Evisceration with implantation of an intrascleral silicone prosthesis in dogs: A retrospective study of 107 cases (2010-2019)

OBJECTIVE

To retrospectively analyze the preoperative clinical characteristics and surgical outcomes of evisceration with implantation of an intrascleral silicone prosthesis (EIISP) procedures in dogs and evaluate whether brachycephalic dogs are more prone than non-brachycephalic dogs to develop postoperative complications after EIISP.

ANIMAL STUDIED

Ninety-One dogs (19 of which were brachycephalic) were included.

PROCEDURES

Medical records from 2010 to 2019 were reviewed. Signalment, reason for EIISP, postoperative complications, follow-up time, and postoperative eye appearance were analyzed.

RESULTS

The most frequently represented breeds were French Bulldog [11/91 (12%) dogs], Jack Russell Terrier [6/91 (7%)], and Shih Tzu [6/91 (7%)]. Brachycephalic dogs were statistically younger than non-brachycephalic dogs at the time of EIISP (p = 1.61 × 10-5 ). Uncontrolled glaucoma was the most common reason for EIISP in both groups. Short-term complications (from D0 to D15) seen in 7/91 (8%) dogs included epithelial corneal ulcers (n = 3), keratoconjunctivitis sicca (KCS) (n = 2), and prosthesis extrusion (n = 2). Long-term complications seen in 26/91 (29%) dogs included KCS (n = 11), epithelial corneal ulcers (n = 7), stromal ulcers (n = 3), entropion (n = 4), and prosthesis extrusion (n = 1). Extrusion of the prosthesis occurred twice in eyes that had undergone diode laser transscleral cyclophotocoagulation. The risk of postoperative complications was not significantly different between brachycephalic and non-brachycephalic dogs (p = .3).

CONCLUSIONS

Brachycephalic status in dogs does not appear to influence the risk of complications from EIISP. Nevertheless, the present study is a reminder that EIISP focuses on esthetics, and considering the possible complications associated with it, it does not provide a benefit to the patient compared to enucleation.

Study shows there are lots of dry eyes in the house

Georgina Mills reports on research that examines the frequency and breed-related risk factors for keratoconjunctivitis sicca in dogs.

Uveodermatologic syndrome concurrent with keratoconjunctivitis sicca in a miniature poodle dog

A 5-year-old, intact female miniature poodle dog was presented with chronic ophthalmic problems, facial poliosis, nasal depigmentation and multiple areas of alopecia over the trunk. Bilateral uveitis preceded dermatologic signs by 5 months and gradually worsened. The dog was diagnosed as having uveodermatologic syndrome (UDS) concurrent with keratoconjunctivitis sicca (KCS). Treatment with immunosuppressive drugs resolved the dermatologic lesions, but uveitis continued to progress.

Studies on keratoconjunctivitis sicca incidence in crossbred dogs

The present study was aimed at determination of keratoconjunctivitis sicca occurrence in crossbred dogs. The investigations covered 36 mongrel dogs with keratoconjunctivitis sicca recognized by the ophthalmic examination. Patients' age and sex was established. The ophthalmic evaluation protocol included: the conjunctiva examination (humidity, redness, discharge), the corneal examination (transparency, vessel ingrowth, pigmentation, defects), Schirmer tear test. The highest incidence among the crossbred dogs was reported between 6 and 9 year of age, males accounted for 64% of cases. In a clinical study involving 61 corneas, 10 appeared to be completely opaque. The pigmentation occured in 75% of corneas. The corneal defects were found in 50% of cases. A 10-15 mm/min Schirmer test was established in 29% while 0-5 mm/min in 28% of cases.

Severe, unilateral, unresponsive keratoconjunctivitis sicca in 16 juvenile Yorkshire Terriers

OBJECTIVE

To present ophthalmic findings, clinical data, and treatment outcomes of 16 juvenile Yorkshire Terriers with severe unilateral keratoconjunctivitis sicca.

RESULTS

Each of the 16 dogs exhibited extreme unilateral dryness associated with blepharospasm, mucoid discharge, and corneal vascularization. Ages of affected dogs at presentation ranged from 5 months to 4 years. Mean Schirmer tear test (STT) result for affected eyes was 1 mm/min. Topical application of 0.2% cyclosporine to the affected eye was not associated with improvement in STT values in any dog. Clinical signs subjectively improved with topical application of 20% chondroitin sulfate ophthalmic solution in some dogs, and transposition of the parotid duct was performed in three dogs. Histopathologic examination in one dog failed to show evidence of orbital lacrimal gland tissue. Clinical signs, age of presentation, disease severity, and lack of response to treatment are consistent with breed-related unilateral aplasia or hypoplasia of the lacrimal gland.

CONCLUSION

Lacrimal gland aplasia or hypoplasia should be considered in young dogs with severe unilateral ocular dryness, especially female Yorkshire Terriers.

Canine keratoconjunctivitis sicca: disease trends in a review of 229 cases

OBJECTIVES

To investigate the disease patterns in dogs with keratoconjunctivitis sicca referred to the University of Glasgow Small Animal Hospital.

METHODS

A retrospective study of 229 cases was carried out.

