Keratoconjunctival effects of diabetes mellitus in dogs

Effects of topical ketorolac tromethamine on tear parameters, meibography, goblet cell density, and conjunctival oxidative stress in healthy dogs

OBJECTIVES

The objective of the study was to evaluate whether a twice-daily instillation of 0.45% preservative-free ketorolac tromethamine (FKT) or 0.4% benzalkonium chloride-preserved ketorolac tromethamine (BACKT), every 12 h for 30 days may affect tear film parameters and the meibography in healthy dogs. Additionally, we assessed whether the same treatments irritated the ocular surface, affected goblet cell density (GCD), and the levels of oxidative stress biomarkers (OSB) in the conjunctiva of the same dogs.

PROCEDURES

Experimental and masked comparison study. In 11 healthy dogs baseline values of the lipid layer thickness, tear meniscus height, non-invasive tear breakup time (NI-TFBT), and the meibomian gland (MG) loss were assessed by OSAvet®. For each dog, one eye received 40 μL of BACKT, while the other received 40 μL FKT, every 12 h for 30 consecutive days. Tear parameters and meibography were repeated 15, 30, and 60 days post-treatments. Conjunctival hyperemia and blepharospasm were monitored at the same time points. At baseline and Day 30, a conjunctival biopsy was collected for GCD and OSB determination.

RESULTS

Conjunctival hyperemia and blepharospasm were not observed. At Day 15, the MG loss increased only in FKT-treated eyes (p < .001). On Day 30, both treatment groups showed increased MG loss, shortened NI-TFBT, and reduced GCD and catalase (p < .05). At Day 30, BACKT-treated eyes showed lower levels of superoxide dismutase (SOD) (p = .006) and higher levels of malondialdehyde (MDA) (p = .02). Differences between treatments were not observed for any parameter at any time point (p > .05). 60 days after treatment, OSAvet® parameters tended to return to values assessed at baseline; however, significant differences remained for MG loss (p < .05).

CONCLUSIONS

Twice-daily instillation of KT, containing or not BAC, for 30 consecutive days shortened NI-TFBT, decreased GCD, and increased the MG loss in healthy dogs. KT should be used with caution when prescribed for long periods, particularly in patients with tear film abnormalities. However, future controlled studies using KT, BAC, and other topical NSAIDs are indicated to further support this finding.

Comparison of the outcomes of phacoemulsification versus topical medication alone in canine diabetic cataracts: a retrospective study

BACKGROUND

Long-term comparisons of phacoemulsification with topical medication are limited in canine diabetic cataracts.

OBJECTIVES

To compare outcomes of eyes submitted to phacoemulsification with those of topical medication for canine diabetic cataracts and identify risk factors for complications.

METHODS

Through medical records review, 150 eyes (76 dogs) with diabetic cataracts were included; 58 eyes (31 dogs) underwent phacoemulsification (phaco-group) and 92 eyes (48 dogs) received ophthalmic solution alone (medication-group). The medication-group was divided into owner-led and vet-led groups depending on who elected not to perform surgery. Comparisons involved time-to-complications, vision, and the number and type of ophthalmic solutions administered. The association between complications and pretreatment clinical findings was investigated.

RESULTS

No difference was found in complication risk between the phaco and owner-led medication groups. Conversely, the vet-led medication-group had a higher complication risk than the other groups. At the last follow-up, 94.8% of the phaco-group had vision, whereas 7.6% of the medication-group restored some visual axis. Poor glycemic control in the medication-group and younger age in the phaco-group increased complication risk. At 1-year post-treatment, the average number of ophthalmic solutions administered was 1.7 and 2.6 in the phaco and medication groups, respectively. The medication-group used anti-inflammatories the most throughout the follow-up, whereas the phaco-group used anti-inflammatories the most until 1-year post-treatment and lacrimostimulants at 1.5-year post-treatment.

CONCLUSIONS

For canine diabetic cataracts, phacoemulsification is recommended because it is superior to topical management alone in terms of maintaining vision and reducing the number of ophthalmic solutions required in the long term.

Decreased corneal subbasal nerve fiber length and density in diabetic dogs with cataracts using in vivo confocal microscopy

OBJECTIVE

To determine whether there is a difference in corneal sensitivity and corneal subbasal nerve plexus (CSNP) morphology in cataractous dogs with diabetes mellitus (DM) versus without DM.

ANIMALS STUDIED

Twenty six domestic dogs with cataracts of various breeds presented for phacoemulsification, 13 with DM and 13 without DM.

