Breeders Option Diagnosis
The Canine Eye Registration Foundation (CERF) has a category known as Breeders Option Diagnosis (or BOD for short.) The BOD is a means for veterinary ophthalmologists to note things found on CERF eye exams which may or may not be genetic, or which may not be on a breed's list of non-certifiable disorders. In Chesapeake Bay Retrievers, dogs with PRA or certain distinct types of cataract may not be CERFed. However, there are other things whicjh may be found on CERF exams that may be hereditary, but do not interfere with a dog's vision. Other things affect structures surrounding the eye, but not the eye itself. And there are "gray area" findings; these are things which may develop further, but are not easily diagnosed at the time of the exam. The veterinary ophthalmologist will note these things on the exam sheet, and CERF will notate them on the dog's CERF certificate. The reverse side of the certificate has a list of the BOD codes and what they stand for. But it does not really tell you what you need to know as a breeder or buyer who encounters a dog with one of these BOD notations.
The BOD is also sometimes known as a Category. This is how CERF divides the diagnoses into classifications. Diagnoses are categorized starting with external structures (eyelids) and working toward the back of the eye. Category A=disorders of eyelids and surrounding structures; B=third eyelid disorders; C=cornea (the clear tissue that covers the surface of the eye); D=iris (the colored part of the eye); E=lens (the part of the eye that focuses light); F=Vitreous (a gel-like liquid that fills the eye) and G=Fundus (the collection of tissues and structures that lines the back of the eye; includes the retina). A Breeders Option Diagnosis may or may not be a permanent part of a dog's CERF report. Since a CERF exam is a physical examination of the dog's eye, a veterinarian may note something at one exam, only for it to be resolved on the dog's next exam. Some things may look like a disorder, but may just be what is called an "artifact", a temporary change in the eye which resembles a hereditary condition. Likewise, there are some conditions (such as entropion or ectropion) which can be corrected through surgery. This also will lead to removal of the BOD from the dog's CERF record. Often times when a BOD is noted during the exam, the veterinarian will tell the owner that the dog should be re-examined within a certain time frame. The vet will want to look to see if there are changes which indicate that the condition is not of concern; conversely, some conditions may become more easy to see with time, and may progress to non-certifiable status.
What does this mean for breeders and puppy buyers? A Breeders Option Diagnosis means that conditions listed may or may not be hereditary in nature. It also means that breeders will need to keep track of trends within their own bloodlines. For instance, a breeder may have a bitch from a bloodline where there are dogs with entropion. While this condition does not stop a dog from being CERF certified, it does get noted on the BOD portion of the certificate. So this breeder may decide to look for a stud dog for his bitch that comes from a line where little or no entropion has been found. In this manner, this breeder can maintain valuable bloodlines, while reducing the chance of producing entropion in future generations.
Common BOD Categories found in Chesapeake Bay Retrievers
This section will describe some of the more common BOD listed on Chesapeake Bay Retriever CERF results. Other diagnoses have been found in Chessies from time to time; this will focus on the most common ones.
A1 - Entropion. This is an inrolling of the eyelids, causing irritation of the eye. Severe cases can cause ulceration of the cornea. Symptoms include chronic tearing/gumminess of the eye(s) affected, pawing at the eye, squinting. Entropion is caused by a combination of factors, including head structure, skin thickness, eye shape and placement, and skin quantity. Entropion can range from very mild cases to severe. Most Chessies do not develop severe entropion; many cases can be managed by "tacking" the eyelids until the pup grows into them. Other cases require surgery to remove excess eyelid folds.
A3 - Distichiasis. Distichiasis is an extra eyelash to a row of eyelashes which may or may not brush against the dog's eye, causing tearing. Many Chessies have distichia, and it seems to occur in every line. This may be a result of the Chessie's unique coat. Dogs may be diagnosed with distichiasis at one exam, not have it at another, only to have it diagnosed again at a later exam. Coat cycle may play a part in this, as when a dog is out of coat, the extra set of eyelashes may not be present. Depending on location, number, and harshness of the eyelash hairs, there may be no symptoms, up to irritation and ulceration of the eye. Extra lashes may be permanently removed via surgery for those dogs experiencing discomfort or eye injury from the distichia.
D3A - Persistent pupillary membrane-iris to iris. The pupillary membrane is a tissue that exists in the fetus, supplying blood to the eye lens before birth. After birth, the membrane is slowly resorbed and disappears, usually by eight weeks of age. In cases where the membrane does not dissolve completely, strands of the PPM may be seen crossing the pupil. When a PPM attaches to the lens, it can cause a cataract. When it attaches to the cornea, it can cause corneal opacities. For this reason, dogs with PPM should not be bred together, as there is no way of knowing if the pups will inherit incomplete resorption of the pupillary membrane, and if it will attach to the lens or other eye structures, creating visual problems.
E1 - Punctate cataract, significance unknown. This is another fairly common condition found in Chessies. E1 dogs have cataracts that are so small, or placed in the lens in such a way that it is not possible to determine with certainty whether it is a hereditary cataract. Please note: the use of the term "punctate" refers to the size (very small, or pinpoint), not to the cause. Many people assume that punctate means "caused by a puncture". This is incorrect. "Punctate" means a tiny dot; a pinpoint in size. In the case of a true cataract, the cataract becomes thicker and easier to identify with time; on the other hand, eye lesions caused by injuries or temporary illnesses may not. For this reason, dogs with E1 diagnoses should be re-examined in six months to a years' time to see if any changes have taken place. Likewise, breeders should keep track of true cataracts occurring within their bloodlines, and keep a close watch on any E1 diagnoses, as these may also develop into hereditary cataract.
G1 - Retinal dysplasia; folds. Retinal dysplasia means incorrect development of the retina. As the eye develops before birth, the tissue at the back of the eye (retina) forms from several layers of embryonic tissue. When these layers do not connect correctly, folds will develop. Retinal dysplasia is therefore congenital, not developmental. Dogs with retinal folds have them at birth, and do not develop more with age. Unlike Labrador Retrievers, Chesapeakes have not been shown to have a form of retinal folds that is genetically linked to dwarfism.