Specular microscopy of the different regions of the cornea in enucleated swine eyes: ex vivo evaluation / Microscopia especular das diferentes regiões da córnea de suínos: estudo ex vivo

The objective of this study was to determine the endothelial cell density (ECD) and hexagonality of the cornea in the different regions of healthy swine corneal endothelium using specular microscopy. Twenty-four eyeballs from 12 male, 6-month-old Large White pigs (Sus scrofa domesticus) were studied. Contact specular microscopy was performed in the central, superior, inferior, lateral and medial regions. The corneal parameters analysed in this study were ECD and hexagonality. The ECD in the central region was 1865 cells/mm2; in the upper region, it was 1877 cells/mm2, in the lower region, it was 1854 cells/mm2, in the lateral region, it was 1847 cells/mm2, in the medial region, it was 1831 cells/mm2. Hexagonality in the central region, was 53%; in the upper region, it was 54%, in the lower region, it was 54%, in the lateral region, it was 54%, in the medial region, it was 54%. There was no significant difference regarding to the evaluated parameters in all corneal regions evaluated. No statistically significantly differences were observed in ECD and hexagonality between the left and the right eyes. This study demonstrates that ECD and hexagonality of the central cornea area represent the entire endothelial mosaic.

O objetivo do presente estudo foi avaliar a densidade endotelial e a hexagonalidade das células endoteliais nas diferentes regiões da córnea de suínos utilizando a microscopia especular de contato. Foram estudados 24 bulbos oculares de 12 suínos (Sus scrofa domesticus), machos, com seis meses de idade e da raça Large White. A microscopia especular de contato foi realizada nas regiões central, superior, inferior, lateral e medial da córnea. A densidade endotelial média na região central foi de 1865 células/mm2, na região superior foi de 1877 células/mm2, na região inferior foi de 1854 células/mm2, na região lateral foi de 1847 células/mm2 e na região medial foi de 1831 células/mm2. Na região central, a hexagonalidade foi de 53%, na região superior foi de 54%, na região inferior foi de 54%, na região lateral foi de 54%, na região medial foi de 54%. Não foram observadas diferenças significativas na densidade celular e na hexagonalidade nas diferentes regiões da córnea analisadas. Este estudo demonstrou que a densidade endotelial e a hexagonalidade da área central da córnea representam todo o mosaico endotelial.

Uso de soro autólogo no tratamento de úlcera ocular em cães: uma revisão bibliográfica / Use of autologus serum in the treatment of ocular ulcers in dogs: a bibliographic review / Uso de suero autólogo em el tratamiento de úlceras oculares em perro: una revisión bibliográfica

Sendo considerada uma doença de alto acometimento na oftalmologia veterinária de cães, a úlcera de córnea é um distúrbio caracterizado por uma ferida exposta na região corneal do olho. Os sinais são variados conforme o grau de agressividade da lesão, acarretando em perda da visão caso a intervenção não seja iniciada imediatamente. Devido a estes fatores e ao elevado nível de importância da doença, torna-se necessário o uso de terapêuticas que auxiliem o processo de reparo ocular, como a utilização do soro autólogo. Essa substância realiza uma função de evitar degradação da córnea e diminuir os sinais inflamatórios, o que torna essa prática um apoio eficaz para a finalização do tratamento, além de ser barato e de fácil acesso. Levando essas informações em consideração, o presente artigo realiza uma revisão com base em publicações apresentando o soro autólogo como um elemento adicional para o paciente poder concluir o tratamento de úlcera de córnea em menor tempo e com maior qualidade, retomando-o ao seu estado saudável.(AU)

Being considered a disease of high involvement in the veterinary ophthalmology of dogs, the corneal ulcer is a disorder characterized by an exposed wound in the corneal region of the eye. The signs vary according to the degree of aggressiveness of the lesion, leading to loss of vision if intervention is not started immediately. Due to these factors and the high level of importance of the disease, it becomes necessary to use therapies that help in the process of ocular repair, such as the use of autologous serum. This substance performs a function of preventing corneal degradation and reducing inflammatory signs, which makes this practice an effective support for the completion of treatment, besides being cheap and easily accessible. Taking this information into consideration, the present article performs a review based on publications presenting the autologous serum as an additional element for the patient to finish the corneal ulcer treatment in less time and with higher quality, returning him to his healthy state.(AU)

Siendo considerada una enfermedad de alto ataque en la oftalmología veterinaria de perros, la úlcera de córnea es una alteración caracterizada por una herida expuesta en la región corneal del ojo. Los signos son variados según el grado de agresividad de la lesión, acarreando en pérdida de la visión en caso de que la intervención no sea iniciada inmediatamente. Debido a estos factores y al alto nivel de importancia de la enfermedad, es necesario utilizar terapias que ayuden al proceso de reparación ocular, como el uso de suero autólogo. Esta sustancia cumple una función de evitar la degradación corneal y disminuir los signos inflamatorios, lo que hace de esta práctica un apoyo eficaz para el final del tratamiento, además de ser barata y de fácil acceso. Teniendo en cuenta esta información, el presente artículo realiza una revisión basada en publicaciones que presentan el suero autólogo como un elemento adicional para que el paciente finalice el tratamiento de la úlcera corneal en menor tiempo y con mayor calidad, devolviéndolo a su estado saludable.(AU)

Evaluation of the corneal epithelium of rabbits treated with preservative-free eye drops containing ketorolac tromethamine or diclofenac sodium / Avaliação dos colírios cetorolaco de trometamina e diclofenaco sódico sem conservantes no epitélio da córnea de coelhos

This study aimed to evaluate the corneal epitheliotoxic effects of preservative-free ketorolac tromethamine 0.5% and diclofenac sodium 0.1% eye drops in rabbits. Seventeen New Zealand rabbits were randomly divided into three groups: the 0.5% ketorolac tromethamine group, the 0.1% diclofenac sodium group, and the control group (0.9% NaCl). For each rabbit, both eyes were treated three times daily according to their treatment group. The corneal epithelia were analyzed using scanning electron microscopy to observe the number of light, grey, and dark cells; the number of epithelial holes; and the loss of hexagonal shape. Both of the formulations administered caused changes in the healthy corneal epithelia of rabbits. Except for number of epithelial holes (p < 0.05), all the parameters showed a statistically significant difference between the groups. The number of dark cells was highest in the ketorolac tromethamine group (p<0.05). The number of grey cells was higher in the diclofenac sodium group than in the control group (p =0.003). A higher number of dark cells was associated with a smaller number of light cells (r =-0.577, p < 0.001). Loss of shape showed a direct correlation with the number of dark cells (r=0.524, p=0.002). Based on the results presented, it was possible to conclude that ketorolac tromethamine 0.5% was more toxic to rabbit corneal epithelium than diclofenac sodium 0.1%.

