August 2023 newsletter
Hello, Vetaheader! Our monthly newsletter is here. Once again, we have papers on mammals, birds and reptiles!
First, we have a paper on the comparison of post-surgical complication rates in two common approaches for elective altering in female rats (Rattus norvegicus): the flank approach (FA) and ventral midline approach (VMA).
These approaches are used for ovariectomy (with or without partial hysterectomy) and ovariohysterectomy, respectively. The flank approach offer some advantages, such as smaller incision, easier access to ovary and suspensory ligament, decreased risk of evisceration secondary to suture line dehiscence, decreased risk of incisional contamination, less pain, shorter surgery time, and shorter incision healing time. However, the main disadvantage is that there is risk of disease for the remaining reproductive tract.
A retrospective analysis was performed on the medical records, and a total of 457 female rats were included in this study; the FA was used in 396 rats, while VMA was used in 61 rats. They also looked for complications accounting for patient age, weight, and surgeon expertise (5 total, 2 ABVP (ECM)).
Complications were reported in 22/396 for FA, while 6/61 were reported for VMA – 14 FA and 5 VMA rats had incisional complications. Mortality rates for FA and VMA within 48 hours were, respectively, 1.2% FA and 0%.
The take home message is that this study reported no statistically significant difference between postoperative complications of FA and VMA for elective surgery in female rats, and no predictive factors for complications could be found.
Second, we have a study on the safety of the IM injection of an intravenous formulation of voriconazole in pigeons (Columba livia f. domestica). Voriconazole is a triazole that acts as a lanosterol 14 alpha-demethylase inhibitor, and IM route has significantly higher bioavailability than oral; currently, avian aspergillosis is treated with voriconazole administered orally.
Sixteen healthy pigeons received IM injections of voriconazole (12.5 mg/kg, q 12 h, for 7 days) and sterile saline in the right and left pectoral muscles, respectively. Additionally, 4 birds acted as controls (no injections). Hematologic and plasma biochemistry panels were performed. Eight birds in the treatment group and 2 of the control pigeons were humanely euthanized 1 day (group 1) and 14 days (group 2) after the final injection for gross and histopathological evaluations of the pectoral muscles.
Their results showed that all biochemical analytes remained within the reference intervals for the species; however, many parameters had statistically significant differences, including AST and lactate dehydrogenase. It is important to note that no liver or renal changes were significant. Also, there were no adverse clinical signs, but there was edema and erythema at site of voriconazole injection. The group 1 birds had advanced gross and histopathological pectoral muscle lesions associated with the voriconazole injections compared with the contralateral side, the group 2 birds, and the negative controls. After 14 days, the pectoral muscles did not reveal any gross or histopathological changes associated with the voriconazole or sterile saline injections.
The take home message is that the use of multidose, IV formulated voriconazole administered IM did not produce clinical, biochemical, or histologically relevant evidence of permanent muscle damage in pigeons.
Lastly, we have a case report of unilateral phacoclastic uveitis in a crested gecko (Correlophus ciliatus). While cataracts secondary to uveitis have been reported in lizards, there are limited reports of lens disease in reptiles in general.
A 4-year-old, intact female crested gecko presented for globe asymmetry, with the left eye smaller than the right, with IOP values between 3 and 7 mmHg, measured via rebound tonometry, in both eyes. Biomicroscopy of the left eye revealed a small globe and a focally extensive area of heavily pigmented iris with miosis. The primary differentials for were phthisis bulbi, cataract, anterior uveal melanoma, and chronic uveitis.
Ten weeks after, the patient returned with weight loss and progression of left phthisis bulbi, which lead to the decision to perform an enucleation. During the enucleation, the endolymphatic sac was accidentaly ruptured.
Bilaterally symmetrical endolymphatic sacs represent an anatomical variation of crested geckos and are located in roof of mouth and believed to serve as calcium storage sites. They are composed of bilateral endolymphatic ducts that originate from sacculus of inner ear and terminate in expanded sacs between meninges of brain, and in close proximity to ocular structures and must be considered when performing ophthalmic surgery.
The gecko recovered uneventfully and skin sutures were removed 6 weeks later. Light microscopic evaluation of the left globe revealed phacoclastic uveitis; this lens rupture was assumed to be traumatic, related to a previous focal globe perforation.
The take home message is that phacoclastic uveitis should be included as a differential in geckos with signs of chronic uveitis such as iris hyperpigmentation and phthisis bulbi.
Hope these help you and, as always, I will see you next month!
Sincerely,
Laila Proença
