A review of equine paranasal sinusitis. Aetiopathogenesis,clinical signs and ancillary diagnostic techniques

The equine paranasal sinuses are air filled cavities of uncertain function that are susceptible to inflammation, usually associated with bacterial infection. A common feature of most types of sinusitis is the accumulation of exudate within the affected sinus and subsequent ipsilateral nasal discharge. Equine sinusitis can have a variety of causes, including primary sinusitis following upper respiratory tract infections, and secondary sinusitis caused by dental infections, intrasinus benign and malignant growths and head trauma.     

Equine paranasal sinus disease: a long-term study of 200 cases (1997-2009): treatments and long-term results of treatments

Reasons for performing study: There is limited objective information available on the treatment and the long‐term response to treatment of the different types of equine sinus disease. Objectives: To document the treatments and long‐term response to these treatments in 200 cases of equine sinus disease (1997–2009). Methods: The treatments of horses affected with subacute primary sinusitis (n = 52); chronic primary sinusitis (n = 37); dental sinusitis (n = 40); sinus cyst (n = 26); traumatic (n = 13); dental‐related oromaxillary fistula (n = 8); sinus neoplasia (n = 10); mycotic sinus disease (n = 7); and intrasinus progressive ethmoid haematoma (n = 7) and the long‐term response to these treatments were retrospectively reviewed. Results: Treatments evolved throughout the study and latterly were as conservative as possible, including sinoscopic lavage and standing sinusotomy, with a maxillary sinusotomy approach preferred for the mainly mature horses treated in this study. Removal of intrasinus inspissated pus, including transendoscopically (by sinusotomy and via existing sinonasal fistulae), was the main treatment for chronic primary sinusitis and sinonasal fistulation was seldom performed latterly. Attempted oral extraction of infected cheek teeth, even if unsuccessful, facilitated subsequent dental repulsion, resulting in few post operative problems. Sinus cyst removal carried an excellent prognosis. Except for cases of sinus neoplasia (only 22% cured), an excellent long‐term response to treatment (91% fully cured, 7% partially cured) was obtained for all other types of sinus disease following a median of one treatment. Conclusions: More conservative treatments, including removal of intrasinus inspissated pus by sinoscopy, pre‐existing sinonasal fistula or sinusotomy, are effective for chronic primary sinus disease. Standing sinusotomy, mainly using a small maxillary site, was suitable for most cases of sinus disease in mature horses.     

Reoccurrence of a paranasal osteoma following surgical removal in a 6-month-old Warmblood filly

A 6-month-old Warmblood filly presented for evaluation of a left sided unilateral mucopurulent discharge of 5 weeks' duration. Upper airway endoscopy revealed a large, smooth mass in the region of the ethmoturbinates. Dorso-ventral and lateral radiographs of the head revealed a large osseous mass in the left paranasal area. A biopsy was performed under general anaesthesia and an osteoma was diagnosed. A computed tomography (CT) examination was performed to guide surgical removal. Surgery was performed under general anaesthesia and a large mass was removed ~15 × 9 cm. A CT examination 3 months following surgery revealed three small areas of mineralisation. It was difficult to differentiate if these were areas of regrowth or portions of the original mass that were not entirely removed. A CT examination 8 months later revealed one of the areas had increased moderately in size. A second surgery was performed standing to remove the growth. A final CT 8 months later revealed no further evidence of a bone growth. This report describes the successful removal of an osteoma regrowth following initial surgical removal and, to the best of the authors’ knowledge, is the first to describe the reoccurrence of an osteoma after surgical intervention. It also describes a successful rhinotomy in the standing equine patient. This case highlights the importance of serial follow-up imaging after surgical removal as osteoma regrowth occurred in this case.     

Heterotopic polydontia as a cause for a cystic lesion in the paranasal sinus of a Thoroughbred filly

A 1-year-old Thoroughbred filly with left bony facial distortion was diagnosed with a multilobar expansile mass within the caudal maxillary and frontal sinuses on computed tomography (CT). Typical findings associated with a sinus cyst, including expression of amber fluid from the mass and a thick lining that could be peeled from the sinus walls, were found on surgical exploration of the sinus under general anaesthesia. Histological examination of firm structures within the fluid-filled cyst contained all components of embryologically normal dental tissue. The filly recovered well and entered training to race as a 2-year-old, as remodelling of the bony distortion and narrowing of the nasal passage was sufficient for airflow. Previous reports of paranasal cystic lesions in horses suggest developmental abnormalities as a causative factor, especially in young horses. Furthermore, heterotopic polydontia is reported as the underlying aetiology in some human paranasal sinus cysts. While polydontia has been reported in the paranasal sinuses and nasal passages of horses, this is the first case report that finds them associated with a cystic lesion within the paranasal sinus.     

