain breeds.
It may take as much as five years for the first signs to become apparent in rare cases. Basically, the first factor determining the condition’s progression pace is its onset.
What is more, not all cataract cases progress at the same pace. In fact, sometimes, the cataract may remain partial forever.
In such cases, the dog will never experience blindness – its vision will be blurry, but it will distinguish the basic shapes.
In other cases, a dog with partial cataracts may lose its vision but not due to the cataract itself but because of its potential complications.
For example, the cataract may lead to glaucoma (a painful and blinding increase of the pressure inside the eye).
If the glaucoma is advancing at a higher rate than the cataract, the reason for the dog’s blindness will be the secondary complication – glaucoma.
All in all, the cataract’s progression and consequences cannot always be predicted because of the differences in its initial onset, advancement pace, progression potential, and presence of secondary complications.
Therefore, all dogs should have their eyes frequently checked. Regular controls ensure early detection of juvenile cataracts or, in cases of already diagnosed cataracts – deterioration control.
Early diagnosis and prompt treatment are linked with better treatment outcomes.
Can Juvenile Cataracts Be Prevented?
All dogs intended for breeding should be examined and tested for cataracts and, according to The Canine Eye Registration Foundation (CERF), excluded from breeding programs if affected or carriers of the disease.
The fact that in some breeds, juvenile cataracts may not appear until six years of age accents the importance of testing even more.
Namely, a dog that does not show visible signs of cataracts can be bred several times before reaching the age of six and actually manifesting its first juvenile cataract signs.
To achieve the best results possible, it is advisable to test the breeding individuals and their parents, grandparents, and great grandparents.
They all need to be free from cataracts for the breeding individual to receive the green light for breeding.
Luckily, if dog parents and dog breeders collaborate, juvenile cataracts can be, if not altogether eliminated, at least controlled in several predisposed dog breeds.