Clinical and pathological findings in five dogs with nodular histiocytic iritis in the United Kingdom: A case series.

PURPOSE: The aim of this study was to describe the clinical presentation, histopathology, management, and outcome of nodular histiocytic iritis, an intraocular variant of nodular granulomatous episcleritis (NGE). METHODS: A retrospective review of the medical records of five dogs with intraocular NGE-type inflammation as diagnosed by histopathology. RESULTS: Four Border Collies and one crossbreed dog, aged 1.5-3.4 years (mean age 2.38 years). The clinical presentation was an extensive, raised, pale iris lesion of variable location. All cases were unilateral. The physical examination was normal. Complete blood count/serum biochemistry (n = 1) and thoracic radiography (n = 1) were normal. Ocular ultrasound (n = 2) was normal apart from increased iris thickness. Enucleation (n = 4) or excisional biopsy (iridectomy, n = 1) was performed because of suspected neoplasia. Following enucleation, the remaining, contralateral eye did not develop additional lesions (9 days-3.7 years follow-up). There was no recurrence following sector iridectomy with 5 months topical 1% prednisolone acetate (3.9 years follow-up). The histopathologic findings in all five cases indicated a focal histiocytic and lymphoplasmacytic anterior uveitis (iritis), similar to that seen in cases of NGE. CONCLUSION: Nodular histiocytic iritis presents as unilateral iris thickening in isolation and young Collies appear to be predisposed. The histopathological findings are similar to NGE. Although the clinical presentation resembles intraocular neoplasia, an inflammatory process should be considered, which may be amenable to medical management. Definitive diagnosis may be obtained by iris sampling.

Progressive ulcerative keratitis in dogs in the United Kingdom: Microbial isolates, antimicrobial sensitivity, and resistance patterns.

OBJECTIVES: The objective of the study was to identify bacterial pathogens and their antimicrobial sensitivity profile associated with cases of canine progressive ulcerative keratitis. MATERIALS AND METHODS: Analysis of microbial culture and sensitivity results from dogs with progressive ulcerative keratitis presenting to a UK referral practice between December 2018 and August 2020. RESULTS: Positive bacterial cultures were obtained from 80/148 (54%) of the canine ulcers sampled with 99 bacterial isolates cultured. Streptococcus canis (n = 29), Pseudomonas aeruginosa (n = 19), and Staphylococcus pseudintermedius (n = 16) were the most common isolates. Pseudomonas aeruginosa was more likely to be isolated whether the ulcer was clinically malacic at the time of sampling (OR = 10.1, p < .001). Ulcers treated prior to culture with fusidic acid were 7.6 times more likely to be positive than those treated with any other antimicrobial(s). Bacterial isolates demonstrated resistance against neomycin (85%), fusidic acid (78%), and tetracycline (68%). Conversely, isolates were most likely to be sensitive to gentamicin (88%), ofloxacin (77%), ciprofloxacin (73%), and chloramphenicol (64%). Antimicrobial combinations of chloramphenicol or gentamicin with a fluoroquinolone (ofloxacin or ciprofloxacin) or chloramphenicol combined with gentamicin were the most effective on in vitro analysis (over 90% susceptibility of all isolates). CONCLUSION: The most common bacterial species associated with canine progressive ulcerative keratitis in a UK referral population were S. canis, P. aeruginosa, and S. pseudintermedius. Combination antimicrobial therapy is recommended pending culture and sensitivity results given the varied antimicrobial susceptibility profiles and significant bacterial in vitro resistance to antimicrobial monotherapy.

Equine conjunctival haemangiosarcoma: Clinical presentation, management, and outcome of seven cases in the United Kingdom.

