What Is Your Diagnosis?

In collaboration with the American College of Veterinary Radiology.

Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Endogenous Opioid Signaling in the Mouse Retina Modulates Pupillary Light Reflex.

Opioid peptides and their receptors are expressed in the mammalian retina; however, little is known about how they might affect visual processing. The melanopsin-expressing intrinsically photosensitive retinal ganglion cells (ipRGCs), which mediate important non-image-forming visual processes such as the pupillary light reflex (PLR), express β-endorphin-preferring, µ-opioid receptors (MORs). The objective of the present study was to elucidate if opioids, endogenous or exogenous, modulate pupillary light reflex (PLR) via MORs expressed by ipRGCs.

Unfolding the diagnosis of subspectacular fluid opacity in a corn snake (Pantherophis guttatus).

Objective: To present the results of clinical, surgical, and histopathologic procedures and how these were compared with the initial presumptive clinical diagnosis in a corn snake (Pantherophis guttatus) presenting with subspectacular fluid opacity; and to improve upon currently established surgical enucleation techniques in the snake.

Animal Studied: An 8-month-old corn snake was presented for enlarged globe OD.

Procedures: The following diagnostics were performed: systemic and ophthalmic examinations, complete blood count, cytology and culture of subspectacular fluid, and histopathology of enucleated globe and spectacle.

μ-Opioid Receptor Activation Directly Modulates Intrinsically Photosensitive Retinal Ganglion Cells.

Intrinsically photosensitive retinal ganglion cells (ipRGCs) encode light intensity and trigger reflexive responses to changes in environmental illumination. In addition to functioning as photoreceptors, ipRGCs are post-synaptic neurons in the inner retina, and there is increasing evidence that their output can be influenced by retinal neuromodulators. Here we show that opioids can modulate light-evoked ipRGC signaling, and we demonstrate that the M1, M2 and M3 types of ipRGCs are immunoreactive for μ-opioid receptors (MORs) in both mouse and rat.

Iridocorneal angle assessment of companion rabbits using gonioscopy, spectral-domain optical coherence tomography (Optovue iVue ), high-resolution ultrasound, and Pentacam HR imaging.

Objective: Iridocorneal angle (ICA) narrowing is a known risk factor for primary glaucoma in multiple species, but has not been described in companion rabbits. This study aimed to develop an ICA grading scheme for companion rabbits to enable early glaucoma predisposition diagnosis.

Animals Studied: Twenty healthy rabbits of varying breeds and ages.

Surgically induced astigmatism in canines following sutured dorsonasal vs dorsotemporal clear corneal incisions.

Objectives: To investigate use of the Pentacam® HR for evaluation of surgically induced corneal astigmatism (SIA) in canines undergoing bilateral phacoemulsification and determine differences between dorsonasal and dorsotemporal clear corneal incisions.

Animals: Client-owned canines undergoing bilateral phacoemulsification.

Procedures: Patients received anterior segment imaging pre-operatively, immediately post-operatively, and 2-4 months post-operatively (follow-up).

Anterior segment parameters in normal dogs using the Pentacam HR Scheimpflug system.

Objective: To describe and compare normative anterior segment parameters between canine age groups using the Pentacam HR Scheimpflug camera (Pentacam).

Animals Studied: Thirty-six sedated dogs (60 eyes) of varying ages and breeds were imaged with the Pentacam; only nondiseased anterior segments were included.

Procedures: Dogs were divided into three age groups: Group 1 (1-5 years), Group 2 (6-10 years), and Group 3 (11-15 years).

Canine central corneal thickness measurements via Pentacam-HR , optical coherence tomography (Optovue iVue ), and high-resolution ultrasound biomicroscopy.

Objective: To compare central corneal thickness (CCT) values in canine eyes using Pentacam-HR Scheimpflug imaging (Pentacam), Optovue iVue spectral-domain optical coherence tomography (SD-OCT), and high-resolution ultrasound biomicroscopy (UBM) and generate normative canine Pentacam CCT values.

Animals Studied: Twenty-four client-owned dogs (37 eyes) with nondiseased cornea(s) presenting to the Colorado State University Veterinary Teaching Hospital.

Procedures: Corneal images were acquired via Pentacam, SD-OCT, and UBM in the listed order.

Comparison between Pentacam-HR and optical coherence tomographycentral corneal thickness measurements in healthy feline eyes.

Objectives: To measure the central corneal thickness (CCT) in healthy feline eyes with Scheimpflug imaging (Pentacam, Pentacam(®) -HR) and to compare these values with those obtained with spectral-domain optical coherence tomography (OCT, Optovue(®) iVue).

Animals Studied: Thirty one sedated Domestic Short-haired cats.

Procedures: Two repeated CCT measurements were obtained from both eyes using Pentacam measured at the pupil center and corneal apex (CCTpupil and CCTapex ) and using SD-OCT (CCTOCT ).