Introduction

Chronic and recurrent sinonasal disease in cats is clinically challenging to treat and the disease pathogenesis is not well understood. Despite a comprehensive diagnostic investigation, an etiology is rarely reported in cases of sneezing and nasal discharge among cats.^1,2 Reports of invasive fungal rhinosinusitis exist; however, localized disease appears to be largely dependent on the host’s immune response and the specific virulence of the infecting agent.^3–9 The purpose of this retrospective case series was to describe the short- and long-term therapeutic outcome of three cats with infectious rhinosinusitis that were treated with surgical debridement and intranasal povidone iodine packing.

Case series description

Case 1

An 11-year-old spayed female domestic shorthair cat, weighing 4.3 kg, was presented for an acutely progressive dorsal nasal swelling, sneezing and congestion. On initial examination, the cat had a 3 cm raised swelling of the dorsal nasal subcutaneous tissues, head aversion, severe mucopurulent nasal discharge and decreased nasal airflow bilaterally. A CT examination depicted bilateral proliferative tissue within the caudodorsal aspect of the nasal cavities and in the right frontal sinus. Lysis along the dorsal aspect of the mid-nasal cavities to include the maxillary bone was present. The patient was placed on clarithromycin (16 mg/kg PO q12h for 3 months), pradofloxacin (7 mg/kg PO q24h for 3 months) and doxycycline (7 mg/kg PO q12h for 3 months). Mycobacterium bouchedurhonense was identified by 16S rDNA sequencing. The patient was placed on moxifloxacin (13 mg/kg PO q24h for 30 days) and then subsequently presumed lost to follow-up. At a recheck, 6 months after initiating moxifloxacin therapy, no appreciable clinical response was observed. On physical examination, the patient had persistent dorsal nasal subcutaneous swelling with ulceration of the overlying skin in addition to exhibiting episodes of dyspnea. A CT examination (Figure 1) revealed a destructive process with soft tissue proliferation and complete occlusion of the right side of the nasal cavity. A dorsal rhinotomy was performed via a midline skin incision made beginning at the rostral end of the nasal bone and extending caudally to the point parallel to the zygomatic processes of the frontal bone. The frontal sinus was accessed by caudodorsal extension of the osteotomy. The surgical site was debrided and curettaged (Figure 2). The site was lavaged and an intranasal povidone-iodine 5% packing was placed and closed routinely (Figure 3). The ends of the umbilical tape exiting the nostril were sutured to the muzzle. The packing was replaced at 24 h postoperatively under general anesthesia. At 48 h postoperatively, the packing was removed, at which point the rhinotomy site was closed. At a routine recheck 4 weeks postoperatively, the patient demonstrated equal airflow bilaterally with resolution of nasal discharge. Antibiotic nebulization (amikacin 50 mg/5 ml) was prescribed for 60 days based on susceptibility testing. The cat had nasal swelling consistent with suspected recurrent M bouchedurhonense infection; however, no nasal discharge was noted at 8 weeks postoperatively. During a recheck 9 months postoperatively, the cat had absent nasal discharge with unchanged nasal swelling. Antibiotic injectable therapy (meropenem 9.3 mg/kg SC q12h for 10 days) was introduced. The patient was subsequently lost to follow-up.

Figure 1

Transverse plane, postcontrast CT image of an 11-year-old spayed female domestic shorthair cat (case 1) with severe swelling of the dorsal nasal subcutaneous tissues, severe mucopurulent nasal discharge and decreased nasal airflow bilaterally. Note the bilateral proliferative tissue within the caudodorsal aspect of the nasal cavities (arrows). This tissue extends to the rostral aspect of the right nasal cavity and appears occluded. The maxillary, nasal and incisive bones are lytic

Figure 2

Intraoperative image of debridement before placement of first nasal packing in case 3

Figure 3

Intraoperative image of nasal packing in place before temporary closure of rhinotomy site in case 3