PROCEDURE

The inclusion criteria for the study were dogs with bilateral cataracts and no clinical evidence of corneal disease. The diabetic group had documented hyperglycemia and was currently treated with insulin. The non-diabetic group had no evidence of DM on examination and bloodwork. Complete ophthalmic examination, corneal esthesiometry, and in vivo confocal microscopy of the CSNP was performed for both eyes of each dog. The CSNP was evaluated using a semi-automated program and statistically analyzed.

RESULTS

The mean (±SD) CSNP fiber length was significantly decreased in diabetic (3.8 ± 3.0 mm/mm2 ) versus non-diabetic (6.7 ± 1.9 mm/mm2 ) dogs. Likewise, the mean (±SD) fiber density was significantly decreased in diabetic (8.3 ± 3.1 fibers/mm2 ) versus non-diabetic (15.5 ± 4.9 fibers/mm2 ) dogs. The corneal touch threshold was significantly reduced in diabetic (2.1 ± 0.8 cm) versus non-diabetic (2.8 ± 0.4 cm) dogs. There was a non-significant trend towards subclinical keratitis in diabetic (9/13) versus non-diabetic (4/13) dogs.

CONCLUSIONS

Morphological and functional abnormalities of the CSNP were present in dogs with DM, including decreased fiber length, fiber density, and corneal sensitivity. These findings are consistent with diabetic neuropathy and could contribute to clinically significant corneal complications after cataract surgery.

Diagnostic Tests Used During the Ocular Examination

This article provides a review of the required ocular tests during the ophthalmologic examinations of canine and feline patients. Knowledge of medications affecting ocular parameters and awareness of available instrumentation and test materials is essential for accurate diagnoses.

A review of diagnostic tests for qualitative and quantitative tear film deficiency in dogs

Dry eye disease (DED) is a complex multifactorial condition caused by loss of ocular surface homeostasis from quantitative and/or qualitative tear film deficiency. Schirmer tear test (STT) is often the only diagnostic test used to assess for DED in veterinary practice. STT is invaluable in the diagnosis and monitoring of quantitative tear film deficiency (i.e., keratoconjunctivitis sicca); however, it is not sufficient to optimize therapy and fully recognize other contributing factors for the disturbance in ocular surface homeostasis. The present work reviews diagnostic tests for assessing aqueous tear production in veterinary medicine, as well as the quality of tears, corneal epithelial barrier integrity, and the lacrimal functional unit.

Salmonella infantis ulcerative keratitis in a dog

This manuscript describes a previously unreported clinical case of Salmonella enterica serovar infantis associated with ulcerative keratitis in a dog. Local immunosuppression of the corneal surface likely contributed to this opportunistic infection. Antimicrobial therapy with topical ofloxacin, tobramycin, and systemic enrofloxacin was successful in resolving the infection.

Insulin facilitates corneal wound healing in the diabetic environment through the RTK-PI3K/Akt/mTOR axis in vitro

Diabetic patients can develop degenerative corneal changes, termed diabetic keratopathy, during the course of their disease. Topical insulin has been shown to reduce corneal wound area and restore sensitivity in diabetic rats, and both the insulin receptor (IR) and insulin-like growth factor 1 receptor (IGF-1R) stimulate cell signaling of the PI3K-Akt pathway. The purpose of this study was to assess a mechanism by which improved wound healing occurs by characterizing expression within the PI3K-Akt pathway in corneal epithelial and stromal cells. In vitro scratch tests were used to evaluate wound healing outcomes under variable glucose conditions in the presence or absence of insulin. Protein expression of intracellular kinases in the PI3K pathway, stromal cell markers, and GLUT-1 was evaluated by immunoblotting.TGF-β1 expression was evaluated by ELISA. Insulin promoted in vitro wound healing in all cell types. In human corneal epithelial cells, insulin did not induce PI3K-Akt signaling; however, in all other cell types evaluated, insulin increased expression of PI3K-Akt signaling proteins compared to vehicle control. Fibroblasts variably expressed α-SMA under all treatment conditions, with significant increases in α-SMA and TGF-β1 occurring in a dose-dependent manner with glucose concentration. These results indicate that insulin can promote corneal cellular migration and proliferation by inducing Akt signaling. Exogenous insulin therapy may serve as a novel target of therapeutic intervention for diabetic keratopathy.

Quantification of tear glucose levels and their correlation with blood glucose levels in dogs

Background

No previous studies have quantified tear glucose (TG) levels in dogs or compared changes in TG and blood glucose (BG) concentrations.

Objective

To quantify TG concentration and evaluate its correlation with BG level in dogs.

