Cataracts

dRAFT last updated 5/1/25

My Research Notes

Cataract

An eye condition where the lens becomes partial or complete opaque (generally whitish) It is the result of pathologic changes in lens protein composition or disruption of lens fibre arrangement.
Cataract can be classified by age of onset:
Congenital Cataracts: These are cataracts that are present at birth.
Developmental (Early Onset) Cataracts: cataracts are those that develop early on in life.
Senile (Late Onset) Cataracts: Cataracts that occur in dogs over six years of age.
There can also be categorised by location of the opacity on the lens
Cataracts are the most common cause of blindness in dogs, it is progressive.

"In cases where cataracts are complete and affect both eyes, blindness results. The prudent approach is to assume cataracts to be hereditary, except in cases known to be associated with trauma, or other causes."
Note
"Congenital cataracts were reported in 1975 as "Red Cocker Spaniels", presumably English Cocker Spaniels, in Denmark. The cataracts affected the anterior capsule; in some cases the cortex and/or nucleus were opaque. Associated findings in some dogs were persistent pupillary membrane (PPM) and/or microphthalmia. It is likely that these cataracts are part of a syndrome characterized by multiple congenital ocular anomalies. The condition is familial, but a specific mode of inheritance has not been defined."

Congenital Cataract

There appears to be a very small incidence of Congenital Cataracts (present at birth)
Research further - re ACVO ref to "red cockers in Denmark - nothing found a yet. CSDB data shows that all affected are in Europe between 1998-2014. (12 of these in the Netherlands)
Research further required in regarding to the % - I'd assume these are these comparable with other breeds generally but it needs to be checked and monitored

Cataracts Around The World

No dogs of NZ origin in reported data to date.

Check and add OFA & CERF
CSDB data below

informal data collected from CSDB
Data lasted updated January 2025

Data for congenital cataracts recorded separately on CSDB

informal data collected from CSDB
Data lasted updated January 2025

% are more important when considering these statistics rather than the numbers recorded above, as some dogs results may have been duplicated in different databases

Responsible breeders are screening their breeding dogs for inherited eye diseases. An ophthalmic examination and certification provide breeders with vital information to improve future eye health.

Most vets can diagnose common eye conditions and disease, but some require a Specialist Veterinary Ophthalmologist.

There is a current accessibility issue with Ophthalmologist Vets in NZ, I believe CHWC are not including Ophthalmologist Eye Certs in LRL submissions, until this can be resolved.
There is no reason we couldn't include Eye Cert from general practise vets.

Cataracts From the ACVO 2020

"Blue Book"

These figures are for all cataracts not specifically Heredity cataracts - which have yet to be specified as a sub category in the ACVO Blue Book data. Based on these figures there has been a significant reduction in the number of dogs tested. Keep in mind that most dogs are only evaluated/tested because clinical symptoms have already developed. The average per year between 1993-2017 was 475 and approximately half this between 2018-2022 254 dogs, I can only assume that this is due to a reduction in clinical symptoms, and if so then the improvement is noteworthy.

The graph below uses these generalised figures and coverts them to yearly averages- this is not a scientific calculation.

NB The ACVO does not determine between pedigree and non pedigree. The breed is as listed by the owner, so if an owner says there dog is a cocker (even though it might be 1/2 fox terrier) it's list in the statistics as a cocker. The same is true for most data acquired through general vets. The majority of industry data is collected by all Insurance based... find my link for this

My thoughts on developing minimum breed standard testing. undertake clinical evaluations for other Eye Conditions.

These other conditions can be diagnosed by regular vets, and we should allow certification from them. This would resolve the ongoing issue of accessibility to Specialist Veterinary Ophthalmologists in NZ. Any vet that identifies any issue should not certify that dog, but it must be referred to a Veterinary Ophthalmologist for a Specialist consultation and certification.

To Research .... Hereditary Cataracts

Hereditary Cataract Eye Disease Cataract is a disease of the lens of the eye in which the normally clear lens becomes opaque or white. This interferes with vision and can result in blindness. Cataracts are the most common cause of blindness in dogs, it is progressive and bilateral (affecting both eyes).

Research - Are cocker spaniels affected by HC ???

HC are an inherited form of cataracts, the most common cause of blindness in dogs. HC are an inherited disease of the lens in a dog’s eye. Essentially it occurs when the clear lens of the eye becomes opaque or white. This interferes with the dog’s vision and puts major strain on the eye resulting in blindness.

According to ophthalmologists, a cataract can occur in varying degrees, it may be the equivalent of a minuscule mark or it may result in total lens opacity. HC may be present at birth or may develop at any age, though early detection is critical in order to prevent progression to a severe stage of visual impairment. Severity - 3 HC has a moderate ‘degree of severity’, while it is not a fatal disease resulting blindness may decrease the quality of life for both you and your dog.

Symptoms Affected dogs will show opacity of the lens in their eye when examined; they may also exhibit signs of impaired vision and be unable to focus on small objects such as a ball or toy. n serious cases affected dogs will show signs of severe visual impairment such as failing to avoid objects in their path and have difficulty moving around familiar areas.

While some dogs may not exhibit severe characteristics of visual impairment, they may still be affected by the disease and it may go unnoticed. This can cause complications later in life, as though the disease can be managed through surgery at early stages, sadly there is no cure for blindness in dogs.

Genetic Testing Animal Network provides a DNA test that determines the genetic predisposition to HC.

HC is autosomal recessive. A direct gene test can determine whether a dog is clear, a carrier or affected. A recessive phenotype (trait or disease) requires two copies of the causative gene variant for the phenotype to be expressed.

If both parents have two copies of the recessive gene variant, then 100% of all offspring will show the phenotype. If one parent has two copies of the recessive gene variant and the other parent is a carrier with a single copy, then 50% of all offspring will show the phenotype and 50% will be carriers. If both parents are carriers of the recessive gene variant then 25% of all offspring will show the phenotype, 50% will be carriers and 25% will be clear. If one parent is a carrier and the other is clear then 50% of offspring will be carriers and 50% will be clear.

Due to the probability of genetic inheritance, the actual outcome of mating's may vary from expected ratios, eg 2 carriers may produce all Clear or all Affected. For an explanation of possible genetic status of offspring please refer to our fact sheet on Breeding Strategies.

There are multiple genes that cause cataracts in dogs – not all forms are hereditary: Australian Shepherds (dominant trait), Boston terrier (Juvenile HC), Staffordshire Bullterrier and French Bulldog.

Breeds Affected Australian Shepherd Boston Terrier French Bulldog Staffordshire Bull Terrier ... To research further - Are cocker spaniels affected by HC ???