A New Inherited Ocular Anomaly in Pigmented White Leghorn Chickens

Abstract

Inherited ocular anomalies in chickens include several types of microphthalmia, retinal dysplasia, retinal degeneration, cataract, buphthalmos and pop-eye, or keratoconus in White Leghorns. [2][3][4][5]7,8,12,[15][16][17][18] In this report, a new ocular anomaly that appeared in pigmented White Leghorns homozygous for a mutation at the dominant white (I) locus is described with emphasis on clinical, gross, and histologic findings to aid in the diagnosis of the ocular lesions.An incompletely dominant mutation, called Smoky Joe (SJ), allows the production of feather pigment, which the I allele inhibits. The SJ mutation originally appeared in ADOL Line 0, a noninbred White Leghorn line maintained at the USDA Avian Disease and Oncology Laboratory (ADOL) in East Lansing, Michigan. Females homozygous for SJ have dark grey feathers with barring and homozygous males have much lighter colored plumage. This dimorphism in color is the result of the dilution that occurs with two copies of sexlinked barring in the males. The plumage of heterozygous birds (I, SJ) is intermediate in color compared to either parental type.Phthisis bulbi was noticed in adult females of the second generation of the homozygous SJ population. None of the parents of these females had apparent ocular lesions. Approximately 30% of the 85 surviving females had phthisis bulbi, while none of the 100 surviving males were affected. There was no clinical evidence of bacterial or viral infection, and the chickens were housed in pens isolated from chickens with experimental viral infections. Because the ocular anomaly appeared to be recessive and sex-linked, 4 test matings were designed to further study the inheritance.In matings 1 and 2, sighted SJ males, which were suspected of being carriers of the syndrome, were mated to either affected or sighted SJ females. These same male birds were then mated to either sighted females of Line 0 (II) (mating 3) or sighted females of ADOL Line 15I 5 (II) and Line 0 (II) (mating 4). All chicks had ophthalmic examinations at hatch and 2, 4, and 8 weeks of age.In mating 1,197 chicks were examined. Of the females, 62% were affected, and 10% of the males were affected. Received for publication January 12, 1997.Twenty-two progeny from mating 2 were examined, and 40% of the females and 8% of the males were affected. In both of these matings, approximately equal numbers of each sex were produced, and fertility and embryo viability were within a normal range. These data confirmed a much higher incidence of the ocular anomaly in females and therefore indicated a sex-influenced expression.In matings 3 and 4, when blind or carrier birds were mated to nonpigmented White Leghorns (II), only one affected chick was observed in 242 progeny. These data support the hypothesis that the anomaly is autosomal recessive. The affected chick in mating 4 was most likely the result of an error in the pedigree.Ophthalmic examinations of the newly hatched chicks were performed by using a slit lamp biomicroscope and an indirect ophthalmoscope. Affect...

Congenital cataract in 1-day-old French Mulard ducklings

“…Ocular lesions appeared by 4 months of age, followed by the development of crooked toes. In White Leghorn chickens, an inherited ocular disease, present at hatching, has been described (Salter et al, 1997). It was characterized by several ocular malformations, including cataract, related to an autosomal recessive mutation associated with the pigmentary epithelium.…”

The chick eye in vision research: An excellent model for the study of ocular disease

“…This strain was first described by Salter et al (1997). Interestingly, not all homozygous SJ chicks display the same phenotype.…”

Intraocular Ossification in the GSP/pe Chicken With Imperfect Albinism

“…13 The present study documents ocular osteogenesis in aged GSP/pe chickens, a new mutant strain with hereditary imperfect albinism.…”

“…1,13 In humans, ossification in the lens 7 and choroid 11 has been reported in eyes affected by phthisis bulbi and in eyes with retinal detachment, intraocular hemorrhage and neovascularization, uveitis, 10 and exudative retinopathy in Coats disease. 9 In young humans, intraocular ossification has been suggested to occur secondary to blunt trauma and, in older individuals, secondary to inflammation.…”

“…5 In older birds of the SJ strain, metaplastic bone and cartilage filled the vitreous chamber, which is similar to our cases of aged GSP/pe chickens, although the original breed of these strains is different. 13 In ovo study of intraocular osteogenesis is possible in birds. Thus, the GSP/pe chicken may be a suitable animal model for investigating the potential of epithelial-mesenchymal transdifferentiation of RPE cells.…”