Biomedical subjects
Publications and source records attributed to F C Stades.
On the occasion of his retirement as an active specialist in Surgery dr. P.H.A. Poll describes the history of the development of the specialties in Veterinary Medicine in The Netherlands and carefully looks forward. As a tribute, his specialist colleagues, all related to the Companion Animal Hospital "De Wagenrenk", publish one or more case reports from there respective disciplines (ophthalmology, surgery, radiology, dermatology).
Eight hereditary eye diseases are discussed. These eight abnormalities follow the main possible patterns of inheritance. The clinical aspects and the prevention of these illnesses are discussed.
Between 1967 and 1987, in the Netherlands 3,775 Dobermans were examined for hereditary eye diseases. In 238 of these dogs severe persistent hyperplastic tunica vasculosa lentis and primary vitreous (PHTVL/PHPV) was diagnosed. After a brief description of the clinical features the results of breeding over the recent years are discussed. The incidence (1978-1987) of severely affected dogs in the litter controls decreased from 5% to 1% in the individual controls from 19% to 8%. This is an encouraging downward tendency. Better results are to be expected once test mating and progeny-testing methods are accepted as breeding methods in dog breeding.
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This report provides transmission electron microscopic observations on the early pathogenesis of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV) in affected canine fetuses at days 28-44 postcoitum. The retrolental tissue by which this anomaly is characterized consists of loosely arranged fibroblasts in a randomly oriented meshwork of collagenous fibrils. Some of these cells contain melanosomes at day 44. In one day-44 eye, cells of neuroectodermal origin (Müller cells; fibrous astrocytes) were observed. From day 37 onward, the posterior subcapsular part of the lens contains rounded, increased intercellular spaces, resembling vacuoles, which deform the shape of the lens fibers. The posterior lens capsule develops normally until day 30. From day 35 onward the capsule has an amorphous ultrastructure, as opposed to the clearly laminated ultrastructure in reference eyes at day 35. In addition, the capsule's thickness increases until day 35, and, instead of growing thicker, decreases thereafter. Based on these results, it is hypothesized that a primary metabolic disorder in the lens fibers, subsequently leading to the formation of an abnormal posterior lens capsule, constitutes the primary defect in the sequence of events leading to PHTVL/PHPV.
This study provides transmission electron microscopic observations on the early morphogenesis (from days 25-35 post coitum) of the canine posterior lens capsule, the tunica vasculosa lentis (TVL) posterior and the anterior part of the vitreous body. The presence of an anlage of the posterior lens capsule as early as day 25, recently described histologically, was confirmed by this study. In the period from day 25 to day 35, the polar part of the posterior lens capsule develops 2-29 continuous and parallel lamellae, matching 50 nm and 1.74 microns, respectively. At these early stages, the TVL consists of capillaries that are simple endothelial tubes. From day 28 onward, these can be classified as A-1-alpha capillaries according to the classification of Bennett et al. [3]. In direct proximity to the lens capsule, the vitreous body contains fibrillar material with a morphological appearance similar to that of the lens capsule. This material probably derives from both the capillary endothelial cells' basal lamina and the lens capsule. Only few cellular components were observed in the anterior vitreous body. The development of the described structures is grossly in accordance with that observed in other mammalian species. The observations presented serve as a reference for studies on the pathogenesis of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV), which is an important cause of leucocoria in children and in some dog breeds.
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This study deals with the early morphogenesis, from day 25 to day 35 post coitum (D25-D35), of the canine lens, lens capsule intraocular vascular system, and vitreous body. The breeding method used provides a higher accuracy as to the gestational age of the obtained fetuses than employed previously. The development of the lens, the intraocular vascular system, and the vitreous body of the dog's eye is analogous to that in other mammal species. The findings of this study, combined with data obtained from the literature, suggest that the period during which ocular development takes place is earlier in larger mammalian species than in the smaller ones. Previous descriptions of ocular development in other mammalian species, and one in the dog, reported that the development of the lens capsule starts posteriorly and proceeds towards the anterior part of the lens vesicle. In the present study, the periodic acid--Schiff positive anlage of the capsule was observed to fully surround the lens vesicle at D25, a development that is different and earlier than described previously in the dog and different from that described in other mammals. Moreover, a clear thickening of the capsule was not observed until capillaries of the tunica vasculosa lentis had reached its proximity.
