Corneo-limbo-conjunctival transposition to treat deep and perforating corneal ulcers in dogs: A review of 418 eyes and corneal clarity scoring in 111 eyes

Prevalence and antibiotic resistance in bacterial isolates of dogs with ulcerative keratitis in São Paulo State, Brazil

OBJECTIVE

Identify microorganisms present in canine eyes affected by ulcerative keratitis and assess its resistance profile to available antimicrobial drugs.

METHODS

Samples were collected from 88 canine eyes that exhibited ulcerative keratitis. They were identified using MALDI-TOF and subjected to antimicrobial susceptibility testing by disk diffusion.

RESULTS

Among the assessed subjects, brachycephalic dogs accounted for 74.48% (50/83) of the evaluated canines. Among the 88 evaluated eyes, 90.9% (80/88) showed positive cultures, with 11.33% (10/88) of the samples isolating more than one species of bacteria. Of all bacterial isolates identified (90), Gram-positive bacteria accounted for 63.33% (57/90), while Gram-negative bacteria constituted 36.66% (33/90), with predominance of Staphylococcus spp. at 35.55% (32/90) being, Staphylococcus pseudintermedius at 68.75% (22/32), and Pseudomonas aeruginosa at 15.55% (14/90), respectively. Staphylococcus spp. exhibited resistance to penicillin (89.29%), sulfadiazine and trimethoprim (60.71%), and tetracycline (67.86%), while doxycycline (88.89%), cefotaxime (85.71%), chloramphenicol (82.14%), gentamicin, and moxifloxacin (78.57%) showed the highest sensitivity rates. Pseudomonas aeruginosa displayed sensitivity (100%) to gentamicin and imipenem, and resistance (8.33%) to norfloxacin, ciprofloxacin, and cefepime. Similarly, the Enterobacteriaceae family showed higher sensitivity to amikacin and gentamicin (88.89%), imipenem (88.24%), and levofloxacin (87.5%), with pronounced resistance to amoxicillin-clavulanate (50%) and cefazolin (47.06%). This highlights multiresistance in 23.33% (21/90) of the isolates.

CONCLUSIONS

The most isolated species in canine ulcerative keratitis are S. pseudintermedius and P. aeruginosa. However, other species were also isolated, demonstrating diversity in ocular microbiota infection. There is a high-rate multidrug resistance associated with canine ulcerative keratitis. Nevertheless, these strains exhibited sensitivity to antimicrobials commonly used in veterinary ophthalmology.

Novel ophthalmic hyaluronic acid-hydrogel with curcumin nanoparticles for enhanced healing of ulcerative keratitis in rabbit model

Corneal ulcers, whether melting or indolent, are common in humans and companion animals. Treatment involves local administration of antibiotic eye drops and corneal healing drugs. Compared to traditional treatments for ulcerative keratitis, herbal medicines offer unique advantages, such as potent anti-inflammatory effects and inhibition of proinflammatory cytokines. Curcumin, extracted from the Curcuma Longa plant, possesses extensive pharmacological properties, such as anti-inflammatory, anti-cancer, and antioxidant properties, and is used in various medicines. In this study, we developed a novel ophthalmic drop hydrogel using a formulation of Curcumin NPs encapsulated with β-cyclodextrin and hyaluronic acid, to accelerate corneal healing and improve the quality of healed structures. The formation of Curcumin NPs into Hyaluronic acid-based hydrogels was characterized by zeta, FTIR, and scanning electron microscope (SEM) analyses. A total of 25 healthy male New Zealand Albino rabbits were experimentally induced with ulcerative keratitis and treated individually with topical medication. Rabbits were divided into five groups. Fluorescein dye staining, corneal clarity score, Schirmer tear test, proinflammatory cytokine measurement, and pathologic factors assessments were used to evaluate the optimised Curcumin NPs with β-cyclodextrin in Hyaluronic acid hydrogel. Our results demonstrated that the optimized Curcumin NPs with β-cyclodextrin in hyaluronic acid hydrogel significantly reduced the frequency of medication administration compared to conventional therapies, enhancing the quality of healed structures and effectively treating ulcerative keratitis. All findings in this study provide new insight into designing and fabricating novel ophthalmic medicine for ulcerative keratitis for topical usage.

