Ocular lesions in cats diagnosed with systemic sporotrichosis

OBJECTIVES

To describe the most common ocular lesions and demonstrate the frequency of ophthalmic involvement in a group of cats with systemic sporotrichosis.

ANIMALS STUDIED

Two hundred seventy-four cats diagnosed with systemic sporotrichosis. The inclusion criteria included previous positive cytopathological examination, histopathological examination, or fungal culture.

PROCEDURES

In a prospective case-control study, 274 cats diagnosed with systemic sporotrichosis underwent ophthalmic evaluation and received treatment for systemic sporotrichosis. Of these animals, 63 had ocular abnormalities which were recorded, and conjunctivitis was scored from 0 to 5. Diagnostic techniques utilized included fungal culture, as well as cytopathological (10 eyes; 10 cats), and histopathological examination of the palpebral conjunctiva and eyes (2 eyes).

RESULTS

Cytopathological and histopathological examination of the conjunctiva, as well as fungal culture, proved to be important tests for the detection of Sporothrix sp. Five cats without the evidence of ophthalmic abnormalities also had a positive fungal culture. The identified ocular lesions in animals with systemic sporotrichosis included increased serous discharge (79 eyes; 53 cats), blepharoconjunctivitis (33 eyes; 25 cats), conjunctivitis (39 eyes, 20 cats), blepharitis (9 eyes; 8 cats), uveitis (5 eyes; 3 cats), and Florida keratopathy-like lesions (2 eyes; 1 cat).

CONCLUSION

Sporotrichosis should be considered a differential diagnosis for conjunctivitis and blepharoconjunctivitis, especially in endemic areas. Fungal culture and cytopathology of ocular discharge and histopathological examinations of the conjunctiva are important for the diagnosis of ophthalmic sporotrichosis, although not all cats underwent laboratory testing in this study. Ocular discharge could be a source of contagion transmission.

Birefringence analysis of collagen supraorganization in cat corneas with tropical keratopathy

OBJECTIVE

To evaluate the birefringent properties of the cornea and examine the supraorganizational aspects of collagen fibers in cats with tropical keratopathy.

PROCEDURE

In this study, 10-micrometer-thick sections of corneal tissue from cats with tropical keratopathy were examined, both in the opaque and transparent areas of the anterior stroma. Control samples were obtained from healthy cat corneas. Polarized light microscopy was employed to evaluate the birefringent properties using two distinct methods. The first method involved measuring the optical retardation associated with corneal birefringence, while the second method assessed the alignment/waviness of the birefringent collagen fibers. Differences were significant when p < .05.

RESULTS

Tropical keratopathy resulted in a significant rise (p < .05) in optical retardation in both opaque and transparent regions of the cat cornea. In the anterior stroma, both the opaque zones and transparent tissue exhibited a higher degree of collagen fiber packing than the control corneas. However, no significant differences (p > .05) in alignment were observed between the transparent tissue of the diseased cornea and the healthy corneas.

CONCLUSION

Supraorganizational changes in collagen fiber packing are not restricted to lesion zones in cat corneas affected by tropical keratopathy. Such alterations also occur in the corneal tissue of the anterior stroma adjoining the lesions. Therefore, it is plausible that the transparent tissue of the anterior stroma in corneas affected by the disease may have functional abnormalities, despite its macroscopic healthy appearance. Additional investigations are required to clarify the implications of these potential defects and their conceivable contribution to tropical keratopathy.

Band-like opacity in the corneas of abattoir-acquired pig eyes

In the course of an investigation into the distribution of immune cells in the porcine cornea, a band-like lesion on the cornea of two-thirds of the eyes acquired from the local abattoir was noted. Histological investigations revealed an area of corneal epithelium debridement with no obvious other pathological changes. Discussions with abattoir staff soon revealed the cause of the lesions to be the scalding process that all pig carcasses undergo immediately post-mortem that serves to remove unwanted hair and reduce skin-dwelling bacterial contamination. We concluded that the band-like opacity was the result of thermal injury to the anterior surface of the cornea between the open eyelids. It is hoped that this short communication will act as a cautionary note to other investigators who currently use or are considering using porcine eyes in research or as a model in surgical training and who may be unaware of the conventional handling procedures in pig abattoirs.

