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Prevalence and progression of pectinate ligament dysplasia in the Welsh springer spaniel: Pectinate ligament dysplasia in WSS
Abstract
Objectives:
To determine the prevalence of pectinate ligament dysplasia in a large group of Welsh springer spaniels; to investigate associations between pectinate ligament dysplasia and age, sex and intraocular pressure and between intraocular pressure and age and sex; and to investigate progression of pectinate ligament dysplasia in individual dogs.
Methods:
In a prospective study, gonioscopy was performed in both eyes of 227 Welsh springer spaniels and intraocular pressure measured by rebound tonometry. Eyes were classified as "unaffected" if 0% of the iridocorneal angle was affected with pectinate ligament dysplasia (grade 0), "mildly affected" if <20% was affected (grade 1), "moderately affected" if 20 to 90% was affected (grade 2) and "severely affected" if >90% was affected (grade 3). In a retrospective study, progression of pectinate ligament dysplasia over time was investigated for 65 dogs.
Results:
One hundred and thirty-nine of 227 dogs (61·2%) were affected by pectinate ligament dysplasia (grades 1 to 3) and 82/227 (36·2%) were moderately or severely affected. There was a significant association between pectinate ligament dysplasia and age. There were no associations between pectinate ligament dysplasia and intraocular pressure or pectinate ligament dysplasia and sex. Thirty-five of 65 dogs (53·8%) demonstrated progression of pectinate ligament dysplasia.
Clinical significance:
Prevalence of pectinate ligament dysplasia was high despite widespread screening and selection against the condition. Our data indicate that gonioscopic features of pectinate ligament dysplasia can progress in the Welsh springer spaniel. Dogs deemed unaffected at an early age may subsequently be diagnosed with pectinate ligament dysplasia.
... Ces races sont considérées comme prédisposées au GPAF. Au Royaume-Uni, le protocole conjointement défini par la BVA (British Veterinary Association) le KC (Kennel Club) et l'ISDS (International Sheepdog Society) recommande actuellement l'examen gonioscopique chez le Basset Hound, le Chien d'eau espagnol, les Cockers américain et anglais, le Retriever à poil plat, le Shiba Inu, les Springers anglais et gallois, et les races suivantes sont en cours d'investigation : Border Collie, Dandie Dinmont Terrier, Dogue allemand, Golden Retriever, Leonberg, Braque hongrois (à poil court et à poil dur), Terrier gallois [5]. En France, l'AFEP -MHOC (Association of French Panelists, Maladies Héréditaires Oculaires Canines), avec l'accord et à la demande du Club de race concerné, recommande de réaliser la gonioscopie sous la forme d'une alerte apparaissant sur la fiche individuelle d'examen dès que la race du chien est saisie. ...
... directe entre ALP et déficit d'écoulement de l'HA n'est pas considérée comme démontrée [3]. L'ALP, qualifiée de « dysplasie » du ligament pectiné dans les publications citées ci-après, peut évoluer dans le temps : examinés en gonioscopie deux fois à 6 ans d'intervalle en moyenne, 39 Retrievers à poil plat sur les 96 suivis montrent une progression de la surface des zones occluses qualifiée de sévère dans 12 observations [8] ; une seconde publication relative au Retriever à poil plat, au Basset Hound et au Dandie Dinmont terrier montre une corrélation positive entre ALP et âge, plus significativement élevée pour le Basset Hound que pour les deux autres races [9] ; de même, une étude rétrospective réalisée sur 65 chiens de race Springer gallois a mis en évidence une progression de l'ALP liée à l'âge chez 35 d'entre eux [5] ; • la distance qui sépare l'origine irienne des FP de leur attache cornéenne endothéliale définit l'ouverture (ou largeur) de l'AIC (OAIC) ; si elle est insuffisante, l'AIC est qualifié d'étroit ( Fig. 4), si les FP ne sont plus visibles, il est qualifié de fermé (Fig. 5). Il a été observé que la hauteur des FP était susceptible de diminuer avec l'âge dans différentes races [5,10,11] ; • les défauts de perforation du LP (ALP, Fig. 2 . ...
