Radiographic and gross anatomy of the nasolacrimal duct of the horse

The anatomy of the nasolacrimal duct of the horse was studied grossly and radiographically, using barium contrast dacryocystorhinography and methyl methacrylate casts. Radiographic contrast studies were performed on 4 specimens and gross dissections were performed on 6 specimens. Dacryocystorhinography accurately delineated the course of the nasolacrimal duct, as was subsequently demonstrated by gross dissection. A 60% barium sulfate suspension produced good radiographic contrast, allowing critical assessment of the anatomic features of the nasolacrimal duct.     

Surgical treatment of recurrent dacryocystitis secondary to cystic dilatation of the nasolacrimal duct in a dog

A 3-year-old, castrated male golden retriever was presented for evaluation of recurrent ocular discharge of 4 months' duration from the left eye. Dacryocystorhinography was performed and demarcated a cystic dilatation of the left nasolacrimal duct with obstruction of the duct distal to the cystic cavity. Surgical exploration of the left maxillary sinus was performed to confirm the diagnosis and reestablish drainage into the nasal cavity. Recovery was uneventful, and the dog has been asymptomatic for >36 months postoperatively. This report documents the third published case of surgical treatment for cystic dilatation of the nasolacrimal duct.     

Congenital nasolacrimal atresia in 4 alpacas

Four alpacas, 2 wk to 1 y of age, were diagnosed with congenital atresia of the nasal puncta of the nasolacrimal duct. Dacryocystorhinography confirmed and localized the atresia. All animals were treated successfully by surgical creation of nasal puncta and patency was ensured by placement of a surgical stent for several weeks.     

Nasolacrimal obstruction caused by root abscess of the upper canine in a cat

A 10‐year‐old, castrated male domestic short hair cat was presented to the Small Animal Clinic at the Western College of Veterinary Medicine with a presenting complaint of chronic, ocular discharge from the left eye. Ocular examination confirmed epiphora and mucopurulent discharge but there were no apparent reasons for the ocular discharge, and nasolacrimal obstruction was suspected. The cat had swelling of the left side of the face, severe periodontal disease and a fractured upper left canine tooth with pulpal exposure. Dacryocystorhinography revealed narrowing of the nasolacrimal duct above the root of the fractured upper left canine and dental radiographs showed a severe periapical lucency at the apex of the upper left canine tooth. The fractured canine tooth was removed. Subsequently, the ocular discharge and facial swelling resolved. After 2 years, the epiphora has never reoccurred. This is a noteworthy case because a suspected root abscess resulted in extralumenal compression of the nasolacrimal duct, which shows the importance of a thorough oral examination when nasolacrimal obstruction is evident.     

Suture exostosis causing obstruction of the nasolacrimal duct in three horses

CASE HISTORY Three horses were presented with facial swelling and epiphora.

CLINICAL FINDINGS: All horses had facial swellings and radiographic findings consistent with exostosis at the lacrimomaxillary suture, and ipsilateral epiphora. Positive contrast dacryocystorhinography demonstrated that the site of obstruction of the nasolacrimal duct was located where the duct traverses the lacrimomaxillary suture.

DIAGNOSIS: Lacrimomaxillary suture exostosis.

CLINICAL RELEVANCE: Lacrimomaxillary suture exostosis should be considered as a differential diagnosis in cases of epiphora in horses. Dacryocystorhinography, preferably retrograde and normograde, may be used as an aid to diagnosis.     

