Atypical primary ocular melanoma in cats

The clinical and pathologic features of six cases of atypical primary ocular melanoma in cats are described. In contrast to diffuse iris melanomas, these atypical tumors originated multifocally from any portion of the uvea and in five of the six cases were very advanced at the time of clinical presentation. Two of the advanced cases involved primarily the ciliary body, while three others showed extensive involvement of the choroid. Histologically, these tumors consisted primarily of round, heavily pigmented cells lacking the anaplastic nuclear features characteristic of advanced diffuse iris melanomas. The advanced stage of the tumors at presentation may have been due to either the posterior uveal origin of these tumors or to more rapid progression. Additional cases with long-term follow-up need to be studied in order to accurately assess the biological behaviour of these tumors.     

Onchocerca cervicalis in Horses from Southern Brazil

The objective of this study was to determine the occurrence of Onchocerca cervicalis in 1200 adult horses from rural areas of Rio Grande do Sul, Brazil. Umbilical skin specimens measuring 2 x 2 cm were minced, suspended in 10 ml of distilled water and incubated at room temperature overnight. The liquid volume was centrifuged and the sediment was screened for microfilariae. The ligamentum nuchae were totally removed, preserved in ice and dissected for the detection of adult forms of Onchocerca cervicalis. Microfilariae of Onchocerca cervicalis were detected in midventral skin biopsy samples in 215 (17.9%) of 1200 horses examined and the adult worms were recovered from 200 (16.6%) ligamentum nuchae from the same animals. These findings provide a basis for further studies to determine infection rates in horses from other regions of the state and to identify the intermediate host that transmits the disease.     

Mutation analysis and gene expression profiling of ocular melanomas in cats

Feline ocular melanomas show a high malignant behaviour, but adjunctive therapies are non‐existent. The aim of this pilot study was to determine, whether feline ocular melanomas harbour mutations comparable to mutations in human melanomas and to evaluate the gene expression status of genes known to be involved in initiation and progression of human melanomas. Mutation hotspot regions of several genes of feline ocular melanomas were analysed by DNA sequencing and RNA expression levels of the respective genes and others were evaluated by quantitative real‐time polymerase chain reaction (RT‐qPCR). Common mutations found in human melanomas are not present in feline tumours. Gene expression analysis revealed a significant upregulation of KIT and LTA4H, as well as a downregulation of GNAQ, GNA11, BRAF and RASSF1 in feline ocular melanomas. As KIT seems to harbour a potential as target gene in human uveal melanomas, future studies should further investigate the potential of KIT as target for adjunctive therapy in feline ocular melanomas.     

A case of canine ocular onchocercosis in Portugal

Onchocercosis is a newly recognized disease in dogs that has been reported with higher frequency in Europe and in the United States. We report a case of a 3‐year‐old male mongrel stray dog from the Algarve region (South Portugal) who had a retrobulbar granuloma containing a filaroid nematode of the genus Onchocerca. A gravid adult female parasite was embedded in a granulomatous inflammation adjacent to the sclera beyond the retina. The parasite was 191 to 267 μm in diameter (mean = 225 μm), surrounded by a cuticule and owing a uterus that was filled with small unsheated microfilariae. The cuticule consisted of two separated layers in longitudinal sections. The external layer had cuticular ridges and the internal layer contained striations. Sequencing of the COI and ND5 mitochondrial genes confirmed the identity of this parasite as Onchocerca lupi. Furthermore, the first sequence of the 12S mitochondrial gene is reported in this study.     

Feline ocular emergencies

Feline ocular emergencies include any ophthalmic condition that has rapidly developed or is the result of trauma to the eye or periocular structures. Common feline emergencies include proptosis, lid lacerations, corneal ulcers, and foreign bodies. Complete ophthalmic examination including procurement of the minimal ophthalmic database (Schirmer tear test, fluorescein stain, and intraocular pressure measurement) should be obtained whenever possible to ensure that the complete and correct diagnosis is made. Concern for the patient's vision and ocular comfort should guide the practioner's diagnostic and therapeutic plan. This article reviews some of the more common feline ocular emergencies, including conditions affecting the orbit and globe, adnexa, conjunctiva, and cornea. Feline uveitis, glaucoma, and lenticular diseases are covered more thoroughly elsewhere in this issue.     

Ocular manifestation of lymphoma in newly diagnosed cats

Ocular manifestations of lymphoma are described in humans and dogs but rarely in cats. In this prospective study, cats with newly diagnosed and treatment‐naïve lymphoma were evaluated concerning clinical stage and ophthalmologic findings. Twenty‐six cats were included. In 12 cats (48%), ocular changes were documented. Uveitis anterior and posterior were predominant findings, being present in 58% of affected individuals. Other findings included exophthalmos, corneal surface lesions and chemosis. Eight cats received chemotherapy, two of which had ocular involvement. In these two cats, a complete remission of an anterior and a partial remission of a posterior uveitis were documented. Due to the detection of ocular involvement, a stage migration from stage IV to V occurred in four patients. In the light of these findings, an opthalmological examination may be considered as an important part of staging in feline lymphoma as well as of follow‐up examination in affected cats.     