... L'ALP, qualifiée de « dysplasie » du ligament pectiné dans les publications citées ci-après, peut évoluer dans le temps : examinés en gonioscopie deux fois à 6 ans d'intervalle en moyenne, 39 Retrievers à poil plat sur les 96 suivis montrent une progression de la surface des zones occluses qualifiée de sévère dans 12 observations [8] ; une seconde publication relative au Retriever à poil plat, au Basset Hound et au Dandie Dinmont terrier montre une corrélation positive entre ALP et âge, plus significativement élevée pour le Basset Hound que pour les deux autres races [9] ; de même, une étude rétrospective réalisée sur 65 chiens de race Springer gallois a mis en évidence une progression de l'ALP liée à l'âge chez 35 d'entre eux [5] ; • la distance qui sépare l'origine irienne des FP de leur attache cornéenne endothéliale définit l'ouverture (ou largeur) de l'AIC (OAIC) ; si elle est insuffisante, l'AIC est qualifié d'étroit ( Fig. 4), si les FP ne sont plus visibles, il est qualifié de fermé (Fig. 5). Il a été observé que la hauteur des FP était susceptible de diminuer avec l'âge dans différentes races [5,10,11] ; • les défauts de perforation du LP (ALP, Fig. 2 . Gonioscopie, Bichon frisé : AIC étroit, présence de fibrae latae ; a : hauteur des fibres pectinées ; b : distance de la base des fibres pectinées à la limite antérieure de la cornée ; 1 : cornée ; 2 : bandes pigmentées (très denses, interne et externe confondues) ; 3 : iris ; AAIC ; AAIC modérée selon la classification actuelle (a < 1/3 b, plus de 50 % de fibrae latae). ...
Résumé
Sur une durée de 20 ans, l’examen gonioscopique a été pratiqué sur 4309 chiens vigiles de 162 races différentes (2149 femelles et 2160 mâles), dont la morphologie du ligament pectiné sur 360° et l’ouverture de l’angle irido-cornéen ont été évaluées : 3810 de 1998 à 2015 selon un protocole personnel, 499 de 2016 à 2018 selon le protocole ECVO, les deux techniques étant extrêmement voisines. Parmi les chiens examinés entre 1998 et 2015, 324 présentaient une anomalie de l’angle irido-cornéen (AAIC), dont 187 avec un glaucome primaire à angle fermé unilatéral (GPAF) ; sur les 137 sujets atteints d’AAIC, 19 ont été revus pour GPAF unilatéral en moyenne 4,97 mois plus tard ; sur les 187 glaucomateux unilatéraux, 6 ont été revus en moyenne 3,66 mois plus tard pour GPAF sur le second œil ; parmi ceux examinés entre 2016 et 2018, 71 présentaient une anomalie de l’angle irido-cornéen. Les résultats du test d’indépendance du Khi-deux (χ²) appliqué au premier effectif de 3810 chiens mettent en évidence une relation forte entre AAIC et GPAF, d’une part, entre la sévérité de l’AAIC et la possibilité de GPAF, d’autre part. Au terme de la discussion, les dominantes raciales de l’effectif étudié sont comparées à celles d’effectifs britanniques et nord-américains. L’intérêt de la gonioscopie dans le dépistage de l’AAIC, donc dans la prévention de la prédisposition au GPAF, notamment dans certaines races de la population canine française, est confirmé par cette étude.
... Pectinate ligament abnormality status of dogs was based on the results of gonioscopy as previously described. 22,24,25 Briefly, gonioscopy was performed bilaterally in conscious dogs following application of 0.5% proxymetacaine (Bausch & Lomb, Chauvin Pharmaceuticals Ltd.) to the ocular surface using a 19 mm Koeppe goniolens (Ocular Instruments) filled with 2 mg/g carbomer gel (Viscotears; Alcon) before placing onto the cornea. The entire 360° of the ICA was then examined using a handheld slit-lamp biomicroscope (Keeler PSL Classic) for the presence of PLA which was quantified according to the percentage of ICA circumference affected, estimating this to the nearest 5%. ...
... Although a previous study which investigated PLA prevalence, using data derived from the same Border Collie dogs as the current study, failed to demonstrate an association of PLA with age, 22 such an age association has been shown in dogs of other breeds. 7,22,[24][25][26] It has also been postulated that the previous Border Collie study was underpowered to detect any association because of the low prevalence of PLA in this breed. 22 Thus, it is still possible that PLA may be progressive in the Border Collie, and these two young dogs may develop PLA in later life. ...