Acquired canaliculocele with intranasal extension in a dog

To describe a case of a nasolacrimal canaliculocele with intranasal extension in a dog. A 6‐year‐old neutered female Jack Russell Terrier was referred to the Centre Hospitalier Vétérinaire des Cordeliers for a slowly enlarging mass adjacent to the medial canthus of the right eye of 5 months duration. Ophthalmic exam, ultrasound, fine needle aspiration, dacryocystorhinography and computerized tomography examinations were performed. Rhinoendoscopic treatment with marsupialisation of the endonasal canaliculocele was performed. Physical examination revealed a 3 cm diameter, subcutaneous mass beneath the medial canthus of the right eye, with a defect in the maxillary bone below. Dacryocystorhinography demonstrated blockage at the level of the nasolacrimal duct. Fine needle aspiration confirmed the cavitary nature of the lesion. During rhinoendoscopy, a mass containing watery fluid was found. Following marsupialisation with a large mass wall resection, the lacrimal drainage system irrigated freely in the nasal chamber. The communication of the lumen of the diverticulum with the lumen of the superior but not the inferior canaliculus was clearly demonstrated during endoscopy. Given negative immunohistochemical staining for smooth muscle actin and desmin, nasolacrimal dacryocele appears to be the most likely diagnosis. Histological examination confirmed that no goblet cells were present in the wall of the diverticulum, which is consistent with the canaliculus rather than the lacrimal sac. Complete resolution was observed without recurrence one year after surgery. Despite its rarity, a canaliculocele should be considered in adult dogs with nasolacrimal duct obstruction. Marsupialisation seems to be the appropriate therapy.     

COMPUTED TOMOGRAPHY-ANATOMY OF THE NORMAL FELINE NASOLACRIMAL DRAINAGE SYSTEM

Computed tomography (CT) of the nasolacrimal drainage system with and without contrast medium (barium sulfate) was used to create an anatomic basis for clinical evaluation in domestic cats. To evaluate and compare the anatomical findings, three casts were carried out and were followed by CT examinations. These CT series were also used for a three-dimensional (3D) reconstruction of the nasolacrimal drainage system within surrounding structures. In noncontrast CT images, osseous structures limiting the nasolacrimal drainage system are easily recognizable. In most cats, this allows the identification of the nasolacrimal drainage system even without contrast enhancement. A distal part of the lacrimal sac adjoins directly to the respiratory mucosa of the nasal cavity without an osseous protection. Thus, this may represent a predilection site for infiltration of adjacent pathologic processes from the nasal cavity onto the lacrimal sac. The nasolacrimal duct begins on level with the maxillary third premolar tooth. The apex of the root of the canine tooth is situated very close to the nasolacrimal duct. This close topographic relation may lead to problems with the nasolacrimal drainage system. In domestic cats the nasolacrimal drainage system consists of a descending and a horizontal part, which form an angle of approximately 90 degrees for unhindered drainage of the lacrimal fluid.     

The course of the nasolacrimal duct in brachycephalic cats

Casts of the nasolacrimal duct system were obtained from 50 euthanised cats including brachy-, meso- and dolichocephalic breeds. The course of the nasolacrimal duct, which was assessed radiographically and gross-anatomically, was strongly related to the shape of the skull. In meso- and dolichocephalic cats the nasolacrimal duct formed a dorsally opened arch with the descending part being directed rostroventrally. The main part of the duct passed the nasal cavity in a rather horizontal course parallel to the hard palate and was located ventrally to the lacrimal foramen. However, foreshortening of the face was associated with a right-angled or even acute-angled alignment of the duct. In higher degrees of brachycephaly the main part of the duct ascended beyond the level of the lacrimal foramen and passed the nasal cavity dorsal to the level of the lacrimal foramen. This specific course of the nasolacrimal duct in brachycephalic cats was consistent with a steeper alignment and attachment of the maxilloturbinate. Accessory orifices of the nasolacrimal duct opening into the nasal cavity had never been observed. The present results strongly suggest that the specific course of the nasolacrimal duct in brachycephalic cats might hinder the drainage of the lacrimal fluid irrespective of the diameter of the lumen of the nasolacrimal duct system.     

