Hereditary cataract in the dog

Hereditary cataract in the dog is described as it occurs in the Boston Terrier, the Staffordshire Bull Terrier, the Miniature Schnauzer, the Golden Retriever, the Labrador Retriever, the American Cocker Spaniel, the Afghan Hound, and the Old English Sheepdog. The mode of inheritance in each breed is also discussed and includes both dominant and recessive patterns.     

Phaco chop technique for cataract surgery in the dog

Phaco chop is a bimanual phacoemulsification technique to remove cataracts. The technique was first presented at the 1993 3rd American-International Congress on Cataract, IOL, and Refractive Surgery in Seattle by Dr Kunihiro Nagahara. He compared the lens with a block of wood and by applying chopping forces parallel to the natural planes of the lens lamellae, as one does in splitting wood, a nucleus can be cleaved with surprisingly little force and time. Dr Nagahara used the phaco tip to impale and high vacuum to hold the nucleus while a second instrument, or chopper, hooked the equator and was pulled centrally, splitting the nucleus along its natural cleavage planes. This was a breakthrough for surgeons who had been utilizing several minutes of phaco energy sculpting grooves and bowls in a lens. Studies have shown that compared with four-quadrant 'divide and conquer', the phaco chop technique uses less phaco time and energy, significantly reducing endothelial cell damage. Other advantages of phaco chop include reduction of zonular and capsular stress because forces are directed toward an opposing instrument and the phaco tip is kept in a central 'safe zone' in the middle of the pupil. This technique has also been successfully adapted to the canine phacoemulsification procedure. The larger canine lens requires some modifications, and lenses with hard nuclear and cortical material may not be amenable to this procedure.     

Anaesthetic management for balloon dilation of cor triatriatum dexter in a dog

A three-month-old female Rottweiler puppy was referred for intravascular correction of a previously identified cor triatriatum dexter. Echocardiography confirmed the presence of a hyperechoic membrane that divided the right atrium into a cranial and caudal chamber. A foramen in this membrane allowed the blood to flow from the caudal to the cranial chamber. Balloon dilation of the defect under transthoracic echocardiographic guidance was scheduled for the following day. The dog was premedicated with 0.5 μg/kg sufentanil and 0.2 mg/kg midazolam administered intravenously. General anaesthesia was induced with 2 mg/kg propofol and maintained with inhaled isoflurane in oxygen; at the same time, a constant rate infusion of 0.5 μg/kg/h sufentanil was administered by means of an infusion pump. Uneventful ventricular and supraventricular tachyarrhythmias developed during the placement of catheters and balloon dilation. At the end of procedure, when the guide wire and balloon catheter were removed, normal sinus rhythm was observed. To the authors’ knowledge, no previous reports have described the anaesthetic management of a balloon dilation procedure for cor triatriatum dexter in dogs.     

Routine lens extraction for the treatment of cataract in the dog*

In dogs treated for cataract by lens extraction, the authors comment on the wide variety of procedures that have been advocated and used in pre-operative treatment, anaesthesia, operative technique and postoperative care. The article outlines the procedures that have been tried and rejected over the last 10 years and those which are now favoured by the authors. Using standard criteria to assess results, the successful outcome of treatment has increased from 50% to 75%.     

犬白内障的临床分类及病理特性

眼是动物体的一个光学器官。眼球的结构很复杂，晶状体是调节眼球视觉焦距的屈光体，其功能或形态可发生各种异常，形成不同类型的晶状体病，临床上将影响视力或未明显影响视力的晶状体混浊称为白内障。所有的白内障绝不仅仅是晶状体本身的病变，而是伴有眼部表现的全身性疾病。如果晶状体囊膜或晶状体组织本身失去透明性，则呈现部分或全部混浊。     

Spontaneous cataract resorption and lens-induced uveitis in the dog.

Spontaneous cataract resorption and the associated lens-induced uveitis occur primarily in young dogs, especially the Afghan Hound, American Cocker Spaniel, Boston Terrier, Miniature and Toy Poodle, and Miniature Schnauzer. The resorption process, if extensive, will restore vision without surgical intervention, but medical control of the lens-induced uveitis by use of mydriatics and, infrequently, topical and systemic corticosteroids is essential. The main potential complications, severe medically nonresponsive uveitis and glaucoma, necessitate immediate cataract extraction.     

The diagnosis and differential diagnosis of cataract in the dog

Cataract is a common eye condition in the dog, classified in several ways and with a varied aetiology. The clinical appearance of hereditary cataract is described in the Boston Terrier, Miniature Schnauzer, Staffordshire Bull Terrier, Cavalier King Charles Spaniel, Golden Retriever, Labrador Retriever, Large Munsterlander, English Cocker Spaniel, American Cocker Spaniel, Afghan Hound, Welsh Springer Spaniel, German Shepherd Dog, Standard Poodle. Cataracts secondary to other eye diseases, both hereditary and non-hereditary, and to systemic conditions are also discussed, as well as the differential diagnosis of cataract.     