Methods

Twenty repetitive tests were performed in alternate eyes of four dogs, with a minimum washout period of 1 week. Tears and blood were collected at 30‐min intervals with successive glucose injections (1 g/kg) every 30 min. Cross‐correlations of BG and TG levels were assessed. The delay and association between TG and corresponding BG levels were analysed for each dog; samples were collected at 5‐min intervals. The tears were collected using microcapillary tubes. Collected tears and blood were analysed for glucose concentration using a colorimetric assay and commercially available glucometer, respectively.

Results

The average baseline BG and TG levels were 4.76 ± 0.58 and 0.39 ± 0.04 mmol/L, respectively. Even with highly fluctuating BG levels, a significant cross‐correlation coefficient (r = 0.86, p < 0.05) was observed between changes of BG and TG levels. The delay time between BG and TG levels was 10 min. On average, BG levels were 16.34 times higher than TG levels. There was strong correlation between BG and TG levels (r_s = 0.80, p < 0.01). Significant differences in TG concentrations between normoglycaemia, mild hyperglycaemia, and severe hyperglycaemia were found (p < 0.05).

Conclusions

Canine TG concentrations have not been quantified previously. Our findings suggest preliminary data for future research on TG levels in dogs and show TG measurement could be used to screen for diabetes mellitus in dogs.

Neurogenic keratoconjunctivitis sicca in 34 dogs: A case series

OBJECTIVE

To describe the clinical findings, imaging features, underlying conditions, treatment, and progression of dogs presented between 2010 and 2019 with neurogenic keratoconjunctivitis sicca (NKCS).

METHODS

Dogs diagnosed with NKCS were searched in the clinical database. Inclusion criteria were STT-1 readings <15 mm/min, clinical signs of KCS with concurrent ipsilateral xeromycteria.

RESULTS

Thirty-four cases were identified. Mean age at presentation was 8.2 years, median 8.9 years (0.3-14.7). Twenty dogs were male, and 14 dogs were female. Concurrent neurological deficits included facial neuropathy (n = 13, 38%), peripheral vestibular syndrome (n = 10, 29%), and Horner's syndrome (n = 5, 15%). Advanced imaging was acquired in 53% of cases (n = 18). Etiologies included idiopathic (n = 18, 53%), endocrinopathy (n = 6, 18%), otitis interna (n = 4, 12%), head trauma (n = 3, 9%), iatrogenic (post-TECA-LBO, n = 1, 3%), brainstem mass (n = 1, 3%), and an area of inflammation in the pterygopalatine fossa (n = 1, 3%). Treatment for NKCS was initiated in most cases (n = 30, 88%) including: oral pilocarpine 2% and lacrimostimulant (n = 19), oral pilocarpine 2% only (n = 3), or lacrimostimulant only (n = 8). A mean time follow-up of 3.7 months, median 3 months (1-14) was available in 23 cases (68%). Eleven cases with follow-up were responsive (48%) with resolution of the clinical signs in a median time 4 months (1-10), and all of them were treated with oral pilocarpine (±lacrimostimulant).

CONCLUSIONS

Most cases presented as idiopathic NKCS; in others, an underlying cause of facial neuropathy was identified. All responsive cases were treated with oral pilocarpine 2%.

Investigation of fluorescein stain-based tear film breakup time test reliability in dogs in a clinical setting

OBJECTIVE

To determine intra- and interobserver reliability of a fluorescein stain-based tear film breakup time (TFBUT) test as performed in a clinical environment with and without administration of a topical anesthetic.

ANIMALS

21 privately owned dogs.

PROCEDURES

A randomized study design was used. Two independent observers that commonly perform the TFBUT test in clinical practice read the same description of TFBUT. Observers performed TFBUT testing for each dog before and after topical administration of 0.5% proparacaine solution in 4 testing periods with a 1-hour interval between periods. Intraclass correlation coefficient (ICC) analysis was used to assess inter- and intraobserver test reliability. Linear mixed models were used to assess the main effects of testing period, observer, eye, and presence of ophthalmic disorders and their interactions on TFBUT.

RESULTS

Mean TFBUT measurements performed by observer 1 and observer 2 were 5.9 seconds and 8.6 seconds, respectively, when adjusted for other effects in the model. Intraobserver ICC was poor for one observer and moderate for the other. Interobserver ICC was poor without use of topical anesthetic and slightly lower when anesthetic was used. Observer and testing period were each significantly associated with TFBUT; the measurements decreased and were more variable after multiple applications of fluorescein stain and proparacaine.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested tear film stability is negatively affected by topical administration of 0.5% proparacaine solution and repeated applications of fluorescein stain. The TFBUT test as performed in this study had poor to moderate reliability.