RESULTS

There were 44 breeds in the study, with four breeds, English cocker spaniels, cavalier King Charles spaniels, West Highland white terriers and shih-tzus, making up 58 per cent of the cases. Among these four breeds, two breed-dependent disease patterns, one chronic and one acute, were identified. English cocker spaniels and West Highland white terriers had a mean age at onset of clinical signs of five years and one month and five years and six months, respectively, with more females affected than males. Clinical signs consisted predominantly of conjunctival hyperaemia and mucopurulent discharge, with a relatively low incidence of ulcerative keratitis. In contrast, cavalier King Charles spaniels and shih-tzus showed a more acute disease pattern with a biphasic age distribution at 0 to less than two years of age, and four to less than six and six to less than eight years of age, respectively, with more males affected than females and a significantly higher incidence of ulcerative keratitis in some cases resulting in corneal perforation.

CLINICAL SIGNIFICANCE

The study reveals interbreed differences with respect to sex, age and risk of ulcerative keratitis which have not been detailed previously in a referral population.

Reduced tear production in three canine endocrinopathies

OBJECTIVES

Previous reports have suggested that hypothyroid and diabetic patients can be predisposed to keratoconjunctivitis sicca. This study aimed to measure tear production in dogs with diabetes, hypothyroidism and hyperadrenocorticism using the Schirmer tear test and to compare these results with Schirmer tear test values for a group of normal dogs.

METHODS

Schirmer tear tests were performed on 16 dogs with hyperadrenocorticism, 18 with diabetes and 12 with hypothyroidism together with 100 control dogs. Corneal sensitivity was also measured in 12 of the 18 diabetic dogs with a Cochet Bonnet aesthesiometer and compared with age- and breed-matched normal dogs.

RESULTS

Schirmer tear test values in dogs with hypothyroidism, hyperadrenocorticism and diabetes were 12.3+/-3.2, 14.0+/-4.0 and 12.3+/-5.3 mm/minutes, respectively. Schirmer tear test values were significantly lower than that for the control group (19.6+/-4.2 mm/minutes) in all dogs with an endocrinopathy. Only in two hypothyroid dogs and three diabetics, this was manifested as profound keratoconjunctivitis sicca with Schirmer tear test value lower than 5 mm/minutes. Diabetic dogs had significantly reduced corneal sensitivity compared with a matched set of control dogs.

CLINICAL SIGNIFICANCE

This study shows a significant reduction in tear production in animals with diabetes mellitus, hypothyroidism and hyperadrenocorticism. Further research is needed to elucidate the mechanisms by which this reduction in tear production occurs. Assessment of tear production should be undertaken in animals diagnosed with these endocrinopathies, as these animals may progress to clinical keratoconjunctivitis sicca.

Sustained release cyclosporine therapy for bilateral keratoconjunctivitis sicca in a red wolf (Canis rufus)

A 12-yr-old intact male red wolf (Canis rufus) diagnosed with bilateral idiopathic dry eye was treated with subconjunctival drug delivery implants designed to release therapeutic levels of cyclosporine from 12-24 mo. Normal tear production and corneal health has been maintained, alleviating the need for daily handling of the animal for topical medication.

Keratoconjunctivitis sicca associated with administration of etodolac in dogs: 211 cases (1992–2002)

OBJECTIVE

To characterize features and response to treatment of keratoconjunctivitis sicca (KCS) associated with oral administration of etodolac in dogs.

DESIGN

Retrospective case series.

SAMPLE POPULATION

65 cases obtained from a survey of veterinary ophthalmologists (group A) and 146 cases reported to Fort Dodge Animal Health (group B).

PROCEDURES

Data analyzed included breed, sex, age, weight, dose and duration of etodolac administration, results of Schirmer tear test at the time of diagnosis and last follow-up, treatments, and response to treatments. Groups A and B were analyzed separately by use of forward stepwise logistic regression models developed to predict probability of complete remission or clinical improvement as a function of several variables.

RESULTS

Most dogs developed severe KCS (84 eyes of 50 dogs [group A]; 111 eyes of 62 dogs [group B]). Resolution of KCS occurred in 7 of 65 (A) and 23 of 146 (B) dogs. No response to treatment was observed in 26 of 65 (A) and 27 of 146 (B) dogs. Fifty-one (A) and 52 (B) dogs had records that were sufficiently complete to use in models. In group B, dogs with etodolac treatment intervals < 6 months prior to the onset of KCS were 4.2 times as likely to have remission as were dogs with treatment intervals > or = 6 months.

CONCLUSIONS AND CLINICAL RELEVANCE

Shorter duration of etodolac administration (< 6 months) was associated with improved outcome in 1 population of dogs. Monitoring of tear production should be considered prior to and during administration of etodolac in dogs.

Effect of age, gender, weight, and time of day on tear production in normal dogs

OBJECTIVE

To investigate the effects of age, weight, gender, and of time of day on tear production in normal dogs.

ANIMALS

studied One hundred ophthalmoscopically and systemically unremarkable dogs.

PROCEDURE

Schirmer tear tests (STT) were performed every 2 h during the day on one randomly chosen eye of each of 100 dogs.

RESULTS

There was a statistically significant effect of time of day and age on the STT measurement. The mean STT decreased by 0.4 mm for every 1 year that age increased (P=0.007). Mean STT values taken at 10:00 am were 0.7 mm lower than values taken at 4:00 pm (P=0.04).

CONCLUSIONS

Tear production decreases with age in the normal dog. In this population of dogs the largest difference was between the 10:00 am and the 4:00 pm STT measurements, but this still only amounted to 0.7 mm. This value is unlikely to be of clinical significance in the diagnosis of keratoconjunctivitis sicca (KCS).

