Uberreiter's syndrome (chronic superficial keratitis) in dogs in the Rocky Mountain area--a study of 463 cases

Cyclosporine A Delivery Platform for Veterinary Ophthalmology—A New Concept for Advanced Ophthalmology

Cyclosporine A (CsA) is a selective and reversible immunosuppressant agent that is widely used as a medication for a wide spectrum of diseases in humans such as graft versus host disease, non-infectious uveitis, rheumatoid arthritis, psoriasis, and atopic dermatitis. Furthermore, the CsA is used to treat keratoconjunctivitis sicca, chronic superficial keratitis, immune-mediated keratitis and equine recurrent uveitis in animals. The selective activity of Cyclosporine A (CsA) was demonstrated to be an immunomodulation characteristic of T-lymphocyte proliferation and inhibits cytokine gene expression. Moreover, the lipophilic characteristics with poor bioavailability and low solubility in water, besides the side effects, force the need to develop new formulations and devices that will provide adequate penetration into the anterior and posterior segments of the eye. This review aims to summarize the effectiveness and safety of cyclosporine A delivery platforms in veterinary ophthalmology.

Genome-Wide Association Analysis for Chronic Superficial Keratitis in the Australian Racing Greyhound

Chronic superficial keratitis (CSK) is a progressive inflammatory condition of the eye (cornea) that can cause discomfort and blindness. Differential disease risk across dog breeds strongly suggests that CSK has a genetic basis. In addition to genetic risk, the occurrence of CSK is exacerbated by exposure to ultraviolet light. Genome-wide association analysis considered 109 greyhounds, 70 with CSK and the remainder with normal phenotype at an age over four years. Three co-located variants on CFA18 near the 5' region of the Epidermal Growth Factor Receptor (EGFR) gene were associated with genome-wide significance after multiple-test correction (BICF2P579527, CFA18: 6,068,508, p_raw = 1.77 × 10^-7, p_genome = 0.017; BICF2P1310662, CFA18: 6,077,388, p_raw = 4.09 × 10^-7, p_genome = 0.040; BICF2P160719, CFA18: 6,087,347, p_raw = 4.09 × 10^-7, p_genome = 0.040) (canFam4)). Of the top 10 associated markers, eight were co-located with the significantly associated markers on CFA18. The associated haplotype on CFA18 is protective for the CSK condition. EGFR is known to play a role in corneal healing, where it initiates differentiation and proliferation of epithelial cells that in turn signal the involvement of stromal keratocytes to commence apoptosis. Further validation of the putative functional variants is required prior to their use in genetic testing for breeding programs.

Progressive retrocorneal pigmentation in dogs: A clinical report of 34 cases

OBJECTIVES

To describe the signalment, ophthalmic examination findings, and follow-up of dogs affected with a previously unreported retrocorneal pigmentary lesion.

MATERIALS AND METHODS

Retrospective record evaluation spanning 2009-2019.

RESULTS

Retrocorneal pigmentary lesions were described in 34 patients (46 eyes). German Shepherds (n = 7), Jack Russel terriers (n = 5), and terrier crosses (n = 4) made up 16/34 (47.1%) of the cases. The mean age was 13.5 years (range 1.4-14.2 years), and 16/30 (53.3%) dogs were female. Most dogs were affected unilaterally (22/34 (64.7%)), the others bilaterally, and 5/34 (14.7%) were referred for it while the others were incidentally diagnosed. The lesions affected the ventral, peripheral, inner cornea and had a round/undulated leading edge. The number of corneal clock hours affected was known for 41/46 (89.1%) eyes and involved 1-3 clock hours in 32/41 (78.1%) eyes, 4-6 in 6/41 (14.6%), 7-9 in 2/41 (4.9%), and 10 in 1/41 (2.4%). The central cornea was affected in 9/46 (19.6%) eyes, and in 5/9 (55.6%), the median corneal clarity score was G2 (scale: G0-G4). The commonest additional findings included free-floating uveal cysts (11/34 dogs, 32.4%), cataracts (6/34 dogs, 17.6%), and primary glaucoma (5/34 dogs, 14.7%). Gonioscopy was available in 16/34 (47.1%) dogs and was normal except in primary glaucoma cases. Follow-up was documented in 13/34 (38.2%) dogs with a mean follow-up of 17 months (range: 5-26 months). Lesion progression was documented in 6/13 (46.2%) dogs.