The effects of cataract stage, lens-induced uveitis and cataract removal on ERG in dogs with cataract

OBJECTIVE: The purpose of this study was to determine the effects of cataract stage, lens-induced uveitis and cataract removal on the electroretinogram (ERG) of dogs with cataract. ANIMALS STUDIED: Fifty-seven dogs diagnosed with unilateral or bilateral cataract whose ERG was recorded at Rakuno Gakuen University Teaching Animal Hospital from 2001 to 2004. PROCEDURES: Four responses were recorded during the ERG: rod ERG, standard combined ERG, single-flash cone ERG and 30-Hz flicker ERG. Cataracts were divided into four stages: incipient, immature, mature and hypermature, and with or without lens induced uveitis (LIU). Noncataractous eyes of dogs with unilateral cataract were used as the control. We compared ERG amplitude, implicit time, and the b- to a-wave amplitude ratio of cataractous vs. noncataractous eyes, preoperative vs. postoperative cataractous eyes, and cataractous eyes with and without LIU. RESULTS: No significant difference was found in ERG amplitude between incipient, immature and hypermature cataractous eyes, while in mature cataractous eyes decreased amplitude was confirmed in all responses compared with control eyes. However, no significant difference in b/a ratio was found at any stage of cataract. In postoperative eyes, increased amplitude was recorded in all responses compared to preoperative values. In eyes with LIU a decreased amplitude in the rod ERG and b-wave of standard combined ERG was recorded and, furthermore, a significant decline was confirmed in b/a ratio. CONCLUSION: ERG values were influenced by cataract stage and LIU. LIU was associated with a reduction in the b/a ratio.     

Immunohistochemical analysis of lens epithelial-derived membranes following cataract extraction in the dog

The objective of the study was to characterize the morphologic and immunohistochemical features of lens epithelial-derived proliferative membranes from the anterior segment of canine globes. These features were correlated with those previously identified for diseases resulting from lens epithelial cell (LEC) proliferation including posterior capsular opacification, traumatic subcapsular cataract, and subcapsular plaques associated with hypermature cataracts. Sixteen canine globes were removed as a result of glaucoma or other complications following cataract extraction. Light microscopic and immunohistochemical analysis was performed on sections from formalin-fixed, paraffin-embedded globes. The tissues were stained with a variety of antibodies for cellular markers for LECs, growth factors or other cellular constituents relevant to cellular metaplasia and proliferation. The membranes were composed of monolayers or multilayers of spindle-shaped cells on the external surfaces of the anterior and posterior lens capsule, ciliary processes, iris leaflets, and iridocorneal angle, and they could be seen extending from an obvious monolayer of LEC within the capsular sac. Variably, scattered pigment cells, presumably of uveal origin, were concurrently present. Cellular components of the membranes stained positive for vimentin, transforming growth factor-beta, basic fibroblast growth factor, and smooth muscle actin. An amorphous eosinophilic extracellular matrix consisting predominately of collagen was associated with the membranes. Proliferative anterior segment membranes following cataract surgery were morphologically and immunohistochemically similar to cellular and matrix components of posterior capsular opacification and capsular plaques seen with hypermature cataracts, both of which result from metaplasia and proliferation of LEC. The presence of these LEC-derived membranes in association with secondary glaucoma suggests that exuberant proliferation of LEC outside the confines of the lens capsular sac may cause pathologic alterations in the eye following cataract surgery in the dog.     

Dermoid sinus removal in a rhodesian ridgeback dog

A three year old Rhodesian Ridgeback dog with a history of a small draining tract in the dorsal cervical area, was found to have a dermoid sinus on surgical exploration. The affected tissue was removed and histopathology done. The sinus is an inherited condition in this breed of dog, with surgical correction and neutering of affected individuals the treatments of choice to reduce the incidence of the dermoid sinus condition in the next generation.     

Posterior lenticonus with congenital cataract in a Shih Tzu dog

A seven-month-old, male Shih Tzu dog weighing 3.7 kg had an immature cataract in its left eye. A biomicroscopic examination revealed numerous vacuolations in the posterior cortices with nucleus cataracts, covered by an intact anterior lens capsule. The changes observed by ocular sonographic examination (OSG) of the left eye were hyperechoic, and a funnel-cone shape was observed posteriorly with cortex hyperechogenicity in the lens. The left eye was diagnosed as having a posterior lenticonus with congenital cataract. Phacoemulsification was performed on the left eye as diagnostic treatment of the posterior lenticonus and cataract. Postoperative OSG on the left eye revealed a V-shaped linear echo that was indicative of a posterior capsule of the lens. Moreover, it was confirmed that hyperechoic cataract material inside the lens had disappeared.     

Spontaneous resorption of a diabetic cataract in a geriatric dog

Spontaneous cataract resorption is described in a geriatric cocker spaniel with a four-month history of diabetes mellitus. Resorption progressed to such a degree that vision was restored in that eye and almost all the cataract material disappeared. This is not common in geriatric dogs despite having been described with relative frequency in young animals with hereditary cataracts.     

Intraosseous approach to the nasolacrimal duct for removal of a foreign body in a dog

A Labrador retriever was evaluated because of chronic mucopurulent discharge from the left eye. A foreign body was identified in the nasolacrimal duct by use of dacryocystorhinography. Attempts to alleviate the inflammation by use of flushing and administration of antimicrobials were unsuccessful. At surgery, the infraorbital foramen was used as a landmark for a skin incision, because the nasolacrimal duct courses dorsal and parallel to the infraorbital canal. An air drill was used to remove the portion of the maxillary bone overlying the nasolacrimal duct, which exposed the intraosseous portion of the duct and allowed removal of a plant-material foreign body. The incision in the duct was allowed to heal by second intention, and the dog recovered without complications.     

Primary bronchotomy for removal of an intrabronchial foreign body in a dog.

An 8-year-old, spayed female toy poodle presented with wounds sustained from a dog fight. The multiple orthopedic injuries present were managed surgically. Months later, a chronic cough developed secondary to an aspirated canine tooth in the mainstem bronchus of the right cranial lung that was nonresponsive to medical management. A thoracotomy and primary bronchotomy were performed to remove the aspirated tooth, resulting in complete resolution of clinical signs. Bronchial foreign bodies are rarely diagnosed in companion animals. Primary bronchotomy is an alternative to bronchoscopy or lung lobectomy in cases that do not respond to medical management.