Risk factors for corneal conjunctival grafting failure in dogs at four referral centers in the southern United States (203 patients): 2015-2021

OBJECTIVE

To report risk factors associated with conjunctival graft failure in dogs at four referral specialty centers.

PROCEDURES

Records of 203 dogs (229 eyes) undergoing conjunctival graft repair of ulcerative keratitis at four hospitals from 2015 to 2021 were reviewed. Success was defined as full graft integration with globe retention at the last postoperative evaluation; vision status was reported separately. Factors assessed included patient signalment, ophthalmic examination findings, surgical factors, and follow-up information.

RESULTS

Conjunctival graft failure occurred in 11% (25/229) of eyes and was significantly associated with ulcer depth, with corneal perforations having increased odds of graft failure compared with descemetoceles (odds ratio [OR] = 3.22, 95% confidence interval [CI] 1.11-9.32; p = .03) and stromal ulcers (OR = 10.89 [95% CI 1.38-86.18], p = .02). Brachycephalic dogs were significantly more likely than non-brachycephalic dogs to experience graft failure (OR = 5.02 [95% CI 1.42-17.74], p < .01). Surgery on the opposite eye relative to surgeon handedness was significantly associated with an increased risk of graft failure (OR 4.28 [95% CI 1.53-11.94], p < .01). The use of 7-0 and 8-0 suture versus 9-0 (p = .03) and the use of a combined simple continuous and interrupted pattern (p = .03) were significantly associated with an increased risk of graft failure. At the last follow-up, (median 61.5 days), 87% of dogs were visual.

CONCLUSIONS

Corneal perforations, surgery on the opposite eye relative to surgeon handedness, suture size and pattern, and brachycephalic conformation were significantly associated with an increased risk of graft failure in this study. These characteristics can be considered when determining prognosis for ulcerative keratitis requiring surgical intervention.

The use of a "horizontal centrifugation protocol" to prepare autologous platelet-rich fibrin membranes for corneal reconstruction surgery in dogs with complicated corneal ulcerations: A case series

OBJECTIVE

The purpose of this case series was to describe the effect of autologous PRF membrane for corneal reconstruction surgery in dogs. PRF membranes made from two healthy dogs unrelated to the current case series were used for PRF histologic analyses.

ANIMALS

Seven dogs with complicated corneal ulcerations.

PROCEDURE

A complete ophthalmic examination, hematology, and fibrinogen analysis were performed pre-surgery. A PRF clot was made from autologous blood in a serum tube after centrifugation in a horizontal Bio-PRF® Centrifuge at 700 × g for 8 min. The PRF clot was processed in a PRF-Box® into a PRF membrane. The PRF membrane was sutured to the corneal ulcer bed. Each dog had a follow-up at days 5-7, 12-14, and 30-40 post-surgery. A final long-term follow-up was performed as well.

RESULTS

A positive outcome with healing and a "good" quality PRF membrane was seen in six out of seven dogs. One dog had a fibrinogen level below normal range and the PRF membrane was of "poor" quality. This dog developed a descemetocele 13 days post-surgery and needed rescue surgery. Mean healing time for all dogs was 9 ± 5.5 days. Minimal scarring, corneal pigmentation, and vascularization were observed at the final long-term follow-up 288 ± 44 days post-surgery.

CONCLUSION

PRF membrane was successful as graft material for corneal ulceration reconstruction surgery. Low fibrinogen appeared to have negative effect on the quality of the PRF membrane, showing the importance for the surgeon to evaluate the quality of the PRF membrane prior to surgery.