Proteomic Analysis of Tear Film Obtained from Diabetic Dogs

Simple Summary

Canine diabetes is a serious disease, which can lead to severe complications, eventually even death. Currently, all the diagnostic procedures are the invasive ones, with blood collection remaining as a golden standard for both initial diagnosis, and later follow-up. Tears can be obtained in a non-invasive manner, which makes them a perfect candidate for a screening tool in canine diabetes. In this study we aimed to analyze the protein composition of the tears collected from the healthy animals and compared it to the diabetic group. There are significant differences between these two groups, and we believe that the identified proteins hold promise as a potential diagnostic tool, which can be later on used both in clinical practice, and for better understanding of the disease.

Abstract

Canine diabetes mellitus is a significant health burden, followed with numerous systemic complications, including diabetic cataracts and retinopathy, leading to blindness. Diabetes should be considered as a disease damaging all the body organs, including gastrointestinal tract, through a complex combination of vascular and metabolic pathologies, leading to impaired gut function. Tear film can be obtained in a non-invasive way, which makes it a feasible biomarker source. In this study we compared proteomic changes ongoing in tear film of diabetic dogs. The study group consisted of 15 diabetic dogs, and 13 dogs served as a control group. After obtaining tear film with Schirmer strips, we performed 2-dimensional electrophoresis, followed by Delta2D software analysis, which allowed to select statistically significant differentially expressed proteins. After their identification with MALDI-TOF (matrix assisted laser desorption and ionisation time of flight) spectrometry we found one up-regulated protein in tear film of diabetic dogs—SRC kinase signaling inhibitor 1 (SRCIN1). Eight proteins were down-regulated: phosphatidylinositol-4 kinase type 2 alpha (PI4KIIα), Pro-melanin concentrating hormone (Pro-MCH), Flotillin-1, Protein mono-ADP ribosyltransferase, GRIP and coiled coil domain containing protein 2, tetratricopeptide repeat protein 36, serpin, and Prelamin A/C. Identified proteins were analyzed by Panther Gene Ontology software, and their possible connections with diabetic etiopathology were discussed. We believe that this is the first study to target tear film proteome in canine diabetes. We believe that combined with traditional examination, the tear film proteomic analysis can be a new source of biomarkers both for clinical practice, and experimental research.

Conjunctival staining with lissamine green as a predictor of tear film deficiency in dogs

OBJECTIVE

To evaluate a grading scheme for conjunctival staining patterns with lissamine green ocular dye in the diagnosis of tear film deficiencies in dogs.

PROCEDURES

Client-owned and research colony dogs were enrolled in a prospective study between February and October 2018 in which slit-lamp biomicroscopy, Schirmer tear test (STT), tear film breakup time (TFBUT), conjunctival lissamine green staining (LGS), and intraocular pressure (IOP) measurement were performed in both eyes of all dogs. Lissamine green staining of the temporal bulbar conjunctiva was graded from 0-3, with a higher grade corresponding to an increased stain intensity.

RESULTS

Fifty-four dogs (107 eyes), comprising 31 males and 23 females with a mean age of 5.0 ± 3.9 years (range 0.5-14.3), were enrolled in the study. STT was <15 mm/min in 21 eyes and ≥15 mm/min in 86 eyes. Lissamine green staining grade for eyes with a STT of <15 mm/min (2.0 ± 0.9) was significantly higher than for eyes with a STT ≥15 mm/min (0.2 ± 0.7) (P < .001). TFBUT for eyes with a STT <15 mm/min (6.5 ± 4.4 seconds) was significantly shorter than for eyes with a STT ≥ 15 mm/min (16.1 ± 3.6 seconds) (P < .001). As LGS grade increased, both STT (P < .001) and TFBUT (P < .001) significantly decreased.

CONCLUSIONS

A higher LGS grade was significantly associated with a lower STT and more rapid TFBUT in dogs. Lissamine green ocular dye can be considered as an adjunctive diagnostic test when evaluating tear film deficiency in dogs.

Preliminary report of postoperative complications of phacoemulsification in Pugs: A multicenter retrospective study of 32 cases

OBJECTIVE

To compare complication rates and visual outcomes following phacoemulsification in Pugs versus dogs of other breeds.

ANIMALS STUDIED

Thirty-two pure-bred Pugs (55 eyes) and 32 dogs of other breeds (56 eyes) undergoing phacoemulsification.

