All 12 dogs showed evidence of nasal turbinate destruction on CT scan. Topical antifungal application in the nasal cavity and frontal sinuses was required for 10 dogs (83.3%), while 1 case was managed with systemic antifungal medication alone. 11 dogs were considered treatment successes (91.7%). CT scanning and rhinoscopy were found to be sensitive tools for diagnosing canine aspergillosis, while histopathology, cytology and fungal culture were less reliable diagnostic methods.

1. Megan Work
ABSTRACT
Objective: To review the imaging findings and treatment decisions in cases of Canine Aspergillus that have
presented to the Small Animal Hospital.
Method: Twenty dogs that had presented to the University of Glasgow Small Animal Hospital with a history of
chronic nasal discharge that had had a CT scan of the head were identified by searching through the Electronic
Patient Record. From these 20 cases, twelvedogs were identified as having been diagnosed with Canine
Aspergillosis; only these 12 dogs were included in this study.
Results: All twelvedogs showed evidence of nasal turbinate destruction on CT scan, and other common
radiographic findings include soft tissue material in frontal sinuses, cribiformplate lysis, and frontal and
maxillary bone lysis. Rhinoscopy allowed visualisation of fungal plaques in 66.7% of cases. Ten of the 12 dogs
(83.3%) required application of a topical antifungal agent in the nasal cavity and frontal sinuses fortreatment;
only one case was able to be managed on systemic antifungal medication alone. 80% of the dogs that received
topical antifungal application required more than one treatment. Three dogs with evidence of cribiform plate
destruction underwent topical antifungal application; 0% developed neurological signs post-treatment. Eleven
dogs were considered treatment successes (91.7%).
Diagnostic test results and treatments used in dogs
diagnosed with Canine Aspergillus
A retrospectivestudy of12 dogs
Introduction:
Fungal rhinosinusitis is an invasive infection that involves the nasal cavity and frontal sinuses
in dogs; Aspergillusfumigatus isthe most commonly isolated organism in affectedcases, causing
destructive rhinitis and sinusitis. Affecteddogs oftenpresent witha history of chronic nasal
discharge, ulceration or depigmentation of the nasal planum, and nasal pain/head-shyness.
Mesaticephalic and dolichocephalic breeds are considered more likely to be affectedby the
disease (Sharp, 1989).
Suspicion of an Aspergillus infectionis often formed on the basis of clinical signs, and a
combination of diagnostic methods such as advanced diagnostic imaging,
rhinoscopy/sinuscopy, cytology,histopathology,or fungal culture are valuable to aid in reaching
a definitive diagnosis (Sharman MJ et al2012). Serological tests whichidentify antibodies to
Aspergillusspp. are also available and offergood sensitivity and excellent specificity for
sinonasal aspergillosis; serological testing is thought to be particularly useful in cases in which
performing advanced imaging studies is not a viable option, or when infection cannot be
confirmed by other methods (PomtantzJS et al. 2007). Howeverit should be noted that a
diagnosis of sinonasal aspergillosis cannot be excluded on the basis of negative serological
results.
Fungal colonies typically establish in the frontal sinuses, howeverthe disease leads to
damage of many surrounding structures and so Aspergillus infectionoftenresults in destruction

2. Megan Work
of the nasal turbinates. This damage can extend caudally and cause destruction of the cribiform
plate. Computed tomography (CT) is considered to be the most sensitive advanced imaging
technique for assessment of the bones surrounding the nasal cavity;typicalradiological signs
evident in affecteddogs include destruction of the nasal turbinate bones, mucosal thickening,
soft tissue material in the sinuses, and reactive maxillary, frontal, and vomer bones. CT also
allows assessment of the integrity of the cribiform plate, and is considered more sensitive to
changes in the cribiformplate when compared to radiography (Saunders et al 2002, Saunders et
al 2003). Rhinoscopy and sinuscopy are also commonly used diagnostic tools, whichoften
confirmthe diagnosis of fungal rhinosinusitis by direct visualisation of fungal plaques in the
nasal cavity and/or frontalsinuses. These endoscopic methods also allow evaluation of the
intranasal and intrasinusal soft tissue, and assessment of nasal turbinate destruction.
Treatment of fungal rhinosinusitis can be difficultand demanding, and requires compliance
from pet owners as well as the patients. Systemic treatments using oral antifungal medications
such as Itraconazoleare considered to have poor efficacy,andrequire prolonged administration
periods. Systemic antifungal medications also carry risks of hepatotoxicity,anorexia, and skin
reactions. Topicalantifungal treatment has been shown to be more efficaciousin treatment of
fungal rhinosinusitis, howeverintegrity of the cribiformplate is considered an important factor
in treatment options for fungal rhinosinusitis; topical infusion of antifungal agents is potentially
contraindicated if the cribiform plate is not intact because of the risk of developing a meningitis
or encephalitis.
MaterialsandMethods:
The Electronic Patient Record (EPR) in the University of Glasgow Small Animal Hospital was
searched forcases that had had a CT scan of the head, and had subsequently been diagnosed
with Aspergillus. Themost recent twenty cases were selected, and from these cases a total of
twelvedogs were eligible to be included in this retrospective study; inclusion criteria required a
history of chronic nasal discharge, findings consistent with fungal rhinosinusitis on CT imaging,
and response to antifungal therapy. Cases were excluded from the study if the definitive
diagnosis was not fungal rhinosinusitis (n=7; final diagnoses forthese exclusions were nasal or
oral tumours), and if the complete medical history was not available (n=1).
Data was collected by examining the case reports to the referring veterinary surgeon forthe
original twenty cases, and any information not included in these reports was searched for using
the EPR. If any data was still absent, paper records were inspected and only if the required
information was then not able to be obtained could a case be excluded on the basis of
inadequate medical history. Collected data included the patient breed, sex, and age at
presentation.
Information regarding the cases’ clinical
signs, investigations, and treatments
prescribed/performed was gathered and
recorded using a tally system. Information
regarding persisting clinical signs after
completion of treatment was also collected
and recorded.
Case No. Age at
Presentation
Breed Sex
1 2 years Labrador M E
2 9 years Border collie M E
3 5 years Retriever F N
4 2 years Border collie M N
5 11 years Retriever M E
6 2 years Retriever M N
7 10 years Cocker spaniel F N
8 11 years Retriever M E
9 4 years Collie-X M N
10 5 years Rough collie M N
11 4 years German
shepherd
M N
12 9 years Border collie F E
Table 1: Signalmentof casesincludedinthe study.