Objetivou-se avaliar os efeitos do cetorolaco de trometamina a 0,5% e do diclofenaco de sódico a 0,1% sem conservantes na córnea de coelhos. Dezessete coelhos da raça Nova Zelândia foram aleatoriamente divididos em três grupos: o grupo de 0,5% de cetorolaco de trometamina, o grupo de 0,1% de diclofenaco sódico e o grupo controle (0,9% de NaCl). Para cada coelho, os dois olhos foram tratados três vezes ao dia durante 90 dias de acordo com o grupo de tratamento. Os epitélios da córnea foram analisados usando microscopia eletrônica de varredura para observar o número de células claras, cinzas e escuras, o número de criptas e a perda do formato celular hexagonal. Ambas as formulações administradas causaram alterações no epitélio da córnea de coelhos. Com exceção da contagem de criptas (p <0,05), todos os parâmetros apresentaram diferença estatisticamente significante entre os grupos. O número de células escuras foi maior no grupo cetorolaco de trometamina (p <0,05). O número de células cinzentas foi maior no grupo diclofenaco de sódio do que no grupo controle (p=0,003). O maior número de células escuras observado foi associado ao menor número de células claras (r=-0,577, p<0,001). A perda do formato celular mostrou uma correlação direta com o número de células escuras (r=0,524, p=0,002). O cetorolaco de trometamina 0,5% foi mais tóxico para o epitélio da córnea de coelhos do que o diclofenaco de sódio a 0,1%.

Úlcera de córnea em bugio-ruivo (Alouatta guariba clamitans) - tratamento com soro heterólogo / Corneal ulcer in a Southern brown howler monkey (Alouatta guariba clamitans) - treatment with heterologous serum

Background: In the routine care of non-human primates, ocular trauma is frequent, however, unlike the small animal clinic, the prevalence of corneal ulcers is not documented. Among the numerous therapeutic options available in dogs, blood serum is being increasingly used as an adjuvant treatment in these conditions, due to its tear-like properties. Based on this, the present study aims to describe a case of corneal ulcer in a southern brown howler monkey (Alouatta guariba clamitans) attacked by a porcupine, and the use of heterologous serum obtained from an equine as an adjuvant treatment. Case: A southern brown howler monkey (Alouatta guariba clamitans), which had been attacked by porcupine quills, was treated at a University Veterinary Hospital. During the clinical examination, the presence of blepharospasm and secretion in the right eye was noticed. The ophthalmological examination, through the fluorescein test, detected the presence of an extensive superficial corneal ulcer in the right eye. After removing the spines, the corneal ulcer was treated with tobramycin-based eye drops, 1% atropine sulfate eye drops, and serum from equine blood in the form of eye drops, as an adjuvant therapy. After 5 days of treatment, the fluorescein test was repeated, which was negative in both eyes due to complete healing of the lesion, and thus the treatment was concluded. Discussion: The scarcity of scientific literature on wild animals is one of the factors responsible for the difficulty in advancing clinical and surgical procedures in non-human primates. Corneal ulcers are characterized by the loss of corneal epithelium with exposure of the stroma. The main clinical treatments adopted include antimicrobial therapy, analgesics, lubricating agents, and antiprotease drugs. Widely used as an adjuvant therapy in corneal ulcers in small animals, blood serum presents some advantages, as it is rich in growth factors, vitamins, immunoglobulins, and anti-collagenolytic substances, in addition to being obtained for a low cost. Considering the aforementioned, in the case reported, it was decided to use blood serum obtained from an equine as an adjuvant treatment of the corneal ulcer in a southern brown howler monkey. Complete healing of the corneal ulcer was confirmed in just five days, contributing to the well-being of this animal and contributing to the evolution of ophthalmology in this species that is still poorly studied.

Carcinoma de células escamosas corneal em um cão - uso da Mitomicina C 0, 02% como adjuvante no tratamento / Corneal squamous cell carcinoma in a dog - use of Mitomycin C 0. 02% as an adjuvant therapy

Background: Although Squamous Cell Carcinoma (SCC) is most commonly seen in the epidermis, this malignant neoplasm can manifest in various other tissues. A wide range of factors may be related to the development of SCC in the cornea, with continuous exposure to ultraviolet radiation and chronic friction to the ocular surface being the most accepted theories. In addition to surgical procedures, the use of mitomycin C in the topical treatment of corneal SCC has shown good results in therapeutic management. Thus, the objective of the current work is to report the satisfactory response observed in the use of mitomycin C in a case of SCC in the cornea of a dog. Case: A 9-year-old male Pug dog was attended by the Veterinary Ophthalmology and Microsurgery Sector (SOMVET) of the University Veterinary Hospital (HVU) of the Federal University of Santa Maria (UFSM) with Squamous Cell Carcinoma (SCC) in the cornea of the left eye, which had recurred after a previous surgical intervention. Secretion and discomfort in the left eye were noted during clinical examination. In addition, both eyes presented pigmentary keratitis in the medial corner. Surgical excision of the neoplasm was performed using the surgical technique of anterior lamellar keratectomy. In the immediate postoperative period, topical therapy was started with eye drops based on mitomycin C at 0.02%, for a period of 28 consecutive days. The use of this chemotherapy drug in the topical form was intended to minimize the chances of recurrence of the clinical condition, since the patient is predisposed to this alteration. In addition, supportive therapy was implemented to improve patient comfort, consisting of the use of tobramycin-based eye drops (6 times a day, for 14 days), atropine 1% eye drops (BID, for 3 days), lubricating eye drops based on sodium hyaluronate (3 times a day, for continuous use), and immunomodulatory eye drops based on tacrolimus 0.02% (twice a day, for continuous use). The patient was evaluated 7, 14, 21, and 28 days after surgery, when good results were observed. One year after treatment, the dog was still showing no signs of recurrence of the treated clinical condition. Discussion: It is known that chronic friction on the surface of the cornea predisposes to the diagnosis of corneal SCC. Accordingly, in the clinical examination of the patient in this report, the presence of bilateral pigmentary keratitis was observed, an alteration that leads to a framework of chronic aggression to the cornea. Surgical treatment is recommended to remove the tumor mass in the ocular region. However, in cases of corneal SCC, the literature highlights that recurrence after surgical excision is a common factor. As the patient in this study arrived at the clinic with a history of recurrence, topical therapy with mitomycin C associated with surgical treatment was instituted. This chemotherapy drug has shown encouraging results in the treatment of some neoplasms, especially SCC. Its use in this case supported previous findings, pointing to a satisfactory result in which the patient had no recurrences after one year of follow-up. In addition, the concentration and frequency used of the active ingredient did not lead to adverse effects in the short or medium term.