PROCEDURES

Multi-institutional retrospective medical record review of perioperative factors, postoperative complications, and visual outcomes. The reference population of dogs of varying breeds included surgical cases following each Pug case at the same institutions. Perioperative risk factors and postoperative complication rates were compared between the two populations.

RESULTS

Pigmentary keratitis and diabetes mellitus were the most common preoperative comorbidities, found in 75% (P < .001) and 72% (P = .12) of Pugs, respectively. No perioperative factors were significantly associated with postoperative complications in Pugs. Postoperative complication rates were similar between groups; however, the most common complication in Pugs was corneal ulceration (15% of operated eyes), whereas glaucoma was most common in the reference population (13% of operated eyes). Three months postoperatively, vision was preserved in 91% of eyes of Pugs (50/55) and 95% of the reference population (53/56). One year postoperatively, 80% (32/40) of Pug eyes and 82% (28/34) of eyes in the reference population remained sighted.

CONCLUSIONS

Comorbidities and complications of cataract surgery in Pugs of this study demonstrate a predisposition for corneal disease. This highlights the importance of preoperative evaluation of factors associated with PK and corneal clarity, and postoperative monitoring for corneal ulceration in this breed.

Tear glucose, creatinine, and urea nitrogen concentrations in cats with normal or increased plasma concentrations

OBJECTIVE

The aim of the study was to determine the lacrimal fluid (LF) contents of glucose, urea nitrogen, and creatinine in cats.

ANIMAL STUDIED

A total of 96 cats were included in the study.

PROCEDURE

Venous blood and LF samples were collected. For LF sampling, three small polyurethane sponges were placed in the ventral fornix of both eyes. Both LF and plasma concentrations of glucose, urea nitrogen, and creatinine were quantitatively analyzed and compared.

RESULT

Glucose (n = 40) and urea nitrogen concentrations (n = 42) measured in LF from both eyes highly correlated. While there was a very strong correlation (ρ = 0.97) between urea nitrogen concentrations in blood plasma and the corresponding tear levels (with the median LF urea nitrogen being 109% of that measured in plasma), the LF glucose concentrations were significantly lower than the corresponding plasma concentrations (with only 13% of the blood glucose concentration detected in the LF). The creatinine concentrations in tears were much lower than those in plasma, and LF creatinine was detectable in only 12/48 cats (25%). Hence, a comparison of the LF creatinine concentrations between both eyes or with the corresponding plasma creatinine concentration was not possible.

CONCLUSION

Measurement of LF urea nitrogen concentrations in cats appears to be reliable and might have potential clinical utility. Measurement of LF glucose concentrations is less reliable but may still be useful in some cats. Creatinine is not reliably detected in the LF in cats. Further studies determining clinical utility of LF metabolites in cats and other companion animals are warranted.

Effect of 0.15% sodium hialuronate and 0.5% carboxymethylcellulose on tear film breakup time in healthy dogs and in dogs with keratoconjunctivitis sicca

ABSTRACT This study aimed to evaluate the effect of the 0.15% sodium hyaluronate (SH) and of 0.5% carboxymethylcellulose (CMC) on tear film breakup time (TFBUT) in 10 healthy dogs and in 32 eyes of dogs with keratoconjunctivis sicca (KCS). In addition, the goblet cell density (GCD) of this population was quantified. TFBUT was assessed at baseline and at different time points following the instillation of SH and CMC. KCS was graded as mild, moderate, and severe. GCD were quantified from conjunctival biopsies. The number of GCD differed significantly between patients with mild and moderate KCS (P<0.01). TFBUT of healthy dogs increased only for 1 minute after treatment with SH (P<0.01). Regarding baseline and treatments, SH significantly increased TFBUT for up to 30 minutes on the ocular surface, in comparison to CMC, in all categories of KCS (P<0.01). TFBUT and GCD correlated positively when the healthy and diseased eyes were grouped (r=0.41, P=0.006). It can be concluded that in dogs with KCS, SH lasts longer periods on the ocular surface than CMC, but such agents does not increase TFBUT in healthy dogs. Additionally, tear film stability tends to reduce in a linear fashion from the mild to severe form of KCS.

Canine Diabetes Mellitus Associated Ocular Disease

Diabetes mellitus (DM) is a commonly encountered disease in companion animal veterinary practice. Ocular complications in dogs with DM are thought to be common but there are no reports of the overall incidence of DM-associated ocular disease. Some complications, such as cataracts and ocular surface disease, can lead to vision loss and significant morbidity among DM patients, therefore early recognition and intervention are essential for successful outcomes. The purpose of this article is to provide a review of several currently known or suspected ocular diseases associated with DM.