CONCLUSIONS

Retrocorneal pigmentation occurs as a slowly progressive lesion of older dogs that could impact vision. Histological studies of affected eyes are warranted.

Pigmentary keratitis in pugs in the United Kingdom: prevalence and associated features

Background

Pigmentary keratitis (PK) is commonly recognised in Pugs, but its aetiology is not completely understood. The aim of this study was to determine the prevalence and associated features of PK in Pugs in the United Kingdom (UK).

Results

A total of 210 Pugs (420 eyes) were recruited from 12 UK dog shows and social events. The median age of Pugs recruited was 2.50 years (range 0.25–16.25 years). Pigmentary keratitis was detected in 369/420 (87.8%) eyes and in at least one eye 193/210 (91.9%) Pugs, of which 17/193 (8.8%) were affected unilaterally and 176/193 (91.2%) bilaterally. Pigmentary keratitis was typically mild to moderate (46.3 and 49.9% of eyes, respectively). Detection of PK was significantly associated with increased age (P = 0.002) and the presence of medial entropion of the lower eyelid (MELE) (P = 0.001). Severity of PK was significantly associated with the grade of MELE (P < 0.001). There was also a correlation between the presence of limbal pigment and PK (P = 0.036) that warrants further study.

Conclusions

This study estimated a high disease prevalence of PK in UK Pugs, and demonstrated significant associations with age and the presence of MELE. These associations, which have not been previously reported, offer an insight into the underlying pathophysiology of this condition in Pugs. The results encourage further population research, such as prospective longitudinal studies. These findings also support the development of clinical and breeding strategies based on the reduction of MELE and, possibly, limbal pigment.

Serum vascular endothelial growth factor changes and safety after topical anti-human VEGF antibody bevacizumab in healthy dogs

OBJECTIVE

To evaluate ocular and general safety of topical anti-human VEGF bevacizumab and the effect on serum vascular endothelial growth factor (VEGF) values in healthy dogs.

PROCEDURES

Nine university-owned beagles received 0.05 mL of 0.25% bevacizumab eyedrops (Avastin® , Roche) in one eye and 0.05 mL of 0.9% saline solution in the other eye as a control, administered at 12 hours intervals over a period of 28 days. Continuous monitoring for vital parameters and ocular examinations were conducted. Complete blood counts including hematology and coagulation parameters were performed before trial start as well as 24 hours, 7 days, and 28 days after trial start. Measurements of serum VEGF values were obtained using an ELISA-based approach at days 0, 7, and 28. The experiment was designed as a masked placebo-controlled study.

RESULTS

No clinical signs of ocular toxicity or systemic incompatibility were noted in any dog at any time point of the study. No signs of pain were present in any dog at any time point. All blood count values remained in normal clinical ranges without relevant variation. There was no significant change in mean serum VEGF values between day 0 and day 7 and between day 0 and day 28.

CONCLUSIONS

The results indicate that topical bevacizumab treatment is safe in healthy dogs. However, further studies are needed to assess safety and efficacy in diseased dogs with naturally occurring corneal neovascularization.

In-vitro binding analysis of anti-human vascular endothelial growth factor antibodies bevacizumab and aflibercept with canine, feline, and equine vascular endothelial growth factor

PURPOSE

Promising results have been described for antibodies binding vascular endothelial growth factor (VEGF) in patients with corneal neovascularization. Whether veterinary patients would also benefit from this therapeutic approach has not been investigated yet. We examined binding properties of anti-human VEGF antibodies bevacizumab (Avastin®) and aflibercept (Zaltrap®) for canine, feline, and equine VEGF.

METHODS

Human, equine, feline, and canine VEGF were analyzed for sequence similarity using the "Basic Local Alignment Search Tool" (BLAST). Western-blot analysis and ELISA were used to assess binding properties.

RESULTS

BLAST analysis revealed a sequence homology of canine, feline, and equine VEGF to human VEGF-A of 93%, 92%, and 89%, respectively. Western-blot analysis showed immunoreactivity of bevacizumab with human, canine, and feline VEGF, but not with equine VEGF. Aflibercept recognized VEGF of all tested species. ELISA data indicated that bevacizumab and aflibercept bind canine VEGF in a dose-dependent manner. Feline VEGF was bound by bevacizumab and aflibercept in a dose-independent manner. ELISA study further confirmed the lack of bevacizumab binding to equine VEGF, and yielded also a dose-independent binding by aflibercept.