Induced corneal ulcers in cats - effects of 2% dorzolamide on epithelization time and on the expression of matrix metalloproteinase-9

Background: Topically administered 2% dorzolamide is among the most commonly used agents to lower IOP. As a complication of glaucoma, blind patients may develop corneal ulcers secondary to trauma. Nonetheless, in patients with a hypertensive or glaucomatous eye, in which the cornea has also been ulcerated, medical hypotensive therapy should not be discontinued. Therefore, the present study aimed to determine whether the instillation of a benzalkonium chloride (BAK)-preserved 2% dorzolamide alters corneal wound healing time and the levels of matrix metalloproteinases (MMP-9) in the tears of cats with experimentally induced corneal ulcers. Materials, Methods & Results: Sixteen cats (8/group) were randomly assigned to receive 40 µL of 2% dorzolamide (TG) or saline (CG) 3 times daily until corneal re-epithelialization. Experimental keratectomies were performed under general and topical anesthesia using an operating microscope. For this purpose, a millimitred trephine was calibrated and used to create a temporal paraxial corneal ulcer with a diameter of 6 mm and a depth of 200 µm. After corneal wounding, the ulcerated area, the healing time, blepharospasm, conjunctival hyperemia, and aqueous flare were compared between groups. Tears were collected at baseline and 24 and 48 h after keratectomy, and the total MMP-9 was quantified by ELISA. Data were assessed statistically using unpaired Student's t test, one-way, and two-way ANOVA followed by a Bonferroni post hoc test. Statistical significance was set at P < 0.05 for all analyses. The average time to achieve corneal wound healing did not differ between groups (P = 0.36) and was 65.50 ± 3.62 h in the CG and 71.00 ± 4.58 h in the TG. Twenty-four h after keratectomy, the ulcerated area in the CG was 3.34 mm2 larger than that observed in the TG (P = 0.04); the rest of the comparisons did not reach statistical significance at any time point between groups (P > 0.05). Higher blepharospasm scores were observed in cats of TG (P = 0.04). When compared with baseline of both groups, the levels of MMP-9 increased significantly at 24 and 48 h post-keratectomy (P < 0.001), but differences between groups were not observed at 24 and 48 h post-keratectomy (P > 0.05). Discussion: In cats, 9 mm axial corneal ulcers created by superficial debridement re-epithelize approximately 48 h postwounding. In the present study, re-epithelialization post keratectomy occurred within an average time of 68.25 h in most cats and in a delayed manner in one cat of the TG after 96 h. In the current study, the lesions in both groups healed without corneal scarring, pigmentation, or vascularization. Although BAC was present in all topical medications used in the present study, the authors attribute the higher scores of blepharospasm in the TG to the rheological characteristics and the pH of the dorzolamide ophthalmic solution. Indeed, the pH value of dorzolamide (5.58) may cause signs of irritation, as the tear film has an approximate pH of 7.6. Previous studies showed that ulcerated corneas presented significantly higher levels of MMP-9 in tears at the early stages (8 to 36 h) post-wounding. In the current study, the levels of this enzyme after wounding did not change significantly in the tears of cats treated with 2% dorzolamide when compared to the eyes in the control group. This study showed that the instillation of a BAC-preserved 2% dorzolamide ophthalmic solution did not impair the corneal wound healing time or the early expression of MMP-9 in the tears of cats with experimentally induced corneal ulcers. However, our results warrant further investigation in patients with ocular hypertension or glaucoma presenting concomitant naturally occurring corneal ulcers to certify our findings.

Dry-eye syndrome in Shih Tzu dog: Ocular surface clinical and morphological aspects in the different stages of keratoconjunctivitis sicca / Síndrome do olho seco em Shih Tzu: aspectos clínicos e morfológicos da superfície ocular nas diferentes fases da ceratoconjuntivite seca

ABSTRACT: This study analyzed clinical and cyto-histomorphological parameters of the ocular surface of Shih Tzu dogs, non-carriers and carriers of quantitative keratoconjunctivitis sicca (KCS) at different stages. Thirty-five eyes from 23 male and female Shih Tzu dogs between two and eight years were evaluated in four groups: control group (CG - without KCS), mild KCS group (KCS1), moderate KCS group (KCS2), and severe KCS group (KCS3). Most clinical variables among KCS carrier groups worsened at the more advanced stages of the disease, with a negative correlation between the Schirmer tear test (STT-1) and tear film break-up time (TBUT). Squamous metaplasia, lymphoplasmacytic inflammatory infiltrate, and decrease in conjunctival goblet cells on histopathological examination comprised disease severity parameters. Quantitative KCS non-carried Shih Tzu dogs have qualitative and tear film distribution changes. The cytomorphological exam is limited to evaluating the inflammatory infiltrate and quantifying conjunctival goblet cells. However, intermediate epithelial cells were higher in healthy eyes compared to eyes with KCS in Shih Tzu dogs. Also, moderate and severe KCS carrier Shih Tzu dogs have qualitative dysfunction of the tear film. KCS in Shih Tzu dogs is common and chronic and may be responsible for the loss of vision of these animals. Early identification of the disease and routine evaluation can improve these dogs' quality of life and ocular health.

RESUMO: Este estudo analizou os parâmetros clinicos e cito-histomorfológicos da superfície ocular de cães da raça Shih Tzu, portadores e não portadores de ceratoconjuntivite seca quantitative (CCS) em diferentes estágios. Trinta e cinco olhos de 23 cães da raça Shih Tzu, machos e fêmeas, entre as idades de dois e oito anos foram avaliados em quatro grupos: grupo controle (GC - sem CCS), grupo CCS inicial (CCS1), grupo CCS moderada (CCS2) e grupo CCS severa (CCS3). A maioria das variáveis clínicas dentro os grupos portadores de CCS pioraram a medida que os estágios da doença avançam, com correlações negativas entre o teste lacrimal de Schirmer (TLS) e o tempo de ruptura do filme lacrimal (TRFL). Metaplasia escamosa, infiltrado inflamatório linfoplasmocítico e diminuição das células caliciformes no exame histopatológico compreenderam parâmetros de severidade da doença. Cães Shih Tzu não portadores de CCS quantitativa tem alterações qualitativas e na distribuição do filme lacrimal. O exame citomorfológico é limitado para a avaliação do infiltrado inflamatório e quantificação de células caliciformes. Entretanto, células inermediárias epiteliais são mais presents nos olhos saudáveis quando comparados aos olhos portadores de CCS em Shih Tzus. Também, Shih Tzus portadores de CCS nos estágios moderados e severos possuem disfunções qualitativas da lágrima. A CCS em Shih Tzu é comum, crônica e pode ser responsável pela perda de visão dos animais. A identificação precoce da doença e avaliações rotineiras podem aumentar a qualidade de vida e a saúde ocular nesses cães.

