The effect of repeated eye examinations and breeding advice on the prevalence and incidence of cataracts and progressive retinal atrophy in German dachshunds over a 13-year period.

OBJECTIVE: To analyze the change in prevalence and incidence of hereditary eye diseases (HED) in dachshunds due to breeding regulations based on biennial examinations performed by the German panel of veterinary ophthalmologists (DOK) from 1998 to 2011. ANIMALS INCLUDED: A total of 12 242 dachshunds examined by the DOK and pedigree data of 318 852 dachshunds provided by the German Dachshund Club (DTK). PROCEDURES: The prevalence of congenital cataract (CC), distichiasis (DIST), hereditary cataract (HC), persistent pupillary membranes (PPMs), persistent hyperplastic tunica vasculosa lentis / persistent hyperplastic primary vitreous (PHTVL/PHPV), progressive retinal atrophy (PRA), retinal dysplasia (RD), and findings such as fiberglass-like cataract (FGC) and prominent suture lines (PSLs) was analyzed. The significance (P), confidence interval (CI), odds ratio (OR), relative risk (RR) and inbreeding coefficients (F) were calculated and P < 0.05 was considered significant. The incidence was evaluated based on affected dogs within birth cohorts from 1993 to 2006. RESULTS: The prevalent conditions studied were as follows: CC 0.5%, DIST 6.7%, HC 3.9%, PPMs 8.4%, PHTVL/PHPV 0.4%, PRA 1.5%, RD 0.2%, FGC 2.2%, and PSL 1.5%. The incidence of PRA decreased significantly from 6.0% to 0.6% for dogs born from 1993 to 2006, while HC showed a decreasing trend from 8.7% to 3.1%. More males than females were diagnosed with HC and PRA. Dachshunds with HEDs had an F that was not significantly higher than that of healthy dachshunds. CONCLUSIONS: The decreasing incidence of PRA and HC in dachshunds supports the use of frequent HED examinations in combination with breeding control.

A large deletion in RPGR causes XLPRA in Weimaraner dogs.

BACKGROUND: Progressive retinal atrophy (PRA) belongs to a group of inherited retinal disorders associated with gradual vision impairment due to degeneration of retinal photoreceptors in various dog breeds. PRA is highly heterogeneous, with autosomal dominant, recessive or X-linked modes of inheritance. In this study we used exome sequencing to investigate the molecular genetic basis of a new type of PRA, which occurred spontaneously in a litter of German short-hair Weimaraner dogs. RESULTS: Whole exome sequencing in two PRA-affected Weimaraner dogs identified a large deletion comprising the first four exons of the X-linked retinitis pigmentosa GTPase regulator (RPGR) gene known to be involved in human retinitis pigmentosa and canine PRA. Screening of 16 individuals in the corresponding pedigree of short-hair Weimaraners by qPCR, verified the deletion in hemizygous or heterozygous state in one male and six female dogs, respectively. The mutation was absent in 88 additional unrelated Weimaraners. The deletion was not detectable in the parents of one older female which transmitted the mutation to her offspring, indicating that the RPGR deletion represents a de novo mutation concerning only recent generations of the Weimaraner breed in Germany. CONCLUSION: Our results demonstrate the value of an existing DNA biobank combined with exome sequencing to identify the underlying genetic cause of a spontaneously occurring inherited disease. Identification of the genetic cause has allowed the development of a diagnostic test, which should help to eradicate the PRA causing mutation from the respective canine line. Thus, planning of future pairings is facilitated and manifestation of this type of PRA can be prevented.

Prevalence and formation of primary cataracts and persistent hyperplastic tunica vasculosa lentis in the German Pinscher population in Germany.

OBJECTIVE: The objective of this study was to describe the prevalences of primary noncongenital cataracts (CAT) and persistent hyperplastic tunica vasculosa lentis (PHTVL) in the German Pinscher population in Germany and to analyze the mode of inheritance of CAT in this dog breed. ANIMALS STUDIED: All German Pinschers with a certified veterinary ophthalmological diagnosis and born between 1993 and 2010 were included in this study. Examinations were performed between 1997 and 2013 by certified veterinary ophthalmologists of the German panel of the European Eye Scheme for Diagnosis of Inherited Eye Diseases in Animals (DOK). PROCEDURES: Data were reviewed retrospectively for the prevalence of PHTVL, and the prevalence, location and age at diagnosis of CAT. Inheritance of CAT was analyzed using the Singles Method. RESULTS: A total of 779 eye examination reports of 409 dogs were available. Primary noncongenital cataracts were diagnosed in 64 (15.6%), and PHTVL in 13 (3.2%) of the examined dogs. The pedigrees included 168 ophthalmologically examined dogs with 104 CAT-unaffected and 64 CAT-affected dogs. All affected animals were offspring of a frequently used stud-dog or closely related ancestors of this stud-dog. Simple segregation analysis revealed a recessive mode of inheritance for CAT. CONCLUSIONS: An early onset form of CAT with various cortical, posterior polar or multiple locations was the most prevalent manifestation among close relatives in German Pinschers. The pedigree analysis indicated a hereditary component of cataract formation with a monogenic autosomal recessive pattern of inheritance.

Analysis of systematic and genetic effects on the prevalence of different types of primary lens opacifications in the wild-boar-colored wirehaired Dachshund.

