What Is ISD?
Though eye problems tend to take a back seat to other health concerns in Dalmatians, an eye disorder known as iris sphincter dysplasia (ISD) has prompted the Dalmatian Club of America (DCA) to form an Eye Study Group (ESG) to learn more about the condition.
ISD is the result of poorly developed iris sphincter muscles. The pupils of dogs with ISD do not properly contract in bright light. Dogs usually are uncomfortable and often squint in sunlight. The disorder exposes the interior of the eye to ultraviolet light that may potentially cause serious vision problems, such as cataracts or retinal damage, as dogs age, experts say.
"We need to find out more about ISD," says Susanne Hughes, D.V.M., a Dalmatian breeder and veterinarian at Colony Park Animal Hospital in Durham, N.C. She wrote an article in 1991 for the DCA publication, The Spotter, in which she reported noticing the condition in her own dog and seeing it in her practice.
Eight years later, in 1999, Hughes enlisted the help of Robert English, D.V.M., PH.D., a board-certified veterinary ophthalmologist in Cary, N.C. English examined about 80 Dalmatians and found that nearly 15 percent of the dogs had some degree of ISD. He attributed the anatomical source of the problem to poorly developed iris sphincter muscles, rather than atrophy.
That same year, an eye clinic was held at the DCA National Specialty in Denver. Steven Roberts, D.V.M., a board-certified veterinary ophthalmologist in Denver, examined 59 dogs and found that 27 percent were affected to some degree with ISD.
In 2002, the DCA formed the Eye Study Group. Members Claudia M. Rusconi, Marie E. Zimmerman and Andrea Paccagnella developed educational materials that include a protocol for eye exams. Dalmatian breeders and owners may provide the protocol to veterinarians to help them detect ISD. In addition, a Dalmatian Eye Registry Database is in its testing phase.
"The No. 1 priority is to determine if ISD is genetic and whether it may lead to more threatening disorders, such as blindness, cataracts or rod-cone degeneration," Zimmerman says. If the condition is determined to be genetic, the second goal should be to determine the pattern of inheritance in order to develop a genetic test. A genetic test would enable breeders to identify dogs carrying genes that cause ISD.
Most importantly, Rusconi says, we want to raise awareness of the condition among breeders and owners. "We are responsible for the future of the breed," she says. "This translates into preserving and improving Dalmatian eye health."
Testing for ISD
The first step toward achieving these goals depends on involvement from Dalmatian breeders. Data needs to be collected to determine the prevalence of the disorder. "We would like to do pedigree studies," Hughes says. "Not as many dogs have been screened as we would like."
Hughes and the ESG encourage Dalmatian breeders and owners to have CERF (Canine Eye Registration Foundation) examinations. CERF recently added ISD as a Category D (iris) eye condition in which information is collected for the CERF database. Please note that CERF refers to ISD as "iris hypoplasia."
For more information about ISD as well as other eye conditions, please visit the CERF web site at www.vmdb.org/cerf.html. You may also visit the web site of the Dalmatian Club of America to learn more about ISD. Background information about the condition and the protocol developed by the ESG can be found at http://www.thedca.org/eyes.html.
It is important to ask the veterinarian to look for ISD before the exam begins so the pupils can be evaluated before pupil-dilating drops are administered. "It's also best for the veterinarian to wait until the dog calms down, as excitement can sometimes cause the pupils to dilate," Zimmerman notes. Regardless whether ISD is found, a notation should be made on the CERF form.
The ESG encourages all Dalmatian owners and breeders to participate in eye screenings and submit data so that statistically significant information can be gathered for future guidelines and studies. Fortunately, gaining access to a veterinarian for an eye examination is not difficult.
"Eye clinics are usually available at all-breed dog shows," Zimmerman says. Or an owner may find a veterinary ophthalmologist certified by the American College of Veterinary Ophthalmology by checking the CERF web site at www.vmdb.org/clinic.html.
Living with an Affected Dog
If a veterinarian diagnoses your dog with ISD, be aware that bright sunlight is not only uncomfortable for him but also could affect his future eye health. "Affected dogs may be at greater risk of forming cataracts and other retinal degenerations," Zimmerman says. "My affected bitch had cataracts and retinal scarring at 2 years of age." She advises owners to keep an affected dog indoors or in a shaded area during the sunniest times of the day.
ISD can lead to difficulty in focusing due to the constant dilation of the pupils. Owners should monitor an affected dog's eye health as the dog ages with frequent eye checkups and careful observation for vision changes. "Until more is known about ISD, it is prudent to have an affected dog regularly checked for cataracts and retinal degeneration," Rusconi says.