Case 2

A 9-year-old spayed female domestic shorthair cat, weighing 3.7 kg, was presented for sneezing and nasal discharge. On initial examination, the cat had moderate mucopurulent nasal discharge and decreased nasal airflow bilaterally. A CT examination (Figure 4a) revealed contrast enhancement of the nasal turbinates and fluid accumulation extending into the sphenoid and frontal sinuses indicative of non-destructive rhinosinusitis. Rhinoscopy was performed, which revealed the presence of moderate diffuse rhinitis with irregular turbinates and fibrinonecrotic tissue. Histopathology revealed extensive fungal plaques with morphology indicative of Aspergillus species. The cat was also positive for Mycoplasma felis on PCR. The cat underwent a dorsal rhinotomy and placement of intranasal packing in the same manner as case 1. The cat was prescribed fluconazole (4 mg/kg PO q24h for 12 weeks) and terbinafine (24 mg/kg PO q12h for 12 weeks), robenacoxib (6 mg PO q24h for 3 days), cefovecin sodium (8 mg/kg SC) and buprenorphine (0.02 mg/kg TM q8–12h for 1 week). At 3 weeks postoperatively, the previously described nasal discharge had resolved and equal airflow bilaterally was observed. A CT examination (Figure 4b) was performed 3 months postoperatively at the conclusion of oral antifungal therapy. CT examination revealed mixed lysis and proliferation of nasal cavities improved from preoperative imaging. Imaging of the right frontal sinus depicted progression of proliferative soft tissue attenuating material, which likely represented redistribution of aspergillosis and progressive right sinusitis. No clinical signs were observed; oral antifungal therapy was extended for a further 6 weeks (for a total duration of 18 weeks) given the imaging findings. At 6 months postoperatively, the cat remained free of nasal discharge and obstruction to nasal airflow. Each subsequent physical examination at 7, 8, 9, 10 and 12 months postoperatively demonstrated no re-emergence of the cat’s sneezing episodes. The cat presented at 16 months postoperatively with no clinical evidence of relapse.

Figure 4

(a) Transverse plane, postcontrast CT image of a 9-year-old spayed female domestic shorthair cat (case 2) with contrast enhancement of the nasal turbinates and fluid accumulation extending to the frontal and sphenoid sinuses (arrow). (b) Transverse plane, postcontrast CT image 3 months postoperatively. Note the proliferative soft tissue attenuating material within the right frontal sinus that likely represented redistribution of aspergillosis and progressive right sinusitis (arrowhead)

Case 3

A 10-year-old neutered male domestic shorthair cat, weighing 7.7 kg, was presented for intermittent sneezing. At the time of presentation, the cat was a controlled diabetic receiving 2.5 IU of insulin glargine (Lantus; Sanofi-Aventis) every 12 h and was asymptomatic for its previously prescribed inflammatory bowel disease managed with budesonide at 0.05 mg/kg q24h. On initial examination, the patient had decreased airflow through the left nostril and mild mucopurulent nasal discharge. Rhinoscopy was performed, which revealed the presence of an infiltrative mass and fibrinonecrotic tissue within the left nasal cavity. A CT examination (Figure 5a) depicted a fusiform mass present in the lateral aspect of the mid to caudal aspect of the left nasal cavity causing severe lysis of the left nasal turbinates and orbital bones. Cytology showed clusters and mats of partially staining, branching and septate, fungal hyphal structures. Rhinoscopic samples retained for histopathology showed fungal hyphae morphologically most consistent with Aspergillus species and bacterial culture demonstrated heavy growth of Staphylococcus pseudintermedius. The cat was prescribed fluconazole (6.5 mg/kg PO q24h for 30 days), terbinafine (8 mg/kg PO q24h for 30 days) and initiated clindamycin (10 mg/kg SC q24h for 10 days). The cat underwent a dorsal rhinotomy and placement of intranasal packing in the same manner as cases 1 and 2. Alternaria species was identified on fungal culture. The dose of terbinafine (16 mg/kg PO q24h) was increased and the frequency of administration of fluconazole (6.5 mg/kg PO q 12h) was increased. At 2 months postoperatively, the patient demonstrated equal airflow bilaterally with complete resolution of sneezing and nasal discharge. A recheck CT (Figure 5b) was performed 7 months postoperatively, which revealed resolution of the larger aspect of the previous lesion in the left nasal cavity. Mild cribriform thinning and focal irregularities were now observed. Antifungal therapy was extended for another 6 months, for a total duration of 8 months. At 12 months postoperatively, the cat remained asymptomatic despite the presence of the previously described soft tissue material present along the left ventrolateral aspect of the cribriform plate and adjacent ethmoturbinates (Figure 5c).