3. Megan Work
The cases were then divided into categories according to the treatment they underwent;
these categories included systemic medication only,topical treatment only, surgical
debridement only,and the combination of systemic medication plus topical treatment. Cases in
whichtopical antifungal agent application was performed were further divided into one of two
groups: cribiformplate intact or not-intact.
The final twelve cases that were included in the study have been summarised in Table 1.
Results:
A total of 12 cases were included in this retrospective study (Table 1). Seven different breeds
were identified in this study, almost all of which were mesaticephalic breeds withthe exception
of the dolichocephalic German shepherd dog. Collie-type breeds (71.4%) and Retrievers
(57.1%) were recognised as the most frequently diagnosed. The number of male dogs
diagnosed with fungal rhinosinusitis was greater than the number of female dogs diagnosed
with the condition; howeverneutering status did not seem to be a significant factorwith 55.6%
affectedmales neutered, and 66.7% affectedfemales neutered. Patients ranged fromtwo to 11
years of age (mean 6.2 years) at initial presentation to the Small Animal Hospital. All dogs
included in this study had clinical and radiological findings consistent withan active nasal
aspergillosis infection,and responded positively to antifungal treatment.
The presenting complaint in all twelvepatients was chronic nasal discharge; in 58.3% of dogs
this was unilateral, while the other 41.7% was bilateral; 25% of cases reported epistaxis or
blood tinged mucus in the nasal discharge. Other frequently reported clinical signs at time of
referral included sneezing (n=9), nasal pain/head-shyness (n=8), nasal planum depigmentation
(n=3) and weight loss (n=3). In all cases airflow was normal from both nostrils. Two dogs
(16.7%) had also been exhibiting neurological signs prior to presentation, both of whichhad
evidence of cribiform plate destruction on CT scan.
All cases received a CT scan of the nose/head during investigations, and 100% showed nasal
turbinate destruction. Softtissue material in the frontal sinuses was commonly reported (n=8)
and 25% of cases demonstrated septal and maxillary lysis. Cribiform plate lysis was evident in
41.7% of dogs (n=5). Rhinoscopy was performed in all twelvedogs, howeverdirect
visualisation of fungal plaques in the nasal cavity was only achieved in 66.7% of cases (n=8);
twodogs had subsequent sinuscopy performed as an additional diagnostic tooland this
revealed presence of fungal plaques in the frontal sinuses in both of these patients. 58.3% of
cases had a diagnosis of Aspergillus infectionconfirmedby the presence of fungal hyphae in
cytology fromimpression smears and/or consistent histopathological findings fromnasal pinch
biopsies (n = 7);two of these cases received additional confirmation of the diagnosis from
positive fungal cultures. One further dog’s nasal discharge grew a positive fungal culture, and
one dog had had a serology panel run forAspergillus at the referring veterinary practice,which
was positive. Therefore 25% of cases (n = 3) did not gain a cytological/culturaldiagnosis,
howevereach of these cases showed presence of fungal plaques on rhinoscopy and so the final
diagnosis was still considered to be fungal rhinosinusitis.

