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Hips, Elbows. Eyes and Hearts: Update on the Big Four
Ann F. Hubbs DVM, PhD
We continue to have increased knowledge about the four examinations which should be completed before Golden Retrievers are included in any breeding program. These are 1) an examination of hips for hip dysplasia with certification free of the disease by the Orthopedic Foundation for Animals (OFA), the Institute for Genetic Disease Control (GDC – now closed but with data available from OFA), Ontario Veterinary College (OVC), or The University of Pennsylvania Hip Improvement Program (PennHIP); 2) examination of elbows for elbow dysplasia with certification by OFA, GDC or OVC; 3) examination of eyes by a board-certified veterinary ophthalmologist; and 4) cardiac examination by a board-certified cardiologist. In Goldens, undergoing these exams is understood to be a pre-requisite for being a breeding dog.
On a general level, if these examinations have been completed and submitted to OFA and/or GDC, normal dogs can be confirmed online at the OFA website, www.offa.org. In addition, results are also available for abnormal dogs if the owner agreed to release data regardless of the findings (the open registry). When eye clearances have been submitted to the Canine Eye Registry Foundation (CERF) and the findings are normal, these findings can be confirmed online at http://www.vmdb.org/verify.html or for dogs who already in the OFA database, the OFA website. The AKC-Canine Health Information Center (CHIC) which is operated by OFA also contains a database at http://www.caninehealthinfo.org/search.html . This database includes public data from OFA, GDC, and CERF as well as other organizations acceptable to GRCA, if that information is submitted by the owner. At this time, a recording fee is charge to owners for submitting normal findings from OVC and PennHIP to CHIC because the normal data is not freely available. Abnormal results from these health registries are included without charge. The GRCA Health and Genetics Committee strongly encourages the free-sharing of normal findings (or open registry information) among the health registries and we are hopeful information sharing will increase with the CHIC database verifying the examination findings for Golden Retrievers.
Importantly, access to online verification does three things. First, it limits the potential for falsified clearances (fraud), particularly when the dog is permanently identified and the identity is confirmed at the time of examination. Second, at the OFA website, online information is available on the examinations of parents, siblings, half-siblings, and offspring. In that regard, it is important to remember that the database only includes abnormal findings that are in the open registry and normal findings that are in either the semi-open or open registry (in other words, an abnormal finding means the owner was willing to disclose any finding and should be commended for doing so). A third and important function of the online information is that it is a public database. As researchers strive to identify genes associated with hip dysplasia, elbow dysplasia, eye defects and heart disease in our Goldens, this information is available to them. It is certainly hoped that, in the future, DNA will be banked at the time examinations are conducted both verify identity and to assist in developing genetic tests for the common genetic diseases of Goldens.
Recent studies on hip dysplasia in Golden Retrievers
The PennHip method for detection of hip dysplasia is accepted as a method for testing Golden Retrievers for hip dysplasia. The test evaluates the looseness (laxity) of the hip joint under anesthesia and light pressure. The current recommendations are for breeding the tighter half of the population (the percentile ranking) in a specific breed rather than selecting a specific tightness (Distraction Index, or DI) as ideal. The importance of that has been demonstrated by peer-reviewed publication (Smith et al, 2001) and some of the data is currently available on the internet (http://www.vet.upenn.edu/research/centers/pennhip/djdprobability.html). For example, in German Shepherd Dogs a DI of 0.3 would have a similar risk for developing degenerative joint disease as a Golden Retriever with a DI of 0.5.
A recent study at the University of Columbia indicates that the incidence of hip dysplasia in Golden Retrievers is about 30% for initially radiographed dogs (those not screened by the veterinarian taking the radiographs). More information on this study is available online at http://www.offa.org/advocatespring2003.pdf . For hips submitted to OFA as adults, approximately 21% are considered dysplastic. We certainly have a large number of Goldens still afflicted by hip dysplasia and this continues to be a concern of the GRCA Health and Genetics Committee.