Characterization of lacrimal gland lesions and possible pathogenic mechanisms of keratoconjunctivitis sicca in dogs with leishmaniosis

In a previous study, it was found that 2.8% of dogs with leishmaniosis had keratoconjunctivitis sicca (KCS). The aim of this study was to characterize the lesions present in the lacrimal glands of dogs with leishmaniosis and to determine the presence of the parasite by means of immunohistochemistry. The inflammatory infiltrate was described as granulomatous or pyogranulomatous and was located around the ductal component of the glands. Immunoperoxidase staining localized the parasites following the same pattern. Samples from eyes that had clinical signs compatible with KCS presented inflammatory infiltrate and parasite more commonly than those from eyes without clinical signs. One of the mechanisms of KCS in dogs with leishmaniosis may be the inflammatory infiltrate located around the ducts of lacrimal glands, producing retrograde accumulation and retention of secretion. Meibomian gland was the most commonly affected by the infiltrate, highlighting the possibility of a qualitative KCS in these dogs.

Analysis of tear uptake by the Schirmer tear test strip in the canine eye

OBJECTIVE

To analyze the uptake of tears in a Schirmer tear test (STT) in vitro and in vitro.

MATERIALS AND METHODS

Uptake of fluid by Schirmer tear test strips was studied in vitro by examining fluid uptake over time from an unlimited fluid supply as well as with specific fluid volumes applied to the test strip. Uptake of fluid by Schirmer tear test strips was evaluated in a population of 100 ophthalmologically normal dogs together with a group of 40 dogs with tear film abnormalities such as keratoconjunctivitis sicca (KCS) or epiphora. Each animal was given a full ophthalmic examination followed by a standard Schirmer tear test extended over between 3 and 5 min with the STT reading recorded every 5 s and plotted over time. To determine the effect of ocular irritation by the test strip, uptake of tears by test strips was determined before and after topical anesthesia in 20 dogs.

RESULTS

In vitro examination of fluid uptake by the STT strips showed an initial rapid uptake followed by a gradual reduction in rate of uptake. Temporal evaluation of STT in vivo showed a similar rapid initial uptake of tear fluid, followed in the majority of cases by a sudden change to a steady state uptake of fluid. The initial gradient was 29.3 +/- 16.9 mm/min followed by a steady state uptake of 5.2 +/- 2.3 mm/min in normal dogs and 1.9 +/- 1.3 mm/min in dogs with KCS. This corresponds to a steady state tear turnover of 7.8 +/- 3.4 microL/min in normal dogs and 2.8 +/- 1.9 microL/min in animals with KCS. Dogs with nasolacrimal blockage and resultant epiphora showed a high initial gradient but final gradients were not statistically different from those of normal dogs. Discussion and conclusions Temporal evaluation of tear uptake by the STT shows substantial differences in rate of tear uptake at different time-points during the period of the test.

RESULTS

of this study suggest that the initial rapid rise in STT value represents uptake from the tear lake followed by a slower tear uptake of tears from steady state tear production. Temporal examination of the Schirmer tear test allows a more precise evaluation of tear production than the standard STT measuring tear uptake in 1 min, together with estimation of the contribution to the test strip tear uptake of tears from the residual tear lake volume and those from continual tear production.

Effect of topical 0.02% tacrolimus aqueous suspension on tear production in dogs with keratoconjunctivitis sicca

OBJECTIVE

To investigate the effect of 0.02% tacrolimus in aqueous suspension on tear production in dogs with keratoconjunctivitis sicca (KCS). Animals studied One hundred five dogs diagnosed with KCS [Schirmer tear test (STT) < or = 10 mm/min and clinical signs of dry eye]. Eyes with marginally decreased STT (11 < or = 15 mm/min) and clinical signs of dry eye were also evaluated.

PROCEDURE

The investigation was conducted in two parts: an initial efficacy study and a subsequent double blinded controlled study. In the efficacy study, the effect of topical tacrolimus (formerly FK-506) on tear production in dogs with primary KCS was evaluated. Dogs were divided into four categories: 1) 59 eyes (38 dogs) naïve to tear stimulation therapy with initial STT < or = 10 mm/min; 2) 28 eyes (21 dogs) naïve to tear stimulation therapy with initial STT 11 < or = 15 mm/min; 3) 30 eyes (15 dogs) maintained successfully on CsA therapy; 4) 47 eyes (24 dogs) unresponsive to CsA therapy. STT and clinical signs were evaluated prior to and after 6 to 8 weeks of twice daily tacrolimus administration. Tacrolimus was substituted for CsA therapy in categories 3 and 4. The controlled study compared the effect of topical tacrolimus in aqueous suspension to administration of the aqueous carrier alone on tear production in 20 dogs with primary KCS.

RESULTS

In the efficacy study, STT increased by 5 mm/min in 84.7%, 25.0%, 26.7% and 51.1% of eyes in categories 1, 2, 3 and 4 respectively after tacrolimus administration. Eighty-three percent of eyes with extremely low initial STT (< or = 2 mm/min), increased 5 mm/min after tacrolimus. In the controlled study, STT increased by 5 mm/min in 7/10 dogs (14/20 eyes) that received tacrolimus and in none of the 10 dogs that received aqueous carrier alone. Dogs receiving just the aqueous carrier were subsequently treated with tacrolimus, and STT increased 5 mm/min in 9 dogs (18/20 eyes) after administration.