Qualitative tear film and conjunctival goblet cell assessment of cats with corneal sequestra

OBJECTIVES

To evaluate the tear film qualitatively and conjunctival goblet cell numbers in cats with and without corneal sequestra. ANIMALS STUDIED AND PROCEDURES: This was a prospective evaluation of 11 cats with corneal sequestra and 14 control eyes that were either the contralateral normal eye when the sequestrum was unilateral or from control cats of similar age with no ocular disease. All cats in this study were examined by a veterinary ophthalmologist. The ophthalmic examinations included a neuro-ophthalmic evaluation, Schirmer tear tests, fluorescein staining, tear film break-up times, applanation tonometry, biomicroscopy, and indirect ophthalmoscopy. The palpebral conjunctiva at the dorsal nasal, ventral nasal, dorsal temporal and ventral temporal fornices were biopsied after topical anesthetic was applied to the cornea and conjunctiva. The conjunctival biopsies were fixed in formalin and sectioned routinely and stained with hematoxylin and eosin, and periodic acid-Schiff. These slides were examined by light microscopy by a blinded examiner. Goblet cell numbers were compared to conjunctival basal epithelial cell numbers by region. The goblet cell numbers by region from the eyes with sequestra was statistically compared to those from eyes without sequestra, with a student's paired t-test. Conjunctival swabs were collected from the cats with corneal sequestra and submitted for polymerase chain reaction for Herpes felis, Chlamydia psiitticia, and Mycoplasma felis. The corneal sequestra were removed by surgical keratectomy and fixed and stained routinely, and examined by light microscopy.

RESULTS

No neurologic abnormalities were detected in any of the cats. The Schirmer tear tests (eyes with sequestra 14+/-5.1 mm/min; normal eyes 15+/-6.8 mm/min) and intraocular pressures (eyes with sequestra 21+/-6.6; normal eyes 22+/-5.8) were within normal reference ranges for cats. Biomicroscopic examinations revealed varied sizes and depths of brown- and amber-colored corneal sequestra. No abnormalities were noted on indirect ophthalmoscopic examinations. The tear film break-up time was 21 s (+/-12) for the normal eyes (n=14) and 14 s (+/-13) in eyes with corneal sequestra (n=11). The average goblet/epithelial cell ratios by region for the normal eyes and the eyes with sequestra respectively were 0.66, 0.56 for the dorsal nasal fornix, 0.68, 0.57 for the ventral nasal fornix, 0.63, 0.48 for the temporal dorsal fornix, and 0.55, 0.49 for the temporal ventral fornix. There were no significant differences in tear film break-up times and goblet cell numbers in eyes with corneal sequestra and those without sequestra. Three conjunctival swabs from two of 11 cats with sequestra were positive with PCR for Herpes felis virus. These included one cat with bilateral sequestra and one cat with unilateral corneal sequestrum.

CONCLUSIONS

The pathogenesis of feline corneal sequestra does not appear to be linked primarily to abnormal goblet cell numbers, qualitative tear film abnormalities, and accelerated tear film break-up time.

Occurrence, clinical manifestation and the epidemiological implications of naturally occurring canine trypanosomosis in western Kenya

Domestic dogs were screened for Trypanosoma brucei infection using the haematocrit centrifugation technique as part of routine active surveillance exercises in the Busia and Teso districts of Kenya. The purpose was to assess the role of dogs as sentinels for the occurrence of human sleeping sickness. Out of 200 dogs screened, five were found to be infected at the various test sites. These five succumbed to the disease within four weeks, and exhibited a distinct and pronounced corneal opacity before death. Blood from two naturally infected dogs were tested for the presence of the serum resistance associated (SRA) gene and one tested positive, confirming it as human infective (T. brucei rhodesiense) prevalence (0.5 %). It is considered that the occurrence of this clinical sign could be used as an early warning prediction of future outbreaks. This type of prediction could form an integral part of an indigenous technical knowledge set in areas lying at the edges of the tsetse (Glossina) belts where T. brucei is the main trypanosome species that affects dogs. The occurrence of corneal opacity in dogs could indicate a rise in the levels of T. brucei a proportion of which could be human infective T. b. rhodesiense circulating in the population early enough before disease outbreak occurs. It is thought that during sleeping sickness epidemics the domestic dog will be the first casualty rapidly succumbing to disease long before it is noticed in man. Prompt prediction of disease outbreaks would thus enable early interventions that would reduce the morbidity, mortality and the general economic losses associated with sleeping sickness to be instituted.

