Acute Blindness

Frequency of retinal detachments in dogs after prophylactic transpupillary retinopexy

PURPOSE

To evaluate the frequency of retinal detachments following prophylactic transpupillary retinopexy (PTPRP).

METHODS

The medical records of dogs that received a PTPRP between 2014 and 2022 were retrospectively analyzed for age, sex, breed, reason for retinopexy, laser power setting, number of retinal burns, follow-up duration, and outcome. Laser power settings were increased until retinal burns could be visualized and were made 360° in a double row in the peripheral retina.

RESULTS

Fifty-seven cases (75 eyes), 28 males and 29 females, had PTPRP performed. The median age was 8 years (4 months-14 years) with Shih tzu (n = 12), Bichon (n = 5), Miniature Poodle (n = 5), and Yorkie (n = 4) being the most common breeds. PTPRP were performed due to severe vitreal degeneration (n = 66), retinal detachment in the contralateral eye (n = 25), capsular tear with escaped lens material during phacoemulsification (n = 6), intracapsular lens extraction (n = 2), and lens luxation during phacoemulsification (n = 3). The median power setting, number of retinal burns, and follow-up time were 300 mW (201-595 mW), 210 burns (35-921 burns), and 473 days (14-1862 days), respectively. Additionally, five patients had a barrier-pexy performed in the contralateral eye, due to partial detachment. Retinal detachment occurred in 3/75 (4.0%) of eyes that received a PTPRP at the final examination. Of the patients with a detachment in the contralateral eye (n = 25), no detachment was noted at the last follow-up examination. Two partial detachments that had barrier-pexies had progressed at the final examination.

CONCLUSIONS

These results demonstrate that PTPRP may be beneficial in decreasing the risk of retinal detachment in selected cases.

Morphological Evaluation of Transscleral Laser Retinopexy in Rabbits: Comparison of Optical Coherence Tomography and Histologic Examinations

Transscleral retinopexy is a preventive technique used against retinal detachment. Fundus examination can allow the monitoring of morphological retinal changes in the progression of photocoagulation lesions, without offering details on the morphological changes by the retinal lesion. The aim of the study was to assess the progression of photocoagulation lesions induced by transscleral retinopexy (840 nm diode laser), by comparing the optical coherence tomography (OCT) and histological images over a period of six weeks on eight pigmented New Zealand healthy rabbits (four males and four females; n = 16 eyes). All rabbits underwent transscleral retinopexy on their left eye on day 0 (D0). Measurements of the photocoagulation lesions were obtained in vivo on D0, D7, D15, D21, and D42 by acquiring OCT images of both eyes from all rabbits. On D1, D7, D21, and D42, two rabbits were euthanized, and their eyes were enucleated. A significant effect by time on the decrease in the central retinal thickness of the photocoagulation lesion was observed from D1 to D7 (p = 0.001); however, no such effect was observed on the horizontal length ((HL) p = 0.584) of the lesion surface. The reliability between the OCT and histological measurements, which were evaluated using intraclass correlation coefficients, was excellent for measuring the retinal thickness at the center (ICC = 0.91, p < 0.001), moderate for the right side of the retinal lesions (ICC = 0.72, p = 0.006), and not significant for the left side and HL (p = 0.055 and 0.500, respectively). The morphological changes observed in the OCT and histopathological images of the photocoagulation lesions were qualitatively described over time. OCT is an effective tool for monitoring changes in photocoagulation lesions. Some measurements and qualitative changes showed an adequate correlation between the OCT and histological findings.