Purpose
Canine primary closed‐angle glaucoma (PCAG) is a complex disease caused by multiple genetic factors. A c.590G>A variant in OLFML3 was recently reported to be a candidate for pectinate ligament abnormality (PLA) and PCAG in the Border Collie. We investigated the association of this variant with PLA and PCAG in Border Collies from the United Kingdom.
Methods
The OLFML3 variant was genotyped in 106 Border Collies comprising 90 with normal eyes (controls) and 16 with PLA (n = 11) and/or PCAG (n = 5) (cases). Genotyping was performed in an additional 103 Border Collies to estimate variant frequency within the population. To investigate the association of the variant with disease in other breeds, genotyping was performed in 337 non‐Border Collies with PLA and/or PCAG.
Results
Of the 90 controls, 71 were homozygous for the wild‐type allele, two were homozygous for the variant, and 17 were heterozygous. Of the 16 cases, three were homozygous for the wild‐type allele, 11 were homozygous for the variant, and two were heterozygous. The association of the variant allele with disease was significant (P = 1.1 x 10⁻⁹). We estimated the frequency of this variant to be 4.4% within the United Kingdom Border Collie population, and it was not identified in clinically affected dogs of any other breed.
Conclusions
This study confirms the association of the OLFML3 variant with PLA and PCAG in Border Collies from the United Kingdom. DNA testing for the variant and selective breeding can reasonably be expected to result in a reduction of PLA and PCAG prevalence in the breed.
... DNA samples from American PCAG dogs were provided by one of the coauthors (MK) and included members of a PCAG colony and client-owned dogs all originating within the USA. Dogs were designated as controls or PLA cases based on the results of gonioscopy performed by the primary author (JO), a board-certified veterinary ophthalmologist, and as previously described [12][13][14]32]. Dogs were designated as PCAG cases following examination by JO and other board-certified veterinary ophthalmologists. ...
Purpose:
To investigate the genetic basis of primary closed angle glaucoma (PCAG) in European Basset Hounds using genome-wide association and RNA sequencing strategies.
Methods:
DNA samples from 119 European Basset Hounds were genotyped on the 170 K SNP CanineHD BeadChip array (Illumina) comprising 37 with normal iridocorneal angles (controls), 57 with pectinate ligament abnormality (PLA cases), and 25 with PCAG (PCAG cases). Genome-wide association studies (GWASs) of the PLA and PCAG cases were conducted. Whole transcriptome sequences of iridocorneal angle tissues from five Basset Hounds with PCAG were compared with those from four dogs with normal eyes to investigate differences in gene expression between the affected and unaffected eyes in GWAS-associated loci. A variant in NEB, previously reported to be associated with PCAG in American Basset Hounds, was genotyped in cohorts of European Basset Hounds and non-Basset Hounds.
Results:
The GWASs revealed 1.4 and 0.2 Mb regions, on chromosomes 24 and 37, respectively, that are statistically associated with PCAG. The former locus has previously been associated with glaucoma in humans. Whole transcriptome analysis revealed differential gene expression of eight genes within these two loci. The NEB variant was not associated with PLA or PCAG in this set of European Basset Hounds.
Conclusions:
We identified two novel loci for canine PCAG. Further investigation is required to elucidate candidate variants that underlie canine PCAG.
Purpose
To investigate the relationship between gonioscopic iridocorneal angle (ICA) morphology and the incidence of postoperative ocular hypertension (POH) and postoperative glaucoma in dogs undergoing cataract surgery.
Animals studied
Retrospective analysis of 138 eyes of 78 canine patients who underwent phacoemulsification at North Carolina State University from December 1, 2015 through April 30, 2017.
Methods
Medical records of all phacoemulsification patients with preoperative RetCam gonioscopic images were reviewed for preoperative, intraoperative, and postoperative variables. Gonioscopic angle indices were calculated using a novel (ZibWest) angle grading system, and these indices were analyzed for outcome‐related significance.