CONCLUSIONS

Twice daily administration of 0.02% tacrolimus in aqueous suspension effectively increased tear production in dogs with KCS. Topical tacrolimus is a promising alternative to topical CsA for treatment of KCS and may be beneficial in patients with less than optimal response to topical CsA.

Efficacy of topical nerve growth factor treatment in dogs affected by dry eye

BACKGROUND

Preliminary data show that nerve growth factor (NGF) may improve tear production in humans. We evaluated the efficacy of topical NGF treatment in dogs who developed dry eye after the excision of the third eyelid lacrimal gland.

METHODS

English Bulldogs (2- to 6-year-old males and females) that had undergone the surgical removal of the prolapsed lacrimal gland of the third eyelid in both eyes at the age of 3-6 months developed chronic keratoconjunctivitis sicca associated with a decrease of Schirmer tear test I values after at least 1 year. One eye, randomly selected, of each dog was treated twice daily with 100 microl of NGF ointment for 1 month, while the fellow eye was used as control and treated with the ointment vehicle only. At baseline and after 1 month of NGF treatment the following examinations were performed: corneal evaluation by slit lamp, fluorescein staining, Schirmer tear test I, tear ferning test, corneal esthesiometry by cotton swab and conjunctival impression cytology.

RESULTS

Topical application of NGF caused a significant improvement of all the evaluated parameters compared with baseline values. In contrast, in the control eyes there was no significant difference between the values measured before and after treatment. In particular, after NGF treatment superficial punctate keratopathy was resolved, corneal haze was reduced from stage 4 to stage 2 and Schirmer test values increased (17.2+/-1.7 mm/min vs 4.5+/-1.3 mm/min; p<0.05), as did the tear mucous component (as demonstrated by ferning test: 2.0+/-0.0 vs 4.0+/-0.0; p<0.05); conjunctival impression cytology evaluation demonstrated the presence of numerous mucous filaments and a significant increase in conjunctival goblet cell density (102.7+/-68.3 vs. 18.2+/-14.3 cell x field; p<0.05). Topical NGF treatment improved corneal sensitivity in two of three eyes.

CONCLUSIONS

This open study suggests that topical application of NGF may enhance the production and functional characteristics in tear film, with an improvement of ocular surface signs in dogs with surgically induced dry eye. These results suggest the possibility of performing further, larger, controlled studies.

The effect of topical pimecrolimus on keratoconjunctivitis sicca and chronic superficial keratitis in dogs: results from an exploratory study

OBJECTIVE

Pimecrolimus is an ascomycin derivative that interferes selectively with the activation of T cells and mast cells and inhibits the production of inflammatory cytokines. This study evaluated the efficacy of an experimental ophthalmic formulation of pimecrolimus in treating keratoconjunctivitis sicca (KCS) and chronic superficial keratitis (CSK) in dogs. ANIMALS AND PROCEDURES: Eight dogs with KCS and six with CSK were included. The dogs were of various breeds, suffered from chronic conditions, and had been pretreated unsuccessfully. The affected eyes were treated with 1 drop of an experimental, corn oil-based pimecrolimus 1% formulation three times a day. Parameters evaluated included Schirmer tear test (STT), ocular discharge, conjunctival inflammation, corneal inflammatory cell infiltrate and scarring, and comfort level.

RESULTS

The effect of pimecrolimus 1% was pronounced (increase in STT values to higher than 4 mm/min, no signs of inflammation) or moderate (increase in STT values of 3-4 mm/min, mild signs of corneal/conjunctival inflammation) in a total of 6/8 animals with KCS. In 4/6 animals with CSK, the effect was either pronounced (total regression of fibrovascular infiltration into the cornea, no corneal scarring) or moderate (distinct regression of pannus, mild corneal scarring). The response to treatment was unsatisfactory in four of 14 animals.

CONCLUSION

Results of this exploratory study suggest that topical 1% pimecrolimus may be a new effective treatment for keratoconjunctivitis sicca and chronic superficial keratitis in dogs.

Immunomodulating agents

Inflammation involves a universally recognized, although incompletely understood, cascade of molecular events orchestrated by lymphokines and other innate biochemicals of immunity. Repeated or extended contact with immunogenic agents results in adaptive immunity involving antigen-induced events that stimulate down-stream immune cells and result in expansion of the inflammatory cascade. When immunogenic stimulation persists or autoregulatory immune mechanisms go awry, however, adaptive immunologic events can result in immune-mediated processes detrimental to systemic or organ-specific homeostasis. Because of the complexities of immunologic events, the potential side effects of long-term corticosteroid therapy, and the focused spectrum of most conventional nonsteroidal anti-inflammatory agents (centered on arachidonic acid-related mechanisms), a variety of other chemotherapeutic immunosuppressive agents have assumed an increasingly prominent therapeutic role in veterinary ophthalmology in the management of chronic ocular inflammatory diseases. In addition, nonimmunosuppressive immunomodulating agents (ie, immuno-stimulants or immunorestoratives) may be used as adjunctive therapies in the management of ocular or visual system diseases.

The tear film and ocular mucins

The trilaminar tear film, composed of the lipid, aqueous and mucin layers, has many functions including defending the ocular surface. The aqueous layer has several soluble antimicrobial factors that protect the ocular surface. Ocular mucins have recently been studied with regard to their role in the defense of the eye as well as in dry eye syndromes. To date, 15 mucin genes have been identified, and six of these mucin genes are localized to or secreted by ocular glands or epithelia. Understanding the production, secretion and function of ocular mucins will aid in the treatment of dry eye syndromes and ocular surface microbial infections.