Genetic selection for good hips is very important in reducing this disease in our breed. Recent studies also emphasize the importance of keeping dogs at a lean and healthy weight by limiting food intake. For example, Labrador Retrievers that were fed 25% less food than their littermates from weaning through adulthood had an impressive reduction in hip dysplasia. The control group (unrestricted food access) had a 68% prevalence of hip osteoarthritis by 8 years of age while their littermates that ate 25% less had a 14% incidence of hip dysplasia (Kealy et al, 2000). In addition, those that ate 25% less generally lived longer (Kealy et al, 2002)
Recent studies on elbow dysplasia
Elbow dysplasia is a designation which groups several conditions that affect the elbow and lead to arthritis, and often lameness. The specific conditions are ununited anconeal process, fragmented medial coronoid process of the ulna, osteochondrosis of the medial humeral condyle, and/or other processes producing degenerative joint disease of the canine elbow. The bad new is that new information about elbow dysplasia in Goldens is limited. The good new is that we do have some good general information about elbow dysplasia in dogs. A couple of good websites for general information include
http://www.acay.com.au/~dissi/elbow.htm, http://www.vets.org.nz/NZVA/QAPs/Dysplasia/elbow/elbowdys.htm and http://www.offa.org/elbowgeninfo.html
Cumulative results of OFA evaluations of elbows in Golden Retrievers are at the OFA website. Currently, 11.9% of Golden Retrievers examined have elbow dysplasia. One recent study is also available from OFA. Some of the results are included in a recent online monograph (Keller, 2003 ). The following table is reprinted from that monograph with permission and demonstrates the increased prevalence of elbow dysplasia in dogs with one or more parent with elbow dysplasia:
Table 7 illustrates the outcome of matings based on information extracted from the OFA database. A total of 13,151 progeny were identified in which both parents had elbow dysplasia evaluations. The percentages of progeny with elbow dysplasia more than doubled if either parent had ED, and more than tripled if both parents had ED, as compared to when both parents were normal. Results of selective breeding practices indicate that elbow dysplasia should be considered in the moderate to high heritability estimate category (See page 7 for discussion on genetics).
Table 7: Elbow scores
Scores on 13,151 progeny from sires and dams with known elbow scores.
Sire |
Dam |
Normal |
Dysplastic |
Normal |
T = 10,245
D = 12.2% |
T = 1,345
D = 31.3% |
Dysplastic |
T = 1,289
D = 26.1% |
T = 272
D = 41.5% |
T = total number of progeny; D = the percentage of progeny with elbow dysplasia
Recent updates on Genetic Eye Diseases in Golden Retrievers:
The big news regarding eyes concerns pigmentary uveitis. Pigmentary uveitis or “Golden Retriever Uveitis” is a progressive disease of Golden Retriever characterized by the appearance of pigment in the front part of the dog’s lens. The disease is associated with the development of glaucoma and, in one study, 46% of the eyes with pigmentary uveitis did become blind because of glaucoma ( Sapienza et al, 2000). When planning breedings, affected individuals should not be bred and breeders are encouraged to ask questions about pigmentary uveitis in the parents of, and littermates to, prospective breeding dogs. Close relatives should be bred only after consultation with a veterinary ophthalmologist and should not be bred into affected lines. Unfortunately, a late age of onset (mean of 8.6 yrs, +/- 2.1 yrs) makes this disease difficult to manage in a breeding program. A copy of the abstract from the original report is available online.
Since the publication of the original report, CERF has not been clearing Goldens with pigmentary uveitis. Unfortunately, pigmentary uveitis does not fit into the categories for data maintained by CERF and no data on the prevalence of pigmentary uveitis in Golden Retrievers is available. Indeed, pigmentary uveitis often causes severe clinical disease and affected Goldens will probably present as clinical cases to veterinary ophthalmologists and will not be seen for routine CERF exams. At the 2003 National, the GRCA Health and Genetics Committee circulated a questionnaire to try and get some idea regarding the extent of the problem. This was not a random survey and there were only 15 who responded but 8 of these did own Goldens with pigmentary uveitis (9 total affected dogs). Fourteen of those responding had heard of pigmentary uveitis before the survey. The responses involved 161 Goldens. The responses suggest that the condition is a problem among some Goldens owned by dedicated Golden Retriever enthusiasts. Texas breeders may want to note that the Nationals were held in Ohio and that none of the respondents but 5 of the 9 affected dogs lived in the Texas. There are a variety of potential explanations for this, but research has not yet been done to indicate if there is a reason behind those numbers, or if it is simply a result of chance.. The questions from the survey are included below with the positive responses in bold numbers.