Endoscopic examination of the nasolacrimal duct in ten horses

Reasons for performing study: No endoscopic examination of the nasolacrimal duct has been described before. In contrast with other imaging techniques, endoscopy provides a direct inspection of the intralumen and ductal mucosa in standing sedation. Objectives: To provide a reference against which the endoscopic and clinical features of obstructive nasolacrimal disease in the horse may be compared. Methods: Endoscopic examination of the nasolacrimal duct was performed in 10 French Thoroughbred bay mares with a 3 mm shaft diameter flexible fibrescope. The duct was divided into 3 zones (1, 2 and 3) from the nostril to the lacrimal sac. Results: Endoscopic examination of the nasolacrimal duct appeared to be quite easy to perform in Zones 1 and 2, while the ease or difficulty of examining Zone 3 depended on the weight and size of the horse for the position of the endoscope in the lacrimal canal. Conclusions: Endoscopic inspection has provided the possibility of a novel diagnostic approach to conditions of the nasolacrimal duct in horses. Potential relevance: Endoscopic examination of the nasolacrimal duct could help to diagnose and treat nasolacrimal diseases by performing sample withdrawal and duct irrigation.     

Intraosseous approach to the nasolacrimal duct for removal of a foreign body in a dog

A Labrador retriever was evaluated because of chronic mucopurulent discharge from the left eye. A foreign body was identified in the nasolacrimal duct by use of dacryocystorhinography. Attempts to alleviate the inflammation by use of flushing and administration of antimicrobials were unsuccessful. At surgery, the infraorbital foramen was used as a landmark for a skin incision, because the nasolacrimal duct courses dorsal and parallel to the infraorbital canal. An air drill was used to remove the portion of the maxillary bone overlying the nasolacrimal duct, which exposed the intraosseous portion of the duct and allowed removal of a plant-material foreign body. The incision in the duct was allowed to heal by second intention, and the dog recovered without complications.     

Repair of anomalous nasolacrimal duct in a bull by use of conjunctivorhinostomy

A proximal nasolacrimal duct anomaly, believed to be congenital, in a bull was repaired by use of conjunctivorhinostomy. Initial attempts at correction, using prolonged nasolacrimal duct catheterization, were unsuccessful. Trephination from the medial canthus to the ventral nasal meatus, combined with long-term catheterization of this new passage, was successful in resolving clinical signs of disease.     

A method of surgical correction of glaucoma in a dog

A new surgical technique is described for the attempted relief of glaucoma in a dog. To achieve aqueous drainage a Supramid thread was placed in the anterior chamber, threaded subconjunctival^ across the globe and inserted into the nasolacrimal duct via the dorsal lacrimal punctum. It is hoped that the level of success achieved in this one case will prompt others, to investigate the nasolacrimal duct as a possible drainage route for aqueous fluid.     

Differential diagnoses,investigation, and management of a periocular swelling close to the nasolacrimal duct in a horse – A case report of Dacryops

To describe the differential diagnoses, investigation, and management of a periocular swelling close to the nasolacrimal duct in a horse that was consistent with a nasolacrimal duct dacryops (lacrimal cyst). A 16‐year‐old gelding, Connemara cross presented with a history of a periocular swelling rostroventral medial to the right eye that had been sampled by the referring veterinary surgeon. A cystic lesion was diagnosed following standing computed tomography. Surgical removal of the cystic lesion was performed, and the tissue was submitted for histopathologic and immunohistochemical examination. Surgical removal of the cyst was curative, and there was no recurrence of clinical signs 7 months later. There was a small amount of mineralized material in the center of the cyst. Histopathologic and immunohistochemical examination confirmed a nasolacrimal duct cyst. Dacryops can form in horses as well as other species and appears to have a favorable outcome if surgically removed.     

The nasolacrimal duct of the mule: Anatomy and clinical considerations

This study investigated the location of the nasolacrimal orifice (NLO) and course of the nasolacrimal duct in the mule using visual examination, gross dissection and computed tomography (dacryocystography [CT‐DCG]) and concluded that the location of the NLO is distinct from that described for horses and donkeys and is easily located, by visual examination alone, within the internal cutaneous tissue of the lateral wall of the external nares. The course of the nasolacrimal duct caudal to the nasal vestibule is similar to that of the horse.     