Morphologic changes of the anterior corneal epithelium caused by third eyelid removal in dogs

Morphologic changes of corneal epithelium after third eyelid removal were observed in six normal Beagle dogs. The observation was conducted on the 17th, 35th and 72nd week after the removal. Morphologic changes were observed on corneal epithelium layers at 17 and 35 weeks post excision of the third eyelid but they were limited to minor changes including abnormal intercellular adhesion and further exfoliation of superficial cells at 72 weeks. The reduced BUT and evidence of vital positive staining correspond with these morphologic changes. Therefore, these changes are thought to be important findings from a morphologic view point in identifying pathologic symptoms of the cornea using clinical evaluation methods such as BUT and vital staining method. Grossly, no clinical indication of ocular disease was indicated by slit-lamp biomicroscopic observation; however, the BUT shortage and positive finding of vital staining indicated that the corneal epithelium layers after third eyelid removal lacked the essential barrier function. Thus, it would seem appropriate to consider that such a condition of the ocular surface would worsen with excessive exposure of the ocular surface, palpebration disorders and other exogenous factors.

Parotid salivary duct mucocoele and sialolithiasis following parotid duct transposition

An 11-year-old, female neutered English springer spaniel presented with recurrent episodes of mucopurulent discharge from the right eye, 17 months after parotid duct transposition, culminating in the development of a swelling over the infraorbital area. A diagnosis of parotid duct obstruction with resulting rupture of the duct and sialocele was made. On exploratory surgery, three sialoliths were removed from various sites within the duct. Surgical repair of the duct restored normal saliva flow.

Use of punctal occlusion in the treatment of canine keratoconjunctivitis sicca

Twenty eyes of 10 dogs with keratoconjunctivitis sicca (KCS) were treated by occlusion of the ventral nasolacrimal punctum with a silicone punctal plug in order to increase the volume of the remaining tear lake. Punctal size was measured using a commercially available punctal gauge and the appropriate sized plug was inserted under local anaesthesia. Seven dogs showed an increase in Schirmer tear test I (STT) value. STT values immediately prior to plug placement were 2.3 +/- 1.7 mm/minute. STT values with punctal occlusion were 6.1 +/- 4.1 mm/minute, giving a mean increase of 3.8 +/- 2.7 mm/minute (P<0.001). In 14 eyes of eight dogs, the increase in STT values was accompanied by a clinical improvement in the appearance of the ocular surface. In the three dogs with no increase in STT values, the use of punctal plugs reduced the frequency of artificial tear replacement therapy required to maintain a healthy ocular surface. These results show that use of punctal plugs in dogs with KCS may be appropriate where other lacrimomimetic medications have been unsuccessful.

Histologic characteristics and local cellular immunity of the gland of the third eyelid after topical ophthalmic administration of 2% cyclosporine for treatment of dogs with keratoconjunctivitis sicca

OBJECTIVE

To evaluate the efficacy of topical administration of a 2% solution of cyclosporine (CsA) for treatment of dogs with keratoconjunctivitis sicca (KCS) and to correlate results with histopathologic characteristics and local cellular immunity of the gland of the third eyelid.

ANIMALS

24 dogs with bilateral KCS.

PROCEDURE

Lacrimal secretion was measured, using Schirmer tear test (STT) strips. Leukocyte and T-lymphocyte subsets were determined in blood samples. Histopathologic changes as well as CD4+, CD8+, and alpha-naphthyl-acetate esterase-positive (ANAE+) lymphocytes were evaluated.

RESULTS

Clinical signs resolved at the end of 1 month in conjunction with significantly increased STT values, compared with baseline values. Fifteen and 30 days after discontinuation of CsA treatment, a decrease was observed in STT values in both eyes; however, only values for the right eye were significantly different. There was a significant decrease in the number of lymphocytes and ANAE+ lymphocytes 15 and 30 days after discontinuation of CsA treatment, compared with baseline values. Differences were not observed in number of CD4+ lymphocytes among treatment groups. However, there was a significant decrease in number of CD8+ lymphocytes with reversal of the CD4+:CD8+ in both eyes after CsA treatment for 30 days, compared with the control group. Increased secretory activity and decreased lymphocyte infiltration were characteristic histopathologic findings.

CONCLUSIONS AND CLINICAL RELEVANCE

Topical administration of a 2% solution of CsA was effective for the treatment of dogs with KCS. Strict follow-up monitoring is required after the cessation of treatment because of the possibility of recurrence of KCS.

Evaluation of results for Schirmer tear tests conducted with and without application of a topical anesthetic in clinically normal dogs of 5 breeds

OBJECTIVE

To evaluate, for clinically normal dogs, results of Schirmer tear tests in eyes without topical anesthetic (STT) and to detect differences associated with breed, sex, age, day, and time of day in eyes in which STT was performed after use of topical anesthetic (STTa).

ANIMALS

41 Beagles, 43 Labrador Retrievers, 25 Golden Retrievers, 26 English Springer Spaniels, and 22 Shetland Sheepdogs.

PROCEDURE

Beagles had STT and STTa values measured twice daily for 5 days. Client-owned dogs of 4 other breeds had STT and STTa values measured once.

