Etiologies of nontraumatic feline uveitis in the UK: A retrospective observational study of 72 cats

Background

Uveitis is a common ophthalmic diagnosis in cats, that can lead to discomfort and loss of vision. Identification of nonidiopathic cases facilitates treatment and could reduce morbidity associated with this condition.

Aim

To evaluate etiologies of nontraumatic uveitis in the UK, to compare diagnostic features between idiopathic cases and those with an established underlying etiology, and to investigate the association of clinical signs and abnormal diagnostic findings with a confirmed etiology.

Methods

Records of cats diagnosed with uveitis at a UK referral center between August 2009 and April 2018 were retrospectively reviewed, excluding traumatic (and reflex) cases. Cases were categorized based on whether an underlying etiology had been established in cases with confirmed etiology, idiopathic, and inconclusive cases. All cases had a minimum of 12-month follow-up unless an underlying etiology had been established. Population characteristics, clinical signs, diagnostic investigation features, and results were reported.

Results

72 cases of uveitis were included, of which male cats and domestic breeds were overrepresented. An underlying etiology was determined in 23.6% of cases: 9.7% had infectious diseases, 5.6% had systemic neoplasia, 4.2% had primary ocular neoplasia, and 4.2% had metabolic disease. Idiopathic uveitis comprised 37.5% of cases, and the remaining 38.9% were inconclusive, of which 35.7% died or were euthanased within the follow-up period. Among the study population, no significant age difference was found between cats with idiopathic disease or confirmed etiology. The unilateral disease was reported in 56.9% of cases and was not different across the idiopathic cases and confirmed etiology groups. The most common ophthalmic clinical sign was an aqueous flare, followed by keratic precipitates and hypotony. Iris color change (p = 0.015) and the presence of an intraocular mass (p = 0.025) were associated with an underlying etiology.

Conclusion

Idiopathic uveitis was found to be the most common diagnosis in this study population. However, a similar proportion of cases had possible underlying etiologies as a high proportion manifested systemic disease within the follow-up time. An underlying etiology could be established only in a quarter of cases. Further studies are required to standardize the investigations required when assessing cats with uveitis to minimize patient morbidity.

The Outcomes of an Opioid-Free Anaesthetic Plan in Fourteen Dogs Undergoing Enucleation Using an Ultrasound-Guided Supra-Temporal Retrobulbar Block: A Retrospective Case Series

The objective of this retrospective case series is to report the outcomes of an opioid-free anesthetic plan in dogs undergoing enucleation surgery. A total of 14 dogs were admitted for enucleation between March and December 2020. A multimodal approach to perioperative analgesia was used, with a focus on retrobulbar anesthesia. A combination of an ultrasound-guided retrobulbblock with a supratemporal approach in association with ketamine, dexmedetomidine and non-steroidal anti-inflammatory drugs was used in the reported cases. Intraoperative nociception was defined as an increase of 20% from the baseline in one or more of the following parameters: heart rate, respiratory rate or mean arterial pressure. An ultrasound-guided retrobulbar block in an opioid-free anesthesia regime was effective at managing the perioperative analgesia of 13 out of 14 dogs. In only one case, a bolus of fentanyl was administered to treat intraoperative nociception. Recovery was uneventful in all the dogs, and the postoperative pain scores remained below the intervention threshold at all time points. To the authors' knowledge, this is the first reported case series of opioid-free anesthesia for enucleation in dogs.

Spectral transmittance of animal intraocular lenses in comparison with the spectral properties of their biological lenses

PURPOSE

To determine the spectral transmittance of artificial intraocular lenses (IOLs) designed for various species (dog, cat, chinchilla, eagle, tiger) and compare them to the spectral properties of the biological lenses of these species.

METHODS

Twenty-seven IOLs were scanned with a spectrophotometer fitted with an integrating sphere.

RESULTS

All IOLs transmitted long wavelengths well before cutting off sharply at short wavelengths, with insignificant transmission below ca. 340 nm. In comparison with the IOLs, the biological lenses of the cat, dog, and probably the chinchilla transmitted significantly more short wavelengths. The spectral properties of the biological lenses of eagles and tigers, while uncertain, may be a closer match to the IOLs made for these species.

CONCLUSION

It is not known if there are any visual or behavioral consequences for animals caused by a mismatch between the spectral properties of their biological lenses and IOLs. However, following IOL implantation there might be a change in the perceived hue of objects due to the removal of UV wavelengths which form a normal part of the visible spectrum for these species and/or a decrease in sensitivity.

A modified technique of keratoleptynsis ("letter-box") for treatment of canine corneal edema associated with endothelial dysfunction

PURPOSE

To describe a modified keratoleptynsis procedure, as a method of preserving central corneal function, and evaluate the outcome in vision, reduction of corneal thickness and treatment of epithelial corneal ulcers in cases with endothelial cell dysfunction.

METHODS

Forty-four dogs (72 eyes) were affected by progressive corneal edema, with or without ulcerative keratitis. All patients were treated with a dorsal and ventral superficial keratectomy followed by conjunctival flaps, maintaining a clear central cornea. Corneal thickness measurements were obtained via ultrasound biomicroscopy.

RESULTS

All eyes showed resolution of ocular discomfort postoperatively, with a median time to resolution of 35 days. Two years post-surgery, vision had been lost in 2 of 29 eyes (7%). From the initial population, 23 dogs (39 eyes) had follow-up evaluations of corneal thickness. The mean central corneal thickness was 1359 ± 251 μm prior to surgery. Thickening of the central cornea was observed one week after surgery to 1559 ± 263 μm. Decreased corneal thickness was reported, at 1 month, 4 months, 10 months and 2 years postoperatively (1285 ± 267 μm, 1102 ± 150 μm, 1121 ± 288 μm, 1193 ± 283 μm, respectively). All eyes showed a similar trend of increasing and then decreasing corneal thickness.

CONCLUSIONS

This surgical technique provided statistically significant reduction in central corneal thickness and sustained relief of ocular pain. Reduction in corneal thickness appeared to be maintained 2 years post-surgery, and all patients remained comfortable. Superficial corneal pigmentation and fibrosis resulted in vision loss in two eyes.

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.