Background: Only 27 cases of equine conjunctival haemangiosarcoma have been reported in the literature over the past 37 years. Out of these, 22% of cases were lost to follow-up, 52% were euthanized, and 26% survived. A scarcity of cases and information is available for this rarely seen conjunctival tumour. Aim: To describe the clinical features, management, and outcome of conjunctival hemangiosarcoma in seven horses in the UK. Methods: Optivet medical records were reviewed for equine cases seen or advised on with a histopathological diagnosis of conjunctival haemangiosarcoma between January 2013 and March 2023. Medical records were accessed for details of signalment, history, management, and follow-up. Histopathology was used to confirm the diagnosis of haemangiosarcoma and assess the surgical margins. Immunohistochemistry was performed in a minority of cases with poorly differentiated solid tumours to support vascular lineage. Results: Seven eyes from seven horses (five geldings and two mares) with a mean age of 16 years and median of 18 years (range 10-21 years) met the criteria. Serosanguinous discharge was seen in six eyes. All eyes were managed surgically; 4 by exenteration and 3 by conjunctivectomy/keratectomy. Adjunctive cryotherapy was performed in two eyes. Metastatic disease in the ipsilateral parotid salivary gland, confirmed with histopathology, was seen in one horse. Surgical margins were clear in all but one eye. Solar elastosis was noted in five eyes. All horses were healthy at the last follow-up (0.2-5 years, mean 2.9 years, and median 2 years). Conclusion: Equine conjunctival haemangiosarcoma is rare. Serosanguinous ocular discharge is a common clinical sign. Early surgical excision is highly effective. Solar elastosis is a common histopathological feature, suggesting a role for UV-light in the pathogenesis.

Malignant ocular teratoid medulloepithelioma in two cats.

Medulloepithelioma is a type of rare primitive neuroectodermal tumour. Most medulloepitheliomas are intraocular and they have been most frequently reported in horses and dogs. A single feline case has been reported but the teratoid form has not been previously reported in cats. Two cats presented with rapidly expanding intraocular masses and ophthalmic examination revealed vascularized uveal tumours extending into the anterior chamber and vitreous chamber. Following enucleation, histopathological examination of each case revealed a focally extensive infiltrative neoplasm that replaced the uveal tract, with retinal detachment and scleral vascular invasion. Rosettes, medullary tubes and heterotopic tissue were present. During follow-up periods of 3.4 and 8.8 years, no evidence of orbital recurrence or metastasis was found in either cat. To the best of our knowledge, these are the first case reports of teratoid medulloepithelioma in cats. Although the risk of metastasis cannot be excluded, as in other species, these findings support enucleation as a curative intervention.

Retrobulbar respiratory epithelial orbital cyst in a dog: A case report.

A 10-month-old female, neutered French Bulldog presented with a history of unilateral right-sided intermittent conjunctivitis and exophthalmos. The patient suffered blunt force trauma to the right eye after a tennis ball impact approximately five months prior to presentation. Examination identified the patient was visual with exophthalmos, lateral strabismus, conjunctival hyperaemia, episcleral congestion, and papilloedema. Magnetic resonance imaging and ultrasonography identified an approximately two centimeter diameter fluid-filled structure directly posterior to the globe leading to displacement of the optic nerve and distortion of the posterior globe wall. Centesis of the lesion demonstrated neutrophilic and macrophagic inflammation with evidence of prior hemorrhage. Within four weeks, the structure had re-filled to its original size and was subsequently excised in its entirety, via a lateral orbitotomy. Histopathologic findings indicated a non-keratinising orbital cyst, the lining of which was consistent with a respiratory epithelial cyst. Recurrence had not occurred seven months' post-surgery. To the author's knowledge, previous reports of retrobulbar respiratory epithelial cysts have not been documented in animals.

Ocular mycobacterial lesions in cats.

