Tag Archives: Bouvier des Flandres

The Lens and Vitreous

The lens develops rapidly in the early stages of embryogenesis, during which time it is nourished by the hyaloid vessel. The fully developed lens is avascular; by the second week of life, no remnants of the hyaloid system should remain. The normal lens often exhibits minor imperfections that can be easily detected with magnification in dogs and cats younger than 1 year. These include prominent anterior and posterior Y sutures and minute granules in its nucleus and cortex. A mosaic of brown pigment spots is occasionally seen on the anterior lens capsule near the center of the pupil, representing remnants of embryonic mesoderm. Disease of the vitreous would be expected to influence the lens or retina because of its attachments at the posterior lens surface and the optic disc. Congenital Abnormalities Congenital lens abnormalities include alterations in size or shape. Congenital absence of the lens (aphakia) is uncommon. In microphakia, the margin of the abnormally small lens along with elongated ciliary processes may be observed after pupillary dilation. Microphakia occurs along with other ocular defects in the Saint Bernard and beagle and in cats. Luxation of the microphakic lens may cause glaucoma. Lenticonus is a Read more […]

The Upper Airway: Nasal Cavity, Paranasal Sinus, Nasopharyngeal, Pharyngeal, and Laryngeal Diseases

Sneezing and nasal discharge are the most common clinical signs of nasal cavity disease. Owners of puppies or kittens that are quickly cleaned by their mother or that are fastidious about licking any appearing discharge may overlook a nasal discharge. Viral disease or environmental irritants usually cause a serous or mucoid discharge; bacterial disease causes a purulent or mucopurulent discharge. Sneezing is usually prominent in acute disease but wanes with chronicity. Acute viral diseases sometimes cause enough destruction of the nasal epithelium to obliterate the sneeze reflex, despite the presence of nasal discharge and other upper respiratory signs. Less common signs of nasal disease include stertorous breathing, pawing or rubbing at the nose or mouth, facial pain, facial deformity, ocular discharge, exophthalmos, or fetid breath. Because clinical signs related to the nose and sinuses can be manifestations of oral, pharyngeal, airway, and pulmonary disease, these areas should be carefully inspected. Evaluation of the nasal cavity should include oral and dental examination, radiographs of the nasal cavity, rhinoscopy, and visual examination of the nasopharynx and internal nares (). Pharyngeal and laryngeal disease Read more […]

The Eye As An Optical Device

A primary function of the eye is to form a crisply focused image on the retina. The optical components through which light travels to reach the retina are the cornea, aqueous humor, lens, and vitreous body. For proper image formation these components must remain transparent and maintain precise relationships to one another. One of the exciting areas of ongoing research is attempting to define the mechanisms whereby these relationships are maintained during growth of the eye. A point source of light located at the visual horizon emits rays that are convergent, divergent, and parallel relative to the eye. At a great distance only rays that are essentially parallel will enter the pupil of the dog. Divergent and convergent rays will pass peripheral to the pupillary aperture. If the eye is focused at infinity (is emmetropic), parallel rays will be refracted and imaged as a point on the dog’s retina. If the dog’s eye is ametropic (either myopic or hyperopic), the rays will not be properly imaged on the retina and will form a blurred circle. As an object is brought closer and closer to the dog’s eye, the percentage of divergent rays entering the pupil will increase, requiring an increase in refractive power of the Read more […]