Repeat histopathology and culture of colonic biopsy specimens after treatment for Escherichia coli-associated granulomatous colitis in a cat

Case summary

A 7.5-year-old neutered male Oriental Shorthair cat presented with an 8-month history of haematochezia, mucoid diarrhoea, tenesmus and vocalisation after a 4-year history of small bowel diarrhoea. Transabdominal ultrasonography confirmed diffuse colonic wall thickening and extensive ulceration and erythema after colonoscopy. Colonic histopathology confirmed periodic acid-Schiff positive macrophages, consistent with granulomatous colitis; Escherichia coli was cultured from colonic biopsy specimens. Fluorescent in situ hybridisation (FISH) identified intracellular E coli, and an 8-week oral course of marbofloxacin, a hydrolysed protein diet and a 5-day course of fenbendazole yielded a transient partial clinical remission of the colitis signs. A reported resolution in the small bowel signs was also reported. Colonoscopy was repeated 5 months later due to the recurrence of colitis signs. Histopathology was not consistent with granulomatous colitis supporting a complete remission; however, a chronic inflammatory enteropathy was confirmed with moderate lymphoplasmacytic, neutrophilic and eosinophilic colitis without a histiocytic component. E coli was again cultured from colonic biopsies with sensitivity to fluoroquinolones; FISH was positive for intracellular E coli. Clinical signs persisted despite a 2-week course of oral marbofloxacin.

Relevance and novel information

E coli-associated granulomatous colitis is rare in cats. Colonic biopsy specimen culture is important to guide appropriate antibiotic therapy. Repeat histopathology, culture and FISH have not been previously reported after treatment of a cat with E coli-associated granulomatous colitis. Persistent clinical signs after treatment with oral marbofloxacin alongside a confirmed complete histologic remission support the presence of a concurrent chronic inflammatory enteropathy and pathology for the cat's ongoing colitis.

Histoplasma capsulatum, Toxoplasma gondii, Bartonella henselae and Bartonella clarridgeiae coinfections in an indoor-only Siamese cat

Case summary

A 6-year-old male castrated Siamese cat was referred for acute-onset blindness and mydriasis. Physical examination revealed serous retinal detachment with panuveitis and systemic hypertension. Abdominal ultrasound showed suspected dilation of the cisterna chyli and abdominal lymphadenopathy. Aspirates of mesenteric lymph nodes revealed intrahistiocytic yeast organisms with mild-to-moderate pyogranulomatous inflammation. Fungal culture and ITS1 sequencing of the lymph node aspirates confirmed infection with Histoplasma capsulatum. PCR performed on whole blood was positive for Bartonella henselae and Bartonella clarridgeiae, and Toxoplasma gondii IgG and IgM antibodies were detected in serum. The cat was prescribed prednisolone (0.5 mg/kg PO q24h), itraconazole (10 mg/kg PO q24h), clindamycin (13 mg/kg PO q12h), amlodipine (0.625 mg PO q24h), prednisolone acetate 1% drops (q6h) and ophthalmic lubricant for both eyes (q6h). The cat was doing well at home after 2 weeks of prednisolone, itraconazole and clindamycin administration, and no abnormalities were detected on repeat abdominal ultrasound 3 months later. The retinal detachment showed mild-to-moderate improvement at that time, but vision was not regained.

Relevance and novel information

This is the first report of coinfection of H capsulatum, T gondii, B henselae and B clarridgeiae in an indoor-only cat living in a H capsulatum non-enzootic area with no known travel history.

Animal Welfare Considerations and Ethical Dilemmas Inherent in the Euthanasia of Blind Canine Patients

Simple Summary

Although many dogs with blindness diagnosis can reach a similar age compared to those not affected, often the owners require euthanasia of their animals. This choice leads to conflicting moral principles relating to what is better for the animal and the owner. This article discusses the suitability of euthanasia in blind dogs. To better assess factors influencing the choice of euthanasia, four different scenarios were constructed that described various situations regarding the animal’s aptitude, pet owner, and veterinarian relations.

Abstract

In dogs, several primary or secondary diseases affecting the ocular structures may cause blindness. In cases where the visual impairment is not associated with severe systemic involvement and the animal can still have, predictably, a good “long-term” quality of life, the veterinarian should inform the owner about the differences between humans and animals, concerning the type of visual perception. In the light of the daily findings in veterinary clinic practice, the Authors report four different scenarios with conflicting views between veterinarians and owners about the euthanasia request for a blind dog. They underline how the diagnosis of incipient or already established blindness in dogs can sometimes lead to an inappropriate request for euthanasia.