A Review of Clinical Outcomes, Owner Understanding and Satisfaction following Medial Canthoplasty in Brachycephalic Dogs in a UK Referral Setting (2016-2021)

Brachycephalic breeds have increased in popularity despite growing awareness of their predisposition to a wide range of conformation-related diseases. The extreme facial conformation of many popular brachycephalic breeds compromises their ocular surface health, increasing the risk of painful corneal ulceration. Medial canthoplasty (MC) is a surgical procedure to address ocular abnormalities in brachycephalic dogs, which are collectively referred to as brachycephalic ocular syndrome (BOS). This study retrospectively reviewed the records of dogs recommended MC at a referral hospital between 2016 and 2021. A questionnaire was designed to identify owners' perceptions pre- and post-operatively. From 271 brachycephalic dogs recommended MC, 43.5% (118/271) underwent surgery and 72.0% (85/118) were Pugs. The majority of dogs (73.7%, 87/118) that underwent surgery had current or historical corneal ulceration. Follow-up was available in 104 dogs, of which 5.7% (6/104) had corneal ulceration post-operatively. Sixty-four owners completed the questionnaire and reported post-operative corneal ulceration in 12.5% of dogs (8/64), reduced ocular discharge (70.8%, 34/48), reduced ocular irritation (67.7%, 21/31) and less periocular cleaning (52.5%, 32/61). Owners were satisfied with the clinical (85.9%, 55/64) and cosmetic (87.5%, 56/64) outcome. In conclusion, MC has high clinical relevance for the surgical management of BOS, restoring functional conformation and improving the quality of life of affected dogs.

Clinical Occurrences in the Neurorehabilitation of Dogs with Severe Spinal Cord Injury

This prospective observational clinical study in a population of tetraplegic and paraplegic dogs (n = 488) with or without deep pain sensation, similar to humans ASIA A and B, investigated the prevalence of clinical occurrences in a rehabilitation center with a hospitalization regime between 15 days and 9 months. A checklist of occurrences was used for easy identification and monitoring, resulting in a total of 79.5% occurrences. There were 58% of dogs with neurogenic bladder, 35.5% with diarrhea, 21.3% with urinary incontinence, and 20.5% with fecal incontinence. A low incidence of respiratory problems (e.g., pneumonia) and urinary tract infections may suggest the efficacy of some applied measures in this study, such as thoracic and abdominal POCUS evaluation, positioning strategies, physical exercises, respiratory kinesiotherapy, and early implementation of a functional neurorehabilitation protocol. These can be essential measures to prevent clinical occurrences, mainly in breeds such as the French Bulldog and the Dachshund.

Multidirectional corneoconjunctival transposition in the treatment of large keratomalacia in 7 dogs and 5 cats

OBJECTIVE

To describe the use of multidirectional corneoconjunctival transposition (CCT) as a surgical treatment for large keratomalacia.

METHOD

A prospective study including dogs and cats initially presenting with keratomalacia larger than 6 × 6 mm and affecting more than half of the corneal thickness. Signalment, concurrent eye diseases, ulcer size, bacterial culture and susceptibility testing results, follow-up, and outcome were recorded. The surgery consisted of harvesting of two or three opposite corneoconjunctival grafts, after removal of the malacic tissue using a square-edge keratectomy. The medical treatment consisted of administration of topical and systemic antibiotics, topical atropine, and N-acetylcysteine. Follow-up examinations were performed at D7, D14, D21, and D28, and then at various time points. The corneal clarity score (CCS) was recorded upon completion of the follow-up period.

RESULTS

Seven dogs and five cats were included. Brachycephalic dogs were overrepresented, with no breed predisposition in cats. Concurrent eye diseases were corneal pigmentation in three dogs, hypopyon in two dogs, nictitating membrane wound in one dog, and corneal perforation in one cat. The size of the keratomalacia ranged from 6 × 6 to 9.5 × 11.5 mm. The short-term complications were suture dehiscence (two of 12) and progression of the keratomalacia (one of 12). The long-term complications were corneal pigmentation (10 of 12), corneal epithelial inclusion cyst (two of 12), and marginal synechiae (one of 12). All animals were sighted at the last follow-up. The median CCS was G3 (range G2-G4).