Results
Increased surgeon experience was associated with increased probability of POH and vision loss. Higher average ZibWest Angle indices (ie, more open angles with less pectinate ligament dysplasia/ abnormality) were associated with a significantly decreased probability of medically unresponsive glaucoma. Increased patient age was significantly associated with an increased probability of both postoperative glaucoma and vision loss. Female dogs were significantly more likely to experience postoperative glaucoma compared to male dogs. Increased surgery time was significantly associated with increased probability of vision loss.
Conclusions
The ZibWest angle index may predict increased risk for developing medically unresponsive glaucoma with cataract surgery. Female sex, and increased patient age, surgical time, and surgeon experience were associated with increased postoperative morbidity.
Objectives:
To investigate inter-examiner variability in gonioscopic evaluation of pectinate ligament abnormality in dogs and to assess level of inter-examiner agreement for four different gonioscopy grading schemes.
Materials and methods:
Two examiners performed gonioscopy in 98 eyes of 49 Welsh springer spaniel dogs and estimated the percentage circumference of iridocorneal angle affected by pectinate ligament abnormality to the nearest 5%. Percentage scores assigned to each eye by the two examiners were compared. Inter-examiner agreement was assessed following assignment of the percentage scores to each of four grading schemes by Cohen's kappa statistic.
Results:
There was a strong positive correlation between the results of the two examiners (R=0·91). In general, Examiner 1 scored individual eyes higher than Examiner 2, especially for eyes in which both examiners diagnosed pectinate ligament abnormality. A "good" level of agreement could only be achieved with a gonioscopy grading scheme of no more than three categories and with a relatively large intermediate bandwidth (κ=0·68).
Clinical significance:
A three-tiered grading scheme might represent an improvement on hereditary eye disease schemes which simply classify dogs to be either "affected" or "unaffected" for pectinate ligament abnormality. However, the large intermediate bandwidth of this scheme would only allow for the additional detection of those dogs with marked progression of pectinate ligament abnormality which would be considered most at risk of primary closed-angle glaucoma.
Pectinate ligament dysplasia (PLD) is significantly associated with primary closed angle glaucoma (PCAG) in several dog breeds. Gonioscopy screening for PLD is advised in breeds in which PLD and PCAG are particularly prevalent in order that affected dogs may be eliminated from the breeding population. The Border Collie (BC), Hungarian Vizsla (HV) and Golden Retriever (GR) breeds are currently under investigation for PLD by the British Veterinary Association/Kennel Club/International Sheep Dog Society (BVA/KC/ISDS) Eye Scheme. The authors aimed to determine the prevalence of PLD in UK populations of BC, HV and GR and to investigate possible associations between the degree of PLD and age and sex. Gonioscopy was performed in 102 BCs, 112 HVs and 230 GRs and the percentage of iridocorneal angle affected by PLD was estimated and classified as unaffected (0 per cent), mildly affected (<20 per cent), moderately affected (20-90 per cent) or severely affected (>90 per cent). Eleven of 102 (13.8 per cent) BCs, 16/112 (14.3 per cent) HVs and 60/230 (26.1 per cent) GRs were moderately or severely affected by PLD. The prevalence of PLD was significantly higher in GR than both BC and HV. There was a significant positive correlation between PLD and age in the HV and GR but not in the BC. There was no association between PLD and sex in any breed.
Background:
Canine distichiasis is a well-known cause of ocular irritation and excessive lacrimation (secretion of tears) in the dog. The term distichiasis originates from the Greek words di and stichos meaning two and rows, respectively, and as the name implies, the condition is characterized by an additional row of cilia, which erupts on the eyelid margin. Many purebred dogs are known to be predisposed to the condition, with many affected individuals within the populations. Even though the problem is widespread, the exact mode of inheritance and the heredity has not been studied extensively. However, some degree of genetic influence has been assumed, due to the high incidences within specific breeds. In the present study we have examined a cohort of English Cocker spaniels in Denmark to determine the prevalence and heritability of the disease.
