Combined clotrimazole irrigation and depot therapy for canine nasal aspergillosis

OBJECTIVES: To evaluate the effect of short duration 1 per cent clotrimazole flush when combined with 1 per cent clotrimazole cream instilled into the frontal sinuses for the treatment of nasal aspergillosis in 14 dogs. METHODS: Fourteen dogs with clinical, radiological, serological and rhinoscopic findings consistent with nasal aspergillosis were treated by frontal sinus trephination and a short, five-minute flushing of 1 per cent topical clotrimazole solution followed by a 1 per cent clotrimazole cream instilled as a depot agent. RESULTS: Twelve of the 14 dogs (86 per cent) responded well to treatment and either had no clinical signs after treatment or had signs consistent with mild rhinitis during a minimum follow-up period of six months. Only one dog required multiple treatments. Treatment was well tolerated by all patients, with minimal complications. CLINICAL SIGNIFICANCE: This treatment compares favourably to previously published data using one-hour topical clotrimazole or enilconazole flushing treatment protocols. The treatment technique significantly reduced treatment time under anaesthesia.     

Comparison of serologic evaluation via agar gel immunodiffusion and fungal culture of tissue for diagnosis of nasal aspergillosis in dogs

OBJECTIVE: To compare the sensitivity and specificity of serologic evaluation and fungal culture of tissue for diagnosis of nasal aspergillosis in dogs. DESIGN: Prospective study. ANIMALS: 58 dogs with nasal discharge and 26 healthy dogs. PROCEDURES: Dogs with nasal discharge were anesthetized and underwent computed tomography and rhinoscopy; nasal tissues were collected for histologic examination and fungal culture. Sera were assessed for antibodies against Aspergillus spp (healthy dog sera were used as negative control specimens). Nasal aspergillosis was diagnosed in dogs that had at least 2 of the following findings: computed tomographic characteristics consistent with aspergillosis, fungal plaques detected during rhinoscopy, and histologically detectable fungal hyphae in nasal tissue. Histologic characteristics of malignancy were diagnostic for neoplasia. Without evidence of neoplasia or fungal disease, nonfungal rhinitis was diagnosed. RESULTS: Among the 58 dogs, 21 had nasal aspergillosis, 25 had nonfungal rhinitis, and 12 had nasal neoplasia. Fourteen aspergillosis-affected dogs and 1 dog with nonfungal rhinitis had serum antibodies against Aspergillus spp. Fungal culture results were positive for Aspergillus spp only for 17 dogs with aspergillosis. With regard to aspergillosis diagnosis, sensitivity, specificity, and positive and negative predictive values were 67%, 98%, 93%, and 84%, respectively, for serum anti-Aspergillus antibody determination and 81%, 100%, 100%, and 90%, respectively, for fungal culture. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that seropositivity for Aspergillus spp and identification of Aspergillus spp in cultures of nasal tissue are highly suggestive of nasal aspergillosis in dogs; however, negative test results do not rule out nasal aspergillosis.     

Intranasal infusion of enilconazole for treatment of sinonasal aspergillosis in dogs

OBJECTIVE: To determine effectiveness of infusion of 1 and 2% enilconazole for treatment of nasal and sinusal aspergillosis, respectively, in dogs. DESIGN: Case series. ANIMALS: 26 client-owned dogs with aspergillosis. PROCEDURE: All dogs had typical clinical signs of aspergillosis and rhinoscopically visible intrasinusal or intranasal fungal plaques associated with turbinate destruction. During rhinoscopy, affected nasal cavities and frontal sinuses were debrided meticulously. Nineteen dogs (group A) were treated with 1% enilconazole by use of a modified noninvasive infusion procedure. Seven dogs (group B) were treated with 2% enilconazole via catheters that were placed via endoscopic guidance into the frontal sinuses. All dogs underwent follow-up rhinoscopy for determination of further treatment until cure was established. RESULTS: Age, disease duration, clinical score, and rhinoscopic score were similar for both groups before treatment. In group A, 17 of 19 dogs were cured; 9, 6, and 2 dogs were cured after 1, 2, or 3 treatments, respectively. The remaining 2 dogs were euthanatized before the end of the treatment protocol. In group B, all dogs were cured; 6 dogs and 1 dog were cured after 1 or 2 treatments, respectively. Only minor adverse effects such as nasal discharge, epistaxis, and sneezing developed. CONCLUSIONS AND CLINICAL RELEVANCE: After extensive rhinoscopic debridement, 1 and 2% enilconazole infused into the nasal cavities and the frontal sinuses, respectively, were effective for treatment of aspergillosis in dogs. Intrasinusal administration via endoscopically placed catheters appeared to require fewer infusions for success. Follow-up rhinoscopy is strongly advised.     