Hydrodissection in the construction of conjunctival flaps in dogs

Background: Hydrodissection is a minimally invasive procedure that consists of injecting fluid into an anatomical space to facilitate dissection during surgery. Although this procedure is employed in several areas of veterinary medicine, including ophthalmology, there are no reports of the use of this maneuver in conjunctival procedures in dogs. The use of this technique can facilitate the construction of conjunctival pedicle flaps, thereby improving the results. The purpose of this work was to evaluate the use of hydrodissection in the construction of conjunctival pedicle flaps in dogs. Materials, Methods & Results: The sample consisted of 20 eyes from 10 healthy dogs that had been subjected to elective surgical procedures of ovariohysterectomy and orchiectomy. The dogs were divided into 2 groups; the 1st group of 10 eyes underwent hydrodissection and the 2nd group of 10 eyes did not. All the patients underwent a complete ophthalmic examination and assessment of their systemic conditions. The patients were then anesthetized and the procedures were performed under a surgical microscope. In the group subjected to hydrodissection, the conjunctival flap was prepared by means of a previous subconjunctival injection of 0.7 mL of 0.9% sodium chloride, followed by preparation of the flap. In the group without hydrodissection, the flap was prepared by means of conventional divulsion using iris scissors. After producing the conjunctival flaps, a conjunctival fragment was collected from both groups for histological analysis and evaluation of the presence of the Tenon capsule. The operating time, degree of hemorrhage and ease of handling the conjunctiva in the intraoperative period were evaluated. Postoperative evaluations were performed at 1, 7 and 14 days after surgery and included: blepharospasm, conjunctival hyperemia and edema, which were classified as absent, mild, moderate or severe; tear production was evaluated using the Schirmer test, and the appearance of the conjunctival scar was assessed based on photographs taken in the postoperative period, and by a visual analogue scale, with healing classified as fair, good or excellent. The 2 groups showed no statistical difference in terms of operating time, bleeding, ease of handling and conjunctival divulsion. A volume of 0.48 ± 0.12 mL of 0.9% sodium chloride was administered to the conjunctiva. Postoperative assessments of hyperemia, blepharospasm, conjunctival edema, and tear production also did not differ statistically. Conjunctival scarring was considered optimal until the 14th postoperative day, with no statistically significant difference between the 2 groups. These results demonstrate that both maneuvers are effective in creating conjunctival flaps. The Tenon capsule could not be identified in histological stains. Discussion: The literature offers numerous descriptions of the use of hydrodissection in surgical procedures in humans in order to facilitate dissection and reduce surgical duration and handling, thereby improving the clinical recovery of patients. Conversely, this technique has not been described frequently in veterinary medicine, notably with respect to conjunctival procedures. In this study, we demonstrated that conjunctival hydrodissection was perfectly feasible, contributing to the divulsion and preparation of conjunctival flaps, thus proving to be a viable option for this type of procedure. The absence of the Tenon capsule in the evaluated samples demonstrates that, in both groups, the techniques were effective in separating them from the conjunctiva. It was therefore concluded that the hydrodissection technique is a feasible maneuver in the construction of conjunctival flaps, providing a new option for surgeons, especially for novice ophthalmologists.

Retinopatia deficiente de taurina em uma gata / Taurine deficiency retinopathy in a cat

Background: Taurine is an essential amino acid for cats and its deficiency causes an ocular disorder called taurine deficiency retinopathy. The retinal lesion is definitive and can be classified into five progression stages. In an advanced stage, it leads to blindness that in most cases is irreversible. This disease is considered rare as taurine is currently supplemented in commercial cat food. The objective of this report is to describe the ophthalmic changes in a cat with advanced taurine deficiency retinopathy, a rare but current disease that is important for differential diagnosis of blindness in cats. Case: We report the case of an adult mixed-breed cat (weighing 3.4 kg), that was attended by the Ophthalmology Service of the College of Veterinary Medicine and Animal Science (UNESP - Botucatu), which was treated due to complaints of poor visual acuity for about 1 year. The animal, which was previously a stray animal, had been adopted for 2 years and provided premium cat food ad libitum. Ophthalmic examination showed bilateral mydriasis, with negative menace, direct pupillary, and consensual light reflexes. No change was observed in the ocular appendages, cornea, anterior chamber, lens, and vitreous humor. The eyes were normotensive and fluorescein test negative. Direct and indirect fundoscopy revealed an area of ellipsoidal hyperreflexia with darkened margins laterally to the optic nerve disk in the tapetal region and intense retinal vascular attenuation in both eyes, with a diagnosis of taurine deficiency retinopathy. Complete blood count and biochemical analysis parameters were within the normal range, including the leukocyte count. The guardian was instructed to continue feeding the cat balanced cat food and received information on the proper care and management of a blind animal. Discussion: Although taurine deficient retinopathy is currently underdiagnosed due to the supplementation of this amino acid in commercial cat food, animals that are not properly fed, such as those receiving dog food or homemade food, may be deficient in this amino acid. Taurine deficiency and in this case, the consequent taurine deficiency retinopathy, was diagnosed by visualizing the lesion characteristic of this amino acid deficit since no other retinal change presents this aspect in cats. Therefore, this lesion is considered pathognomonic of this deficiency. Hyperreflective retinal lesions with darkened margins indicate the slow chronic progression in the already stabilized lesions. The animal in this report presented pigmented lesion margins, indicating the chronicity of these retinal changes. Moreover, lesion signs are visible on fundoscopy only after a period of 2-11 months of nutritional amino acid deficiency, and complete retinal atrophy usually occurs after at least nine months of taurine deficiency. Thus, complete blindness associated with advanced retinal changes reinforced the suspicion that the animal had taurine deficiency for a prolonged period of time prior to its adoption. Its guardian was instructed to provide balanced commercial cat food, because although retinal lesions are irreversible, cardiac changes resulting from taurine deficiency are reversed with dietary supplementation. In addition, taurine deficiency affects other organs and systems, such as the central nervous, immune, and reproductive systems. In conclusion, although taurine deficiency retinopathy is currently rare, this condition should be considered one of the possible differential diagnoses for blindness in feline patients.