CONCLUSIONS

Bevacizumab and aflibercept turned out to bind VEGF with species-specific differences. Further studies are required to investigate their efficacy and safety under clinical conditions.

Heat Shock Proteins 70kDa, Eosinophil Cationic Protein, and Nitric Oxide During Chronic Superficial Keratitis in Dogs

The objective of the study is to determine the levels of eosinophil cationic protein (ECP), heat shock proteins 70, and nitric oxide ions measured as nitrite ions (Griess reaction) in dogs with chronic superficial keratitis (CSK). The study was conducted on 24 dogs with CSK. Blood sera from the animals were tested for concentrations of heat shock proteins 70, ECP, and nitrite ions before treatment and again 5 weeks and 6 months after treatment. Dogs with CSK were treated for 6 months with various regimes involving the use of ophthalmic drops containing dexamethasone, dimethyl sulfoxide, and cyclosporine. The control group consisted of 16 clinically healthy German Shepherds. The results obtained indicated a significant (P ≤ 0.05) elevation in the concentrations of heat shock proteins 70 and nitrite ions in dogs with CSK in comparison to healthy dogs and dogs after 5 weeks of therapy. After 6 months of treatment, concentrations of heat shock proteins 70, ECP, and nitrite ions had fallen below pretreatment values. Significant correlations were found between concentrations of heat shock proteins 70, ECP, and nitrite ions in healthy animals and animals with CSK. The elevated concentrations of heat shock proteins 70, ECP, and nitrite ions in dogs with CSK may indicate that the disease was both localized and systemic. The significant correlation between levels of heat shock proteins 70 and nitrite ions suggests that these parameters may be used as indirect indicators of CSK.

A retrospective study of the occurrence of chronic superficial keratitis in 308 German Shepherd dogs: 1999-2010

Chronic Superficial Keratitis (CSK) is an autoimmune mediated inflammation of the cornea, that is usually bilateral but often with nonsymmetrical manifestation. The aim of this study was to determine the occurrence and appearance of clinical symptoms of CSK in German Shepherd dogs in Poland and Slovakia. CSK was diagnosed in 308 German Shepherds for a period of 11 years (from 1999 to 2010). The highest incidence of the CSK (p < 0.001) in Slovakia and in Poland was in dogs between the ages of 5-8 years. This study found similarity in gender ratio of affected patients with CSK in two neighboring countries. This disease occurs most often in males, with almost identical frequency in both countries, Slovakia 65.63% and Poland 61.32%, respectively. The incidence of depigmentation and thickening of the external surface of the third eyelid together with CSK was observed in 69.19% of dogs in Poland and in 63.15% of dogs in Slovakia. CSK is often recognized in advanced stage-affected areas with inflammatory process by CSK, obtained frequently from 2 to 3 quadrants.

MHC class II risk haplotype associated with canine chronic superficial keratitis in German Shepherd dogs

Canine chronic superficial keratitis (CSK) is an inflammatory ocular disease of an autoimmune origin leading to blindness if untreated. The main symptoms of CSK are progressive, bilateral vascularisation, fibrous tissue formation and pigmentation of the anterior corneal stroma. Although CSK is found in many breeds it is most prevalent in German Shepherd dogs (GSDs). Since Major Histocompatibility Complex (MHC) class II is associated with several autoimmune diseases in dogs we investigated the possible role of DLA-DRB1, -DQA1 and -DQB1 in GSDs affected with CSK. Our study population included 25 healthy controls and 30 CSK dogs. Most of the affected dogs were females suggesting a female predisposition. We identified 11 unevenly distributed haplotypes of which DLA-DRB1*01501/DQA1*00601/DQB1*00301 was significantly associated with the CSK dogs (OR=2.67, CI=1.17-6.44, p=0.02). We also found that overall homozygosity of MHC class II increases risk for CSK (OR=4.37, CI=1.27-18.46, p=0.02) and homozygosity of the risk haplotype by over eight-fold (OR=8.5, 95% CI=1.4-224, p=0.017). This study identifies a MHC class II risk haplotype for CSK in GSD and further supports the autoimmune origin of the disease.

Immune-mediated canine and feline keratitis

Although the normal cornea is devoid of vasculature and lymphatics, there are still several immune-mediated corneal conditions that can occur in dogs and cats. An overview of corneal immunology is presented. Diseases of dogs, including chronic superficial keratitis, superficial punctate keratitis, and canine adenovirus endotheliitis, as well as feline diseases, including eosinophilic keratitis and herpesvirus-related conditions, are discussed.