Recommendations for Breeders
It's difficult to make breeding recommendations until more is known about ISD. "At a minimum, you wouldn't want to breed two affected dogs," Hughes says. Since the disorder has varying degrees of severity, it's possible to have an affected dog without being aware of it. The ESG suggests that breeders CERF and ISD test their stud dogs and bitches before mating.
In addition to testing breeding stock, litters can be tested as young as 6 weeks. "All puppies (show and pet quality) should be tested for ISD before leaving to their new homes, between the ages of 6 and 8 weeks," states the ISD protocol developed by the ESG.
The exam is painless and does not require dilated pupils or undue stress. "If the trait follows a recessive pattern of inheritance as previous researchers suspected, carriers would not show signs of the condition whilst eventually passing it to future g
enerations," states the protocol.
The discovery of affected puppies would help identify carriers. Thus, the ESG recommends a standard CERF exam starting at the age of 1 year. For adult dogs, other than breeding stock, that weren't screened as puppies, the protocol calls for testing between the ages of 1 and 2 years, then once more between 7 and 8 years.
The Eye Database
The Dalmatian Eye Registry Database currently is being tested. As of May 22, 2004, data on 20 Dalmatians was included. Once the system is running smoothly, data will be forwarded regularly to the Orthopedic Foundation for Animals (OFA) where it will be connected to CHIC (Canine Health Information Center), says Denise Powell, the outgoing chairwoman of the DCA Health and Research Committee.
"Dals that are free of eye problems including ISD will receive an Eye-D number," Powell says. "Embedded in the number will be the year the exam was performed and the age of the dog at the time of the exam so that anyone looking at the Eye-D number will know if it is current."
In order to study whether Dalmatians develop iris problems as they age, data is needed over time. "The only way we will be able to learn more about ISD is to gather data on as many Dals as possible multiple times during their lives," Powell says.
The Color Connection
"ISD may be a problem primarily in liver-spotted dogs," Hughes says. That could be because liver dogs have lighter eyes making the dilated pupils more obvious. However, English's screening found the same incidence in livers and blacks, she says.
The ESG is anxious to look at the color question more closely, but can only do so if Dalmatian owners have their dogs screened and added to the eye database. More statistical data needs reviewed before a concluding statement can be made related to color and ISD in Dalmatians, says Rusconi.
What the Future Holds
Dalmatian breeders can help the Eye Study Group learn more about iris sphincter dysplasia by screening their dogs and contributing data to the Dalmatian Eye Registry Database. This data can provide the basis for scientific research that could lead to a determination of the mode of inheritance and ultimately a genetic test for ISD.
Signs of ISD
Dalmatian owners or breeders who notice any of the following signs should make an appointment with a veterinary ophthalmologist to have their dog checked for iris sphincter dysplasia or other eye problems:
- Squinting when exposed to bright light
- Abnormally dilated pupils or pupils that don't adjust to different light situations
- Difficulty seeing at night or in poor light
- Partial or total blindness
- Cataracts (cloudiness in the eyes)
- Difficulty adjusting to the light after coming inside from the bright sun
- Oval-shaped irises
The Dalmatian Eye Registry Database
Dalmatian owners who decide to have a CERF (Canine Eye Registration Foundation) exam including an iris sphincter dysplasia (ISD) test for their Dalmatian should print out the ISD protocol developed by the Eye Study Group (ESG) of the Dalmatian Club of America (DCA) to take along. The protocol may be found at www.thedca.org/isd2.html.
CERF recently added ISD as a Category D (iris) eye condition in which information is collected for the CERF database. However, please note that CERF refers to ISD as "iris hypoplasia."
You should give the protocol to the ophthalmologist before the exam, so that the ISD test can be done prior to the pupils being dilated. Whether your dog is affected or unaffected with ISD, the veterinarian should report that on the CERF form.
The ESG encourages breeders and owners to send in information from the CERF test to the Dalmatian Eye Registry Database developed by the ESG. You will then be given a registry number.
To add a dog to the Dalmatian Eye Registry Database, please send the following information to database manager, P. Karen McDonnell, at 351 El Margarita Road, Yuba City, CA 95993-9380:
- A legible copy of the CERF exam form
- A copy of the dog's pedigree or AKC registration certificate (Information on affected dogs without pedigrees is still helpful, notes Zimmerman.)
- A self-addressed stamped envelope or e-mail address
- A check for $1 made out to the Dalmatian Club of America
- Permanent identification number (tattoo or microchip), if available