Persistência do vítreo primário hiperplásico e catarata em cão / Persistence of hyperplastic primary vitreous and cataract in a dog

Background: Persistent hyperplastic primary vitreous is a rare ocular condition that is usually unilateral, formed when normal regression of the hyaloid vascular system does not occur. Diagnosis is possible through ultrasonography, by obtaining images that provide information and also serve as a differential diagnosis. Clinically the condition presents with signs of leukocoria, microphthalmia, and cataracts, and it can be further classified into 6 degrees according to the evolution. The objective of this work is to describe the case and treatment of a canine of the Pointer breed that presented opacity in both eyes, with diagnosis confirmed through ocular ultrasonography. Case: A 6-year-old male pointer dog, weighing 27 kg, was referred to the Veterinary Medical Teaching Hospital of the Federal University of Santa Maria (UFRGS), Santa Maria, RS - Brazil with a history of blindness. According to the owner, the animal's right eye has always been "white", since it was a puppy and the left eye began to present the same characteristic a short time ago. On ophthalmological examination, neither eye showed signs of ocular discomfort, the Schirmer's tear test was within the range expected for the species, fluorescein and threat tests were negative, and a positive pupillary reflex was observed in the left eye. The right eye had total corneal opacity associated with a chronic lesion and the presence of pigment cells in the medial portion of the eyeball, the opacity making it impossible to visualize the other internal structures of the eyeball. The left eye presented lens opacity. In the ultrasound of the right eye, there were several alterations, the presence of a triangular-shaped hyperechogenic structure in the vitreous chamber, a decrease in the depth of the anterior chamber, and the presence of abnormality in the development of the lens. The findings are compatible with and confirmed the diagnosis of PHPV. In the left eye, the ultrasound images indicated hyperechogenicity of the posterior and anterior poles of the lens, findings compatible with cataracts. Through the animal's history, complete ophthalmic examination, and use of ocular ultrasonography, it was possible to diagnose and differentiate the causes of the white eye in the patient. The preoperative screening was continued with an electroretinography examination, which showed a satisfactory electrical response for the retina of the left eye and an unsatisfactory electrical response for the retina of the right eye. Phacoemulsification surgery was performed to remove the cataract in the left eye with intraocular lens implantation. The positive threat reflex returned in this eye, with a return of visual acuity. Discussion: Persistent hyperplastic tunica lentis and persistent hyperplastic primary vitreous (PHTVL/PHPV) are congenital anomalies caused by a failure to regress the fetal hyaloid vasculature. These conditions are not common, but occur sporadically in dogs. The PHPV classification can be classified into degrees, based on the morphological aspect of the lesion. Following this classification scheme, the PHPV of the animal in question refers to the 6th degree of evolution. The total opacity of the cornea in the right eye was associated with the presence of a hyperplastic primary vitreous and the leukocoria in the left eye was due to the presence of a mature cataract. The conclusion of the diagnosis was only possible through ocular ultrasonography, which is very useful to differentiate the causes of ocular opacity and leukocoria, in addition to allowing complete evaluation of the intraocular structures and being considered an essential exam to confirm the diagnosis of PHPV.

Pólipo fibroepitelial atípico em córnea de um cão Lhasa Apso / Atypical fibroepithelial polyp in the cornea of a Lhasa Apso dog

Background: Fibroepithelial polyps are benign tumors of mesenchymal and ectodermal origin. Regarding the localization related to the cutaneous region, they may affect the eyelid and periocular area. In veterinary medicine, polyps located in the urethra of dogs and monkeys, vagina of bitches and on the skin have been described. Fibroepithelial polyps may present as single to multiple nodules, exophytic to pedunculated, usually arising on a smooth surface of a common base. The aim of this paper is to describe the ocular and histopathological changes of a corneal fibroepithelial polyp of recurrent character in a dog. Case: A 20-year-old Lhasa Apso dog, with a history of progressive corneal neoformation in the right eye for 4 months. Patient was submitted to routine ophthalmic evaluation. At biomicroscopy, a discrete mucopurulent discharge was observed in the nasal corner, a nodule in the lower eyelid (± 3 mm), moderate conjunctival hyperemia, vascularization and corneal edema between 12 and 5 h, presence of a pinkish proliferative mass in 3 h, affecting the anterior stroma and opacity of the lens, Schirmer's Tear Test (STT) 20 mm/min and intraocular pressure (IOP) 10 mm/Hg. In the left eye, the STT and IOP were within normal range (17 mm/min and 11 mg/Hg, respectively) and at biomicroscopy only lens opacity was observed. Given the presence of the neoformation in the cornea, the patient underwent lamellar keratectomy to excise the mass and third eyelid flap. The tissue was then submitted to histopathology. The histopathological examination showed a proliferation of fibrous component with areas presenting reactive fibroblasts, with acidophilic cytoplasm and with little volume and slight neovascularization, presence of hyperplasia of the lining epithelium and cells with round to oval nuclei, with inconspicuous nucleoli, compatible with fibroepithelial polyp, without evidence of malignancy. After 18 months, the patient presented recurrence of the condition with a history of slow evolution (about ten months). The ophthalmic evaluation showed lesions very similar to the initial one, describing a recurrence of the lesion. Discussion: Corneal neoplasms are uncommon in dogs. The clinical findings in patients with ocular neoplasms include irregular to nodular masses, gray to reddish in color, and typically associated with a vascular supply. These features are related to the type of tumor and its degree of evolution. There are reports in the literature of ocular neoplasms such as squamous cell carcinoma, papilloma, melanocytoma, fibrosarcoma, hemangiosarcoma, melanoma, lymphoma. Related to fibroepithelial polyp with ocular involvement, there are rare reports in human literature and none in veterinary medicine. There is a human description of the presence of a polyp affecting the cornea associated with a corneal dermoid and e other cases of polyps of conjunctival origin. As far as treatment is concerned, the polyp should be surgically removed because of the possibility of recurrence, tissue metaplasia, or even transformation into a malignant tumor, as seen in the case reported here, in which even with surgical removal there was recurrence and metaplasia of the cells. Based on the histopathological findings, it can be concluded that this is a fibroepithelial polyp with a recidivating characteristic, not well described in the veterinary literature, with an atypical presentation affecting the cornea.