RESULTS

Mean +/- SD values of Beagles for STT and STTa were 20.2 +/- 2.5 and 3.8 +/- 2.7 mm/min. Mean values for STT and STTa were as follows: Labrador Retriever, 22.9 +/- 4.1 and 9.6 +/- 3.8 mm/min; English Springer Spaniel; 20.7 +/- 3.2 and 5.4 +/- 3.4 mm/min; Golden Retriever, 21.8 + 3.7 and 8.8 +/- 3.1 mm/min; and Shetland Sheepdog, 15.8 +/- 1.8 and 3.6 +/- 2.8 mm/min. Overall mean values for STT and STTa were 20.2 +/- 3.0 and 6.2 +/- 3.1 mm/min. Differences for STT and STTa were detected among breeds, but significant differences were not associated with sex or age within each breed or in overall values for all dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

Results for the STT reported here compare favorably with reported values, except for results of Shetland Sheepdogs; however, results for the STTa differ dramatically from reported values. Clinicians should consider effects attributable to breed when evaluating results of STT and STTa in dogs.

Comparison of absorptive capacities of original and modified Schirmer tear test strips in dogs

OBJECTIVE

To compare in vitro and in vivo absorptive capacities of modified Schirmer tear test strips with those of original strips, and to establish reference values for use with the modified strips.

DESIGN

Prospective study.

ANIMALS

100 dogs.

PROCEDURE

In vitro absorptive capacity was determined by immersing strips in an irrigating solution for 15 seconds and recording amount of wetting. In vivo absorptive capacity was determined by placing an original Schirmer tear test strip in 1 eye and a modified strip in the other eye of 50 dogs with normal or abnormal tear production. Time required to wet 10 mm of each strip was recorded. Measurements were repeated 30 minutes later after reversing which strip was placed in the left or right eye. Reference values (mean +/- SD) were determined by recording the time required to wet 10 mm of the modified strip in 50 healthy dogs.

RESULTS

Amount of wetting was significantly less and time required to wet 10 mm was significantly greater for the modified strip, compared with the original strip. Reference values determined for the modified strip were 32 +/- 11 seconds in the right eye, 33 +/- 11 seconds in the left eye, and 32 +/- 10 seconds in both eyes.

CONCLUSIONS AND CLINICAL RELEVANCE

Absorptive capacities of the original and modified Schirmer tear test strips were significantly different. Reference values determined for 1 strip should not be used for the other strip.

Low-dose oral administration of interferon-alpha for the treatment of immune-mediated keratoconjunctivitis sicca in dogs

This preliminary study was designed to evaluate the effectiveness and dosage of oral use of interferon-alpha (IFN-alpha) in the treatment of naturally occurring, immune-mediated, canine keratoconjunctivitis sicca (KCS). Dogs with chronic immune-mediated KCS were selected from the two clinic populations. All medication, except topical artificial tears, was discontinued at least 2 weeks prior to beginning the clinical trial. IFN-alpha was administered orally once daily to the dogs by their owners as the sole therapy for the KCS. Examinations of the dogs were performed every 2 weeks for the duration of the trial (12 weeks). Each dog was given either two or three separate, escalating doses (20, 40, 80 IU of the IFN-alpha. A favorable response was observed in 55% (11/20) of all dogs treated. Clinical findings of those dogs that responded included increased wetting of the eyes, decreased mucus discharge, and fewer signs of discomfort. There was a nearly significant difference (p = 0.08) in pretreatment mean Schirmer's tear test (STT) between the dogs that responded (6.4 +/- SEM 0.62 mm/min) and those that did not respond (4.7 +/- SEM 0.69 mm/min) to the orally administered IFN-alpha. Seven of 11 dogs with favorable outcomes had an increased STT of at least 5 mm/min after treatment with oral IFN-alpha and the group had a post-treatment STT (10.5 +/- SEM 1.4 mm/min) significantly greater than baseline (p = 0.0004). The post-treatment STT of the dogs that did respond was significantly greater (p < 0.01) than the post-treatment mean STT of dogs that did not respond. All dogs that responded did so with the 20 or 40 IU dose of IFN-alpha. No side effects were noted and all dogs tolerated the treatment well.

Tear production in three captive wild herbivores in Israel

The Schirmer tear test (STT) I was performed to evaluate tear production in 12 captive Nubian ibex (Capra ibex nubiana), 10 captive Burchell's zebras (Equus burchelli) and five Arabian oryx (Oryx leucoryx) at the Tel-Aviv Ramat-Gan Zoological Center (Israel). Mean (+/- standard deviation) STT values were 13.2 +/- 5.1 mm/min in the ibex, 23.4 +/- 3.4 mm/min in the zebra and 12.7 +/- 4.8 mm/min in the oryx. There were no significant effects of gender, age, weight, or side of the eye. There were no significant differences in STT values between ibex and oryx, but tear production in both species was significantly lower than in zebras. Knowledge of normal tear production values is important for the differential diagnosis of conjunctivitis and keratitis in these species.

The role of apoptosis in the pathogenesis of canine keratoconjunctivitis sicca: the effect of topical Cyclosporin A therapy

PURPOSE

The exact etiology of dry eye is unknown but is believed to be multifactorial. Apoptosis has been implicated in the pathogenesis of autoimmune diseases such as Sjögren's syndrome (SS). This study attempted to gain a better understanding of the role of apoptosis and its regulation in the patho-physiology of dry eye. The therapeutic effect of immunomodulatory agents such as cyclosporin A (CsA) in the treatment of dry eye, particularly its impact on the level of apoptosis in the target tissues, is also investigated.