Ocular mycobacterial infections are an under-recognized cause of morbidity in the domestic cat. This study aimed to explore the distribution, histopathological appearance, and severity of feline ocular mycobacterial lesions, and to characterize the immune cell population with immunohistochemistry. Routine histological staining with hematoxylin and eosin, and Masson's trichrome, was performed to identify ocular lesions and assign an inflammation score based on the number of cells present. Acid-fast bacilli were detected with Ziehl-Neelsen, and immunohistochemistry for ionized calcium-binding adaptor protein-1 (Iba1), calprotectin, cluster of differentiation 3 (CD3), and Pax5 was undertaken on formalin-fixed paraffin-embedded tissue samples from 24 cases of ocular mycobacteriosis. Posterior or panuveitis with concurrent retinitis was identified in 20/24 cases (83%), with retinal detachment in 16/20 (80%) of these cases. Choroidal lesions had the highest median inflammation score. Ziehl-Neelsen-positive organisms were detected in 20/24 cases (83%), with the highest prevalence of acid-fast bacilli detected in choroidal lesions (16/20, 80%). Lesions were typically granulomatous to pyogranulomatous, characterized by abundant numbers of Iba1-positive macrophages, followed by calprotectin-positive granulocytes and monocytes, fewer T cells, and rarer B cells. However, where iritis was identified, inflammation was typically lymphoplasmacytic (11/16 cases, 69%). Where diagnostic testing was performed, tuberculosis (ie, infection with Mycobacterium bovis, Mycobacterium microti, or a nonspeciated Mycobacterium tuberculosis-complex pathogen) was diagnosed in 20/22 cats (91%), with Mycobacterium lepraemurium infection identified in the other 2/22 cats (9%). These results suggest the choroid is the primary site of lesion development in most cases of feline ocular mycobacteriosis, and inflammatory changes are associated with the presence of mycobacteria localized to ocular tissues.

Evaluation of partial tarsal plate excision using a transconjunctival approach for the treatment of distichiasis in dogs.

PURPOSE: To evaluate the clinical outcome, possible complications, and recurrence rate of distichiasis in dogs treated with partial tarsal plate excision (PTPE) technique using a transconjunctival approach. METHODS: Retrospective study including 17 client-owned canine patients affected with distichiasis and presenting with associated clinical signs (ie, blepharospasm, epiphora, chronic keratoconjunctivitis, or corneal ulceration) that underwent surgical removal of the aberrant lashes using a PTPE technique between January 2018 and February 2019. Data collected included breed, age, sex, affected eyelid(s), number of distichia, and tear film breakup time (TBUT). Resected cilia-bearing tarsoconjunctival strips were submitted for histopathological analysis. RESULTS: Thirty eyes (52 eyelids) from 17 dogs were included in the study. The median age was 688 days (range 118-4243 days). A successful outcome, defined as complete resolution of clinical signs attributable to the distichia, occurred in all eyes after a single procedure, with a mean follow-up time of 239 days (range 69-480 days). Appearance of new distichia occurred in 14/30 eyes (46.3%), and of these, three eyes needed a new PTPE procedure. Recurrence of the distichia only occurred in one eye (3.3%) which was asymptomatic. Following surgery, TBUT decreased below the normal value in 7/24 eyes (29.1%) although none developed clinical signs of qualitative tear film deficiency. Post-operative complications included trichiasis and cicatricial entropion, which developed in two eyes (6.6%), and these were successfully managed with corrective eyelid surgery. CONCLUSIONS: Partial tarsal plate excision, using a transconjunctival approach, had an excellent clinical outcome with a low incidence of complications.

Bilateral third eyelid ectopic cilia in an adult horse.

A 15-year-old Cob mare presented with a 4-month history of chronic epiphora and intermittent blepharospasm in the right eye. On ophthalmic examination, two translucent aberrant hairs were identified at the third eyelid margin corresponding to an area of corneal fibrosis and neovascularization. Partial excision of the third eyelid was performed, and histopathology confirmed ectopic hair follicles. Two weeks later, clinical signs recurred in the same eye. Examination revealed another pair of aberrant hairs on the bulbar surface of the third eyelid near its leading edge. This portion of the third eyelid was also excised, and histopathology confirmed two additional ectopic hair follicles. Eight months later, the horse developed similar clinical signs in the left eye. Ophthalmic examination showed a single aberrant translucent hair at the third eyelid margin associated with focal fibrosis and neovascularization of the ventromedial cornea. Partial excision of the third eyelid was performed, and histopathology confirmed an ectopic hair follicle within the third eyelid conjunctiva. Excision was curative at 4 years postoperatively with no further recurrence in either eye.

Microsporidial keratopathy in two dogs.

