Long-term effect of oral cannabidiol administration to healthy adult dogs on tear production, intraocular pressure, and tear concentrations.

OBJECTIVE: To determine the chronic effects of oral cannabidiol (CBD) use on tear production, intraocular pressure (IOP), and concentration of CBD in tears of healthy dogs. ANIMALS STUDIED: Eighteen healthy research Beagles. PROCEDURES: This was a masked, placebo-controlled, randomized prospective study. Eighteen dogs were randomly assigned to three groups (six dogs per group) based on daily dosage of oral MCT oil (placebo), CBD 5 mg/kg, and CBD 10 mg/kg. Schirmer tear test (STT-1) and IOP were measured twice daily (7 am and 7 pm) every 4 weeks for 36 weeks. Week 36 tears were collected and analyzed for CBD concentrations (ng/mL) using liquid chromatography/mass spectrometry. A mixed linear model was used as the statistical method and p-value <.05 was considered significant. RESULTS: No significant differences were found between placebo vs. 5 mg/kg vs. 10 mg/kg for STT-1 or IOP (AM and PM). CBD was detected in 10 out of 11 (91%) viable tear samples receiving 5 mg/kg or 10 mg/kg dosages. One sample in the 5 mg/kg group had inadequate tear volume for analysis. The CBD concentration in tears was at or below the lower limit of quantification in placebo group, 4.12-11.2 ng/mL for the 5 mg/kg group, and 6.22-152 ng/mL for the 10 mg/kg group. CONCLUSIONS: Long-term administration of oral CBD in healthy research beagles demonstrates a favorable safety profile regarding ocular tolerability. Oral CBD administration does not appear to affect tear production or IOP over a 36-week period. This is the first canine study positively identifying concentrations of CBD in tears following oral administration.

Effect of topical non-steroidal anti-inflammatory drugs on healing times and complications in dogs with spontaneous chronic corneal epithelial defects.

BACKGROUND: Little is published regarding topical NSAID effect on corneal healing in dogs. This retrospective cohort study aimed to compare healing times and complications in dogs with spontaneous chronic corneal epithelial defects (SCCED) treated with and without topical non-steroidal anti-inflammatory drugs (NSAID). METHODS: Medical records of 66 dogs (71 eyes) diagnosed with SCCED between 2008 and 2019 were included. Eyes were divided into: (1) those receiving topical NSAIDs (n = 33) versus (2) those not receiving topical NSAID (n = 38). Follow-up until healed, such as comfortable eye, negative fluorescein stain was required. Use of topical or systemic anti-inflammatories outside of NSAID or presence of ocular disorders or systemic endocrinopathies that may contribute to delayed healing resulted in study exclusion. RESULTS: Healing times were significantly longer in eyes that received topical NSAID (p = 0.008), however, the use of more topical medications for treatment was also associated with longer healing times (p = 0.001). The majority of eyes in the NSAID group received multiple medications, compared to the non-NSAID group, so it was not possible to separate the effects of NSAID from a number of medications. Complications occurred in three eyes of three dogs within the NSAID group. CONCLUSIONS: In these canine SCCED eyes, the use of more topical medications, including NSAID, was associated with significantly delayed healing time.

Golden retriever pigmentary uveitis: Vision loss, risk factors for glaucoma, and effect of treatment on disease progression.

OBJECTIVE: In previous reports, almost half of Golden Retrievers with Pigmentary Uveitis (GRPU) have lost vision in an eye within a year of diagnosis. The purpose of this study was to determine the proportion of GRPU affected dogs with vision loss, risk factors for the development of glaucoma, and effect of treatment on disease progression. ANIMALS STUDIED: Client owned Golden Retrievers. PROCEDURES: Two complete ophthalmic examinations were performed at least 6 months apart. Visual status, presence of glaucoma, GRPU score, and treatment were recorded. A proportional odds (ordinal logistic) model was fitted to determine whether the use of topical steroidal or non-steroidal (NSAID) ophthalmic preparations was associated with a change in GRPU scores. RESULTS: Twenty-nine Golden Retrievers, 58 eyes, were included. One eye was enucleated after the first examination. On first examination, 57/58 (98.3%) eyes and 29/29 (100%) dogs were visual. At the second examination, 48/57 (84.2%) eyes and 25/29 (86.2%) dogs were visual. Vision loss in 7/9 (77.8%) eyes was secondary to glaucoma. Posterior synechia and fibrinous material in the anterior chamber were significant risk factors for the development of glaucoma (P < .001). There was no significant difference in the change in GRPU score between eyes receiving topical steroids and topical NSAIDs (P = .14). Time between examinations was a significant factor in disease progression (increased GRPU score; P = .016). CONCLUSION: The number of eyes and dogs that retained vision was higher than previous reports. No topical treatment was superior in slowing disease progression. Golden Retriever Pigmentary Uveitis is a slowly progressive disease.