Keratitis in six dogs after topical treatment with carbonic anhydrase inhibitors for glaucoma

Immune-mediated polyarthritis and anterior uveitis secondary to zonisamide administration in a dog with refractory epilepsy

The objective of this article is to describe a case of suspected zonisamide-induced immune-mediated polyarthritis (IMPA) and anterior uveitis in a dog. A 7-year-old male neutered Siberian Husky with a history of refractory idiopathic epilepsy was presented for cluster seizures. Following the addition of zonisamide to the antiepileptic regime, the dog developed new IMPA and anterior uveitis. Within a few weeks of discontinuation of the zonisamide, the dog's IMPA and anterior uveitis resolved. These immune-mediated conditions were thus presumed to be an idiosyncratic reaction to zonisamide. To our knowledge, this is the first report of IMPA and anterior uveitis in dogs associated with zonisamide administration at its recommended dose.

Role of Inflammation in Canine Primary Glaucoma

Primary glaucoma is a painful, progressive, and blinding disease reported in many canine breeds, characterized by intraocular pressure (IOP) elevation in the absence of antecedent intraocular disease. Clinical observations of dogs with primary glaucoma suggest that many affected eyes develop concurrent intraocular inflammation in addition to elevated IOP. In this work, we summarize the current knowledge that relates inflammation to primary glaucoma in dogs, reviewing studies focused on genetics, physiology, histopathology, bioanalysis of ocular fluids, therapeutics, and clinical outcomes of glaucomatous patients. Through disruption of the blood-aqueous and blood-retinal barriers, pigment dispersion, and biochemical changes to the aqueous humor and tear film, the pathogenesis of canine primary glaucoma appears to involve inflammatory changes to various extents and with various consequences from the front to the back of the eye. Among others, inflammation further impacts IOP by reducing aqueous humor outflow at the level of the iridocorneal angle and accelerates vision loss by promoting neuronal degeneration. As such, the vicious cycle of ocular inflammation and IOP elevation might warrant the use of anti-inflammatory medications as a core component of the treatment regime for dogs with primary glaucoma, either therapeutically (i.e., actively glaucomatous eye) or prophylactically in the yet unaffected contralateral eye.

Topical Ocular Therapeutics in Small Animals

This article reviews the administration of common topical ophthalmic medications, in relation to factors influencing absorption including composition of topical ophthalmic preparations, and potential systemic effects. Commonly prescribed, commercially available topical ophthalmic medications are discussed with respect to pharmacology, their indications for use, and adverse effects. Knowledge of topical ocular pharmacokinetics is essential for the management of veterinary ophthalmic disease.

Delayed periocular dermatitis as a rare side-effect of topical anti-glaucoma eyedrop instillation in two Shih-Tzu dogs with atopic dermatitis

Two Shih-Tzu dogs with atopic dermatitis presented with delayed periocular dermatitis (PD) following the instillation of dorzolamide and dorzolamide/timolol combination eyedrops; the development of dermatologic signs took 94 and 104 d in cases 1 and 2, respectively. Hypersensitivity to anti-glaucoma eyedrops was highly suspected, and treatment was discontinued. Delayed PD was significantly relieved in cases 1 and 2, at days 155 and 64 after discontinuation, respectively. In this study, the clinical characteristics and progression of delayed PD were described to inform clinicians who may encounter this rare side effect.

Conjunctival staining with lissamine green as a predictor of tear film deficiency in dogs

OBJECTIVE

To evaluate a grading scheme for conjunctival staining patterns with lissamine green ocular dye in the diagnosis of tear film deficiencies in dogs.

PROCEDURES

Client-owned and research colony dogs were enrolled in a prospective study between February and October 2018 in which slit-lamp biomicroscopy, Schirmer tear test (STT), tear film breakup time (TFBUT), conjunctival lissamine green staining (LGS), and intraocular pressure (IOP) measurement were performed in both eyes of all dogs. Lissamine green staining of the temporal bulbar conjunctiva was graded from 0-3, with a higher grade corresponding to an increased stain intensity.

RESULTS

Fifty-four dogs (107 eyes), comprising 31 males and 23 females with a mean age of 5.0 ± 3.9 years (range 0.5-14.3), were enrolled in the study. STT was <15 mm/min in 21 eyes and ≥15 mm/min in 86 eyes. Lissamine green staining grade for eyes with a STT of <15 mm/min (2.0 ± 0.9) was significantly higher than for eyes with a STT ≥15 mm/min (0.2 ± 0.7) (P < .001). TFBUT for eyes with a STT <15 mm/min (6.5 ± 4.4 seconds) was significantly shorter than for eyes with a STT ≥ 15 mm/min (16.1 ± 3.6 seconds) (P < .001). As LGS grade increased, both STT (P < .001) and TFBUT (P < .001) significantly decreased.

CONCLUSIONS

A higher LGS grade was significantly associated with a lower STT and more rapid TFBUT in dogs. Lissamine green ocular dye can be considered as an adjunctive diagnostic test when evaluating tear film deficiency in dogs.

Colistin in Pig Production: Chemistry, Mechanism of Antibacterial Action, Microbial Resistance Emergence, and One Health Perspectives

Colistin (Polymyxin E) is one of the few cationic antimicrobial peptides commercialized in both human and veterinary medicine. For several years now, colistin has been considered the last line of defense against infections caused by multidrug-resistant Gram-negative such as Acinetobacter baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Colistin has been extensively used orally since the 1960s in food animals and particularly in swine for the control of Enterobacteriaceae infections. However, with the recent discovery of plasmid-mediated colistin resistance encoded by the mcr-1 gene and the higher prevalence of samples harboring this gene in animal isolates compared to other origins, livestock has been singled out as the principal reservoir for colistin resistance amplification and spread. Co-localization of the mcr-1 gene and Extended-Spectrum-β-Lactamase genes on a unique plasmid has been also identified in many isolates from animal origin. The use of colistin in pigs as a growth promoter and for prophylaxis purposes should be banned, and the implantation of sustainable measures in pig farms for microbial infection prevention should be actively encouraged and financed. The scientific research should be encouraged in swine medicine to generate data helping to reduce the exacerbation of colistin resistance in pigs and in manure. The establishment of guidelines ensuring a judicious therapeutic use of colistin in pigs, in countries where this drug is approved, is of crucial importance. The implementation of a microbiological withdrawal period that could reduce the potential contamination of consumers with colistin resistant bacteria of porcine origin should be encouraged. Moreover, the management of colistin resistance at the human-pig-environment interface requires the urgent use of the One Health approach for effective control and prevention. This approach needs the collaborative effort of multiple disciplines and close cooperation between physicians, veterinarians, and other scientific health and environmental professionals. This review is an update on the chemistry of colistin, its applications and antibacterial mechanism of action, and on Enterobacteriaceae resistance to colistin in pigs. We also detail and discuss the One Health approach and propose guidelines for colistin resistance management.