1) Approximately how many different Goldens that you own have had CERF exams since 2000? (67)
2) How many, if any, have been diagnosed with pigmentary uveitis or "Golden Retriever uveitis" since 2000? (7)
3) Approximately how many different Goldens that you own have had CERF exams prior to 2000? (94)
4) How many, if any, have been diagnosed with PU or GR uveitis prior to 2000? (2)
5) In what state(s) did you reside at the time you raised or owned any affected dogs? (VT-1, ONT-2, NY-1, OH-1, MI-1, WI-1)
6) How many, if any, Goldens from your breeding program have ever been diagnosed with PU or GR uveitis? (9)
7) In what state(s) have these dogs lived? (VT-1, ONT-1, Newfoundland-1, TX-5, NY-1)
8) How many, if any, of the affected dogs reported above have progressed to clinical signs and/or blindness? (2)
9) How many, if any, Goldens from your breeding program have ever been diagnosed with:
a. Any form of uveitis (inflammation inside of the eye) # (7)
b. Iris cysts # (21)
c. Glaucoma # (1)
d. A combination of any of the three conditions above # (2)
10) Prior to this survey, have you ever heard of pigmentary uveitis? (14 yes, 1 no)
11) How serious do you consider this disease? Please check one:
(5) Very serious concern to the breed
(1) Minor concern to the breed
(1) Serious only to affected dogs
(0) Not important to the breed
(2) Somewhat serious to the breed
(4) Not sure
(2) Other (please explain) (not enough data)
Recent updates on Genetic Heart Diseases in Golden Retrievers:
The major inherited heart disease of Golden Retrievers is believed to be subvalvular aortic stenosis (SAS) although arrythmias, which may or may not be inherited, are seen in a similar percentage of Goldens. The most recent Golden Retriever breed health survey was conducted in 1998-1999 (Glickman et al, online), involved 1444 Golden retrievers owned by 746 people and indicated that of the 152 Goldens with heart conditions reported in the survey, 11.6% of these were diagnosed with SAS and 12.2% were diagnosed with arrythmias. The prevalence of another developmental heart disorder, cardiomyopathy, was half the prevalence of SAS. These statistics probably greatly under-report the actual disease prevalence as some of the heart conditions of Goldens, such as SAS, are difficult to diagnose. OFA maintains a registry and database of heart diseases in dogs and this database indicates that cardiac examinations have been equivocal in 0.8% of Goldens with 0.5% of Golden Retrievers affected (OFA, online). The actual prevalence of congenital heart disease is probably much higher as many owners do not submit reports from affected Goldens to OFA. Since OFA accumulates data such as the table above on elbow dysplasia, even from dogs in the closed registry, and future studies may be linked with DNA, owners are strongly encouraged to submit both positive and negative reports. (As mentioned previously, there is no charge to submit affected dogs.) While it is the owner’s decision whether to include the data in the open or closed database, both databases can provide useful information. The open database reveals your dog’s identity to all breeders but even the closed database can provide useful population data to future breeders. A study from the University of California, Davis, School of Veterinary Medicine indicates that Golden Retrievers have a 5.5 fold increased risk of SAS relative to dogs in general (Kienle et al, 1994).
In regards to the OFA database, it supplies information on dogs that are phenotypically normal but includes data from specialists (designated with an “S) and practitioners (designated with a “P”). While some of these veterinarians have the expertise needed to diagnose SAS, a veterinary cardiologist (designated with a “C”) is a veterinarian with post-graduate training in internal medicine with specialized training in heart disease who has passed an examination certifying both their general knowledge of internal medicine and their specialized expertise in heart disease (current training requirements are at http://www.acvim.org/uploadedFiles/gig/GIG06-07.pdf). The official title of such an individual is Diplomate, American College of Veterinary Internal Medicine, Specialty of Cardiology. Obviously, veterinary cardiologists are veterinarians who have demonstrated their knowledge of heart disease and it is for this reason that veterinarian cardiologist reports are recommended by GRCA in evaluating the cardiac status of Golden Retrievers.