METHODS

A colony of dogs with spontaneous chronic idiopathic keratoconjunctivitis sicca (KCS) was maintained. Nictitans lacrimal gland (NLG), an accessory lacrimal gland, and conjunctival biopsies of the KCS and normal dogs were obtained before and after 12 weeks of treatment with 0.2% topical CsA ophthalmic emulsion b.i.d. (Allergan, Inc., Irvine, CA, U.S.A.). Tissues were prepared for the terminal deoxynucleotidyl transferase-mediated dUTP-digoxigenin nick end labeling (TUNEL) apoptosis assay and immunohistochemical analysis for various apoptosis mediators.

RESULTS

The TUNEL assay demonstrated that (i) the normal NLG and conjunctival epithelial cells exhibited a limited level of apoptosis; (ii) in KCS dogs, lacrimal acinar and conjunctival epithelial cells underwent an increased apoptosis, whereas the lymphocytes had a significantly lower level of apoptosis compared to those of the normal dogs; (iii) after topical CsA, apoptosis was induced in the lymphocytes and suppressed in the acinar and conjunctival epithelial cells in KCS dogs. Immunohistochemistry revealed that p53, fas, and fasL, but not bcl-2 were highly expressed in the target tissues of KCS dogs. The immunoreactivity of p53 was significantly decreased, whereas the bcl-2 level was increased after CsA administration.

CONCLUSIONS

The induction of epithelial cell apoptosis and the suppression of lymphocytic apoptosis in the NLG and ocular-surface tissues, such as conjunctiva of KCS dogs, indicates the important role of this phenomenon in the etiology of dry eye. Topical CsA appears to facilitate lymphocytic apoptosis and suppress epithelial cell apoptosis in the KCS dog. The differential expression of various apoptotic mediators after topical treatment implicates CsA in facilitating the reestablishment of the normal apoptotic balance, suggesting additional mechanisms by which CsA is therapeutic for dry-eye syndrome.

A comparative approach to topical cyclosporine therapy

Topical cyclosporine has been used by veterinary ophthalmologists since 1989 for the treatment of ocular surface inflammatory disease and keratoconjunctivitis sicca (KCS). As well as ameliorating clinical signs of ocular surface lymphocyte-driven inflammation in the dog, cat and horse, topical cyclosporine significantly raises tear production in both normal and KCS-affected animals. A licensed ointment preparation of 0.2% cyclosporine, Optimmune (Schering-Plough), is now available for administration to dogs. In this paper we examine the mechanisms by which cyclosporine exerts both its immunomodulatory and its lacrimogenic actions. The pharmacokinetics of topical cyclosporine are examined to determine whether these effects are truly local or are influenced by generalised immunosuppression caused by systemic absorption of topically applied drug. The paper reviews the few side effects of cyclosporine preparations in the experience of veterinary ophthalmologists and the experimental evidence which appears to implicate the vehicle rather than the active agent cyclosporine as causing many of these effects. Given that topical cyclosporine has been so widely accepted as a valuable ophthalmic preparation in the veterinary world and licensed as such, it is surprising that human ophthalmologists have not employed the drug to the same extent for conditions from vernal keratoconjunctivitis to Sjögren's syndrome.

Cellular immunity in dogs with keratoconjunctivitis sicca before and after treatment with topical 2% cyclosporine

Peripheral cellular immunity of ten dogs with keratoconjunctivitis sicca (KCS) that had not been treated with topical corticosteroids or cyclosporine was evaluated (by use of in vitro lymphocyte proliferation assays and CD4+/CD8+ lymphocyte subset analysis) before and after 1 and 3 months of treatment with topical ocular 2% cyclosporine (CsA). In vitro lymphocyte proliferation and CD4+/CD8+ lymphocyte subset analysis was done in eight normal dogs at the 0, 1 and 3 month time periods to use for comparison. There was no significant difference in lymphocyte proliferation or numbers of CD4+ or CD8+ lymphocytes in dogs with KCS and normal dogs prior to CsA treatment. However, by 1 month's time, lymphocyte proliferation had decreased in the CsA-treated Dogs with KCS, and by 3 months there was a significant difference (P < 0.0001) from the normal dogs. These results suggest that dogs with KCS may not have altered peripheral cellular immunity and that use of topical 2% cyclosporine for treatment of KCS causes a suppression of lymphocyte proliferation after 1 to 3 months of use.

Treatment of keratoconjunctivitis sicca in dogs with cyclosporine ophthalmic ointment: a European clinical field trial

The results are reported of a six-week clinical trial of the efficacy of 0.2 per cent cyclosporine ophthalmic ointment for the treatment of chronic idiopathic keratoconjunctivitis sicca in dogs in the United Kingdom, Germany and France. The 87 dogs were referral cases with a history of chronic unresponsive keratoconjunctivitis sicca of which the aetiology was unknown, and they had to meet stringent criteria before being included in the trial. The clinical response to the therapy was monitored after seven, 21 and 42 days and the results for the right and left eyes were analysed separately. There was a statistically significant increase in lacrimal secretion throughout the study, with most of the increase occurring during the first week of treatment. The percentage of eyes with improved lacrimal secretion was higher in the dogs with initial Schirmer tear test values > or = 2 mm/min than in those with initial values of 0 or 1 mm/min. The observed steady improvement in conjunctival health was not always correlated with an improvement in lacrimal secretion. The incidence of blepharospasm, other signs of discomfort and corneal oedema decreased significantly during the study. No improvement in corneal vascularisation or pigmentation was observed during the six-week trial. Overall, 76 per cent of the left eyes and 87 per cent of the right eyes were considered to have improved at the end of the treatment period. No serious adverse reactions were observed and only mild irritation was noticed by the owners immediately after the application of the ointment. This irritation resulted in the recording of an adverse reaction at the scheduled observations in only three cases.

