Introduction of a chronic sinusitis case on a horse

This case report describes dental and sinus interventions performed on S., a 22-year-old AQH horse with a history of sinusitis and a mass in the maxillary sinuses. S. is also being treated for PPID (Cushing's disease) and has a history of laminitis.

Case Description 

(August 13, 2024 – First consultation at Equide)

The horse was referred for sinusitis with a mass visible on radiography. He had experienced unilateral left nasal discharge since April (4 months), initially causing severe irritation treated with corticosteroids. However, this treatment led to laminitis, complicating the clinical picture.

The clinical diagnosis revealed a non-odorous nasal discharge, slight swelling of the left mandibular lymph node, and a 7 cm right thyroid mass. The horse also exhibited "headshaking" (sinus pathologies can affect major cranial nerves, sometimes leading to headshaking). Radiographic examination did not show significant dental pathology, although the left sinus was radio-opaque, with pus and fungi observed in the maxillary and frontal sinuses via endoscopy. A bone sequestrum was detected, but extraction through the nasal route proved challenging.

Methods and Treatments 

• Medication: Detomidine (D) and Torbugesic (T) for sedation, Pergoquin for PPID treatment.
• Surgical Procedures: Intensive flushing of the left sinus complex with saline (NaCl) to remove pus. Multiple attempts to extract the bony/cartilaginous sequestrum nasally. Finally, removal of the bony/cartilaginous sequestrum via trepanation (12mm).
• Follow-up: Anti-inflammatory treatment. Antibiotic treatment (doxycycline) is considered in case of fever. 

(September 9, 2024 – Follow-up consultation at Equide) 

A follow-up was conducted after one month. S. was generally stable, but a sinoscopic examination revealed persistent fungi in the maxillary sinus (limited), as well as granulation tissue at the trepanation site (inner surface), indicating good healing. A preventive odontoplasty was performed to remove excessive enamel points, maintaining a functional and healthy chewing surface.

Local antifungal treatment with Nystatin (double sinoscopy via the nasal route) and removal of the remaining resorbable suture at the trepanation site.

Upon returning home, the horse’s owner noticed that headshaking decreased over time, and the horse no longer exhibited nasal discharge or odor.

Discussion 

The interventions on S. illustrate the complexity of treating chronic sinusitis in elderly horses, especially those with PPID. Managing this sinusitis was complicated by the modified sinus anatomy and size of the bony sequestrum. The treatment was well tolerated, despite several attempts being necessary to completely remove the sequestrum.

The odontoplasty aimed to prevent injuries associated with excessive enamel points, a common issue in horses with occlusal abnormalities like postnormal occlusion.

Conclusion 

This case highlights the importance of a multidisciplinary approach in managing horses with complex chronic conditions, especially when endocrine disorders such as PPID are present. Regular care and follow-up treatments, including preventive dental procedures, are essential to maintaining the quality of life in these horses.

FAQ

1. What is chronic sinusitis in horses?
Chronic sinusitis is a long-standing inflammation or infection of one or more paranasal sinuses. Unlike an acute case, a chronic form often involves biofilm formation, more complex infections, and resistance to simple treatments.

2. How is chronic sinusitis diagnosed in older horses?
Diagnosis usually involves a combination of:

• Clinical signs (unilateral nasal discharge, facial swelling, reduced appetite) 

• Endoscopy or sinoscopy to visualize inside the sinus 

• Imaging (radiographs, CT) to detect fluid lines, masses, tooth root involvement 

3. What are the treatment options and prognosis for chronic sinusitis?

• Medical: Frequent sinus lavage, using appropriate antibiotics based on culture, and anti-inflammatories. In chronic cases biofilm and resistant bacteria can make medical therapy alone insufficient. 

• Surgical: transnasal sinoscopy treatment, Trephination, sinusotomy (bone flap) or sinus flap surgery to allow drainage, removal of exudate, access for flushing.

• Prognosis: If the root cause is identified and treated, many horses can return to function. However, relapse is possible, especially in chronic or secondary cases