SAS is particularly difficult to distinguish from murmurs that can occur in very fit and athletic dogs and the expertise of the examiner can be critical in making the diagnosis. OFA’s maintains the database both for research and to provide a database for dogs that appear to be phenotypically normal when making breeding decisions but makes the following statement regarding SAS and cardiomyopathy:
“At this time inherited, developmental cardiac diseases like subaortic stenosis and cardiomyopathies are difficult to monitor since there is no clear cut distinction between normal and abnormal. The OFA will modify the congenital cardiac database when a proven diagnostic modality and normal parameters by breed are established. However at this time, the OFA cardiac database should not be considered as a screening tool for these diseases.”
Breeding studies on Newfoundlands indicate that SAS in Newfoundlands is inherited either as a defect involving multiple genes (polygenetic condition) or as a dominant gene that is modified by other genes (Pyle et al, 1972). The Canine Health Foundation sponsored a study of SAS in Golden Retrievers and Newfoundlands. In that study, SAS in Goldens and Newfoundlands, appeared to be inherited as a dominant gene with incomplete penetrance and variable expression (Lehmkuhl and Meurs, online abstract).
Thus, the current status of our knowledge is that Golden Retrievers are at increased risk for developing SAS, which is fatal in some dogs, and SAS is inherited. The diagnosis is difficult in mildly affected dogs.
The difficulty in diagnosing SAS is due to similarities between the heart murmur heard with SAS and the heart murmur which can be heard in athletic and excited dogs (these are called physiologic murmurs). For example, the incidence of grade I to II heart murmurs is 15.8% in unconditioned sled dogs, 27.8% in lightly conditioned sled dogs and 39.6% in highly conditioned sled dogs. As exercise increases, the heart rate decreases so that for unconditioned sled dogs the mean heart rate is 131 beats/minute, the mean resting heart rate in lightly conditioned sled dogs is 126 beats/minute and the mean heart rate in highly conditioned sled dogs is 102 beats/minute. In sled dogs, the presence of an athletic heart murmur appears to be associated with improved athletic performance (Constable et al, 1994). Thus, dogs that can develop athletic murmurs may be the best performers and not the dogs we want to exclude from breeding.
In differentiating SAS from physiologic murmurs, echocardiography with Doppler flow studies are frequently used but require great expertise from the examiner. The presence of a ring of tissue beneath the aortic valve which leads from the heart to the rest of the body is a definite indication of SAS but there are other, but less specific, indicators as well. These include increased flow rates through the aortic valve. However, recent studies in boxers suggest that while heart murmurs are associated with increased left ventricular outflow tract velocities in boxers, neither murmurs nor increased left ventricular outflow tract velocity are specific for SAS in boxers ( Koplitz et al, 2003). Such studies, have not yet been reported in Goldens, which makes distinguishing physiologic murmurs from SAS murmurs particularly difficult.
Until such studies are conducted, a couple of suggestions may help breeders in taking their dogs to heart exams. Owner may want to avoid situations that can produce physiologic murmurs and increase false positive diagnoses. Athletic murmurs occur in dogs that are subjected to regular exercise programs. In general, SAS murmurs appear before one year of age and examinations any time after a year of age are considered permanent. To eliminate the confusion, if a Golden is over a year of age and is about to start a conditioning program, it is best to have the cardiologist examine the heart before the heavy conditioning begins. If your dogs is already in a heavy conditioning program, record how often, how intensely and for how long your dog exercises and bring this with you to the exam (for example, if you tell the cardiologist that the dog has been exercising at 5 mph, 20 minutes/day, 6 days a week on a treadmill, there is a good reason for your dog to have a murmur though your dog could have had mild SAS before developing an athletic murmur which can be very difficult for anyone to sort out). The baseline exam is also usually an exam in a relaxed dog. Do not let a couple of young Goldens play in the exam room before their exam - this can result in changes associated with exercise during their baseline exam and can produce murmurs on auscultation and raise flow rates on Doppler exams. If your dog can’t stay relaxed in a vet’s office, use common sense, leave them in a crate in a cool quiet location or teach them to “stay”. Many cardiologists will exercise your dog as part of the exam – just don’t present them with an exercised dog for the baseline exam. Finally, consider working with a single veterinary cardiologist to understand and control congenital heart disease. A cardiologist who has examined multiple dogs within a pedigree and their close relatives has a great deal more information with which to distinguish physiologic murmurs from SAS murmurs.