Tear protein profiles vs. clinical characteristics of untreated and cyclosporine-treated canine KCS

BACKGROUND

Topically administered cyclosporine A (CsA) decreases ocular surface inflammation in canine keratoconjunctivitis sicca (KCS) and exerts lacrimomimetic effects. This study was performed to find correlations between clinical signs and tear protein levels in untreated and CsA-treated canine KCS.

METHODS

Clinical profiles were scored in 16 KCS-affected dogs before and 6 weeks after commencing treatment with 0.2% topical CsA emulsion. Tear samples were also collected using polished micropipettes for specific protein assay by high-performance liquid chromatography (HPLC) and enzyme-linked immunosorbent assay (ELISA).

RESULTS

Tear levels of serum proteins correlated with conjunctival clinical signs. Levels of lacrimal gland proteins in tears correlated most often with corneal clinical signs.

CONCLUSIONS

The inflammatory features of KCS appear to link conjunctival signs to serum proteins in tears, while corneal signs are linked to lacrimal gland proteins.

Microorganisms isolated from the corneal surface before and during topical cyclosporine treatment in dogs with keratoconjunctivitis sicca

The effect that topical administration of cyclosporine would have on the number and type of microorganisms isolated from the corneal surface of dogs with keratoconjunctivitis sicca was studied. Schirmer tear test wear performed on and corneal swab specimens were collected from 61 eyes of 31 dogs with keratoconjunctivitis sicca prior to and after 3, 6, and 12 months of treatment with cyclosporine. In eyes that responded to cyclosporine treatment (Schirmer tear test value increased by > or = 5 mm/min, compared with pretreatment value), the percentage of eyes from which bacteria were isolated 3, 6, and 12 months of treatment was significantly (P < 0.001) less than the percentage from which bacteria were isolated prior to treatment. However, among eyes that did not respond to treatment, we did not detect a significant change over time in prevalence of bacteria or type of bacteria isolated. The percentage of eyes from which fungi were isolated decreased during treatment; however, the small number of eyes in which fungal culture results were initially positive precluded demonstration of a significant differences over time in the frequency with which specific bacterial genera were isolated, with the exception of beta-hemolytic Streptococcus spp. Opportunistic corneal infections were not detected even though none of the dogs received antibiotics. An increase in production of tears, which contain anti-infection, proteins, was believed to be the primary factor responsible for the decrease in the percentage of eyes from which microorganisms could be isolated.

A quantitative study of the effects of Tribrissen on canine tear production

The effect of trimethoprim-sulfadiazinea on Schirmer tear test (STT) values was studied in a population of dogs treated with the drug for a variety of medical and postsurgical conditions. The objectives of the study were to determine the incidence of keratoconjunctivitis sicca (KCS) secondary to trimethoprim-sulfadiazine therapy; to determine if such incidence was related to dose, duration, or both; and to identify any other factors that increased patient risk. The package insert accompanying Tribrissen states that "Dogs can tolerate up to ten times the recommended therapeutic dose without exhibiting ill effects." The results of this study indicated a 15.2% (5/33) incidence of KCS in the population of treated dogs.

Effect of topical pilocarpine treatment on tear production in dogs

Tear production, evaluated every 2 hours from 8 AM to 8 PM by use of the Schirmer tear test over a 3-day period, was not significantly different between left and right eyes in 12 dogs. However, a significant diurnal pattern was evident. Tear production was lowest at midday and highest in the late afternoon/early evening. After pilocarpine HCl ophthalmic solution (0.25, 1.0, or 2.0%; 1 drop) was administered topically to the left eye of each dog at 7 AM on days 4, 6, and 8, respectively, tear production was determined for both eyes every 2 hours from 8 AM to 8 PM on the day of treatment. Analysis of tear values between eyes and between each eye's treatment and pretreatment values did not reveal significant change for the treated eye, but tear production was significantly less in the untreated eye, compared with its pretreatment values and with values in the treated eye. On day 10 (48 hours after the last treatment), tear production values were not significantly different between left and right eyes, and for both eyes, were not significantly different from the mean pretreatment tear production values. Topical application of 0.25, 1.0, or 2.0% pilocarpine HCl consistently caused blepharospasm, conjunctival hyperemia, and miosis of the treated eye, without significant increase in tear production. We concluded that topical application of pilocarpine, at the concentrations used, may have little value in treating disorders involving reduced tear production.

Allergic- and immunologic-mediated diseases of the eye and adnexae

Significant allergic- and immunologic-mediated diseases of the eye are reviewed. Included are diseases of the lacrimal gland namely keratoconjunctivitis sicca, immune-mediated diseases of the conjunctiva, atopic blepharoconjunctivitis, and marginal blepharitis, uveitis including lens-induced uveitis, episcleritis, orbital cellulitis, and optic neuritis. Significant diagnostic features, an approach to diagnostic workup, and treatment are presented.