Atherosclerosis with multifocal myocardial infarction in a Pacific walrus (Odobenus rosmarus divergens Illiger)

A 25-yr-old male captive walrus (Odobenus rosmarus divergens Illiger) died after suffering from periods of inactivity, anorexia, and weight loss for 8 wk. Necropsy revealed prominent, generalized atherosclerosis of cardiac arteries with widespread chronic myocardial infarction. Severe disseminated myocardial fibrosis most likely resulted in insidious cardiac failure that was ultimately the cause of death. Bouts of abdominal pain and disseminated cutaneous ulcers that had been observed 3 and 4 days before death, respectively, were attributed to circulatory failure and thrombosis. The cause of the vascular lesions remains unknown. When compared with humans, atherosclerosis is rare in animals and has not been described in a walrus.

A case of Peters' anomaly in a springer spaniel

An 8-week-old springer spaniel presented with a large central corneal opacity of the left globe, which was accompanied by cords of tissue spanning from the iris collarette to the posterior cornea. A posterior cortical cataract was noted in the right eye. At the owner's request the puppy was humanely destroyed, and a necropsy was performed. Upon sectioning the left globe in the vertical plane, a circle of pigmented strands of tissue was observed spanning the anterior chamber from the iris to the posterior aspect of the cornea. The right globe appeared normal when inspected grossly. Histologically, a membrane of pigmented tissue covered the posterior aspect of the broad central corneal leukoma of the left globe. This membrane and the cords traversing the anterior chamber were composed of vascular uveal tissue. Descemet's membrane and the corneal endothelium were reduced or absent in the zone of corneal opacity. Other than the changes associated with cataract, the right globe was histologically normal. The clinical and histological findings in the left globe were identical with those described for Peters>> anomaly in human beings.

Disseminated T-cell lymphoma in a guinea pig with bilateral ocular involvement

A 2-year-old female shorthair guinea pig was presented to the Veterinary Medical Teaching Hospital, University of Wisconsin-Madison, for evaluation of a unilateral corneal opacity of 1 week duration. Physical examination revealed a markedly thickened right cornea and lymphadenopathy of the submandibular and prescapular lymph nodes. Cytology of a lymph node aspirate was highly suggestive of lymphoma. The animal was humanely euthanized. Postmortem examination revealed a disseminated lymphadenopathy involving the submandibular, anterior cervical, prescapular, bronchial, anterior mediastinal, and mesenteric nodes, and hepatomegaly with accentuation of lobular morphology. The right cornea was dark red, dry and dull, and diffusely thickened, and the globe was exophthalmic. Microscopically, pleomorphic neoplastic lymphoblasts were present in the lymph nodes, spleen, liver, lungs, heart, rhinarium, bone marrow, and kidneys. Bilateral infiltration of the eyes by neoplastic lymphoblasts was noted, which was more extensive on the right. The neoplastic cells stained immunohistochemically as T-lymphocytes using antibodies directed against CD3 antigen.

Thelazia rhodesii (Desmarest, 1828) infections in cattle in Mindanao, Philippines

Thelazia rhodesii was found in the eyes of 149 of 643 bovine heads (23%) that were examined at the abattoir of Cagayan de Oro City, Philippines, during the period February 1994 to February 1995. In nearly half of the animals both eyes were infected and an average of 4.1 worms per infected animal was recovered. Of the 1286 eyes examined, 17% were infected; worm burdens ranged from one to 36 (average 2.9) worms per infected eye. Monthly prevalence of infection ranged from 13% to 36%. T. rhodesii infection was significantly more common in cattle of more than 3 years of age (25%) than in younger animals (15%). Ocular lesions were observed in 73 (11%) cattle; 22% of these were infected with T. rhodesii. There was no relationship between presence of T. rhodesii and ocular lesions.

