Abnormal ocular pigment deposition and glaucoma in the dog

The combined occurrence of ocular pigment deposition and glaucoma has been described in Cairn Terriers. Recently, this condition was also observed in two other breeds: the Boxer (two cases) and the Labrador Retriever (one case). Six dogs were referred to the Ophthalmology section of the Department of Clinical Sciences of Companion Animals and to a private referral clinic because of glaucoma or blindness in one or both eyes. In five cases ophthalmic examination showed pigment depositions in the sclera around the entire circumference of the perilimbal zone. Eight enucleated eyes (four eyes of two Cairn Terriers, three eyes of two Boxers and one eye of a Labrador Retriever) were examined microscopically. All eyes showed the same findings: an extensive infiltration of large melanin-containing cells with an eccentric nucleus, located in the iris, ciliary body, retina, choroids and sclera. Transmission electron microscopy of two of the examined eyes revealed that the morphology of most of these cells was consistent with melanophages. While reports in the veterinary literature concerning this condition are limited the cells concerned have been described to be melanocytes. Further research is needed to conclusively identify the cell type. As described in the present report, the histologic and transmission electron microscopic findings suggest a different etiology of the ocular pigment deposition and glaucoma compared with the pigment dispersal syndrome in humans.     

Familial non-rcd1 generalised retinal degeneration in Irish setters

Four Irish setters were diagnosed with bilateral retinal degeneration and cataracts at an age ranging from six to 11 years. In three of these dogs, progressive night blindness was reported from an age of eight to 11 years. In the fourth dog, aged six, no signs of visual impairment had been noticed. In all four dogs, the rod-cone dysplasia type 1 (rcd1) mutation was excluded as a cause, using an allele-specific PCR. From their three-generation pedigrees, a familial relationship was detected in three out of four dogs, which were also related to four additional Irish setter dogs with a history and clinical signs suggestive of late-onset progressive retinal degeneration. These results suggest the existence of a possibly hereditary, late-onset, progressive retinal atrophy in the Irish setter breed, that is distinct from rcd1.     

Intraocular osteosarcoma in a dog

A 10-year-old German shepherd dog was presented with unilateral uveitis and hyphaema. Treatment was unsuccessful and the eye was enucleated. Intraocular osteosarcoma was diagnosed by histological examination.     

Collie eye anomaly in Collies in the Netherlands

Summary

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.     

Persistent hyperplastic tunica vasculosa lentis and persistent hyaloid artery in a 2-year-old basset hound.

A 2-year-old Basset hound with unilateral persistent hyperplastic tunica vasculosa lentis and primary vitreous is described. There was leukokoria in the left eye, caused by bluish-white polar densities and haemorrhagic discoloration in the nucleus of the lens. Ultrasonographic examination of the eye revealed a small hyperechoic lens and a hyperechoic linear soft-tissue strand extending from the posterior pole of the lens through the optic disc. Power Doppler imaging revealed blood flow in this persistent hyaloid artery, but 5 months later, immediately prior to surgery, there was no flow in this artery. Ultrasonography, including Power Doppler imaging, was useful to confirm the diagnosis and to estimate the complications of surgery, especially the risk of vitreal haemorrhage after cutting of the persistent hyaloid artery. Comparison of the ultrasonographic images with those obtained by computed tomography suggested that the resolution of computed tomography is inadequate for identifying structures as fine as a persistent hyaloid artery.     

Progressive retinal atrophy in Abyssinian and Somali cats in the Netherlands (1981-2001)

From 1981 to 2001, 248 Abyssinian and 127 Somali cats in the Netherlands were examined for hereditary eye disease. Distinct ophthalmoscopic signs consistent with hereditary progressive retinal atrophy (PRA) were observed in 11 Abyssinian cats, and subtle signs in 3 Abyssinian cats. A familial relationship was detected in 13 out of 14 of these cats, which supports a hereditary basis to the condition. Distinct funduscopic signs of retinal degeneration were observed at a median age of 4 years. One cat with advanced retinal degeneration was only 7 months old, whereas the remaining 10 cats were between 2 and 12 years old at the time of diagnosis. These differences in the age of onset are suggestive of at least two types of PRA occurring in Abyssinian cats in the Netherlands: a dysplastic, early-onset and a late-onset retinal degeneration. A large-scale and systematic examination programme for hereditary eye disease will be necessary to assess the incidence of PRA in the Dutch population of Abyssinian and Somali cats as a whole, and to provide a basis for a preventive breeding programme.     

