A cataract is an opacity of the lens of the eye. The lens is like an onion; made up of many layers. A thickening anywhere in the lens results in a cataract. As a dog matures and ages, the layers continue to grow, much as an onion does. This growth may eventually make a cataract more visible when it originally was not. There are many different types of cataracts. Cataracts are classified by their location within the lens of the eye, how thick they are, and how much of the lens they cover.
Several types of cataract have been found in Chesapeakes. Not all cataracts are hereditary in nature. Many times, a cataract may be too small for it to be classified correctly, or even to tell if it is a true cataract. These will result in a Breeder's Option Diagnosis of "E1-punctate cataract, significance unknown" notation on a dog's CERF certificate. Dogs with this notation should be re-examined at least six months to a year after the initial examination, to see if it is a cataract, and if so, what kind.
Cataracts may occur as a secondary condition to another existing medical problem such as diabetes or Progressive Retinal Atrophy. Some are secondary to trauma. One type of secondary cataract seen in Chessies is an artifact left behind by a Persistent Pupillary Membrane. PPMs are hereditary, and increasingly being diagnosed in Chessies.
Primary Cataracts are generally hereditary in nature. Posterior polar ("triangular") cataracts are the most commonly found primary cataract in this breed. However, they differ in several important ways from PPCs found in Labradors or Golden Retrievers. The inheritance pattern for these type of cataracts in Chessies is not known. Research is ongoing to obtain more information on cataracts in all retriever breeds, including Chessies.
Information on 1979 JAVMA Cataract Article
Below is an excerpt from a JAVMA article relating to Posterior Polar cataracts in Chesapeake Bay Retrievers. Also included is information on how you may receive a free copy of this article. Much research is ongoing into cataracts in the Chesapeake breed; as you can see, this has been a recognized condition for at least the last 30 years. To date, we still do not have many answers into canine cataracts.
Cataracts in Chesapeake Bay Retrievers
Kirk N Gelatt, VMD; R David Whitley, DVM; J Daniel Lavach, DVM, MS; Kathleen P Barrie, DVM; Leslie W Williams DVM
Journal of the American Veterinary Medical Association, 1979;175:1176-1178
SUMMARY: Cataracts developed in 13 of 27 related Chesapeake Bay Retrievers. The posterior pole, "Y" sutures, and equatorial cortices of the lens were predominantly affected. In one affected dog, the cataracts had progressed to hypermaturity, permitting restoration of vision. The trait was believed to be dominant, with incomplete penetrance.
DISCUSSION: Cataracts have been reported in the Golden Retriever, Labrador Retriever, and now the Chesapeake Bay Retriever, but their clinical appearance differs among the three breeds. In the Golden and Labrador Retrievers, the cataract develops as a posterior axial triangular zone that infrequently progresses to total lens involvement. The mature cataracts that infrequently affect the Golden Retriever have been theorized to occur in dogs homozygous for the trait. The posterior polar cataracts in the Chesapeake Bay Retriever are similar to those in the Golden and Labrador Retrievers; the Y suture and equatorial involvement appear unique to the Chesapeake Bay Retriever. Analysis of the pedigree did not identify the mode of inheritance; however, a dominant trait with incomplete penetrance might be the mode.
To obtain a copy of the complete article, please contact Diane A Fagen (firstname.lastname@example.org), American Veterinary Medical Association. Include your name and mailing address, and note that you are being forwarded from the ChessieInfo.net web site. The article will be sent to you immediately at no charge.