Effects of topically applied heterologous serum on reepithelialization rate of superficial chronic corneal epithelial defects in dogs

OBJECTIVE To assess the effects of topical application of undiluted heterologous serum on time to corneal reepithelialization in dogs with superficial chronic corneal epithelial defects (SCCEDs). DESIGN Multicenter, randomized, double-masked, controlled clinical trial. ANIMALS 41 client-owned dogs. PROCEDURES After collection of baseline clinical and historical data, dogs were randomly assigned to receive topically applied undiluted heterologous serum (n = 22) or isotonic saline (0.9% NaCl) solution (19) along with tobramycin and atropine. Epithelial debridement (at all visits) and grid keratotomy (at visits 2, 3, and 4) of SCCEDs were performed. Ophthalmic examination including fluorescein application was performed once weekly for 4 weeks or until corneal reepithelialization. Clinicians and owners were masked to treatment group. RESULTS No differences in baseline data were detected between treatment groups. No difficulties with medication administration, noncompliance, or adverse reactions were noted. All SCCEDs in both groups healed by 4 weeks after treatment began. Median time to reepithelialization (2 weeks) was not significantly different between serum-treated and placebo-treated eyes. Irrespective of treatment group, median time to reepithelialization was not significantly different for Boxers versus non-Boxer breeds. Direct correlations were detected between time to reepithelialization and vascularization score at study entry, vascularization score at time of reepithelialization, and ulcer area at study entry in both groups. Time to reepithelialization was not correlated with age, sex, or duration of signs in either group. CONCLUSIONS AND CLINICAL RELEVANCE Topical application of undiluted heterologous serum was well tolerated by dogs with SCCEDs but, as an adjunct to standard treatment, did not reduce time to corneal reepithelialization.

Allogeneic Mesenchymal Stem Cell Transplantation in Dogs With Keratoconjunctivitis Sicca

Keratoconjunctivitis sicca (KCS) is a dysfunction in tear production associated with clinical signs, which include conjunctival hyperemia, ocular discharge, discomfort, pain, and, eventually, corneal vascularization and pigmentation. Immunosuppressive drugs are routinely administrated for long periods to treat KCS but with side effects and limited results. Evaluation of the clinical benefits of intralacrimal transplantation of allogeneic mesenchymal stem cells (MSCs) in dogs with mild-moderate and severe KCS was done. A total of 24 eyes with KCS from 15 dogs of different breeds were enrolled in the present study. A single transplantation of MSCs (1 × 10⁶) directly into lacrimal glands (dorsal and third eyelid) was performed. The Schirmer tear tests (STTs) and ocular surface improvements were used to assess short- and long-term effects of these cells. The STTs were carried out on day 0 (before MSCs transplantation) and on days 7, 14, 21, and 28, as well as 6 and 12 months after MSC transplantation. Our data demonstrate that allogeneic MSC transplantation in KCS dogs is safe since no adverse effects were observed immediately after transplantation and in short- and long-term follow-ups. A statistically significant increase in the STT and ocular surface improvements was found in all eyes studied. In all the eyes with mild-moderate KCS, STT values reverted to those of healthy eyes, while in eyes with severe KCS, although complete reversion was not found, there was improvement in tear production and in other clinical signs. Our study shows that a single dose of a low number of MSCs can be used to treat KCS in dogs. In contrast to immunosuppressive drug use, MSC transplantation has an effect over a long period (up to 12 months), even after a single administration, and does not require daily drug administration.

Clinical evaluation of a nutraceutical diet as an adjuvant to pharmacological treatment in dogs affected by Keratoconjunctivitis sicca

Background

Canine keratoconjunctivitis sicca (cKCS) is an inflammatory eye condition related to a deficiency in the tear aqueous fraction. Etiopathogenesis of such disease is substantially multifactorial, combining the individual genetic background with environmental factors that contribute to the process of immunological tolerance disruption and, as a consequence, to the emergence of autoimmunity disease. In this occurrence, it is of relevance the role of the physiological immune-dysregulation that results in immune-mediated processes at the basis of cKCS. Current therapies for this ocular disease rely on immunosuppressive treatments. Clinical response to treatment frequently varies from poor to good, depending on the clinical-pathological status of eyes at diagnosis and on individual response to therapy. In the light of the variability of clinical response to therapies, we evaluated the use of an anti-inflammatory/antioxidant nutraceutical diet with potential immune-modulating activity as a therapeutical adjuvant in cKCS pharmacological treatment. Such combination was administered to a cohort of dogs affected by cKCS in which the only immunosuppressive treatment resulted poorly responsive or ineffective in controlling the ocular symptoms.

