Hereditary Cataracts:

 Blinding to the Cavalier King Charles Spaniel

The Cavalier King Charles Spaniel is prone to develop either of two types of hereditary cataracts, according to the American College of Veterinary Ophthalmologists (ACVO).  The most common form in the CKCS is an early-onset juvenile cataract, which appear by 6 months of age in both eyes and progress to complete cataracts and total blindness by between ages 2 and 4 years.

 What It Is

A cataract is defined as an opacity in the lens. The eye's lens usually is clear or transparent, and focuses light rays on the retina. The opacity is usually white, but can have a yellowish or grayish appearance as well, and it scatters the light rays. The extent of the vision impairment is determined by the size and location of the cataract in the lens.  The size ranges from pinhead marks to total lens opacity. The larger the cataract, the more severe the effect on sight.

The other form of inherited cataract which has been identified in Cavaliers is congenital, meaning that it was present at and existing from the time of birth or before 8 weeks of age.  The congenital cataract  is bilateral, but not necessarily symmetrical, with the two eyes often being affected to different degrees, and it often is associated with micropthalmos, an abnormal smallness of the eyeball. The more severe the micropthalmos, the more extensive is this type of cataract.

Cataracts also are a consequence of diabetes. In diabetic dogs, cataracts may advance much more  rapidly than inherited cataracts.

All CKCSs should be examined at least annually by a board certified veterinary ophthalmologist.  They are listed on this webpage of the website of the ACVO: www.acvo.org/locate.htm

 Symptoms

Cataracts usually are discovered first by noticing discoloration in the Cavalier's eyes.  The center of the eye will appear light gray or yellowish, or white.  Also, the owner likely will observe the dog having visual difficulties. The Cavalier may bump into things, including familiar objects, or appear tentative about moving up or down on stair steps.

 Diagnosis

Cataracts are visible using an ophthalmoscope and may be discovered during a routine eye examination.

Treatment

If the cataracts seriously affect the dog's vision, they may be removed by surgery.  Some ophthalmologist surgeons also will insert an artificial replacement lens which reportedly will restore near-normal vision.  Implant replacement surgeries usually take about an hour per eye and reportedly are about 90% of them have been successful for dogs deemed to be good candidates for the surgery.  Surgeons usually recommend operating on both eyes at the same time, since if a cataract is diagnosed in one eye, the other eye usually will develop one, as well.

Cataract surgery and the related services reportedly cost between $1,500.00 and $2,500.00 for both eyes, depending upon whether or not replacement lenses are implanted.  Following the surgery, the dog will be required to wear an Elizabethan collar for about three weeks, to avoid scratching the eyes while they are healing.

A new topical eye drop product consisting of N-acetyl carnosine and antioxidants and nutrients, called OcluVet, has been developed by PractiVet. The manufacturer represents that clinical studies of the product have shown "a measurable reduction in opacity" of the cataracts in 80%+ of the eyes in the studies.  The degree of improvement seems to hinge on the age of the cataract, with immature cataracts being more responsive to the treatment than mature cataracts. See Current Research, below, for additional details.

Current Research

4N-acetyl carnosine. In a study of 64 dogs and other species, conducted by veterinarians in 23 clinics in the United States, 64 patients with cataracts or lenticular sclerosis conditions were treated with eye drops consisting of antioxidants and nutrients, including N-acetyl carnosine, L-Carnosine, L-Taurine, and Glutathione.  After eight weeks of treatment, 56 of the 64 patients showed a measurable reduction in opacity density or improved acuity.  The study was conducted by PractiVet, the manufacturer of the eye drop product, which is called OcluVet.  PractiVet is located in Phoenix, Arizona. Its website is http://www.ocluvet.com

In a 2006 article, Dr. David L. Williams of the Department of Clinical Veterinary Medicine at the University of Cambridge in the UK reports the results of a similar study with the same OcluVet product. His results:

"Fifty-eight eyes of 30 dogs were evaluated, 22 with mature cataract, 13 with immature cataract, 9 with cataract associated with other intraocular disease such as uveitis and 14 with nuclear sclerosis alone. One dog was unilaterally anophthalmic after previous enucleation and one had a phthytic eye after previous uveitis-induced glaucoma. Image analysis showed a reduction in mean LOI in all cataract groups (mean resolution in opacity of 2.3± 0.33% for all cataracts), although this was only statistically significant in those eyes with immature cataract (mean resolution of opacity 4.5± 0.33%) or nuclear sclerosis (mean decrease in opacity 5± 0.37%). Reduction in lens opacity was seen in eyes with mature cataract (0.5± 0.4%) and in miscellaneous cataract associated with intraocular inflammation (1.3± 0.4%), but these changes were not statistically significant. Owner evaluation of visual capability, however, suggested improvement in vision in 80% of cases by the end of the study."

Dr. Williams concluded that: "This study demonstrates some marginal reduction in lens opacification in a substantial number of cases of canine cataract with the use of a topical nutritional antioxidant formulation including N-acetyl carnosine. Lens opacification was improved with treatment in eyes with immature cataract or nuclear sclerosis while in eyes with mature cataract or cataract with associated intraocular inflammatory pathology less reduction was seen."

Dr. Williams may be contacted at, telephone in the UK: 07939 074682; email: doctordlwilliams@aol.com; website: http://davidlwilliams.org.uk

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