C3 fixed in vivo to cornea from horses inoculated with Leptospira interrogans

C3 was detected bound in vivo to the opaque cornea of horses inoculated with killed Leptospira interrogans. Employing epithelial corneal cells isolated from a monolayer in tissue culture, we proved that C3 is fixed in vitro to the intact cell surface after incubation with a fresh equine anti-Leptospira serum. These findings, in addition to the infiltration of cornea with neutrophils and lymphocytes, may explain the mechanisms of tissue damage in recurrent uveitis of horses with leptospirosis.

Encephalomyelitis, reproductive failure and corneal opacity (blue eye) in pigs, associated with a paramyxovirus infection

A new clinicopathological disorder associated with a paramyxovirus infection in pigs is described. Central nervous system manifestations and corneal opacity are the main features in piglets two to 21 days old. Older pigs seem to be more resistant and only corneal opacity is commonly observed. In pregnant sows the virus appears to be responsible for reproductive disturbances such as stillbirth, mummification and a return to oestrus. The changes are mainly microscopic and characterised by a non-suppurative encephalomyelitis, interstitial pneumonia and anterior uveitis with corneal oedema. Experimental infection of one-day-old piglets with the virus reproduced clinical signs similar to those described in naturally infected piglets. The virus was recovered from the tonsils, lung and brain of the experimentally infected piglets between the fourth and 20th day after infection.

Tears and aqueous humor from horses inoculated with Leptospira contain antibodies which bind to cornea

An antigenic relationship between Leptospira interrogans and equine cornea was previously described by us. An enzyme-linked immunosorbent assay was employed in the present work to investigate the existence of anti-leptospira and anti-cornea antibodies in tears, aqueous humor and serum from horses inoculated i.m. with those antigens. Ten days after a booster by the same route, antibodies that bind to microtiter plates, coated with an homogenate of either equine cornea or leptospira, were detected in those fluids and in the sera. At the same time, the corneas of the horses began to develop a diffuse opacity. This finding of anti-leptospira antibodies in equine tears and aqueous humor shows the pathway along which they arrive at the cornea and bind to it.

Anterior corneal dystrophy of American Dutch belted rabbits: biomicroscopic and histopathologic findings

Spontaneously occurring anterior corneal opacities were present in related, juvenile American Dutch belted rabbits. Slit lamp biomicroscopy revealed focal opacities of epithelium, basement membrane, and subepithelial corneal stroma. Lesions were characterized histologically by thin and disorganized surface epithelium, thickened and intensely staining epithelial basement membrane, fimbriated and irregular basement membrane-stromal juncture, and disorganized subepithelial stroma. Biomicroscopic and histopathologic features of anterior corneal dystrophy of American Dutch belted rabbits appear similar to those of human anterior corneal dystrophies.

Characterization of a paramyxovirus isolated from the brain of a piglet in Mexico

A virus morphologically resembling members of the family Paramyxoviridae has been isolated from the brain of a piglet with a central nervous disorder accompanied by pneumonia and corneal opacity. The virus, designated LPM, grows in a large variety of cultured cell types and elicits a cytopathic effect including formation of syncytia and cytoplasmic inclusion bodies. The virus has hemagglutinating, neuraminidase and hemolytic activities. Studies on experimental transmission showed that young pigs are susceptible to infection which induced a disease similar to that in natural cases. The virus killed mice and chicken embryos. The structural proteins of LPM virus, as resolved by polyacrylamide gel electrophoresis are similar to those described for other paramyxoviruses. Serologically the virus proved to be distinct from the paramyxoviruses tested so far.

Spontaneous corneal opacities in laboratory mice

Corneal opacities were observed in numerous strains and stocks of laboratory mice (Mus musculus) from different microbiological environments. The opacities were characterized as acute and chronic inflammatory lesions of the corneal epithelium and anterior corneal stroma, including corneal ulcers and erosions, acute keratitis, stromal neovascularization and mineralization of the basement membrane zone. Some strains and stocks of mice from barrier-reared colonies had a high incidence of corneal opacities [DBA/2 (29.1%), C3H (16.2%), CF1 (16.2%) and BALB/c (10.0%)] while others had a lower incidence [CD-1 (4.3%) and C57BL/6 (4.1%)]. Axenic and gnotobiotic mice had a very low incidence of corneal opacities (1.6%). An experimental study demonstrated that twice weekly cage cleaning would reduce the incidence of corneal opacities to a very low level. A bacterial product, such as ammonia, is proposed as a significant factor in the pathogenesis of spontaneous corneal opacities in laboratory mice.