Results

Fifty dogs of different breeds affected by immune-mediated cKSC were equally distributed and randomly assigned to receive either a standard diet (control, n = 25) or the nutraceutical diet (treatment group, n = 25) both combined with standard immunosuppressive therapy over a 60 days period. An overall significant improvement of all clinical parameters (tear production, conjunctival inflammation, corneal keratinization, corneal pigment density and mucus discharge) and the lack of food-related adverse reactions were observed in the treatment group (p < 0.0001).

Conclusions

Our results showed that the association of traditional immune-suppressive therapy with the antioxidant/anti-inflammatory properties of the nutraceutical diet resulted in a significant amelioration of clinical signs and symptoms in cKSC. The beneficial effects, likely due to the presence of supplemented nutraceuticals in the diet, appeared to specifically reduce the immune-mediated ocular symptoms in those cKCS-affected dogs that were poorly responsive or unresponsive to classical immunosuppressive drugs. These data suggest that metabolic changes could affect the immune response orchestration in a model of immune-mediated ocular disease, as represented by cKSC.

Immune-mediated keratoconjunctivitis sicca in dogs: current perspectives on management

Keratoconjunctivitis sicca (KCS) is a frequent canine ophthalmic disease, resulting from the deficiency of one or more elements in the precorneal tear film. There are different known causes of KCS in dogs, including congenital, metabolic, infectious, drug induced, neurogenic, radiation, iatrogenic, idiopathic, and immune mediated, though the last one is the most prevalent form in dogs. Initially, clinical signs of KCS include blepharospasm caused by ocular pain, mucoid to mucopurulent ocular discharge, and conjunctival hyperemia; secondary bacterial infection may also occur, with chronicity, corneal epithelial hyperplasia, pigmentation, neovascularization, and corneal ulceration. The diagnosis of KCS is based on the presence of consistent clinical signs and measurement of decreased aqueous tear production using the Schirmer tear test. Therapy is based on administering the following topical drugs: ocular lubricant, mucolytics, antibiotics, corticosteroids, pilocarpine, and immunomodulators. These last drugs (eg, cyclosporine, pimecrolimus, and tacrolimus) have immunosuppressive activity and stimulate tear production. Furthermore, the nerve growth factor is a new subject matter of the research. Although these therapies are advantageous, stimulation of natural tear production seems to provide the highest recovery in clinical signs and prevention of vision loss. The goal of the following article is to describe the recent developments about KCS in dogs emphasizing the use of new therapies.

Effect of once daily topical 0.3% naltrexone on tear parameters and corneal sensitivity in dogs with uncontrolled keratoconjunctivitis sicca: a double-masked randomized placebo-controlled clinical trial

OBJECTIVE

To determine the effect of once daily topical 0.3% naltrexone (NTX) on tear production, tear film breakup time (TFBUT), and corneal sensitivity in dogs with uncontrolled keratoconjunctivitis sicca (KCS).

ANIMALS STUDIED

Sixteen dogs with uncontrolled KCS.

PROCEDURES

A randomized placebo-controlled trial was performed in 16 dogs with topical 0.3% NTX once daily or topical saline solution drops once daily. A baseline was obtained at week 0 for tear production (Schirmer tear test 1 and 2-STT1, STT2), TFBUT, and corneal sensitivity. STT1, STT2, and TFBUT were then subsequently measured at weeks 1, 2, and 4 while on NTX or saline drops. Corneal sensitivity measures were repeated at week 4. The drops were subsequently discontinued and all parameters rechecked at week 5.

RESULTS

There was no statistically significant difference in tear parameters or corneal sensitivity between the NTX-treated and the saline-treated groups.

CONCLUSION

Topical 0.3% NTX given as a once daily dose over 4 weeks did not alter tear production, tear film stability, or corneal sensitivity in dogs with uncontrolled KCS.

[Cataracts in dogs--overview and guideline for decision making in treatment]

Cataract is the leading cause of impaired vision and vision loss in dogs. Because of the considerable progress in cataract surgery in recent decades, lens opacities can now be operated on with very good short-term success (90-95%), taking into account that proper patient selection is essential to maximize the probability of a successful surgical outcome. Following a description of anatomical and physiological lens characteristics, the etiology and complications of untreated cataracts are discussed. Furthermore, specific criteria for patient selection are addressed while delineating essential steps of the examination. This article aims to aid decision making in cataract therapy on the basis of diagnostic guidance and to facilitate the selection of an appropriate point of time for surgery.