Observations on (postnatal) persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous (PHTVL/PHPV) in man and dog have been published previously. Up to the present, no evidence on the etiology of this entity was available. The hereditary occurrence of the disease in the Dobermann pinscher dog and the similarity of ocular development in mammals has provided a useful model in providing ontogenetic data. The present study deals with the early morphogenesis of PHTVL/PHPV, from day 25 to 44 post-coitum (D25-D44), in genetically affected dog fetuses. Normal beagle dog fetuses served as reference material, which has been described separately. At D30, the hyaloid system, including the tunica vasculosa lentis posterior, had developed further than in the reference fetuses. From that stage onward, a retrolental fibrovascular membrane developed. In some of the eyes of D37, posterior polar subcapsular cataracts and preretinal glial proliferations were observed. Capsular anomalies and distortions of the lens shape as seen in clinical PHTVL/PHPV were not observed, and are believed to be secondary entities. Extrapolation of some of the obtained data from dog to man is possible by the use of comparable gestational time scales. The anterior form of (PHTVL/PHPV) in man probably develops its main features in the period of approximately 43 to 66 days of pregnancy. Recently, anti-angiogenetic properties of normal vitreous have been described. This, and the fact that overdevelopment and subsequent incomplete regression of the hyaloid system plays a major role in the pathogenesis of PHTVL/PHPV, gives rise to the hypothesis that a changed amount or effectiveness of such (humoral) factors is an important factor in the etiology of this disease.
A review will be presented of some available eyelid reconstructive methods--such as the inverse triangles; and the H and rotation flap method for the correction of lid defects, e.g. after lidtumor removal. Emphasis will be put on the choice of method, handling, reconstruction and suturing of skinflaps and lid edges.
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Glaucoma is diagnosed frequently in dogs and cats. A review of case records at the University of Utrecht Small Animal Clinic revealed that during a 4-year period glaucoma accounted for 8.6% of all ophthalmological diagnoses. Glaucoma is defined as an increased intraocular pressure, which sooner or later leads to loss of function of the eye. Primary and secondary types can be distinguished. In primary glaucoma an increased intraocular pressure exists in the absence of other primary eye disorders. By gonioscopy a discrimination can be made between open and narrow or closed anterior chamber angle forms of primary glaucoma. This requires a clear distinction between the definitions of chamber angle and filtration angle. In the Netherlands primary glaucoma is seen especially in the American Cocker Spaniel, Bouvier and Basset breeds. In secondary glaucoma an increased intraocular pressure occurs as a consequence of another primary eye disorder. Dislocation of the lens is the main cause for secondary glaucoma. Several-mainly small-terrier breeds are predisposed to this entity.
The pathobiological backgrounds, breed predispositions and classification of glaucoma have been described in a previous publication. The symptoms of acute glaucoma (corneal edema and vascular injection of the scleral conjunctiva) may bear an insidious resemblance to those of a 'keratoconjunctivitis'. However, it is of great importance to diagnose glaucoma as soon as possible after onset, since lack of treatment may lead to irreversible blindness within one week. When glaucoma becomes chronic the eyeball becomes enlarged. The prognosis concerning vision is then grave. The most important diagnostic and prognostic examinations are retrograde illumination, slitlamp examination, gonioscopy, examination of the fundus and tonometry. Provocative tests may also be useful. Glaucoma can be treated medically or surgically. Medical treatment includes the administration of timolol). Combinations may be useful. Surgical treatment is directed toward improving the outflow of aqueous humor (iridectomy, iridencleisis) and decreasing the rate of formation of aqueous humor (cyclocryotherapy). When all therapies have failed to lower the intraocular pressure and there is no hope of preserving vision, enucleation of the globe can be performed.
It was calculated in the Dutch bulletin for drugs, that chloramphenicol--even in topical treatment--should only be used in human bacterial infections in which the bacteria are solely susceptible to chloramphenicol. Information is supplied stating that these conclusions are based on wrongly chosen patients. It is concluded that the indications for use of topical chloramphenicol in dogs or cats continue to be unchanged.
Progressive retinal atrophy (PRA) is a collective term comprising a group of hereditary degenerative lesions of the retina. A central and a generalized form can be differentiated. The central form (day blindness, hemeralopia) is characterized by accumulations of pigment in the layer of pigmented epithelium of the retina, atrophy of the cones and subsequent atrophy of the rods, eventually terminating in blindness. The generalized form (night blindness, nycteralopia) is marked by dysplasia of the rods and or cones, followed later by atrophy of the rods and cones, or it may be marked solely by atrophy of the rods and cones. Blindness occurs between the first and seventh years of life, varying with the breed and form. Hereditary transmission of the generalized form is recessive. Detection of patients is essential in controlling the disease. The number of carriers can be estimated on the basis of this detection, part of the carriers can be identified and the likelihood of an animal being a carrier can be calculated. The condition may be controlled by test matings to determine the genetic patterns of breeding dogs where progressive retinal atrophy is concerned.
The eyes of 160 Collies were examined for Collie Eye Anomaly, Progressive Retinal Atrophy, and any other eye abnormality present. The incidence of CEA in 160 Collies was 40.6 per cent. There were no cases of PRA. Other abnormalities noted were distichiasis, persistent pupillary membranes, distinct remnants of the hyaloid artery, corneal dystrophy and unilateral cataracts.
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The clinical, pathological and genealogical features of Retinal Dysplasia in a family of Yorkshire terrriers were studied. The ocular changes were characterized by retinal detachment and retinal neovascularization. Dogs of three litters and their sire were affected. RD was suspected to be inherited as a recessive trait.