Figure 5

(a) Transverse plane, postcontrast CT image of a 10-year-old neutered male domestic shorthair cat (case 3) with bilateral nasal discharge and decreased nasal airflow through the left nostril. Note the moderately sized mass in the left nasal cavity causing nasal turbinate and orbital bone lysis (thin arrow). (b) Transverse plane, postcontrast CT image of the same case 7 months after initial presentation. Note the severe lysis of the mid left nasal turbinates and left orbital bones and moderately sized, fusiform mass present along the mid to caudal aspect of the left nasal cavity tapering caudally to the level of the ethmoturbinates (thin arrow). (c) Transverse plane, postcontrast CT image of the same case 12 months postoperatively. The previously described soft tissue within the left ethmoturbinates is nearly completely resolved. There is a small amount of soft tissue material along the left ventrolateral aspect of the cribriform plate with focal irregularity and thinning (arrowhead)

Discussion

Current treatment recommendations are centered on a combination of surgical debridement of involved tissues, prolonged use of systemic medications and topical intranasal azole infusion.^4,8,10–12 Debridement has been shown to be the most effective modality in improving the interface of antimicrobial therapy and host tissue through physical disruption.^13,14 This technique forces the community to increase metabolic activity for remodeling, thus presenting an ideal window for employing antimicrobial therapy where susceptibility is considered the highest.^15–18 Intranasal packing allows for prolonged contact with residual disease after debridement thereby offsetting the limitations of variable distribution and retention of topical clotrimazole and enilconazole.¹⁹

This technique aims to mitigate the reported risks of meningoencephalitis in reported cases of intranasal azole infusions.^20–22 Relapse of infection has been reported in numerous cases of premature withdrawal of systemic therapy as a result of adverse effects, including azole-related hepatoxicity and adverse neurologic events.^23,24 In the present case series, all three cats exhibited resolution of nasal discharge and restoration of nasal airflow with a long-term follow-up of 16 months, suggestive that surgical debridement and intranasal packing may have contributed to attenuating turbinate destruction, once antibiotic therapy use had stopped.

The choice of povidone-iodine as an adjunctive treatment procedure was centered on its reported effectiveness in nasal decolinization.^25–28 The effective broad spectrum of activity against various bacteria, fungi, viruses and protozoa as well as its anti-inflammatory properties makes povidone-iodine a desirable instrument in many clinical domains.^29,30 Povidone-iodine solution 5% has been formulated to be safe, tolerable and rapidly bactericidal against a variety of aerobic Gram-positive and Gram-negative bacteria, as well as fungi associated with chronic rhinosinusitis.^27,28

This case series describes three cats that tolerated the sustained application of 5% povidone-iodine as a nasal antiseptic packing over the course of 2 days. In cases where postoperative CT was available, systemic therapy was extended owing to evidence of redistribution or progression of disease. Aspergillus species morphology and Alternaria species were detected on histopathology in case 2 and on fungal culture in case 3 where fluconazole was selected and extended after repeat CT. Inappropriate drug selection based on the intrinsic fluconazole resistance of Aspergillus and Alternaria species may be a reason why there was subclinical progression of disease identified on imaging.^31,32 A repeat CT examination after an extended course of systemic therapy is recommended to better inform treatment strategies whereby a second intranasal packing procedure could be considered.

The present study is limited by its retrospective design and small sample size. Furthermore, this series did not select for standardization of final diagnoses. The treatments outlined in this case series reflect an alternative to gold-standard treatment with topical antifungal infusion and/or systemic antimicrobial therapies guided by susceptibility testing. This treatment may be suitable in cases where concern for secondary colonizing bacteria and the subsequent chronic inflammatory mucosal changes seen with mixed infections are present. In addition, if a breach in the cribriform plate is identified, the use of 0.9% povidone-iodine may be considered a safe alternative to intranasal azole infusion.³³

These findings reveal preliminary insight into the potential benefits of povidone-iodine packing as an adjunctive microbicidal agent in cats with infectious rhinosinusitis when financial limitations exist or if there is considerable concern for the use of topical antifungal agents.

Conclusions

Surgical debridement and 5% povidone-iodine packing in combination with appropriate systemic antibiotic or antifungal therapy eliminated clinical signs related to intranasal disease for cats with follow-up times of up to 16 months postoperatively. The improvement in subjective wellbeing as described by the pet owners was attributed to restored nasal airflow and resolution of nasal discharge in all cases.