Abscesso estromal em córnea de cão / Corneal stromal abscess in a dog

Background: The eye is an important sense organ responsible for sight. The cornea is the outermost of many eye layers,being predisposed to several lesions, some of them being frequent in small animal clinics meanwhile others are unusualand seldom reported in specialized literature. The stroma abscess is a common condition in horses, but atypical in dogs,it’s a condition in which a microperforation in the corneal epithelium allows microorganisms or a foreign body to penetratethe corneal stroma, and those become inside the cornea after a re-epithelialization, producing an intense inflammatoryresponse. Therefore, this case reports a case of deep stromal abscess in a Shih Tzu dog.Case: A 4-year-old female Shih Tzu, weighing 4.6 kg, was submitted to ophthalmic examination in which the left eyepresented an opaque yellowish-white protruding structure located on the right side, in the center of the cornea (3 o´clockposition), bulbar and palpebral conjunctival hyperemia and congestion, chemosis, blepharospasm, and a moderate amountof mucous discharge. The clinical diagnosis was stromal abscess with reflex uveitis. A differential diagnosis should includeconditions affecting the anterior part of the cornea, such as an epithelial inclusion cyst and a corneal ulcer. The inclusioncyst, contrarily to the corneal abscess, doesn’t cause pain, meanwhile, the corneal ulcer was ruled out by the FluoresceinStaining Test. The recommended treatment was surgical, through lamellar keratectomy, followed by overlapping pedicledconjunctival graft and third eyelid flap. In association with the surgical treatment, oral antibiotics, anti-inflammatory,and opioids, plus topical antibiotics and autologous serum eye drop. Seventy days post-surgery, the previously observedinflammatory signs were no longer present. In the conjunctival graft insertion site perpetuated a scar leucoma with few...

Abscesso estromal em córnea de cão / Corneal stromal abscess in a dog

Background: The eye is an important sense organ responsible for sight. The cornea is the outermost of many eye layers,being predisposed to several lesions, some of them being frequent in small animal clinics meanwhile others are unusualand seldom reported in specialized literature. The stroma abscess is a common condition in horses, but atypical in dogs,its a condition in which a microperforation in the corneal epithelium allows microorganisms or a foreign body to penetratethe corneal stroma, and those become inside the cornea after a re-epithelialization, producing an intense inflammatoryresponse. Therefore, this case reports a case of deep stromal abscess in a Shih Tzu dog.Case: A 4-year-old female Shih Tzu, weighing 4.6 kg, was submitted to ophthalmic examination in which the left eyepresented an opaque yellowish-white protruding structure located on the right side, in the center of the cornea (3 o´clockposition), bulbar and palpebral conjunctival hyperemia and congestion, chemosis, blepharospasm, and a moderate amountof mucous discharge. The clinical diagnosis was stromal abscess with reflex uveitis. A differential diagnosis should includeconditions affecting the anterior part of the cornea, such as an epithelial inclusion cyst and a corneal ulcer. The inclusioncyst, contrarily to the corneal abscess, doesnt cause pain, meanwhile, the corneal ulcer was ruled out by the FluoresceinStaining Test. The recommended treatment was surgical, through lamellar keratectomy, followed by overlapping pedicledconjunctival graft and third eyelid flap. In association with the surgical treatment, oral antibiotics, anti-inflammatory,and opioids, plus topical antibiotics and autologous serum eye drop. Seventy days post-surgery, the previously observedinflammatory signs were no longer present. In the conjunctival graft insertion site perpetuated a scar leucoma with few...(AU)

Primary corneal hemangiosarcoma in a tapir (Tapirus terrestris)

Background: Hemangiosarcoma is a malignant vascular tumor commonly described in veterinary ophthalmology as emerging at the margin of the third eyelid and bulbar conjunctiva. The primary corneal attachment of the tumor is considered rare, as the cornea is an avascular structure, but there are sparse reports of primary occurrences in the cornea of dogs, cats, and horses. No reports were found in wild animals. The Tapirus terrestris, commonly known as Tapir, is a perissodactyl mammal that inhabits South America regions, being considered the largest terrestrial mammal of Brazil and one of the most popular animals in zoos in various countries. This paper aims to report the first case of primary corneal hemangiosarcoma in a 25-year-old female Tapir (Tapirus terrestris) held in captivity. Case: A 25-year-old Tapirus terrestris female presented an irregular mass in the right cornea, mucopurulent secretion, and inconclusive previous cytological evaluation. It also had a history of a milky cornea for many years, and in the last 12 months, a tissue growth was observed, as well as the occurrence of mucopurulent secretion. The menace response in the right eye was negative. In the ophthalmologic examination, a red-colored, lobed, hemorrhagic, and ulcerated mass occupying approximately 90% of the cornea was observed, and in the peripheral cornea, there was an intense discoloration. Due to the extension of the mass and visual loss, the transpalpebral enucleation was performed under general inhalation anesthesia. The histopathological analysis evidenced a vascular tumor restricted to the central peripheral cornea, composed of blood vessels of small and large caliber, showing polygonal endothelial cells with moderate atypia, anisocytosis, and anisocariasis, in addition to dense stroma and inflammatory cells. The mass occupied the anterior corneal stroma, and there was no involvement of bulbar conjunctiva, sclera, or intraocular structures. The immunohistochemical study revealed the positivity of neoplastic cells for CD31, and the proliferative index of the lesion was evaluated by the Ki-67 as inferior to 10%. Discussion: The histopathologic and immunohistochemical examinations evidenced a hypercellular lesion, and the diagnosis of primary corneal hemangiosarcoma (HSA) was possible due to the significant cellular atypia identified in the lesion. To the authors' knowledge, this is the first case of corneal hemangiosarcoma described in Tapirus terrestris. The HAS is a malignant neoplasm originating in the vascular endothelial cells. There is a significant correlation between the HSA and prolonged exposure to solar radiation. The tapir of this report lived in a high-altitude region with exposure to ultraviolet rays; therefore, it might be an important predisposing factor for the HSA emergence. The chosen treatment for vascular tumors according to the visual prognostic is the lamellar keratectomy; however, the transpalpebral enucleation was the elected treatment since the eye was not visual, the neoplasm had a great extension, the animal was in advanced age and lived in captivity, and it was difficult to handle the animal without sedation to perform adjuvant therapies. Since the mass corresponded to 90% of the cornea, total removal with free edges would not be possible as described in the literature, and, therefore, there was an increased risk of relapse. In the follow-up after 3 years of surgical excision, the animal remained free of metastasis, reinforcing the diagnosis of primary corneal hemangiosarcoma.