Squamous cell carcinoma of the paranasal sinuses in two horses

This case report describes the history, clinical findings, diagnostic imaging (including computed tomography), gross pathology and histopathology of 2 cases of squamous cell carcinoma in the paranasal sinuses. Radiography of the skull is a useful tool to detect a mass in the paranasal sinuses, but the position, extent and character of the lesion can be better visualised with computed tomography.     

Pyogenic meningitis and trigeminal neuritis secondary to periodontogenic paranasal sinusitis in a red deer (Cervus elaphus)

An adult female red deer died of a severe seizure and dysbasia. Postmortem computed tomography (CT) and magnetic resonance imaging (MRI) were performed. On CT, deciduous right maxillary second and third premolar teeth were observed, and the right infraorbital canal was disrupted. MRI showed that the right trigeminal nerve was enlarged and the right subarachnoid cavity was occupied by fluid and gas. On gross examination, the right paranasal sinus, swollen muscles of the orbit and tonsils, right trigeminal nerve, and right cerebrum surface contained a yellowish-white, cheese-like pus. Based on these findings, the deer was believed to have developed pyogenic meningitis caused by a neuropathic infection secondary to periodontogenic paranasal sinusitis.     

Treatment of equine oro-nasal and oro-maxillary fistulae

Equine oro-nasal or oro-sinus fistulae are usually problematic disorders to treat. As these lesions are mainly a sequel to standard dental repulsions, it is obvious that safer exodontia techniques such as oral extraction should now be used. The initial treatment of such fistulae is to ensure that there is a healthy granulating alveolus, without any dental or alveolar sequestrae and that all epithelium lining the fistula is removed. Provided there is a tooth on either side of the fistula, the initial and usually successful treatment is the use of an acrylic alveolar plug attached to adequately prepared adjacent teeth. Reinforcing such prostheses with wire tied between adjacent teeth will stabilise such prostheses. For fistulae that extend far onto the hard palate or those at the Triadan 06 or 11 alveolar sites that cannot be treated by acrylic prostheses, a variety of surgical treatments including; mucoperiosteal sliding flap, transposition of facial muscles, maxillary bone flap or an ear cartilage graft are all potential therapies, but there  are no large, objective long-term reports on their success available.     

A review of swellings of the frontal region of the equine head

Gross swellings of the equine frontal area are most commonly caused by the poorly understood disorder of nasofrontal suture line periostitis that is usually self‐resolving, sinus cysts that are highly amenable to treatment, sinus tumours that in contrast usually respond poorly to treatment and facial trauma that may later lead to nasofrontal suture line periostitis. Other causes of conchofrontal sinus disease such as intrasinus progressive ethmoid haematoma, primary sinusitis and dental sinusitis seldom cause gross swellings of the overlying bones.     

Calcified tumours of the paranasal sinuses in three horses

Three horses, a 10-year-old Thoroughbred mare, a 9-year-old Thoroughbred gelding and a 6-year-old Arab gelding, with calcified tumours of the paranasal sinuses, are described. All horses presented with purulent nasal discharges and facial distortion. Exophthalmos, blepharospasm and ocular discharge were also a feature in individual horses. A presumptive diagnosis of a calcified tumour was made on the basis of clinical signs and radiographic and endoscopic findings. The tumours ranged from 15 to 25 cm in diameter. A large frontonasal bone flap was used to expose the tumours, which were cleaved into several pieces with an osteotome and removed. Histological examination of the masses identified cementomas in two cases and an osteoma in the third. Long term follow up from 18 months to 5 years after surgery indicated that there was no recurrence. This case series demonstrates that, although calcified tumours of the paranasal sinuses are rare in horses, they should be considered in the differential diagnosis of purulent nasal discharge, facial swelling and ocular distortion, and are amenable to surgical treatment.     