Results:
Data from English Cocker spaniels with an ECVO eye examination registered between 2004-2013 were included in the study. The number of dogs examined during this period was 799, and the prevalence of distichiasis within this cohort was estimated at 49.31 % with a gender predisposition that females are more likely to get distichiasis than males. The correlation between the distichiasis status of the parents and their offspring revealed a significant association between the breeding combination of the parents and the occurrence of distichiasis in the offspring (p <0.0001). A relative risk (RR) ranging from 1.3 to 1.8 demonstrates that offspring of two affected parents are more likely to be affected than offspring descending from either one or two unaffected parents. The heritability was estimated to be moderate to high, i.e., 0.22 to 0.51.
Conclusions:
The prevalence of distichiasis in English Cocker spaniels from Denmark, examined in 2004-2013 was shown to be extremely high. The relative risk of developing the disease was 1.3 and 1.8 for offspring of one or two affected parents respectively. This together with the moderate to high heritability of the condition indicates that selective breeding could be used to reduce the incidence of distichiasis.
Glaucoma is a common ocular condition in humans and dogs leading to optic nerve degeneration and irreversible blindness. Primary glaucoma is a group of spontaneous heterogeneous diseases. Multiple factors are involved in its pathogenesis and these factors vary across human ethnic groups and canine breeds, so the clinical phenotypes are numerous and their classification can be challenging and remain superficial. Aging and oxidative stress are major triggers for the manifestation of disease. Multiple, intertwined inflammatory and biochemical cascades eventually alter cellular and extracellular physiology in the optic nerve and trabecular meshwork and lead to vision loss.
Objective
To determine the prevalence of pectinate ligament dysplasia (PLD) in UK Leonbergers and identify cases affected by glaucoma. Also, to define the spectrum of pectinate ligament (PL) appearance in this breed and determine whether gonioscopic monitoring should be recommended.Animals studiedData were compiled from 78 prospective gonioscopy examinations performed by one author (GF) and retrospective analysis of 233 UK eye scheme certificates (2009–2014). Clinical cases of glaucoma in Leonbergers diagnosed by UK veterinary ophthalmologists, where gonioscopy of the fellow eyes or histology of affected eyes had been performed, were also reviewed.ProcedureIn the prospective study, intraocular pressure was recorded prior to gonioscopy using a rebound tonometer. Gonioscopy was performed using a slit-lamp biomicroscope with a Koeppe goniolens. PLD was categorized according to the percentage of the iridocorneal drainage angle affected (grade 0 = <25% affected; grade 1 = 25–50% affected; grade 2 = 51–75% affected; and grade 3 = >75% affected), and the degree of narrowing of the angle was noted.ResultsOf 78 dogs examined prospectively, 64/78 (82%) were grade 0, 7/78 (9%) were grade 1, 3/78 (4%) were grade 2, and 4/78 (5%) were grade 3. A large phenotypic variation was observed. Spearman's rank correlation showed a positive correlation between age and severity of PLD (P < 0.0055). 52 (22%) of Leonbergers examined under the UK eye scheme 2009–2014 were affected by PLD. Five clinical cases of glaucoma were reviewed where gonioscopy had been performed and one where histology was performed. All individuals had grade 3 PLD with gonioscopy of the contralateral eye or severe goniodysgenesis with histological sections of the affected eye.Conclusion
This survey suggests the prevalence of PLD is sufficient to justify ongoing screening of Leonbergers.
Primary glaucomas are a leading cause of incurable vision loss in dogs. Based on their specific breed predilection, a genetic cause is suspected to be responsible, and affected dogs should be excluded from breeding. Despite the high prevalence of primary glaucomas in dogs, their genetics has been studied in only a small number of breeds. The identification of canine glaucoma disease genes and the development of genetic tests will help to avoid the breeding of affected dogs in the future and will allow for earlier diagnosis and potentially more effective therapy.
Copyright © 2015 Elsevier Inc. All rights reserved.
Two of the authors (DG, BS) independently observed that a number of Flat-Coated Retrievers (FCRs) previously unaffected by pectinate ligament dysplasia (PLD) appeared to develop the condition later in life. This study was instigated to investigate progression of PLD within individual dogs over time.
Flat-Coated Retrievers that had previously undergone gonioscopy under the UK/ECVO hereditary eye schemes were included in the study.