Bilateral congenital lacrimal fistula in a Brown Swiss bull

A five-year-old Brown Swiss bull was referred to the Department of Farm Animals, University of Zurich, because of bilateral epiphora that was unresponsive to treatment. Clinical examination revealed a fistulous opening medial to the medial canthus of both eyes and mucopurulent discharge from both openings. Attempts to flush the nasolacrimal duct via the lacrimal points resulted in the fluid exiting via the fistulous opening. Retrograde flushing of the nasolacrimal duct from the nasolacrimal opening resulted in the flush fluid flowing back out the nasolacrimal opening. Bilateral lacrimal fistula medial to the medial canthus of the eye was diagnosed based on the findings. The same anomaly was diagnosed a year later in 4?related female animals referred to our Department for other reasons. Three of the cases were sired by the bull described above and one was sired by his half-brother. Therefore, an autosomal recessive mode of inheritance of this anomaly was assumed. Clinical, epidemiological and molecular studies of the offspring of both bulls are underway to further investigate this anomaly.     

Computed tomography dacryocystography evaluation of the nasolacrimal apparatus

Computed tomography-dacryocystography (CT-DCG) was used to evaluate the nasolacrimal system in four patients (three dogs and one horse) that were admitted for evaluation of chronic epiphora, facial swelling, or facial trauma. The four patients are reviewed and the technique for performing CT-DCG is described. Additionally, the indications for this procedure are discussed. CT-DCG is advantageous because cross-sectional imaging provides superior resolution of the nasolacrimal apparatus and the relatively long, small-diameter, bony nasolacrimal canal in most veterinary patients.     

Bilateral nasolacrimal duct atresia in a cria

A 2-month-old, male alpaca had a 1-month history of mucoid ocular discharge from the left eye. Signalment, history and clinical findings were suggestive of a congenital nasolacrimal outflow obstruction. A dacryocystorhinogram confirmed bilateral nasolacrimal duct atresia, which involved the distal half of both nasolacrimal ducts. In order to establish alternative outflow, a conjunctivomaxillosinusotomy and conjunctivorhinostomy were performed on the right and left eye, respectively. The surgical openings remain patent after 11 months, and there have been no clinical signs of nasolacrimal disease.     

Endoscopic management of a cystic naso-lacrimal obstruction in a dog

A young adult Dachshund was presented with a cystic obstruction of the nasolacrimal duct causing maxillo-turbinate destruction but no epiphora. The lesion was demonstrated by dacryocystorhinography and identified on nasal endoscopy which also permitted the successful creation of a permanent fistula without resort to invasive surgery. Histological examination of the cystic wall of the duct showed normal turbinate structures replaced by chronic inflammatory tissue.     

Microvascular anatomy of the third compartment of the stomach of llamas

OBJECTIVE: To characterize the vascular anatomy of the third compartment of the stomach of llamas. ANIMALS: 7 adult llamas. PROCEDURE: Immediately after each llama was euthanatized, vascular replicas of tissue from the third compartment were prepared by use of methylmethacrylate monomer and catalyst. Following chemical removal of tissue, the casts were further prepared for examination via scanning electron microscopy. By use of barium solution, microangiography was also performed on fixed tissue samples; the infused tissue was sectioned and imaged radiographically. Tissue samples were also collected for histologic evaluation after fixation and H&E staining. RESULTS: The third compartment was supplied by 4 pairs of primary arteries and veins located around the circumference of the structure. From these vessels, smaller arteries and veins branched to supply the serosal surface and penetrated deeper through the tunica muscularis to supply the submucosal and mucosal layers. An extensive capillary network was arranged in a hexagonal array surrounding the gastric glands, such that the mucosal aspect of the replicas had a honeycomb-like appearance. Histologically, variably sized villous projections lined by a single layer of epithelial cells with an extensive glandular network were observed. CONCLUSIONS AND CLINICAL RELEVANCE: The third compartment of the stomach of llamas is a highly vascular structure with an extensive anastomotic capillary network at the luminal surface. Branching vessels provide extensive collateral circulation, and it appears that surgical incisions should heal well. Incisions in the third compartment should be oriented parallel to the longitudinal plane.