A microsporidial keratopathy is described in two dogs. Both dogs presented with a unilateral stromal keratopathy characterized by multifocal coalescing opacities, and the diagnosis was made on histopathologic examination of keratectomy specimens. Transmission electron microscopy (TEM) on formalin-fixed, paraffin-embedded corneal tissue was performed in one dog, and the morphologic features were consistent with Nosema species infection. Both dogs were initially diagnosed and treated by superficial keratectomy. One dog received additional antifungal medication and underwent a penetrating keratoplasty following local recurrence two years later. No other systemic lesions attributable to the microsporidial infection were identified clinically. The clinical and diagnostic pathology findings, treatment, and follow-up are discussed.

Outer retinal degeneration in two closely related Goeldi's monkeys (Callimico goeldii).

This case report comprises studies of four Goeldi's monkeys (Callimico goeldii) from the same enclosure. Globe samples from two related C goeldii (the female C goeldii and her male offspring) were available for a histopathological evaluation. Both cases presented histopathologically evident outer retinal degeneration with differences in severity. There was marked outer retinal atrophy characterized by loss of the outer and inner photoreceptor segments, and depletion of the outer retinal nuclear layer. Furthermore, we report a reduction in the thickness of the outer retinal plexiform, inner retinal nuclear layer, and inner retinal plexiform layer in these C goeldii monkeys. To the authors' knowledge, these findings have not yet been reported in wild- or captive-bred population of C goeldii.

Iris biopsy to investigate feline iris hyperpigmentation.

OBJECTIVE: To evaluate the benefit of iris biopsy in cats with iris hyperpigmentation to differentiate melanosis from early feline diffuse iris melanoma (FDIM). METHODS: The medical records of cats with unilateral iris hyperpigmentation that had undergone iris biopsy between February 2013 and September 2016 at Willows Veterinary Centre & Referral Service were reviewed. RESULTS: Seven cats with unilateral iris hyperpigmentation were included in this retrospective study. The biopsy procedure was performed under general anesthesia (n = 7) with neuromuscular blockade (n = 6) following pre-operative topical miotic therapy (n = 5). One to six biopsy samples per eye were harvested from areas of hyperpigmentation. The samples were partial thickness (n = 4 eyes) and full thickness (n = 3 eyes). Complications were minor: mild intra-operative hemorrhage (n = 4), fibrin clot (n = 2), corneal ulcer (n = 1), post-operative ocular hypertension (n = 1), dyscoria (n = 1), and pseudopolycoria (n = 2). The first biopsy was diagnostic in six cats; a repeat biopsy was necessary in one cat. Histopathology was consistent with melanosis in five cats and with early FDIM in two cats. Screening for signs of metastatic disease (thoracic computed tomography and abdominal ultrasonography) was negative in the two cats with a preliminary diagnosis of early FDIM. Subsequent enucleation and histopathology confirmed the initial diagnosis in both cases. CONCLUSIONS: Iris biopsy in cats with iris hyperpigmentation can be beneficial to differentiate melanosis from early FDIM and thereby help to justify the decision for early enucleation.

Cholesteatoma in a cat.

CASE SUMMARY: A 14-year-old neutered female Burmese cat was referred for investigation of a caudal oropharyngeal mass. CT showed a thin walled cyst-like structure filling and expanding from the right tympanic bulla. Histopathology showed fragments of mildly dysplastic squamous epithelium and aggregates of keratin. These findings were considered consistent with a diagnosis of cholesteatoma. RELEVANCE AND NOVEL INFORMATION: To the best of our knowledge, this is the first reported case of a cholesteatoma in a cat. Cholesteatoma should be considered a differential diagnosis for cats presenting with a caudal oropharyngeal mass, a history of chronic ear disease or a history of previous, surgically managed middle ear disease. Advanced imaging and biopsies should be considered important in the diagnosis of these lesions.

Feline Ocular Mycobacteriosis: Clinical Presentation, Histopathological Features, and Outcome.