Computed Tomographic Assessment of Noninvasive Intranasal Infusions in Dogs With Fungal Rhinitis

The distribution of infusate administered to 12 dogs with fungal rhinitis, using a noninvasive, intranasal technique, was evaluated by computed tomography (CT). In every dog, contrast medium was identified on the postinfusion CT images, within the frontal sinuses, and throughout all areas of the nasal cavity. Adverse effects were transient and mild. The results of this study indicate that intranasal infusion may be a viable alternative to trephination of the frontal sinuses to administer antifungal medications in dogs with fungal rhinitis.     

Clotrimazole and enilconazole distribution within the frontal sinuses and nasal cavity of nine dogs with sinonasal aspergillosis

Objectives: Multiple topical treatments are often required for clinical cure of mycotic rhinosinusitis in dogs. The objective of this study was to describe the distribution and retention of enilconazole and clotrimazole solutions using a temporary trephination protocol. Methods: Nine client-owned dogs diagnosed with mycotic rhinosinusitis between March 2008 and December 2009 were prospectively enrolled and were sequentially allocated to receive treatment with either clotrimazole (1% in polyethylene glycol) or enilconazole (10% solution), after imaging and rhinoscopic assessment. Both frontal sinuses were trephined, debrided and flushed with saline. Infusion was administered via frontal sinuses with dogs in sternal recumbency and computed tomography (CT) performed 5 minutes after completion. Distribution was scored 1 to 4 at the canine tooth, premolar 4, cribriform plate and frontal sinus on both sides, for a maximum score of 32. Results: Distribution of antifungal agents to all regions of the nasal cavity and frontal sinuses was achievable, but varied considerably. Retention was poor in 10 of 18 regions assessed. Clinical Significance: Distribution of antifungal agents within the frontal sinuses is achievable using temporary trephination; however, distribution is variable and retention is often poor.     

COMPUTED TOMOGRAPHIC FINDINGS IN 35 DOGS WITH NASAL ASPERGILLOSIS

The purpose of this study was to describe the computed tomographic (CT) features of nasal aspergillosis in dogs. Initial (n = 35) and follow-up (n = 12) CT images were available from 35 dogs. The most commonly encountered CT findings were (1) moderate to severe cavitary destruction of the turbinates with presence of a variable amount of abnormal soft tissue in the nasal passages, (2) non-specific thickening of the mucosa adjacent to the inner surface of bones of the frontal sinus, maxillary recess and nasal cavity and, (3) thickened reactive bone. The findings were consistent with a disease initially affecting one nasal cavity then progressing into the ipsilateral frontal sinus, the contralateral nasal cavity and the contralateral frontal sinus. Two dogs with associated nasal foreign body had a more localized invasion of the nasal cavity. Attenuation values and contrast enhancement were not specific. With follow-up examinations, a reduction in the amount of abnormal soft tissue was observed in all dogs except one, but this reduction could not be quantified.     

COMPARISON OF RADIOGRAPHY AND COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF CANINE NASAL ASPERGILLOSIS

To compare the radiographic and computed tomographic (CT) findings and to evaluate the sensitivity of radiography and CT for diagnosis of nasal aspergillosis in dogs, the radiographic and CT studies of 48 dogs with chronic nasal disease were reviewed separately. The radiographic and CT findings were recorded, and a diagnosis was made. The results obtained in the dogs with nasal aspergillosis (n = 25) were used. Based on definite aspergillosis as diagnosis, CT had a sensitivity of 88% and radiography of 72%. Considering definite and probable aspergillosis as equivalent, CT had a sensitivity of 92% and radiography of 84%. The sensitivity was higher in dogs with lesions affecting the entire nasal cavity and frontal sinus on at least one side (n = 20) with a sensitivity of 100% for CT and 90-95% for radiography than in dogs with lesions restricted to the nasal cavities (n = 5) where CT had a sensitivity of 60-80% and radiography of 0-40%. CT was superior to radiography for evaluation of the nasal cavities (mucosal thickening along the nasal bones, surrounding bone hyperostosis/lysis), frontal sinuses (mucosal thickening along the frontal bone, fluid/soft tissue, frontal bone hyperostosis/lysis), and differentiation between a cavitated-like or a mass-like process. This study suggests that CT is more sensitive than radiography for diagnosis of nasal aspergillosis in the dog because of a better demonstration of some changes suggestive of nasal aspergillosis. A diagnosis of a nasal aspergillosis restricted to the nasal cavities or associated with an FB is challenging, even with the use of CT.     