A review of equine sepsis

Sepsis is defined as an exaggerated, systemic inflammatory response to infection and is a common condition in horses. Systemic inflammatory response syndrome (SIRS) associated with bacterial infection is a hallmark of sepsis. Sepsis in neonatal foals is a common sequela of failure of passive transfer and, in addition to development of SIRS, may be characterised by bacteraemia, pneumonia, enterocolitis, omphalophlebitis, meningoencephalitis or arthritis. Sepsis in mature horses is most commonly observed secondary to gastrointestinal lesions that result in disrupted mucosa and bacterial translocation into circulation (endotoxaemia). Pleuropneumonia and metritis may also cause sepsis in mature horses. Diagnosis of sepsis is based on SIRS criteria as well as suspected or confirmed infection. Due to the relatively low sensitivity of microbial culture and the subjectivity of sepsis scoring, many sepsis biomarkers are being studied for their usefulness in diagnosis and prognostication of sepsis in horses. Treatment of sepsis requires an intensive care approach that includes antimicrobial drug administration, fluid resuscitation and pressure support, and treatment for inflammation, endotoxaemia and coagulopathy. Early recognition of sepsis and prompt antimicrobial drug treatment are critical for a successful outcome. Multiple organ dysfunction syndrome may occur in severe cases of sepsis, with common manifestations including laminitis and coagulopathies. Although prognosis for septic mature horses depends highly on the primary disease process, the overall survival rate in septic neonatal foals ranges from 26 to 86%, with most studies indicating a survival rate of 45–60%.     

Extra-nasal approach to access the dorsal and ventral conchal bullae in horses

Nasal conchal bulla empyema can be found in up to 20% of horses with paranasal sinus disease but remains difficult to diagnose and can result in persistent unilateral discharge before presentation. Our aim in this experimental ex vivo study was to describe two extra-nasal approaches to access the nasal conchal bullae. Six cadaveric heads were used to determine the ideal landmarks to access the dorsal and ventral conchal bullae through two rhinocenteses performed with the aid of a 14G needle and a mallet through the maxillary bone, and to access both bullae simultaneously through a 13-mm diameter trephination. Both techniques were performed bilaterally. To assess correct placement of the rhinocenteses and trephination, each bulla was injected with a coloured insulating foam before performing a maxillary bone flap to inspect the bullae. Both bullae were successfully entered with the 14G needle in all instances. The nasolacrimal duct was damaged while entering the ventral conchal bulla in 3/12 approaches. Trephination of the maxillary bone allowed access to both nasal conchal bullae in all cases but one, where the portal was placed too dorsally and did not allow access to the ventral conchal bulla. The opening created with the trephine could allow the use of a small instrument such as a rongeur which could have diagnostic and therapeutic benefits. The limitations are that this was an ex vivo study and nasolacrimal duct damage could have clinical repercussions if the duct becomes obstructed after accessing the ventral conchal bulla. It was concluded that the techniques described are simple, minimally invasive and provide access to the conchal bullae for diagnostic and therapeutic purposes. Additionally, they may reduce the need for CT or laser for the diagnosis and treatment of bulla empyema.     

A review of equine sarcoid

Equine sarcoid is the most common tumour of horses and accounts for over half of all equine skin tumours. Six types of sarcoid based on gross appearance and clinical behaviour have been described including occult, verrucous, nodular, fibroblastic, mixed and malevolent. Common locations for sarcoid development include the periocular region, ear pinnae, lips, neck, extremities and ventrum (including groin region). Bovine papillomavirus (BPV) is causally associated with equine sarcoid with genetic haplotype, fly vectors and skin trauma identified as potential risk factors for development of the disease. Histopathology is required for definitive diagnosis of equine sarcoid but incomplete excision is thought to activate latent BPV and stimulate growth. Although there are no uniformly effective treatment options, several modalities have been successful in eliminating or managing equine sarcoid. Surgical excision, intratumoural chemotherapy, cryotherapy, hyperthermia, radiotherapy, immunotherapy and immune modulators are used with degrees of success relative to the accessibility and invasiveness of the tumour. Prevention of equine sarcoid may be facilitated by future development of vaccines against bovine papillomavirus.