Research which benefits our Goldens is continuing. Please expect that this research will improve diagnostic techniques and help prevent the inherited diseases that affect our Golden Retrievers. We believe that this increased knowledge will prevent Golden suffering and bring the power to control these diseases to the breeder. Recent research updates have increased our understanding of breed differences in hip dysplasia, our understanding of genetic influences on elbow dysplasia, have identified pigmentary uveitis as an inherited eye defect of Goldens which causes pain and blindness, and have suggested the need for additional studies on Doppler examinations in athletic or excited young dogs. The future of our breed should be healthier and is very exciting.
References
Constable, P.D., K.W. Hinchcliff, J. Olson, and R.L. Hamlin. Athletic heart syndrome in dogs competing in a long-distance sled race. J. Appl. Physiol. 76: 433-438, 1994.
Glickman, L., N. Glickman, & R. Thorpe. The Golden Retriever Club of America National Health Survey 1998-1999. Available online at http://www.grca.org/healthsurvey.pdf
Kealy, R.D., D.F. Lawler, J.M. Ballam, G. Lust, D.N. Biery, G.K. Smith, and S.L. Mantz. Evaluation of the effect of limited food consumption on radiographic evidence of osteoarthritis in dogs. J Am Vet Med Assoc 217: 1678-1680, 2000.
Kealy, R.D., D.F. Lawler, J.M. Ballum, S.L. Mantz, D.N. Biery, E.H. Greeley, G. Lust, M. Segre, G.K. Smith, and H.D. Stowe. Effects of diet restriction on life span and age-related changes in dogs. J Am Vet Med Assoc 220: 1315-20, 2002.
Keller, G. The use of health databases and selective breeding, a guide for dog and cat breeders and owners, 4 th edition, 2003. available online at http://www.offa.org/monographweb.pdf
Kienle, R.D., W.P. Thomas, and P.D. Pion. The natural clinical history of canine congenital subaortic stenosis. J Vet Intern Med. 8: 423-431, 1994.
Koplitz S.L., K.M. Meurs, J.B. Bonagura, and V. Luis Fuentes. Left ventricular outflow tract size in boxer dogs. 2003 American College of Veterinary Internal Medicine Forum.
Lehmkuhl, L..B., and K.M. Meurs. Completed Grant No. 1419: Inheritance and Molecular Genetic Evaluation in Newfoundlands and Golden Retrievers with Subvalvular Aortic Stenosis.
OFA. Congenital Cardiac Disease Statistics. Available online at http://www.offa.org/cardiacstatbreed.html
Pyle, R.L., D.F. Patterson, and S. Chacko The Genetics and Pathology of Discrete Subaortic Stenosis in the Newfoundland Dog., American Heart Journal, Vol. 92, No. 3, pp. 324-334, September 1976
Sapienza JS, FJ Simo, and A Prades-Sapienza. Golden Retriever uveitis: 75 cases (1994-1999).Vet Ophthalmol. 3:241-246, 2000.
Smith , G.K., PD Mayhew, AS Kapatkin, PJ McKelvie, FS Shofer, and TP Gregor. Evaluation of risk factors for degenerative joint disease associated with hip dysplasia in German Shepherd Dogs, Golden Retrievers, Labrador Retrievers, and Rottweilers. J Am Vet Med Assoc. 219: 1719-24, 2001.
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