Effect of short-term diphenhydramine administration on aqueous tear production in normal dogs

OBJECTIVE

To perform a randomized, placebo-controlled, masked clinical trial using a cross-over design to determine the effect of oral diphenhydramine on aqueous tear production in normal dogs.

ANIMALS STUDIED

Seventeen dogs with normal ophthalmic examinations.

PROCEDURES

Baseline tear production was established for each dog by performing Schirmer tear test I (STT I). Dogs received 20-day treatment courses of both oral diphenhydramine and placebo solutions with a 10-day washout period between treatment periods. Each dog was randomly assigned to receive diphenhydramine or placebo at the outset of the study. Measurements of STT I values were measured at regular intervals during the study and were conducted at the same time of day throughout the study to control for diurnal variations in tear production. The significance of the impact of diphenhydramine treatment on the quantity of aqueous tear production, as determine by STT results over time, was evaluated using regression analysis with appropriate transformation.

RESULTS

Statistical comparisons at each measurement time, including baseline measurements between control and treatment groups, revealed no significant differences. Mean STT I levels also did not differ significantly at any measurement time compared to baseline for treatment or control groups.

CONCLUSIONS

Short-term administration of oral diphenhydramine does not result in a significant decrease in aqueous tear production in normal dogs.

Evaluation of tear production with modified Schirmer tear test-1 during the neonatal period in cats

The study aimed to evaluate tear production by means of modified Schirmer tear tes-1 (mSTT-1) in neonate cats. Likewise, correlation between mSTT-1 and STT-1 was assessed in vitro. Standard SST strips were cut in half and after eye lid opening, tear production of neonates (n=15) was daily measured in both eyes (mSTT-1), until the 7th day, and at day 14, 21, and 28. Animals were daily weighted until 28 days of age. Results were compared statistically (P<0.05). During the first 7 days, the overall mSTT-1 mean was 0.76 wetting/minute. Significant differences between right and left eyes were not observed at any time point (P=1.00). Tear secretion increased significantly, from the 14th to 28th day, in comparison with 7 first days (P<0.05). Positive correlation between maturity parameters and tear secretion was observed (P<0.0001). Distance between slopes of each strip changed significantly (P<0.0001). It was concluded that tear secretion in the neonatal period of cats is very below the reference values described for young and adults of the same species. It is not possible to extrapolate results obtained with mSTT-1 to standard STT-1.

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.

Corneal sensitivity and aqueous tear production in dogs undergoing evisceration with intraocular prosthesis placement

OBJECTIVE

To determine whether there is an association between evisceration with intraocular prosthesis placement via a dorsal scleral approach and decreased corneal sensitivity or aqueous tear production in dogs.

DESIGN

Prospective study.

PROCEDURE

Twenty-one dogs scheduled to undergo unilateral evisceration with intraocular prosthesis, and with a normal normotensive contralateral eye, based on slit-lamp biomicroscopy, indirect ophthalmoscopy and applanation tonometry, were included in the study. Central corneal sensitivity was measured with a Cochet-Bonnet esthesiometer prior to (week 0) and 2, 7, 14 and 28 weeks following surgery. Other pre- and postoperative data collected were Schirmer's tear test (STT I), Schirmer's tear test with topical anesthesia (STT II), corneal fluorescein retention, and intraocular pressure (IOP; postoperative control eye only). Axial globe length was determined for both eyes. Scleral incision length in the surgery eye was also recorded.

RESULTS

Corneal sensitivity was significantly lower in eyes undergoing evisceration with intraocular prosthesis than in control eyes both preoperatively and postoperatively at all time points. There was no significant difference between preoperative and postoperative corneal sensitivity within the two groups. There was no significant difference in STT I or STT II-values between control eyes and surgery eyes preoperatively. There was a significant difference between preoperative and 2-week postoperative STT I in the surgery eye. There was a significant difference between the preoperative and 28-week postoperative STT II in the surgery eye. The 28-week postoperative STT I-values differed significantly between control and surgery eyes. Corneal sensitivity tended to decrease with increased degree of buphthalmos or with increased scleral incision length, although neither relationship was statistically significant.

CONCLUSIONS

Eyes that have sustained chronically elevated intraocular pressure had decreased axial corneal sensitivity compared to normal eyes, which persisted even after intraocular pressure was reduced. The presence of buphthalmos appeared to be a factor in globes developing decreased corneal sensitivity. Evisceration via a dorsal scleral incision did not result in a significant further reduction in axial corneal sensitivity. A mild reduction in aqueous tear production occurred over time in globes following evisceration with intraocular prosthesis.