The aims of this study were to analyze the influence of systematic environmental effects on the prevalence of primary non-congenital cataract (CAT), fibreglass cataract in the nucleus (FCN), and prominent suture lines (PSL) and to estimate the heritabilities of these eye diseases in the wild-boar-colored wirehaired Dachshunds (WWD) bred in the German Dachshund Club 1888 e.V. (DTK). Data included 2,430 WWD born between 1995 and 2003 that were examined between 1996 and 2005 by veterinary ophthalmologists. CAT was diagnosed in 3.83% of the 2,430 dogs, FCN in 3.74%, and PSL in 2.76%. Sex, size, inbreeding coefficient, the age of the dog at examination, experience of the veterinary ophthalmologist and the additive genetic effect of the animal were considered in the multivariate linear model. The age of the dog at examination had a significant influence on the prevalence of FCN. The degree of experience of the veterinary ophthalmologist significantly influenced the prevalence of FCN and PSL. Using a transformation into the Dempster-Lerner threshold model, heritability estimates (h(DL)2) for WWD were h(DL)2 = 0.39 +/- 0.13 for CAT, h(DL)2 = 0.36 +/- 0.11 for FCN and h(DL)2 = 0.49 +/- 0.12 for PSL. Positive genetic correlations (r(g)) were found between CAT and FCN (r(g) = 0.58 +/- 0.21), between PSL and FCN (r(g) = 0.83 +/- 0.23), and between CAT and PSL (r(g) = 0.79 +/- 0.06). The eye diseases investigated here in the Dachshund were found to be genetically influenced and positively correlated traits.

A retrospective study on the prevalence of primary cataracts in two pedigrees from the German population of English Cocker Spaniels.

OBJECTIVE: Two pedigrees from the German English Cocker Spaniel population are presented to illustrate the familial occurrence of primary cataract (CAT) in single- and multicolored English Cocker Spaniels. The aim was to characterize similarities and differences in the prevalence and formation of CAT in these separately bred color variants of English Cocker Spaniels. MATERIALS: The study was based on the veterinary records for presumed inherited eye diseases of 1232 English Cocker Spaniels which were provided by the German panel of the European Eye Scheme for diagnosis of inherited eye diseases in animals (DOK, ). Data included information on 615 single-colored and 617 multicolored English Cocker Spaniels. RESULTS: CAT was diagnosed in 92 (14.96%) of the single-colored and 34 (5.51%) of the multicolored English Cocker Spaniels. The pedigree of the single-colored English Cocker Spaniels included 40 ophthalmologically examined dogs with 18 unaffected and 22 affected dogs. The pedigree of the multicolored English Cocker Spaniels contained 16 ophthalmologically examined dogs with 11 unaffected and five affected dogs. CONCLUSIONS: In both color variants of the English Cocker Spaniels different forms of primary CAT with respect to location within the lens occurred among close relatives. Appearance of CAT was very heterogeneous without obvious sex differences. The sample pedigrees do not support the assumption of familial segregation of specific forms of primary CAT in English Cocker Spaniels.

Analysis of systematic and genetic effects on the prevalence of primary cataract, persistent pupillary membrane and distichiasis in the two color variants of English Cocker Spaniels in Germany.

Genetic parameters were estimated for prevalences of primary cataract (CAT), persistent pupillary membrane (PPM) and distichiasis (DIST) in 615 single-colored and 617 multi-colored English Cocker Spaniels (ECS) bred in the German kennel club for Spaniels (Jagdspaniel-Klub e.V.). CAT or CAT diagnosed in dogs up to three and a half years of age (early-onset cataract, CAT-early) and CAT diagnosed in dogs over three and a half years of age (late-onset cataract, CAT-late), PPM and DIST were included as binary traits in multivariate genetic analyses. Heritabilities on the underlying liability scale were 0.15 for CAT, 0.34 for CAT-early, 0.13 for CAT-late, 0.46 for PPM, and 0.62 for DIST in single-colored ECS and 0.06 for CAT, 0.13 for CAT-early, 0.14 for CAT-late, 0.10 for PPM, and 0.61 for DIST in multi-colored ECS. There were indications for a different genetic basis of CAT-early and CAT-late in single-colored ECS as genetic correlations were close to zero. In multi-colored ECS, a similar tendency for CAT-early and CAT-late could be observed.

[Analysis of the mode of inheritance for distichiasis in the Elo dog breed using complex segregation analyses]. / Analyse des Erbgangs von Distichiasis bei der Hunderasse Elo mittels komplexen Segregationsanalysen.

The inheritance of distichiasis was analyzed in the dog breed Elo using complex segregation analyses. The different hypotheses of monogenic, mixed-monogenic-polygenic and polygenic inheritance as well as a pure environmental model were tested. In further analyses the number of examined Elo dogs per ophthalmologist and the proportion of genes of Eurasian and Old English Sheepdogs were included in the models as covariates. Seven families were randomly collected for the analyses. The seven families comprised a total of 296 animals with 218 examined and 65 affected dogs. A genetic component was verified for the prevalence of distichiasis. Mixed models with a recessive, dominant or arbitrary major gene effect and the polygenic model represented likely hypotheses of inheritance. The prevalence of distichiasis observed was insufficiently explained by non-genetic factors and the breed composition. Therefore, a model only including non-genetic factors and the breed composition could be excluded.

[Analysis of the prevalence of distichiasis in the dog breed Elo]. / Analyse der Prävalenz von Distichiasis bei der Hunderasse Elo.

The Elo is a recently established dog breed in which the eye anomaly distichiasis has been frequently observed. Out of a total of 234 Elo dogs ophthalmologically examined over four years, 27.8% of the dogs showed between 1 and 31 distichia. There were twice as many distichia in the upper than in the lower eyelid. Litter size, the number of examinations of Elo dogs per ophthalmologist and the proportion of genes of the Eurasian dog had a significant influence on the prevalence of distichiasis. The error probability for the inbreeding coefficient and the proportion of genes of the Old English Sheepdog were just above the significance limit of p = 0.05. No significance was found for the remaining effects. Heritability for distichiasis was estimated using a linear animal model. After transformation of the linear observed estimate onto the underlying liability scale the heritability estimate was h2 = 0.43.