Use of topical povidone-iodine dressings in the management of mycotic rhinitis in three dogs

Three dogs with mycotic rhinitis were treated with a proprietary wound dressing product intended to produce a sustained release of povidone-iodine. All of the dogs had been refractory to other treatments. One dog had extensive soft tissue involvement, including extension into the orbital tissues, and another had evidence of involvement of the supporting bones of the nose. In all cases, the affected nasal cavity and/or frontal sinus was exposed via a dorsal approach and partial turbinectomy was performed. The wound dressing was applied and retained with a 'tie-over' dressing. The dressing was replaced every 48 to 72 hours until all exposed tissue was covered by healthy granulation tissue, at which time the rhinotomy was closed by soft tissue reconstruction. There was no evidence of recurrence of the fungal infection at follow-up times of up to 20 months postsurgery.     

Idiopathic lymphoplasmacytic rhinitis in dogs: 37 cases (1997-2002)

OBJECTIVE: To determine clinical signs and rhinoscopic, computed tomographic, and histologic abnormalities in dogs with idiopathic lymphoplasmacytic rhinitis. DESIGN: Retrospective case series. ANIMALS: 37 dogs. PROCEDURE: Clinical information was obtained from medical records. Nasal computed tomographic images and histologic slides of biopsy specimens were reviewed. RESULTS: Dogs ranged from 1.5 to 14 years old (mean, 8 years); most (28) were large-breed dogs. Nasal discharge was unilateral in 11 of 26 (42%) dogs and bilateral in 15 of 26 (58%) dogs. In dogs with unilateral disease, duration of clinical signs ranged from 1.5 to 36 months (mean, 8.25 months; median, 2 months), and in dogs with bilateral disease, duration of signs ranged from 1.25 to 30 months (mean, 6.5 months; median, 4 months). Computed tomography (n = 33) most often revealed fluid accumulation (27/33 [82%]), turbinate destruction (23/33 [70%]), and frontal sinus opacification (14/33 [42%]). Rhinoscopy (n = 37) commonly demonstrated increased mucus and epithelial inflammation; turbinate destruction was detected in 8 of 37 (22%) dogs. Bilateral biopsy specimens from all 37 dogs were examined. Four dogs had only unilateral inflammatory changes. The remaining 33 dogs had bilateral lesions; in 20, lesions were more severe on 1 side than the other. CONCLUSIONS AND CLINICAL RELEVANCE: Findings suggest that idiopathic lymphoplasmacytic rhinitis is a key contributor to chronic nasal disease in dogs and may be more common than previously believed. In addition, findings suggest that idiopathic lymphoplasmacytic rhinitis is most often a bilateral disease, even among dogs with unilateral nasal discharge.     

Association of magnetic resonance imaging findings and histologic diagnosis in dogs with nasal disease: 78 cases (2001-2004)

OBJECTIVE-To determine whether magnetic resonance imaging (MRI) features correlated with histologic diagnosis in dogs with nasal disease. DESIGN-Retrospective case series. ANIMALS-78 Dogs undergoing MRI for evaluation of nasal disease. PROCEDURES-Medical records and MRI reports of dogs were reviewed to identify MRI features associated with histologic diagnosis. Features evaluated were presence of a mass effect, frontal sinus involvement, sphenoid sinus involvement, maxillary recess involvement, nasopharyngeal infiltration by soft tissue, nasal turbinate destruction, vomer bone lysis, paranasal bone destruction, cribriform plate erosion, and lesion extent (ie, unilateral vs bilateral). RESULTS-33 Dogs had neoplastic disease, 38 had inflammatory rhinitis, and 7 had fungal rhinitis. Lesion extent was not significantly associated with histologic diagnosis. Absence of a mass effect was significantly associated with inflammatory disease. However, presence of a mass was not specific for neoplasia. In dogs with evidence of a mass on magnetic resonance (MR) images, nasal turbinate destruction, frontal sinus invasion, and maxillary recess invasion were not useful in distinguishing neoplastic from nonneoplastic disease, but cribriform plate erosion, vomer bone lysis, paranasal bone destruction, sphenoid sinus invasion, and nasopharyngeal invasion were. CONCLUSIONS AND CLINICAL RELEVANCE-Results suggested that in dogs with nasal disease, the lack of a mass effect on MR images was significantly associated with inflammatory disease. In dogs with a mass effect on MR images, vomer bone lysis, cribriform plate erosion, paranasal bone destruction, sphenoid sinus invasion by a mass, and nasopharyngeal invasion by a mass were significantly associated with a diagnosis of neoplasia.     