This study describes clinical and histopathological features, treatment, and outcome of cats diagnosed with ocular mycobacteriosis. Cases diagnosed from 2012 to 2017 were reviewed for (a) histopathological evidence of ocular (pyo)granulomatous inflammation containing acid-fast bacilli with mycobacterial morphology, (b) positive mycobacterial culture and/or mycobacterial DNA identified by polymerase chain reaction of ocular tissue, or (c) presumed mycobacteriosis based on ophthalmic examination and positive interferon-gamma release assay. Twenty-five cats (31 eyes) were included; 14 cats (17/31 eyes, 55%) were blind at presentation (unilateral: n = 12 cats; bilateral: n = 2 cats); one unilaterally affected cat later became bilaterally blind. Another 5 cats (7/31 eyes, 23%) became blind after initially being bilaterally visual (unilateral: n = 3 cats; bilateral: n = 2 cats). The commonest ocular finding was uveitis (87%). The main histopathological features were granulomatous to pyogranulomatous chorioretinitis with retinal detachment, anterior uveitis, optic neuritis, episcleritis, scleritis, and/or retrobulbar cellulitis. Nineteen cats (76%) had systemic signs, with disseminated disease being diagnosed in 9, defined by interstitial pulmonary disease, generalized lymphadenopathy, and/or nonocular infection. Nine cats were diagnosed with Mycobacterium bovis, 2 with Mycobacterium microti, 1 with Mycobacterium tuberculosis complex, and 1 with Mycobacterium avium-intracellulare complex. The infecting species was unknown in the remaining cats. Combined surgery (enucleation: n = 5 cats; biopsy: n = 3 cats) and systemic treatment with 2 or 3 appropriate antibiotics for 2 to 7 months resulted in remission in 8 of the 10 cats treated; however, the cat treated with dual therapy relapsed after 8 months. A total of 16 cats (64%) were euthanized; 2 were lost to follow-up.

Clinical and pathological findings in three dogs with a corneocentric presentation of nodular granulomatous episcleritis.

PURPOSE: To describe the clinical signs, management, histopathologic findings, and outcome of three dogs with a corneocentric presentation of nodular granulomatous episcleritis (NGE). METHODS: Three dogs of varying breeds were presented for a unilateral, nonpainful, and infiltrative corneal lesion in the dorsal aspect of the eye. Clinical response to symptomatic topical treatment directed at a presumed inflammatory or immune-mediated cause was poor. Due to this, and concerns of neoplasia, ultrasonography (n = 1), incisional biopsy (n = 2), and/or enucleation (n = 2) were performed. RESULTS: The inflammatory infiltrate observed on histopathology was identical to that seen in nodular granulomatous episcleritis in all three cases. However, atypically the inflammation was confined to the cornea and limbus, without episcleral or conjunctival involvement. Inflammation of the cornea was full thickness to Descemet's membrane. Following enucleation (n = 2), there were no postoperative complications, and no reported ophthalmic disease in the remaining eye. Currently, the single non-enucleated case remains controlled with systemic and topical immunosuppression. CONCLUSION: To the best of the authors' knowledge, this is the first report of an NGE condition purely affecting the full thickness of the cornea, without episcleral or conjunctival involvement. The authors propose this to represent an atypical corneocentric variant of NGE. This clinical presentation can resemble neoplasia; incisional biopsy is recommended for a definitive diagnosis. Further research into the optimal treatment strategies for this variant of NGE is required.

Oculodermal Melanocytosis: Nevus of Ota in a Dog.

This report describes the clinical presentation, diagnosis, and histopathologic features of oculodermal melanocytosis in a young dog. A 3-year-old male neutered Labrador Retriever presented with conjunctival and scleral hyperpigmentation of the right eye, with concurrent ipsilateral cutaneous hyperpigmentation involving the right side of the face. Initial skin and conjunctival biopsies revealed an accumulation of histologically benign melanocytes within the dermis and conjunctival stroma, respectively. Enucleation was elected 19 months later by the referring veterinarian due to the progression of ocular pigmentation with concurrent marked corneal lipidosis and the suspicion of a scleral mass. On gross and histopathologic examination of the globe, there was marked panuveal melanocytosis with extension into the sclera, bulbar conjunctiva, and connective tissue surrounding the optic nerve, as well as sharply demarcated ipsilateral hyperpigmentation of the facial skin. The findings are characteristic of oculodermal melanocytosis (nevus of Ota), a dermal melanocytic hamartoma presenting as cutaneous facial hyperpigmentation that corresponds to the distribution of the ophthalmic and maxillary branches of the trigeminal nerve, often with ipsilateral ocular involvement.

Immunohistochemical characterization of feline lymphoplasmacytic anterior uveitis.