Experimental demonstration of an antigenic relationship between Leptospira and equine cornea

Horses inoculated with either equine cornea or killed Leptospira interrogans serovars pomona, tarassovi, icterohaemorrhagiae, wolffi and hardjo, developed corneal opacity and produced antibodies which made it possible to demonstrate partial antigenic identity between equine cornea and four of those serovars employed. These antibodies were isolated by means of immunoadsorptions, purified by ion-exchange chromatography (DEAE-Sephadex A-50) and run by immuno-electrophoresis in agar gel. Both antibodies, anti-equine cornea and anti-leptospira, showed that they corresponded to the IgGb subclass. They bound themselves to equine cornea in vivo and in vitro as was proved by immunofluorescence. This antigenic relationship may be in part responsible for pathogenesis of corneal opacity in leptospirosis of horses.

Lipid keratopathy and atheromatosis in an SPF laboratory rabbit colony attributable to diet

Sporadic cases of corneal opacity occurred in an SPF rabbit colony fed on a diet containing 10% white fish-meal. Routine histological monitoring also revealed atheromatous lesions involving the intima of the aorta, coronary arteries and the arteries of other organs in 29 rabbits examined. Serum cholesterol levels above 10 mmol/l were found in 7 rabbits, including 4 affected with corneal lesions, which proved to be lipid keratopathy on histochemical and electron microscopical examination. The serum cholesterol level was found to be within normal range (below 2.27 mmol/l) in 10 rabbits reared entirely on a modified version of the diet, where the 10% fish-meal content was replaced with 10% grass-meal. No more ocular or atheromatous lesions have been found since the adoption of the new diet for the colony.

Neonatal ophthalmology

This discussion of normal and abnormal findings on routine ophthalmic examination of the foal should prove useful to the equine practitioner who must provide counsel to the concerned owner and/or breeder. Early diagnosis and treatment of ocular abnormalities improve the prognosis for continued function and aid determination of the significance of lesions observed in later life.

Spontaneous eye lesions in laboratory animals: incidence in relation to age

Examination of the eye in experiments designed to test the toxicity of drugs or chemicals is of considerable importance and the investigator must have a clear idea of the spontaneous eye changes he can expect in the test species. We have attempted to review the literature relating to commonly used laboratory animals--the rat, mouse, and dog as well as the hamster--but as there is still only a handful of workers that publish their findings, the literature is not fully comprehensive. Our own unpublished data have been used to try and provide a more complete account. There is, therefore, a considerable need for further work in this area and, in the future, newer techniques such as electron microscopy and histochemistry can help us in the understanding of the pathogenesis of age-related changes in laboratory animals.

Oval lipid corneal opacities in beagles

Naturally occurring, oval opacities at the junction of the middle and inferior thirds of the cornea were found in an experimental beagle dog colony and were examined by light and electron microscopy. Abnormalities were limited to the anterior stroma and consisted of extracellular rhomboid crystalline spaces. Spherical or elliptical vacuolar spaces, sometimes containing electron-dense amorphous debris, distorted stromal lamellae. Stromal keratocytes in affected areas revealed a range of changes from hyperplasia of organelles to degeneration and necrosis.

Canine adenovirus-induced ocular lesions in the Afghan hound

A series of referred cases of CAV-1-induced ocular disease suggested increased susceptibility of the Afghan Hound. Of a litter of Afghan Hound puppies inoculated with a commercial vaccine containing attenuated CAV-1, three developed corneal edema and the litter as a whole showed marked febrile and serological responses to the virus. Under experimental conditions Afghan Hounds inoculated with CAV-1 at two levels of attenuation showed more profound clinical responses than Beagles receiving similar inocula. An enhanced generalized susceptibility to infection is suggested as a possible explanation for the greater incidence of CAC-1-induced ocular lesions in this breed.