Treatment of canine nasal aspergillosis with a new non-invasive technique. Failure with enilconazole

A new, non-Invasive technique recently described for the treatment of canine nasal aspergillosis was performed on four dogs. The antimycotic agent used was a 10 per cent enilconazole suspension, with the drug left in situ for a period of one hour. None of the dogs responded to single treatment. One dog died from an acute septic response secondary to pyelonephritis and bacterial endocarditis eight days after a second treatment. A second dog responded completely to a second treatment and remained free of fungal disease for a follow-up period of H months. In the remaining two dogs, extensive and profuse fungal growth was seen on rhinoscopic reexamination. Conventional treatment, with tube Implantation into the frontal sinuses and nasal irrigation for two weeks, was performed. Successful resolution of infection was obtained. Although the new, non-invasive technique was simple to carry out and well tolerated by the dogs, instillation of 10 per cent enilconazole appears to have poor therapeutic efficacy and exacerbated fungal growth in two of the animals.     

Radiographic, magnetic resonance imaging, computed tomographic, and rhinoscopic features of nasal aspergillosis in dogs

OBJECTIVE: To determine radiographic, magnetic resonance imaging (MRI), computed tomography (CT), and rhinoscopic features of nasal aspergillosis in dogs. DESIGN: Prospective study. ANIMALS: 15 client-owned dogs. PROCEDURE: All dogs had clinical signs of chronic nasal disease; the diagnosis of nasal aspergillosis was made on the basis of positive results for at least 2 diagnostic tests (serology, cytology, histology, or fungal culture) and detection of typical intrasinusal and intranasal fungal colonies and turbinate destruction via rhinoscopy. Radiography, MRI, and CT were performed under general anesthesia. Rhinoscopy was repeated to evaluate lesions and initiate treatment. Findings of radiography, MRI, CT, and rhinoscopy were compared. RESULTS: MRI and CT revealed lesions suggestive of nasal aspergillosis more frequently than did radiography. Computed tomography was the best technique for detection of cortical bone lesions; the nature of abnormal soft tissue, however, could not be identified. Magnetic resonance imaging allowed evaluation of lesions of the frontal bone and was especially useful for differentiating between a thickened mucosa and secretions or fungal colonies; however, fungal colonies could not be differentiated from secretions. Rhinoscopy allowed identification of the nature of intranasal and intrasinusal soft tissue but was not as useful as CT and MRI for defining the extent of lesions and provided no information regarding bone lesions. CONCLUSIONS AND CLINICAL RELEVANCE: The value of CT and MRI for diagnosis of nasal aspergillosis was similar and greater than that of radiography. Rhinoscopy is necessary because it is the only technique that allows direct visualization of fungal colonies.     

Open Nasal Cavity and Frontal Sinus Treatment of Chronic Canine Aspergillosis

Five dogs with nasal aspergillosis were treated by surgical exposure and delayed closure of the nasal cavity and involved frontal sinus. Diseased tissue was excised, and 10% povidone-iodine solution was applied three times daily with cotton-tipped applicators. Skin wounds were closed at weeks 6 through 8. In one dog, the frontal sinus was partially obliterated with a temporalis muscle flap before skin closure. At months 6 through 34, all dogs were clinically free of aspergillosis. Open treatment has potential clinical application as a primary approach to nasal aspergillosis or for cases that are unresponsive to previous medical management.     