ULTRASONOGRAPHIC DIAGNOSIS OF PERSISTENT HYPERPLASTIC TUNICA VASCULOSA LENTIS/PERSISTENT HYPERPLASTIC PRIMARY VITREOUS IN TWO DOGS

Ultrasonography was performed on a Basset hound and a Doberman clinically suspected of persistent hyperplastic tunica vasculosa lentis/persistent hyperplastic primary vitreous. In both dogs, hyperechoic lenses with a triangular-shaped echodense structure retrolentally were visible, and a very thin hyperechoic strand was seen penetrating the anechoic vitreous from this retrolental tissue to the area of the optic nerve. Using color Doppler imaging, blood flow was evident in parts of the retina in both dogs. With power Doppler imaging there was blood flow in the lens and hyperechoic strand of the Basset hound on the first examination; whereas, on re-examination 5 months later, this was not found. Other abnormalities, such as retinal detachment, endophthalmitis, vitreous hemorrhage, microphthalmia, and posterior neoplasia could be excluded.     

Comparison of the use of new handheld tonometers and established applanation tonometers in dogs

OBJECTIVE: To examine the practical aspects, accuracy, and reproducibility of 2 new automatic handheld tonometers in dogs and compare them with results for 2 established applanation tonometers. ANIMALS: 15 freshly enucleated canine eyes for manometric evaluation and 20 conscious research dogs, 20 client-owned dogs, and 12 dogs with acute glaucoma for clinical tonometry. PROCEDURE: Calibration curves were determined for all 4 tonometers on 15 enucleated canine eyes. Intraocular pressure (IOP) was measured with each tonometer consecutively in conscious dogs, with the MacKay-Marg applanation tonometer as the reference device. Measurements were repeated in 20 sedated dogs. An induction-impact tonometer was evaluated clinically on dogs with acute glaucoma. Additionally, measurements obtained by an experienced and an inexperienced examiner and with or without use of topical anesthesia were compared. RESULTS: The portable pneumatonometer was cumbersome and time-consuming. Compared with results for the reference applanation tonometer, and confirmed by manometry, the portable pneumatonometer increasingly underestimated actual IOP values with increasing IOP. The induction-impact tonometer provided accurate and reproducible measurement values. There was a significant strong correlation between the IOP values obtained by the 2 examiners (r2, 0.82) and also with or without topical anesthesia (r2, 0.86). In dogs with glaucoma, the fitted line comparing values for the reference applanation tonometer and induction-impact tonometer closely resembled an ideal 1:1 relationship. CONCLUSIONS AND CLINICAL RELEVANCE: Use of the portable pneumatonometer in dogs appears to have disadvantages. The induction-impact tonometer appears to provide a promising alternative to the use of applanation tonometers in dogs.     

DNA-diagnosis of congenital diseases in companion animals and the role of the practicing veterinarian

The knowledge on the impact of gene defects on the development of disease in companion animals is increasing rapidly. The gene defects may be differentiated in an initiating defect, which is the cause of illness, and a promoting defect, which enhances the chance on illness. Up till now only initiating defects are known in dogs and cats. All this is of great importance for breeding purposes, because within a breed there is narrow relationship which means the genetic diversity is small, and with all the disadvantages thereof. The identification in good time of gene defects in breeding animals, so that these animals being excluded from breeding, is of utmost importance in preventing congenital diseases. For that reason more and more the owners will appeal to veterinary surgeons to cooperate in procedures to screen potential breeding animals, or to declare the animals free from gene defects. The problems with regard to the diagnostic tests, including the DNA-tests, and their predictive values are discussed.