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.

Histological and immunohistochemical evaluation of canine chronic superficial keratitis

Chronic superficial keratitis (CSK) is an inflammatory disease of the canine cornea, characterised by infiltration of leucocytes into the anterior corneal stroma. The present study describes a quantitative histomorphometric analysis of the cell types infiltrating the corneal stroma in this disease. Infiltrating cells were quantified in samples taken at superficial keratectomy and processed for routine histology. Further characterisation of lymphocyte phenotypes was achieved by immunohistochemistry performed using a panel of monoclonal antibodies recognising canine lymphocyte CD antigens. Lymphocytes expressing the CD4 antigen were found to be the predominant infiltrating cell types in the CSK lesion. A significantly smaller number of lymphocytes expressed the CD8 antigen. The CD4/CD8 ratio was consistently above 2 and rose to above 4 at the advancing border of the lesion. A proportion of lymphocytes were shown by immunohistochemistry to contain gamma interferon. This study forms a basis for work further evaluating the cytological events central to the development of this spontaneous potentially auto-immune corneal disease.

Comparison of cyclosporin A and dexamethasone in the treatment of canine nictitans plasmacytic conjunctivitis

Thirteen dogs with nictitans plasmocytic conjunctivitis were treated with 2.0 per cent cyclosporin drops in the right eye and with 0.1 per cent dexamethasone ointment in the left eye. The response to both therapies was monitored for six weeks, repeat biopsy specimens were taken, and the time for the clinical signs to recur recorded. Conjunctival cultures were taken before and after both therapies. There were no significant differences between the treatments in the remission of clinical signs, the reduction of inflammatory infiltrate in the biopsy specimens, or the time to recurrence of the condition or its subsequent severity. However, the eyes treated with 0.1 per cent dexamethasone tended to recover more rapidly than the eyes treated with 2.0 per cent cyclosporin, and the eyes treated with 2.0 per cent cyclosporin tended to be protected from a recurrence for longer than the eyes treated with 0.1 per cent dexamethasone.

Treatment of canine nictitans plasmacytic conjunctivitis with 0.2 per cent cyclosporin ointment

Nictitans plasmacytic conjunctivitis, commonly referred to as plasma cell infiltrate of the nictitans or plasmoma, was diagnosed in 12 dogs (23 eyes) on the basis of clinical signs and nictitans conjunctival biopsy specimens. These dogs underwent a clinical therapeutic trial with twice daily 0.2 per cent cyclosporin ophthalmic ointment. Response to therapy was monitored over a six-week period and repeat biopsy specimens were then taken. Significant (P < 0.05) reductions between pre- and post trial scores were recorded for: mucopurulent ocular discharge quantity; degree of bulbar conjunctival hyperaemia; areas of nictitans hyperaemia, thickening and depigmentation. Schirmer tear test values significantly increased between the start and end of treatment. Biopsy specimens were subjected to selective detection procedures for plasma cells (methyl green-pyronin staining) and T lymphocytes (CD3 antigen labelling). Mean cell counts showed a significant reduction in plasma cell numbers, but the trend towards reduced T lymphocyte numbers was not significant.

Superficial stromal keratitis in the dog

Superficial stromal keratitis or pannus is a syndrome of corneal, conjunctival and third eyelid inflammation. Superficial stromal keratitis mainly presents as a subepithelial corneal infiltration of vascular connective tissue, and usually arises from the lateral (temporal) limbal area. In some dogs perilimbal hyperaemia and third eyelid blepharitis can be present without corneal involvement. The most commonly affected breed of dog is the German Shepherd. Most cases of superficial stromal keratitis can be controlled with topical corticosteroids, and only rarely is cryosurgery or superficial keratectomy required to remove excessive pigment and or granulation tissue. The precise aetiology of SSK is unknown, but is likely to be multifactorial, with sunlight being a significant factor. Corneal lipidosis and keratoconjunctivitis sicca can occur secondary to superficial stromal keratitis.

A report on drug-induced kerato-conjunctivitis sicca in dogs

Kerato-conjunctivitis sicca is reported in beagle dogs treated with an antispasmodic compound for 26 weeks during a routine toxicity study. There was a deficiency of lachrymal secretion associated with keratitis and corneal vascularization. Histopathologically, the changes were characterized by vascularization, fibroblast proliferation and infiltration of inflammatory cells in the substantia propria. In some cases, the inflammation also occurred in corneal epithelium, ocular conjunctiva and corneal limbi.