DISTINGUISHING RHINITIS AND NASAL NEOPLASIA BY RADIOGRAPHY

To compare the incidence of radiographic signs in dogs with rhinitis and primary nasal neoplasia and to assess the performance of observers for distinguishing these conditions, the nasal radiographs of 72 dogs with either rhinitis (n = 42) or primary nasal neoplasia (n = 30) were examined by two independent observers using custom-designed forms to record their interpretations. Rhinitis was associated with a higher incidence of focal or multifocal lesions, localised soft tissue opacities, lucent foci, and a lack of frontal sinus involvement. Neoplasia was associated with soft tissue opacities and loss of turbinate detail that affected the entire ipsilateral nasal cavity, signs of invasion of the bones surrounding the nasal cavity, and soft tissue/fluid opacities within the ipsilateral frontal sinus. The signs with the highest positive predictive value (PPV) for rhinitis were absence of frontal sinus lesions and lucent foci in nasal cavity (PPV of each 82%), and invasion of surrounding bones for neoplasia (PPV 88%). There were no significant differences in the position of the lesion within the nasal cavity, incidence of unilateral versus bilateral lesions, calcified lesions, or absence of teeth. There was moderate agreement between observers about the diagnosis (kappa 0.59). Areas (SE) under ROC curves were 0.94 (0.03) and 0.96 (0.03) for observers A and B, respectively (not significantly different; P = 0.68). These results indicate a high accuracy for radiologists examining dogs with nasal diseases. Differentiation of rhinitis and nasal neoplasia should be based on finding combinations of radiologic signs that together have a high PPV. Differences in interpretation between experienced observers in this study suggest that certain signs are potential sources of error.     

Bilateral orbital and nasal aspergillosis in a cat

A 12-year-old, 4 kg, castrated male Persian cat was referred with a 2-month history of sneezing and bilateral mucopurulent nasal discharge. Rhinoscopically acquired nasal biopsies at this time revealed bilateral lymphoplasmacytic rhinitis. A tapering dose of oral prednisone caused the complete remission of the clinical signs, but 2 months after discontinuation of the therapy, the rhinitis recurred and the OD became exophthalmic. Computed tomography showed a soft tissue mass in both sides of the nasal cavity, both frontal sinuses, the right orbit, and to a lesser extent the left orbit. A fine needle aspirate of the right orbit revealed pyogranulomatous inflammation and Aspergillus spp. hyphae. Repeat nasal biopsy demonstrated multi-focal necrosis and a mixed inflammatory cell process which now included macrophages and scattered septate fungal hyphae. A few days later the cat became bilaterally blind and a contrast enhancing lesion involving the optic chiasm was found on magnetic resonance imaging. Despite a poor prognosis, therapy consisted of exenteration of the right orbit and trephination of both frontal sinuses before the planned initiation of medical antifungal therapy. Unfortunately, the cat died of cardiac arrest intraoperatively. Aspergillus fumigatus was cultured from both orbits at necropsy. Orbital aspergillosis has been rarely reported in cats and its relationship with lymphoplasmacytic rhinitis is unclear. In this patient lymphoplasmacytic rhinitis or previous antibiotic/corticosteroid therapy may have allowed secondary fungal invasion of the nasal mucosa and subsequently both orbits and the brain. Alternatively, Aspergillus infection may have preceded the lymphoplasmacytic rhinitis.     

Distribution of Topical Agents in the Frontal Sinuses and Nasal Cavity of Dogs: Comparison Between Current Protocols for Treatment of Nasal Aspergillosis and a New Noninvasive Technique

To document and compare patterns of distribution of topically applied antifungal medication, heads from 42 canine cadavers were assigned to seven treatment groups which included two current surgical treatment protocols for nasal aspergillosis, and a new, noninvasive method. Catheters (8 Fr) were placed through trephine holes into the frontal sinuses and nasal cavity. Dilute dye was injected through the catheters and the heads were sectioned sagittally. The administration of 5 mL of dye into the lateral frontal sinus and nasal cavity (group IA, 10 mL total) was compared with 25 mL injected through catheters placed bilaterally in the lateral frontal sinus and nasal cavity (group II, 100 mL total). Both were compared with the administration of 50 mL of dye through a catheter placed in the dorsal nasal meatus via each nostril (group III). The heads in group III had significantly ( P <.05) better dye distribution to all cavities than group IA and better distribution to the rostral frontal sinus than group II. Groups IV to VI were designed to show the pattern of distribution of dye to the contralateral nasal cavity and frontal sinuses. In all groups, dye injected into the lateral frontal sinus did not cross into the ipsilateral rostral frontal sinus or vice versa unless the transverse septum dividing the compartments had been penetrated during trephination.     