A second gonioscopic examination was performed 1.92-12.58 years later (mean 6, median 5.75 years) and the results compared. 39 FCR (17 males, 22 females) in the UK and 57 FCR (27 males, 30 females) in Switzerland were included. Slit-lamp biomicroscopy, indirect ophthalmoscopy, and gonioscopy were performed in all dogs. Gonioscopy allowed classification as either unaffected or affected; percentage of the iridocorneal drainage angle (ICA) affected by PLD was determined, before calculating progression observed as mild, moderate, or severe.
39 of 96 (40.6%) dogs demonstrated progression of PLD (P < 0.0001). Of these, 13 of 96 (13.5%) were classified as mild progression (from either unaffected to 10-20% or 10-20% to 20-90% ICA affected). Progression was more extensive in 26 of 96 (27.1%) dogs (P < 0.0001), of which 12 of 96 (12.5%) went from unaffected to severe PLD of >90% ICA affected, consistent with a high risk of glaucoma.
To the authors' knowledge, this is the first report describing progression of PLD in individual dogs over time, in a breed affected by primary, angle closure glaucoma.
This paper reports 28 cases of primary angle closure glaucoma in the Welsh springer spaniel, a breed not previously reported to be affected by this condition. Females are affected more frequently than males (2–4:1). The age of onset ranges from 10 weeks to 10 years; however, the distribution is skewed towards the younger dog. The mode of inheritance appears to be dominant, which should make elimination of the trait through breeding control more straightforward. Gonioscopy on clinically affected and clinically normal dogs revealed three angle types; open (normal), partially open and partially closed (equivocal) and closed (affected). The equivocal cases may represent the heterozygous state and the closed the homozygous; alternatively the gene(s) may show variable expression.
Closure of the iridocorneal angle is the cause of a primary form of glaucoma which occurs in certain breeds of dog, but the precise mechanism involved in that closure is not completely understood. However, narrowness of the angle is considered to be the important predisposing factor, and in gonioscopic survey work the author has demonstrated that angle narrowness occurs with some frequency in the English Cocker Spaniel and Basset Hound breeds.
The iridocorneal angle of the left eye was investigated in 203 Samoyeds. Comparison was made of judgements of the width of the anterior opening of the ciliary cleft when performing gonioscopy with an objective method of estimation based on measurements on goniophotographs. Results indicated high degree of correlation. Various degrees of narrowness of the iridocorneal angle width were revealed and clinical glaucoma with total-angle closure was found in 6 of 203 dogs. The intraocular pressure was significantly (P less than 0.01) higher in eyes with closed iridocorneal angles than in eyes with any other width of the angle. Appearance of the structures of the iridocorneal angle, particularly the pigment bands, indicated extensive individual variation. In approximately 25% of the eyes, dysplasia of the pectinate ligaments of variable degree existed, indicating that this anomaly is common in the Samoyed breed. Significant difference was not evident in intraocular pressure in eyes with different degrees of dysplasia of the pectinate ligaments.
The present study examined the postnatal development of the pectinate ligaments and uveal trabecular meshwork of the normal canine chamber angle of the Beagle breed at one day, one through ten weeks, three, four and six months, and one and two years of age. Angle tissue was prepared and examined by standard techniques for light microscopy and scanning and transmission electron microscopy. Developmentally, pectinate ligaments matured by the third week although areas continued to develop through the eighth week. Each primary pectinate ligament possessed a large, posterior extracellular space at its iridal attachment. The uveal meshwork, which developed by rarefaction, was not formed at birth and did not appear adult-like until the end of the second month. Adult trabecular cells were ultrastructurally identical throughout the angle, having been characterized by having cilia and "special" rough endoplasmic reticulum.
Pectinate ligament dysplasia (PLD) in dogs is a congenital ocular abnormality affecting the iridocorneal angle, the presence of which may be associated with adult-onset primary glaucoma. This study demonstrates a significant association between PLD and glaucoma in Flat Coated Retrievers, and also a higher prevalence of PLD in Flat Coated Retrievers compared with other breeds. It is shown that the association between PLD and glaucoma was robust and not due to a small increase in PLD with age. There was also a significant association between PLD in offspring and parents and, using the offspring-parents regression, the heritability of PLD was estimated as approximately 0.7. As glaucoma is significantly related to PLD, glaucoma may also be heritable. Thus, glaucoma can be controlled by gonioscopic examination and elimination of animals with a high degree of PLD from a breeding program. Breeding from only those animals with a moderate or low PLD value or score should limit the expected prevalence of glaucoma in the resulting population to < 0.2%. The preceding study describes in detail the PLD survey, gonioscopic technique and some initial results obtained prior to this epidemiological investigation.