CONCLUSION

Multidirectional CCT is an effective surgical treatment for large keratomalacia in dogs and cats.

Effects of corneoconjunctival transposition, posterior lamellar keratoplasty and modified deep lamellar endothelial keratoplasty on streak retinoscopy in equine cadaver eyes

OBJECTIVE

Evaluate the effects of corneoconjunctival transposition (CCT), posterior lamellar keratoplasty (PLK) and modified deep lamellar endothelial keratoplasty (DLEK) on streak retinoscopy in equine cadaver eyes.

METHODS

Intraocular pressure (IOP) was maintained at 25 ± 3 mmHg in 35 equine cadaver eyes. Streak retinoscopy was performed prior to (NO VISCO) and following (VISCO) intracameral injection of 1.0 ml of viscoelastic. Following optical coherence tomography (OCT), an axial CCT [n = 11] or PLK [n = 12], or peripheral DLEK [n = 12] was performed. Streak retinoscopy and OCT were repeated postoperatively.

RESULTS

Postsurgical net meridional and spherical refraction for CCT [Horizontal (H): 3.4 (95% CI 2.4-4.4) diopters (D), p < .001, Vertical (V): 3.5 (95% CI 2.7-4.4) D, p < .001, Spherical: 3.5 (95% CI 2.6-4.3) D, p < .001] and PLK [H: 3.2 (95% CI 2.2-4.1) D, p < .001, V: 2.8 (95% CI 2.0-3.6) D, p < .001, Spherical: 3.0 (95% CI 2.2-3.8) D, p < .001] were significantly increased from presurgical (VISCO) values. No difference between presurgical (VISCO) and postsurgical values were identified for the DLEK. Postoperative OCT revealed space between anterior and posterior corneal grafts and corneal undulation associated with suture placement.

CONCLUSION

Meridional and spherical refraction had a hyperopic shift following CCT and PLK, with a significantly higher value in the vertical meridian for the CCT. Pre- and postoperative refraction was not significantly different for the DLEK. This supports that the DLEK has a lesser effect on immediate postoperative refraction compared with CCT or PLK.

Effects of commercial amniotic membrane extract on the re-epithelialization time and the early expression of matrix metalloproteinase-9 in cats with experimentally induced corneal ulcers

OBJECTIVES

To investigate whether a commercially available amniotic membrane extract (AME) can accelerate corneal wound healing and suppress the early expression of MMP-9 in the tears of cats with experimentally induced superficial ulcerative keratitis.

PROCEDURES

A total number of 16 cats were included. At the end of keratectomy, cats in the treatment group (TG, n = 8) received 40 μl of AME (EyeQ® Amniotic Eye Drops, Vetrix®) four times daily, while cats in the control group (CG, n = 8) received 40 μl of saline at the same time points. Tears were collected 24 and 48 h after keratectomy, and the total MMP-9 was quantified by ELISA.

RESULTS

The corneal re-epithelialization rate did not differ between groups (p = .26), being 0.48 ± 0.05 mm² /h in the CG and 0.41 ± 0.03 mm² /h in the TG. Similarly, the average time to achieve corneal wound healing did not differ between groups (p = .25) and was 61.50 ± 3.54 h in the CG and 70.50 ± 6.71 h in the TG. The dimensions of the ulcerated areas also did not differ at any time point between the groups (p > .05). In both groups, corneas healed without scarring, pigmentation, or vascularization. The expression of MMP-9 in the tears was similar in both groups at 24 h post-keratectomy, with a slight decrease at 48 h (p > .05).

CONCLUSIONS

The instillation of a commercial AME (EyeQ®) is safe, but it did not decrease the corneal re-epithelialization time or the early expression of MMP-9 in the tears of cats with experimentally induced superficial ulcerative keratitis in this study.

