Pigmentary Uveitis Study

Findings from a research study published late last year (Esson D et al, 2009) have raised questions about the underlying nature of pigmentary uveitis (PU). This disease previously had been believed to include inflammation as a consistent feature, and indeed, even the suffix “itis” in the name refers to inflammation. This new study closely examined the enucleated (surgically removed) eyes from dogs with advanced disease, and found minimal to moderate inflammation in eight eyes, but no evidence of cellular inflammation in the remaining seven. However, three features present in all of the eyes were cysts; abnormal pigment; and changes in the structure that drains fluid from inside the eye (which in turn frequently lead to the development of glaucoma, as it did in these eyes). Because of the consistent presence of cysts, pigment, and structural changes that often result in glaucoma – and the inconsistent presence of inflammation – the study authors suggested renaming the disease “Pigmentary and Cystic Glaucoma of Golden Retrievers.”

This research reinforces an important message for breeders: do not take this disease lightly! This new information should help to remind breeders that pigmentary uveitis is not yet well understood, and among the questions that are not fully answered is exactly what role inflammation plays. Affected dogs are often treated with anti-inflammatory drugs such as steroids and NSAIDs (non-steroidal anti-inflammatory drugs), but despite the best treatment available, the disease frequently progress to glaucoma and blindness. It appears that some breeders have been under the impression that PU is a generally manageable disease that may not progress providing treatment is begun early, but that is clearly not the case. Pigmentary uveitis is a serious disease that usually results in significantly diminished quality of life, and because of that it ranks among the most important heritable diseases in Golden Retrievers.

Another study that GRCA members and other dedicated Golden owners have supported by providing blood samples from affected dogs was conducted by Dr Wendy Townsend, previously at Michigan State University and now at Purdue. As confirmed in the above study, there has been a long-known association between PU and iris cysts, and Dr Townsend’s work also strengthened that association. The question has been raised as to whether a finding of iris cysts alone may represent a mild form of PU in some dogs. Since other breeds also get iris cysts, this would not apply to all Goldens with iris cysts, and at this time there is no way to determine in which dogs the cysts are associated with PU. Dr Townsend is continuing to investigate this, but the warning to breeders is to be very cautious about breeding a dog with iris cysts, even though he/she may have a CERF number. Goldens with iris cysts should be followed every six months by an ophthalmologist, and suspicions should be heightened if the dog is closely related to a Golden with PU.

Some very good news for the breed is that Dr Townsend is also beginning work to identify the gene responsible for PU, so that a DNA test can be developed. She continues to need blood samples and pedigrees from affected dogs and their close relatives. Although it would be a very unfortunate accidental breeding, she most needs samples from families in which both parents have been subsequently diagnosed with PU. While many breeders do not talk openly about this disease, the scary reality is that the breed incidence of PU now appears to be high enough that some of these accidental breedings are in fact occurring.

A number of careful and highly respected breeding programs have been hit extremely hard by pigmentary uveitis, and with an often very late age of onset, literally all lines are at risk. Anyone who thinks they are safe in this regard is simply mistaken. But while no one asks for this, many breeders are still not responding appropriately to this threat to our breed. Over recent years the Health & Genetics Committee has strongly urged that breeders continue to do eye exams and to CERF those results for the lifetime of any dog that has been bred. Yet some owners still do not submit eye examination results for CERF certification, while many dogs that were previously CERF’d simply disappear from current CERF status after a period of time. These practices leave the breed extremely vulnerable to late onset eye disease because breeders cannot make good decisions about diseases like pigmentary uveitis without access to large amounts of data that span dogs’ lifetimes. This cannot be accomplished by circulating copies of eye exams from person to person, and only public databases can provide permanent and broad access to information that current breeders need and future generations will depend on. It cannot be overemphasized that lifelong CERFing is a breeder’s ethical duty, and it’s time for everyone to step up and do the right thing.

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Sample submission information:

Blood samples from dogs with pigmentary uveitis (and sometimes their first degree relatives) are needed for research to help identify the disease gene and develop a DNA test. A diagnostic report from an ophthalmologist and a pedigree is also required, and all pedigrees and dog identities will be kept confidential.

Please contact Dr Wendy Townsend in advance if possible at 765-494-1107 or townsenw@purdue.edu to verify that the dog is a candidate.

Overnight blood samples to:

Enucleated (surgically removed) eyes from dogs with advanced pigmentary uveitis are also requested. Please contact Dr Townsend as above to arrange submission, and please ask the surgeon to place the eye in formalin if contact has not been made prior to the surgery.

Reference

Esson D, Armour M, Mundy P, Schobert CS, Dubielzig RR The histopathological and immunohistochemical characteristics of pigmentary and cystic glaucoma in the Golden Retriever. Vet Ophthalmol. 2009 Nov-Dec;12(6):361-8.

Updated August, 2010

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