Feline early life ocular disease

Objectives Histomorphologic changes in six globes from six cats, which experienced early life ocular disease of undetermined etiology, are described. Design A retrospective morphologic study of six eyes from six cats with early life ocular surface disease of unknown etiology, from 2002 to 2006 extracted from a pathology collection, which includes 2200 feline submissions. Procedure Sections of affected globes, stained with H&E were examined with a light microscope. Results The mean age of the affected cats, at the time of enucleation, was 7.5 months ranging from 7 weeks to 2 years. The cats were one male, one female, one male neutered, and one female spayed cat. For the remaining two cats the sex was not known. All cats were DSH. Significant histomorphologic findings included collapse of the globe in all cases and a broad corneal perforation with protrusion of the anterior uvea, which was epithelialized in all cases. Three cases revealed uveal hematopoiesis in the anterior and posterior uvea. All cases had recognizable corneal tissue at the limbus on both sides. Inflammation in all cases consisted of variable but generally mild uveitis and no eyes had endophthalmitis. Four of the globes had no recognizable lens tissue. Three of the cats had symblepharon formation described as part of the clinical condition. The other three cases had no mention of symblepharon. Conclusions These cases are considered to represent changes associated with early life corneal ablation of unknown etiology. Uveal prolapse, mild inflammation, and symblepharon are considered to be either secondary or caused by the same destructive primary event that affected the cornea. These cases are the first cases we are aware of with uveal extramedullary hematopoiesis in cats. Careful consideration of cell morphology is necessary to distinguish this condition from round cell neoplasms or inflammation.     

Canine ocular onchocerciasis in the United States: two new cases and a review of the literature

Since 1991, 53 cases of canine ocular onchocerciasis have been reported in the literature worldwide, 43 of these were from Greece, five from Hungary, and five from the western United States. Information on the histopathologic features of canine ocular onchocerciasis is limited. We describe the histopathologic features of canine ocular onchocerciasis in two dogs from California that presented clinically with firm episcleral nodules and uveitis unilaterally. Pertinent literature and pathogenesis are reviewed; recognizable clinical features and treatment are discussed. The cases presented were diagnosed via histopathology of the enucleated globes and episcleral granulomas at the Comparative Ocular Pathology Laboratory of Wisconsin (COPLOW). Positive identification of adult Onchocerca within episcleral granulomas was made based on light-microscopy features. Histopathologic examination of both globes revealed episcleral parasites surrounded by granulomas containing few to moderate numbers of eosinophils. Other sequelae, in both cases, included lymphoplasmacytic uveitis, preiridal fibrovascular membranes, peripheral anterior synechiae, retinal degeneration, and optic nerve head cupping. Both male and female worms were present, as were in utero microfilariae in both cases. Worms in both cases were tentatively identified as Onchocerca lienalis. Ocular onchocerciasis should be a differential consideration in cases of canine conjunctival nodules or periorbital swelling, particularly in dogs from the western United States.     

Red cell morphologic alterations in cats with hepatic disease

Medical records from 39 cats with hepatic disease, examined at the Veterinary Medical Teaching Hospital, University of Florida, between 1987 and 1992 were retrospectively evaluated for alterations in red blood cell (RBC) morphology. Diagnoses included: hepatic lipidosis, neoplasia, cholangiohepatitis, hepatitis/hepatopathy, systemic histoplasmosis, and portocaval shunt. A total of 56 laboratory data sets were studied which included complete blood counts and serum chemistry results. Stained blood smears were evaluated from 51 of the data sets. Twenty-two cats (56%) were determined to have poikilocytosis on the basis of blood smear evaluation. Eleven (28%) cats had moderate to marked poikilocytosis (2+ to 4+). Acanthocytes accounted for 62.6 -/+ 22.1% of morphologically abnormal RBC and were observed in blood smears from 100% of cats with poikilocytosis. Elliptocytes (ovalocytes) comprised 19.5 -/+ 15.8% of poikilocytes and were found in smears from 82% of cats with poikilocytosis. Keratocytes (7.0 -/+ 6.8%), schistocytes (3.6 -/+ 4.4%), and blister cells (2.6 -/+ 6.4%) were present in lower numbers and in fewer cats. Serum total cholesterol values were significantly greater (p < 0.05) in cats with moderate to marked alterations in RBC morphology. Cats with hepatic lipidosis were significantly (p < 0.04) more likely to have poikilocytosis than cats with other types of hepatic disease.     