Sheep corneal endothelium morphology - evaluation with trypan blue and alizarin red

Background: The endothelium is a layer fundamental to maintaining corneal transparency. In ophthalmology, sheep eyes have been used as a model in research related to corneal transplantation. Different techniques have been used to evaluate the corneal endothelium. Concerning vital dyes, corneal endothelial cell analyses have not yet been studied in ovines. The purpose of the present study was to evaluate the morphology of endothelial cells from different regions of the cornea of sheep after staining with alizarin red and trypan blue using an optical microscope. Materials, Methods & Results: Twenty healthy eyes of 10 male sheep obtained from a licensed commercial slaughterhouse were studied. The study was approved by the Research Committee of the Faculty of Veterinary at UFRGS and followed the ethical standards of the Association for Research in Vision and Ophthalmology (ARVO). Immediately after the slaughter, the eyes were enucleated and underwent eye examination. The corneal endothelium was stained with trypan blue and alizarin red and examined and photographed using an optical microscope. The central, superior, inferior, nasal and temporal areas of the cornea were evaluated for cell morphology. Data were compared by t-tests. Differences were considered statistically significant at P < 0.05. Immediately after staining the corneal endothelium, it was possible to examine with an optical microscope, obtain images and analyse the shape of endothelial cells from all regions of the sheep cornea. Polygonal, uniform and continuous cells were observed in all samples studied. Considering all the corneas analysed, cells with 6 sides (75.11%), 5 sides (12.76%) and 4 sides (12.12%) were found. In the central region of the cornea 75.91% of cells with 6 sides, 12.6% of cells with 5 sides and 11.48% with 7 sides were found. In the superior region of the cornea 76.07% of cells with 6 sides, 13.25% with 5 sides and 10.68% with 7 sides were found. In the lower region were found 74.72% of cells with 6 sides, 13% with 5 sides and 12.27% with 7 sides. In the temporal region, 74.14% were 6-sided cells, 11.42% had 5 sides, and 14.43% had 7 sides. Furthermore, in the nasal region, 74.72% of the cells had 6 sides, 13.54% had 5 sides, and 11.73% had 7 sides. No significant differences were found between cell morphology in all corneal regions evaluated. In addition, no significant difference was found when comparing the right eye with the left eye. Discussion: Different methods are used for the analysis of corneal endothelium. For ex vivo research optical microscopy after endothelial staining is an alternative low-cost technique that allows the analysis of all regions of the cornea. Quantitative analyses must characterise the endothelial parameters of the different species. The analysis of the morphology of corneal endothelium with an optic microscope after staining with alizarin red has been described as an effective, rapid and cost-efficient method, since this dye blends with the borated cells, allowing identification. In the present study, using optical microscopy and coloration with alizarin red it was possible to explore and obtain images of the ovine endothelium of all regions of the cornea. In the current study, the endothelium had a predominance of cells will 6 sides in all regions studied. This study allowed us to obtain images of the endothelium as well as quantitative data on the morphology of the different regions of the sheep cornea. This study demonstrated that morphology did not differ between the central and peripheral regions. The findings of this study represent a further source of reproducible data that should be considered when using sheep cornea as ex vivo model for experimental research.

Cisto de inclusão epitelial corneal em canino / Corneal epithelial inclusion cyst in canine

Este estudo descreve-se o caso de um canino com cisto de inclusão epitelial corneal. Um cão, sem raça definida, macho de 12 anos, foi atendido apresentando uma massa em seu olho esquerdo, a qual apresentava uma evolução de 5 meses sem resposta positiva a diferentes protocolos terapêuticos. O tutor relatou não haver lesão prévia ou trauma, assim como nenhum sinal de desconforto apresentado pelo animal, como epífora ou blefaroespasmo. O exame oftalmológico revelou uma deformação na estrutura corneana, sem sinais de dor. Alterações em outras estruturas oculares não foram observadas. Associado ao exame oftalmológico e ao resultado da citologia, chegou-se ao diagnóstico de cisto corneal e foi feita a excisão completa por meio de uma ceratectomia lamelar. Devido ao fato da massa não ultrapassar a porção média do estroma, o recobrimento da superfície não foi realizado. Dois meses após a cirurgia, o paciente não apresentou qualquer tipo de secreção ocular ou sinais de dor. Além disso, a córnea não continha neovascularização nem sequelas do processo cicatricial, recuperando sua transparência.

This study described the case of a canine with a corneal epithelial inclusion cyst. A twelve-year-old male dog of undefined race was attended presenting a mass on his left eye, which did not respond to any therapeutic protocols for the last five months. The tutor reported that there was no previous injury or trauma, as well as no signs of discomfort presented by the animal, such as epiphora or blepharospasm. The ophthalmological examination revealed a deformity in the corneal structure, without signs of pain. Alterations in other ocular structures were not observed. Regarding the ophthalmological exam and cytology result, a diagnosis of corneal cyst was obtained and the complete excision by a lamellar keratectomy was done. Since the mass did not exceed the middle portion of the stroma, the surface covering was not performed. Two months after surgery, the patient did not present any type of ocular secretion or signs of pain. Moreover, the cornea did not contain neovascularization or sequelae of the healing process, recovering its transparency.

Corneal ulcer in a sheep - treatment with third eyelid flap

Background: Corneal ulcers are frequently reported in the literature in several species, however, the treatment of traumaticlesions on the corneal surface of ruminants is still poorly described. The use of the third eyelid flap is questioned whenapplied to deep ulcers, since the technique prevents the evolutionary follow-up of corneal healing and compromises care.However, several authors report its successful use for the treatment of superficial and deep corneal ulcers. This techniqueprotects the ocular surface and prevents the occurrence of new lesions or their aggravation. The aim of this study was toreport the treatment of corneal ulcers in sheep through the third eyelid flap associated with the use of topical antibiotics.Case: A 2-year-old male Dorper sheep, with ocular discomfort, conjunctival hyperemia and mucopurulent secretion in theleft eye, was assisted in a private rural property in the West region of Bahia, Brazil. The owner reported that before seeking veterinary help he used a spray based on oxytetracycline and hydrocortisone, which worsened the animal’s condition.Upon inspection, it was observed eyelid asymmetry, slight lateralization of the head to the left, periorbital alopecia onthe left face, intense blepharospasm in the left eye, with projection of the third eyelid occurring at times. The ophthalmicexamination was performed after application of anesthetic eye drops based on proxymetacaine to reduce eye discomfort.A corneal stromal lesion, edema and fibrovascular tissue in the left eye were identified, but the cause of the lesion was notdefined, with lagophthalmia, entropion, dystychiasis or ectopic cilia being ruled out. So, it was suggested that the lesionhad occurred by a foreign body, such as dust...