Crystalline corneal opacities in the Siberian Husky

Bilaterally symmetric opacities were detected in the corneal stroma of 78 (14%) of 560 Siberian Huskies, aged 7 months to 12 years, examined in ophthalmology screening clinics. The opacities were round or horizontally oval and consisted of a diffuse gray homogeneous haze in the anterior stroma or an array of fine polychromatic crystals in the posterior stroma, or both. The corneas were not inflamed. The frequency of occurrence and density of the opacities increased with age. Several affected dogs were closely related, but a specific inheritance pattern could not be established. Light and electron microscopy disclosed clusters of extracellular, thin, needle-shaped, crystalline clefts. Histochemical stains on frozen sections identified neutral fats, phospholipids, and cholesterol as components of the crystals.

The effects of severe keratitis on corneal transmission

An investigation into the effects of keratitis on corneal light transmission is presented. Transmission data from 9 diseased corneas are compared to those of 22 normal corneas in the 0.3-0.8 micron spectral range. Rhesus monkey corneas were used in the study. Several color photographs illustrate varieties of idiopathic keratitis in rhesus monkeys.

Persistent pupillary membrane in the Basenji

One hundred and five Basenjis of varying ages were examined for the presence of persistent pupillary membrane. Lesions were detected in 75 individuals and were judged to be of minor significance in 26 cases, and of major significance in 49 cases. A system of scoring individuals for breeding merit was devised. The condition would appear to be a major problem in the breed in Victoria and some control measures are warranted.

Cultivation of mycoplasma from conjunctiva and production of corneal immune response in guinea pigs

Mycoplasma canis was the most frequent mycoplasmal isolant obtained from the conjunctival surface of the eyes of dogs. Nine mycoplasmal isolates, 5 were M canis, were recovered from the lower cul-de-sac of 101 dogs. Experimentally induced immune keratitis was produced by sensitizing guinea pigs to 3 antigen preparations of M canis and then administering intracorneal challenge inoculation. The guinea pigs were clinically observed by leukocyte migration-inhibition (LMI) technique and by histopathologic study of their corneas. The corneal reaction of the guinea pigs was not identical to a clinical entity of the dog.

Infectious bovine keratoconjunctivitis I. Experimental production

One or both eyes of 20 calves were inoculated one or more time with variou(s combinations of microorganism (live oor killed Moraxella bovis, infectious bovine rhinotracheitis virus, bovine adenovirus, bovine parainfluenza-3 virus and Mycoplasma bovoculi) by conjunctival instillation or direct inoculation of the conjunctivea or cornea. The eyes of all the calves received natural or artificial ultraviolet irradiation. Neither the adenovirus nor parainfluenza-3 virus became established in the eye or produced keratoconjunctivitis. Both M. bovis and infectious bovine rhinotracheitis virus became established in the bovine eye and produced disease. Subconjunctival or intracorneal inoculation of M. bovis caused a severe disease, simulating natural infectious bovine keratoconjunctivitis. Only the intracorneal inoculation of mycoplasma produced severe keratoconjunctivits. Eyes that on initial exposure to M. bovis became severly inflamed were more resistant to a second or third exposure to M. bovis, presumably by enhanced local defence mechanisms.

Ocular involvement with Chlamydia psittaci (strain M56) in rabbits inoculated intravenously

Fourteen albino rabbits were inoculated intravenously with 10(3.5)-10(4.0) mouse ICLD(50) of Chlamydia psittaci (strain M56) of mammalian origin. Ocular lesions accompanied the chlamydial infection in the rabbits. Bilateral anterior uveitis, a common occurrence, began on the second or third day and subsided by the tenth day whereas keratoconjunctivitis was observed infrequently. After 15 days the most prominent microscopic lesion was iritis. Accumulations of inflammatory cells, mainly plasma cells, were observed in the iris and ciliary body and elementary bodies were found infrequently in macrophages. Chlamydiae were recovered consistently by conjunctival swabbing from the fifth to the twenty-fourth day. The agent was present within the eye (viz. iris-ciliary body) in three of four rabbits killed at 15 days and in five of ten rabbits killed 60 days after inoculation. Chlamydiae had persisted in the cerebrum and joints as well. Although neutralizing antibody was consistently present in sera at 60 days none of the samples of aqueous humor were capable of neutralizing the agent. It is suggested that systemic chlamydial infections in the rabbit provide a model for the study of endogenous uveitis, a common ophthalmological problem.