COMPUTED TOMOGRAPHIC FINDINGS OF FUNGAL RHINITIS AND SINUSITIS IN CATS

The computed tomographic (CT) findings of fungal rhinitis/sinusitis in cats were characterized. The CT images of 10 cats ranging in age from 7 to 13 years were examined. The mean age was 10.8 years and all were neutered males. Nasal aspergillosis was diagnosed in five cats, cryptococcosis in three cats, hyalohyphomycosis in one cat, and trichosporonosis in one cat. Bilateral disease was present in eight cats, seven had abnormal soft tissue attenuation in two-thirds of the nasal cavity, and six had turbinate lysis. Seven cats had also lysis of the hard palate, nasal septum, or frontal bone. One cat had lysis of the cribriform plate. Five of the nine cats whose lymph nodes were imaged had lymph node enlargement. There was contrast medium enhancement in the nasal cavity in all cats, with either a primarily peripheral rim or heterogeneous pattern. There appears to be an overlap of clinical signs, age, and CT features of cats with nasal neoplasia and those with fungal rhinitis/sinusitis.     

Molecular detection of microbes in nasal tissue of dogs with idiopathic lymphoplasmacytic rhinitis

Lymphoplasmacytic rhinitis (LPR) is a common histologic finding in dogs with chronic nasal disease; however, potential etiologies of this disorder have not been examined. We investigated the hypothesis that specific microbes contribute to clinical disease in dogs with LPR. Paraffin-embedded nasal biopsies were obtained from 19 dogs with LPR, 10 dogs with nasal neoplasia, and 10 dogs with nasal aspergillosis. Nucleic acids were extracted from paraffin blocks, and real-time quantitative polymerase chain reaction (PCR) was employed for detection of target genes for bacterial and fungal DNA, canine adenovirus 2 (CAV-2), parainfluenza virus 3 (PI-3), Chlamydial Chlamydophila spp., and Bartonella spp. Conventional PCR was used for detection of Mycoplasma spp. Statistical analysis was performed using the Mann-Whitney U-test for nonparametric data, and significance was set at P < 0.05. DNA or RNA for CAV-2, PI-3, Bartonella, Mycoplasma, and Chlamydophila was not detected in any nasal biopsy. DNA loads for bacterial DNA did not differ among disease groups. Detection of fungal DNA in nasal biopsies was highest in dogs with aspergillosis (P < 0.0001); however, nasal biopsies of LPR dogs also displayed higher fungal DNA levels than samples from dogs with nasal neoplasia (P = 0.016). Detection of high levels of fungal DNA in nasal biopsies of dogs with LPR suggests that fungal organisms may be causally associated with the inflammation observed, although the possibility of entrapment or accumulation of fungi in the nasal cavity due to chronic inflammation cannot be excluded. Further investigations are required to elucidate the underlying etiopathogenesis of LPR.     

Rhinoscopy

This article presents a diagnostic protocol for nasal disease evaluation that provides consistent success in diagnosis of chronic cases. The protocol includes history, physical examination, blood clinical pathology assessment, radiographs, culture and sensitivity tests, rhinoscopy, histopathology, fungal serology, and allergy screening. The sequence of diagnostic procedures and their techniques are discussed, and rhinoscopic appearance of the normal nasal cavity is presented, along with findings of commonly seen nasal diseases, including neoplasia, mycotic rhinitis and sinusitis, foreign body obstruction, dental disease, allergic rhinitis, bacterial rhinitis, and idiopathic rhinitis. Rhinoscopy is a highly effective diagnostic technique with minimal morbidity and mortality that has virtually eliminated the need for exploratory rhinotomy.     

Chronic frontal sinusitis in dairy cattle: 12 cases (1978-1989).

Chronic frontal sinusitis in 12 dairy cattle most often was associated with a history of dehorning, in which the sinus was entered (67%), or with respiratory tract disease (25%). The most common organisms isolated were Actinomyces pyogenes and Pasteurella multocida. Signs of infection did not develop for months in some cattle and were often intermittent. The most common clinical signs included anorexia, lethargy, fever, frontal bone distortion, exophthalmos, abnormal posture, nasal discharge, and neurologic abnormalities. Treatment consisted of trephination at 2 sites, drainage and lavage of the sinus cavity, and administration of antibiotics and analgesics. Eight cattle responded well to treatment and were discharged, but 4 others had signs of CNS involvement and died or were euthanatized. Trephination of the frontal sinus cavity at carefully chosen sites and antibiotic treatment are indicated when sinusitis is suspected. Drainage of the sinus cavity is imperative to avoid extension of the infection into the CNS.