Anti-A isoagglutinins in two blood type B cats are IgG and IgM

Sera from two blood type B cats had strong isoagglutinating and isohemolyzing titers against blood type A erythrocytes. In order to determine the class of the immunoglobulins, sera from the cats were pooled, ammonium sulfate precipitated, and gel filtered using sepharose 6B to separate the immunoglobulins by molecular size. The immunoglobulin concentrate separated into two fractions. The initial part of the first fraction was shown in an ELISA to contain IgM and to be devoid of IgG by immunoelectrophoresis and to have agglutinating activity (a titer of 1:4 with a protein concentration of 0.8 mg/ml). Treating this fraction with the reducing agent dithiothreitol (DTT) eliminated agglutinating activity. The latter portion of the second column fraction was shown to contain IgG by immunoelectrophoresis, and to be devoid of IgM by ELISA. Agglutinating activity was also present in the second fraction (a titer of 1:2 with a protein concentration of 1.9 mg/ml); hemagglutinating activity was not decreased by DTT treatment. These studies show that the predominant anti-A isoagglutinating activity in pooled sera from two blood type B cats is IgM and that some isoagglutinin activity can be associated with IgG.     

A matched observational study of survival in cats with enucleation due to diffuse iris melanoma

Although a small number of cases of feline diffuse iris melanoma have been documented to metastasize, the prognosis is not known. In this matched observational study, the survival time of 34 cats with enucleation due to histologically confirmed diffuse iris melanoma was recorded. These results are compared to the survival times of 83 age-matched control cats. Affected cats had enucleation between 2 and 10 years prior to the study. One group of control cats with eye disease had enucleation for either lymphoplasmacytic uveitis (27 cases), ocular trauma (seven cases), or endophthalmitis (four cases). In these control cats, enucleations were performed between 2 and 10 years prior to this study. Forty-five additional control cats presented for vaccination between 2 and 10 years prior to the study. The extent of diffuse iris melanoma at the time of enucleation in affected cats was graded according to the extent of involvement of ocular tissues and the invasiveness of the tumor. Affected cats have a significantly decreased survival compared with control cats and cats with extensive tumors at the time of enucleation have the lowest survival rates. Cats with tumors confined to the iris survive at the same rate as controls. These results suggests that early enucleation is important to avoid premature death, presumed to be due to cancer metastasis in cats with diffuse iris melanoma.     

Feline corneal sequestrum: laboratory analysis of ocular samples from 12 cats

Feline corneal sequestrum is a common ocular condition typified by brown to black discoloration of the cornea. The nature of the discoloration has not been identified. The purpose of this study was to perform a laboratory investigation of ocular samples from 12 clinical cases of feline corneal sequestrum in an attempt to characterize the nature of the discoloration. The 12 cases were referred to the Ophthalmology Unit at the Animal Health Trust between April and September 2000, and were also part of a clinical review of 64 cases of feline corneal sequestrum described separately. Five laboratory techniques that are routinely performed at the Biomaterials Unit, Aston University were employed for analysis of the ocular samples. Ocular material included corneal sequestrum, tear samples, meibomian gland secretions, and bandage contact lenses from the 12 clinical cases. High-performance liquid chromatography data showed that total tear lipid in affected eyes was significantly lower than in control eyes (P = 0.016); total tear lipid in affected eyes was lower than in the unaffected, contralateral eyes of the same cat but the difference was not significant (P = 0.29). The presence of an unknown lipid class was observed in tears and meibomian secretions of affected, contralateral and control eyes. Scanning electron microscopy showed that the discoloration in affected corneas was not due to the presence of iron. Fluorescence spectroscopic analysis of sequestra, unaffected corneas and contact lenses (from affected and contralateral/unaffected eyes) showed that lipid and protein were present but did not play an important role in sequestra. Ultraviolet-visible light absorbance spectroscopy revealed a peak at 385 nm in unaffected corneas that was absent in sequestra and the difference was significant (P < 0.0001); this peak may be a characteristic feature of the normal feline cornea. The absorbance spectra displayed a peak at 280 nm in two sequestra suggesting that chromophore groups (e.g. melanin) were present. Optical microscopy performed on 10 sequestra revealed the presence of particles, which were consistent with the appearance of melanin particles, providing laboratory evidence that characterized the nature of the discoloration as melanin for the first time.     

Ocular manifestations of systemic disease in cats

Systemic feline diseases (parasitic, bacterial, fungal, viral, neoplastic, metabolic, vascular, and immune-mediated) are often associated with ocular symptoms. An ocular examination is an important diagnostic tool and should be part of any physical examination. Conversely, cats afflicted with systemic disease require periodic ocular examinations for prognostic information and to prevent vision threatening complications. Typical feline systemic diseases encountered by the practicing clinician are presented with their commonly associated ocular signs.     

Treatment of primary immune‐mediated hemolytic anemia with mycophenolate mofetil in two cats

Objective – To describe the use of oral mycophenolate mofetil (MMF) as an adjunctive therapy in 2 cats with primary immune‐mediated hemolytic anemia. Case Series Summary – Two cats suffering from presumptive primary immune mediated hemolytic were treated with MMF as part of their treatment regimens. Both cats had improved complete blood counts following therapy. New or Unique Information Provided – This is the first reported use of oral MMF as adjunctive treatment for cats with immune‐mediated hemolytic anemia. Outcome was favorable in both cats and no adverse effects were noted from the MMF.