Introduction

• Formaldehyde coagulates proteins by hydrolysis → reduction in tissue volume and reduced hemorrhage.
• Ethmoid hematomas Ethmoid: hematoma: progressive ethmoid hematomas (PEH) cause clinical signs relating to impingement in the paranasal sinuses and nasal passages, secondary infection and spontaneous bleeds.

Uses

• Reduction in mass of ethmoid hematoma Ethmoid: hematoma:
  • Small lesions ideal.
  • Location in the nasal passage ideal.
• Follow up treatment of recurring lesions that have been surgically ablated.

Advantages

• Done in standing sedated horse Anesthesia: standing chemical restraint.
• Minimum specialized equipment required.
• Can be repeated.
• Easy to evaluate.
• High percentage of cases result in remission of clinical signs.

Disadvantages

• Formaldehyde (formalin) is toxic and irritant.
• 60% complete resolution of lesion by endoscopic evaluation.
• Access by endoscopy may be inadequate → need to use trephine Head: trephination and/or bone flap Paranasal sinus: bone flap technique to access lesions projecting into paranasal sinus.
• Not suitable for large lesions that are causing acute clinical signs.

Requirements

Preparation

Procedure

Aftercare

Outcomes

Prognosis

• Guarded: recurrence of lesions is likely.
• Frequent re-evaluation by transnasal endoscopy or radiography is recommended, as regrowth can be controlled with repeated intralesional formalin injections.

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Barker W J, Perkins J D & Witte T H (2013) Three horses with bilateral sinonasal progressive haematomas not associated with the ethmoidal labyrinth. Equine Vet Ed 25 (10), 503-507 WileyOnline.
• Frees K E, Gaughan E M, Lillich J D et al (2001) Severe complication after administration of formalin for treatment of progressive ethmoidal hematoma in a horse. JAVMA 219 (7), 950-952 PubMed.
• Schumacher J et al (1998) Transendoscopic chemical ablation of progressive ethmoidal hematomas in standing horses. Vet Surg 27, 175-181 (Detailed description of the technique and case results) PubMed.