An eye on the Shih Tzu dog: Ophthalmic examination findings and ocular surface diagnostics

OBJECTIVE

To characterize the ocular surface parameters and determine the prevalence of ocular pathology in Shih Tzu dogs.

ANIMAL STUDIED

Fifty Shih Tzu dogs (28 male, 22 female).

PROCEDURES

Each dog underwent a complete ophthalmic examination (recording any pathology) and a series of diagnostics, allowing for a 10 min-interval between tests: intraocular pressure (IOP), blink rate, palpebral fissure length (PFL), corneal tactile sensation (CTS), Schirmer tear test, and nasolacrimal reflex without (STT-1, NL-STT1) and with topical anesthesia (STT-2, NL-STT2), tear ferning, strip meniscometry test (SMT), tear film breakup time (TFBUT), and punctate fluorescein staining (PFS) of the cornea.

RESULTS

Mean ± SD test values were as follows: IOP (17.9 ± 3.7 mmHg), blink rate (2.4 ± 1.4 blinks/min), PFL (23.8 ± 1.8 mm), CTS (1.8 ± 0.7 cm), STT-1 (22.0 ± 5.5 mm/min), NL-STT1 (24.2 ± 4.7 mm/min), STT-2 (16.9 ± 6.5 mm/min), NL-STT2 (18.5 ± 7.5 mm/min), SMT (7.5 ± 3.5 mm/5 s), TFBUT (5.3 ± 2.4 s), tear ferning (1.3 ± 0.7), and PFS (1.6 ± 0.6). PFL was significantly greater in male vs. female Shih Tzus (p< .001). Age was negatively correlated with TFBUT results (r = -0.31, p = .027). Lagophthalmos was observed in 82% eyes. Ocular surface pathology was common, including adnexal abnormalities (100% eyes with caruncular trichiasis and medial lower lid entropion) and corneal opacification (27% pigmentation, 20% fibrosis, 12% neovascularization).

CONCLUSIONS

Qualitative tear film deficiency (low TFBUT), along with several anatomical abnormalities that promote ocular irritation and reduce globe protection, together help explain the concerningly high prevalence of ocular surface disease in the Shih Tzu breed. Prophylactic measures (e.g., medial canthoplasty, topical lubrication) could be considered to improve ocular health in Shih Tzus.

The use of acellular porcine corneal stroma xenograft (BioCorneaVet™ ) for the treatment of deep stromal and full thickness corneal defects: A retrospective study of 40 cases (2019-2021)

OBJECTIVE

To document the effectiveness and outcome of corneal grafting using acellular porcine corneal stroma (APCS) for veterinary use (BioCorneaVet^™ ) to restore corneal integrity in dogs.

METHODS

A review of medical records of patients that underwent keratoplasty with APCS graft to repair deep corneal defects, descemetoceles, and perforations between 2019 and 2021 was carried out. Only animals with intact dazzle reflex, consensual PLR before the surgery and a minimum follow-up of four weeks were considered for the study, with forty dogs (1 eye each) meeting the inclusion criteria.

RESULTS

Brachycephalic breeds were the most frequently represented, and 20 right eyes and 20 left eyes were affected with 25 perforations, 8 descemetoceles, and 9 deep stromal defects (1 eye had both perforation and descemetocele). Most of the patients had concurrent ocular diseases or had undergone previous surgery on the other eye. Two different thickness of xenograft was used (300 or 450 µm), and the diameter ranged from 3 to 10 mm. Postoperative complications included mild to severe corneal vascularization, partial dehiscence, melting, and glaucoma. Follow-up time ranged from 28 to 797 days (mean: 233 days). Ocular integrity was maintained in 37/40 cases (92.5%), and vision was preserved in 36 cases (90%).

CONCLUSION

The use of APCS (BioCorneaVet^™ ) is an effective surgical treatment for deep stromal defects, descemetocele, and perforations in dogs, providing a good tectonic support and preserving anatomical integrity and vision. The cosmetic appearance was considered good in all the cases and continued to improve with time.