Corneal ulcer in a sheep - treatment with third eyelid flap

Background: Corneal ulcers are frequently reported in the literature in several species, however, the treatment of traumaticlesions on the corneal surface of ruminants is still poorly described. The use of the third eyelid flap is questioned whenapplied to deep ulcers, since the technique prevents the evolutionary follow-up of corneal healing and compromises care.However, several authors report its successful use for the treatment of superficial and deep corneal ulcers. This techniqueprotects the ocular surface and prevents the occurrence of new lesions or their aggravation. The aim of this study was toreport the treatment of corneal ulcers in sheep through the third eyelid flap associated with the use of topical antibiotics.Case: A 2-year-old male Dorper sheep, with ocular discomfort, conjunctival hyperemia and mucopurulent secretion in theleft eye, was assisted in a private rural property in the West region of Bahia, Brazil. The owner reported that before seeking veterinary help he used a spray based on oxytetracycline and hydrocortisone, which worsened the animals condition.Upon inspection, it was observed eyelid asymmetry, slight lateralization of the head to the left, periorbital alopecia onthe left face, intense blepharospasm in the left eye, with projection of the third eyelid occurring at times. The ophthalmicexamination was performed after application of anesthetic eye drops based on proxymetacaine to reduce eye discomfort.A corneal stromal lesion, edema and fibrovascular tissue in the left eye were identified, but the cause of the lesion was notdefined, with lagophthalmia, entropion, dystychiasis or ectopic cilia being ruled out. So, it was suggested that the lesionhad occurred by a foreign body, such as dust...(AU)

Use of automated central lamellar superficial keratectomy in the treatment of chronic pigmentary superficial keratitis in dogs / [Uso da ceratectomia superficial lamelar central automatizada no tratamento das ceratites superficiais pigmentares crônicas em cães]

Pigmentary superficial keratitis (PSK) is a chronic corneal disorder with different causes, which may include immune-mediated diseases and reactions to ultraviolet rays. This study aimed to evaluate the use of automated central lamellar superficial keratectomy (ACLSK) in the treatment of chronic pigmentary superficial keratitis (CPSK) in dogs. We enrolled 24 animals with CPSK and loss of visual function even after clinical treatment with preserved post-corneal transparent media, and the potential for recovery of visual function after surgical treatment. The microkeratome was positioned on the eye surface, and the central corneal lamellae were obtained after translation. With ACSLC, 21 animals (87.5%) recovered their visual function. In 3 animals (12.5%), the formation of granuloma and posterior central leukoma in the cornea compromised the transparency of the visual axis. This study concludes that ACLSK is a viable surgical alternative for the restoration of visual function in dogs with severe PSK, thus improving their quality of life. The short execution time of this procedure reduces the costs and anesthetic risks.

A ceratite pigmentar superficial (CPS) é uma doença crônica da córnea, com diferentes causas, que podem incluir doenças imunomediadas e reação aos raios ultravioleta. Este estudo teve como objetivo avaliar a utilização da ceratectomia superficial lamelar central automatizada (CSLCA) no tratamento da ceratite superficial pigmentar crônica (CSPC) em cães. Vinte e quatro animais incluídos apresentaram CSPC e perda da função visual mesmo após o tratamento clínico, porém mantiveram os meios transparentes pós-córnea preservados e o potencial de recuperação da função visual após o tratamento cirúrgico. O microcerátomo foi posicionado na superfície do olho e, após o término de sua translação, foram obtidas as lamelas centrais da córnea. Com a CSLCA, 21 animais (87,5%) recuperaram a função visual. Em três animais (12,5%), a formação de granuloma e leucoma central posterior na córnea comprometeu a transparência do eixo visual. Este estudo conclui que a CSLCA é uma alternativa cirúrgica viável para o restabelecimento da função visual em cães com CPS grave, melhorando, assim, sua qualidade de vida. Seu curto tempo de execução proporciona redução de custos e de riscos anestésicos.

Cryosurgery using dimethyl ether in the treatment of pigmentary keratitis in pug dogs / Criocirurgia usando o dimethyl ether no tratamento da ceratite pigmentar em cães da raça Pug

Corneal pigmentation and vascularization eventually result in blindness in dogs. Pigmentary keratitis describes a relatively common presentation comprising the deposition of melanin in the cornea and conjunctival surface associated with chronic inflammation. Cryosurgery is indicated as a treatment for pigmentary keratitis in dogs. Due to melanocytes sensitivity to cold, cryosurgery is a viable treatment for severe refractory corneal pigmentation. The aim of this work was to evaluate the use of dimethyl ether in the treatment of pigmentary keratitis in 14 eyes of seven Pug dogs. Follow-up occurred after 30 days in four animals and six months in three animals. In all treated animals, there was a reduction in corneal pigmentation. Cryosurgery causes intracellular and extracellular ice crystal formation and other mechanisms that result in rupture and death of the melanocytes. The technique used was easy to perform, has a low cryogen cost and has few undesirable or serious side effects. However, after 30 days repigmentation occured in treated patients. Cryosurgery shows good results in the first four weeks, but partial recurrence occurred in all cases.

A pigmentação e a vascularização da córnea eventualmente resultam em cegueira em cães. A ceratite pigmentar é descrita com uma apresentação relativamente comum que compreende a deposição de melanina na córnea e na superfície conjuntival associada à inflamação crônica. A criocirurgia é indicada como tratamento para ceratite pigmentar em cães. Devido à sensibilidade dos melanócitos ao frio, a criocirurgia é um tratamento viável para pigmentação corneana refratária grave. O objetivo deste trabalho foi avaliar o uso do éter dimetílico no tratamento da ceratite pigmentar em 14 olhos de sete cães da raça Pug. O acompanhamento foi de 30 dias em quatro animais e seis meses em três animais. Em todos os animais tratados, houve redução da pigmentação da córnea. A criocirurgia causa a formação de cristais de gelo intracelular e extracelular e outros mecanismos que resultam na ruptura e morte dos melanócitos. A técnica utilizada foi de fácil execução, baixo custo de criogenia e poucos efeitos colaterais indesejáveis ou graves. No entanto, após 30 dias, ocorreu repigmentação nos pacientes tratados. A criocirurgia apresenta bons resultados nas primeiras quatro semanas, mas ocorreu recidiva parcial em todos os casos.