Comparative Anatomy of the Human and Canine Efferent Tear Duct System – Impact of Mucin MUC5AC on Lacrimal Drainage

Nasolacrimal sac foreign body extraction using vitreoretinal forceps in 28 dogs

PURPOSE

To describe a novel technique of nasolacrimal foreign body extraction in dogs by using a 20G vitreoretinal forceps introduced through the superior lacrimal punctum.

METHODS

A retrospective review of the medical records of dogs with dacryocystitis due to nasolacrimal foreign bodies between the years 2001 and 2022 was performed. We recorded the breed, age, affected eye, type and number of foreign bodies, concomitant diseases, and the use of imaging techniques. All animals underwent the same procedure of a 20G vitreoretinal forceps insertion through the upper canaliculus reaching the lacrimal sac and retrograde extraction of the foreign bodies.

RESULTS

A total of 28 dogs were included, 16 males and 12 females, with a mean (±SD) age of 4.7 (±3.2) years. The most common breeds were Wire-Haired Dachshund (4/28; 14.29%) and Labrador Retriever (3/28; 10.71%). Additional imaging techniques were used, such as orbital ultrasound in 13 cases (13/28; 46.43%) and computed tomography in one case (1/28; 3.57%). The most common type of foreign body retrieved was grass awns, although seeds and plant debris were also found. Dacryocystitis resolved after removal of the foreign body and appropriate medical therapy was ensured in all cases in the 1-month postprocedure follow-up.

CONCLUSION

Extraction of nasolacrimal foreign bodies with vitreoretinal forceps is a novel, noninvasive, and easily applicable technique that, although not successful in all cases, can be attempted before performing more aggressive surgery.

An eye on the dog as the scientist's best friend for translational research in ophthalmology: Focus on the ocular surface

Preclinical animal studies provide valuable opportunities to better understand human diseases and contribute to major advances in medicine. This review provides a comprehensive overview of ocular parameters in humans and selected animals, with a focus on the ocular surface, detailing species differences in ocular surface anatomy, physiology, tear film dynamics and tear film composition. We describe major pitfalls that tremendously limit the translational potential of traditional laboratory animals (i.e., rabbits, mice, and rats) in ophthalmic research, and highlight the benefits of integrating companion dogs with clinical analogues to human diseases into preclinical pharmacology studies. This One Health approach can help accelerate and improve the framework in which ophthalmic research is translated to the human clinic. Studies can be conducted in canine subjects with naturally occurring or noninvasively induced ocular surface disorders (e.g., dry eye disease, conjunctivitis), reviewed herein, and tear fluid can be easily retrieved from canine eyes for various bioanalytical purposes. In this review, we discuss common tear collection methods, including capillary tubes and Schirmer tear strips, and provide guidelines for tear sampling and extraction to improve the reliability of analyte quantification (drugs, proteins, others).