OBJECTIVE: To characterize the immune cells present in different forms of feline anterior uveitis. SAMPLES: Eyes were obtained from 49 cats diagnosed with chronic idiopathic lymphoplasmacytic anterior uveitis, 7 cats with feline infectious peritonitis (FIP), and 9 cats euthanized for nonocular disease. METHODS: H&E sections were scored on the level of infiltrate in the anterior uvea. Immunohistochemistry was performed for FoxP3, CD3, and IL-17A, and positive cells were quantified in multiple images of each sample. A generalized estimating equation tested for an association between the level of inflammation and the prevalence of these cell types. RESULTS: Cells stained positive for IL-17A in idiopathic uveitis but not in FIP samples. We found significantly fewer FoxP3+ and CD3+ cells in low-grade compared with high-grade inflammation in idiopathic uveitis or FIP samples (P values all <.005), but no difference between FIP and high-grade samples. CONCLUSIONS: Idiopathic, but not FIP-associated, uveitis appears to have Th17 cell involvement. The numbers of FoxP3+ and CD3+ T-cells present appear directly correlated; thus, the severity of disease does not appear directly determined by the numbers of regulatory cells.

Glomus cell tumour on the head of a cat.

CASE SUMMARY: A solitary, sessile, non-ulcerated, freely mobile cutaneous mass approximately 1 cm in diameter on the left temporal region of a 7-year-old neutered female cat was examined. A fine-needle aspirate and wedge biopsy were performed by the referring veterinary surgeon and indicated a neoplasm of uncertain cell lineage. On histopathological examination, the deep dermis contained a discrete, non-encapsulated and vascular neoplasm with morphological and immunophenotypical features typical of a glomus cell tumour. Neoplastic cells were immunopositive for vimentin, muscle actin and smooth muscle actin, and immunonegative for cytokeratin, S100, desmin and von Willebrand factor (factor VIII-related antigen). RELEVANCE AND NOVEL INFORMATION: Glomus cell tumours arise from modified smooth muscle cells and are rare in animals, particularly cats. Specific immunohistochemistry is of fundamental importance in the correct diagnosis of these tumours and should be considered for masses when cytology and histology results are inconclusive or uncertain.

Diagnosis of anaplastic large-cell lymphoma in a dog using CD30 immunohistochemistry.

Anaplastic large-cell lymphoma or null-cell lymphoma is a clinical entity reported in people, classified according to the unique appearance of large pleomorphic cells that express CD30. Null-cell lymphoma has also been described in dogs when neither CD3 nor CD79α is expressed by the tumor. We describe a case of lymphoma in the dog in which neoplastic cells did not express routine B- or T-lymphocyte markers on flow cytometry or immunohistochemistry; however, cells immunohistochemically labeled for CD30. The dog in our case died 5 mo after initial presentation, confirming a poor prognosis. Identification of further similar cases in dogs would provide additional prognostic information for this subset of lymphomas. CD30 may also serve as a potential therapeutic target in anaplastic large-cell lymphomas.

Orbital paraganglioma in a dog.

A 10-year-old Rottweiler presented with right-sided moderately painful exophthalmia, blindness, absence of dazzle and pupillary light reflexes, a swollen optic nerve head and ventrolateral indentation of the globe. On magnetic resonance imaging, a 3 x 2 x 2 cm mass with a fluid filled center and contrast-enhancing periphery was noted posteriolateral of the globe. Orbital ultrasound was used for a guided fine needle aspirate of the mass. Cytology revealed moderate numbers of polygonal cells with lightly basophilic cytoplasm. Several cells showed nuclear pseudoinclusions. Histopathology following exenteration of the orbit revealed an infiltrative, extradural neoplasm surrounding the optic nerve. Cells were arranged in packets. Neoplastic cells were immunopositive for neuron specific enolase, synaptophysin and chromogranin A and immunonegative for cytokeratin. Findings were consistent with an extra-adrenal paraganglioma (neuroendocrine tumour). Although complete excision could not be confirmed on histopathology, the owners reported no apparent tumour recurrence 25 months after surgery. In conclusion a paraganglioma should be considered as a differential diagnosis of an orbital mass.