Pectinate ligament dysplasia (PLD) in dogs is a congenital ocular abnormality affecting the iridocorneal angle, the presence of which may be associated with adult-onset primary glaucoma. This paper describes the objectives, methods and results of a survey of PLD in Flat Coated Retrievers in the UK, including the technique used for gonioscopic assessment of the degree of PLD. In a random sample of 389 Flat Coated Retrievers, 34.7% were found to have a degree of PLD. In a 'target' sample of 48 Flat Coated Retrievers (close relatives of dogs from the random sample with high degrees of PLD, or dogs presented with primary glaucoma), 83.3% were found to have a degree of PLD. The percentage of animals with a degree of PLD was only 6.0% in a 'control' sample of 100 dogs from other breeds. The relationship between PLD and canine glaucoma is discussed.
To assess the association between goniodysgenesis, ocular measurements, and glaucoma in Great Danes.
180 Great Danes.
Eye examination and measurements were obtained from 180 Great Danes; for 30 of these dogs, depth of the anterior chamber, vitreal body length, and total depth of the globe were also measured. These data were merged with electronic pedigree information on 43,371 kennel club registered Great Danes. Relationships among goniodysgenesis, ocular measurements, and glaucoma and the heritability of goniodysgenesis were estimated.
The degree of goniodysgenesis was significantly and positively associated with the likelihood of glaucoma. There was a significant association between the degree of goniodysgenesis in offspring and parents. The estimated heritability of the degree of goniodysgenesis was 0.52. The depth of the anterior chamber of the eye was also a good predictor of goniodysgenesis (ie, the dog was almost certain to have glaucoma if the depth was < 3.7 mm). If both parents had goniodysgenesis < 70%, then with 95% confidence, the occurrence of glaucoma in the ensuing offspring would be < 4/1000. This strategy translates to ensuring that the depth of the anterior chamber of the eye is > 3.7 mm for both parents.
The strong and significant correlation among goniodysgenesis, other eye measurements, and glaucoma and the significant heritability of goniodysgenesis suggests that glaucoma may be heritable in Great Danes. If so, glaucoma can be controlled by breeding only from sires and dams with a minimum degree of goniodysgenesis.
The aim of the study was to evaluate if tonometry and gonioscopy could serve as predictors of later glaucoma development in the English Springer Spaniel, a breed prone to developing primary glaucoma.
Gonioscopy was performed on 279 English Springer Spaniel dogs, 119 males and 160 females, with clinically normal eyes. In addition, 14 dogs, five males and nine females were examined for glaucoma.
A positive relation between pectinate ligament dysplasia (PLD) and narrowing of the relative width of the ciliary cleft (RWOCC) and also between PLD, RWOCC and age was demonstrated. The prevalence of PLD was 25.5%, which is higher than in other breeds reported. A positive association was demonstrated between PLD and glaucoma, as well as between narrowing of the RWOCC and glaucoma. Glaucoma was not observed in dogs with normal appearance of the iridocorneal angle. English Springer Spaniels related to dogs with glaucoma show more narrowing of the RWOCC and more PLD than unrelated dogs.
This study demonstrates the positive association between PLD and glaucoma, between narrowing of the iridocorneal angle and glaucoma and the effect of age on the iridocorneal angle. Mating of dogs with normal iridocorneal angles appears to reduce the presence and degree of abnormal appearance of the iridocorneal angle in the offspring. However, breeding only dogs with normal iridocorneal angles without consideration of their relationship to dogs with glaucoma is not a guarantee for preventing glaucoma in the offspring.
Veterinary Ophthalmology
- K. N. Gelatt
- D. E. Brooks
- M. E. Källberg
Age‐related changes in intraocular pressure and iridocorneal angle in Samoyeds
- Ekesten B.
Survey of the incidence of pectinate ligament dysplasia and glaucoma in the UK Leonberger population
- Fricker