4. Megan Work
Ten of the 12 dogs (83.3%)required application of a topical antifungal agent in the nasal
cavity and frontal sinuses; only one case was able to be managed on systemic antifungal
medication alone. 80% of the dogs that received topical antifungal application required more
than one treatment. Similarly, intranasal instillation of Clotrimazole was utilised in 16.7% cases
(n=2).
Twodogs (16.7%) required rhinotomy forsurgical debridement of fungal plaques and
necrotic nasal turbinates, and one of these cases also required a frontal sinusotomy. Both of
these patients had evidence of cribiform plate destruction on CT scan. One of these patients
recovered wellwith almost complete resolution of clinical signs, while the other required an
additional 8 week treatment with systemic antifungal medications after a relapse in clinical
signs.
One case (8.3%) in this study was successfully managed using only systemic antifungal
medication.
Fungal rhinosinusitis is frequently complicated by a bacterial rhinitis; 75% of the cases in this
study required at least one course of an antibiotic agent. Amoxicillin-clavulanic acid was the
most commonly prescribed option (n = 5), with Doxycycline(n= 3) and Cephalexin (n = 1)
prescribed in other cases. It should be noted that these antibiotics were chosen based on
culture and sensitivity from nasal discharge in all cases.
Of the fivedogs that had shown evidence of cribiform plate lysis/destruction, 60% required
topical application of an antifungal agent in the frontal sinuses tocure the disease. None of the
dogs that received sinus instillation of Clotrimazole displayed any neurological signs post-
treatment.
After completion of treatment, 41.7% of cases (n=5) were described to be doing well
clinically;owners reported no concerns, with complete resolution of nasal discharge and
sneezing. Of these fivecases, 80% had been treated with topical antifungal instillation. Outwith
these fivecases, three dogs (25%) were reported to be sneezing occasionally,and three dogs
(25%) continued to show nasal discharge intermittently after completing treatment. One case
was considered a treatment failure.
Discussion:
This study concurswith the consensus that mesaticephalic and dolichocephalic dogs are
predisposed to canine aspergillosis. A disease predilection in Retriever dogs has been
consistently reported by many authors (Sharp NJH, 1989; Lefebvre J et al.2005); while
Retrievers were largely represented in this study, there were a greater proportion of Collie-type
breeds identified. Breed predilection in Collie dogs have not been previously recognised in
canine aspergillosis; howeverthe high representation in this study may reflectthe frequently
presented breeds to the University of Glasgow Small Animal Hospital, and so may not be a true
overrepresentation. Conversely, German shepherd dogs have a recognised breed predilection
for this condition, while this study only contained one dog of this breed. A typical age range of
0.5 – 13.5 years has been reported, and these findings are consistent with this as all cases in this
study fall within this reported age range. In literature, male dogs seem to be more likely to
develop fungal rhinosinusitis; this study concurs withthose findings, withmale dogs three
times more likely to be diagnosed with fungal rhinosinusitis.

5. Megan Work
Clinical signs that are frequently reported in cases of fungal rhinosinusitis include chronic
mucopurulent nasal discharge, nasal pain / head-shyness, ulceration or depigmentation of the
nasal planum, and bouts of epistaxis (Sharp, 1989). In this study, all dogs werepresented with a
history of chronic nasal discharge, but only 25% had reports of epistaxis. Other commonly
described clinicalsigns in this retrospective study included sneezing (n = 9), nasal pain/head-
shyness (n = 8), nasal planum depigmentation (n = 3) and weight loss (n = 3); while some of
these signs are consistent withprevious literature, it should be noted that in this study
incidence of epistaxis and nasal planum depigmentation was relatively low and so a diagnosis of
fungal rhinosinusitis should not be excluded on the basis of absence of these signs. Conversely,
sneezing is rarely mentioned in literature while in this study, sneezing was a major finding
reported in 75% of cases. Facial deformity/asymmetry and poor airflow from nostrils were not
common clinical findings in previous studies regarding dogs diagnosed with fungal
rhinosinusitis, and seem to be associated more with nasal neoplastic processes. This study
concurs withthose conclusions.
Based on the results of this study, computed tomography (CT) and rhinoscopy/sinuscopy –
alone or in combination – are sensitive and reliable investigations for the detection of intranasal
and intrasinusal evidence of disease. Commonly reported radiological findings of fungal
rhinosinusitis include destruction of the nasal turbinate bones, cribiform plate lysis, mucosal
thickening, soft tissue material in the sinuses, and reactivemaxillary, frontal, and vomer bones
(Saunders et al 2002, Saunders et al 2003). In this study, all of these radiological findings were
reported in at least one case. Evidence of nasal turbinate destruction was present in 100% of
cases, and so should be considered the most important radiological feature of fungal
rhinosinusitis. Rhinoscopy and sinuscopy are considered to be valuable in the assessment of
intranasal and intrasinusal soft tissue material, and oftenfacilitate direct visualisation of fungal
plaques in the nasal cavity and sinuses (Saunders JH et al. 2004, Johnson LR et al. 2006). In this
study, fungal plaques in the nasal cavity werevisualised via rhinoscopy in 66.7% of cases; two
cases in whichfungal plaques were not visualised in the nasal cavity subsequently underwent
sinuscopy, in whichfungal plaques were able to be visualised in the frontal sinuses. This
positively correlates with previous studies regarding the worth of performing these procedures
as part of an investigation of nasal disease, as direct visualisation of fungal plaques was possible
in 83.3% of cases. Histopathology, cytology,and fungal culture were all considered to be less
reliable means of diagnosis, with 25% (n=3) of cases that demonstrated radiological and
rhinoscopic changes consistent with fungal rhinosinusitis unable to be diagnosed using these
methods.
The most common treatment option in this retrospective study was bilateral frontal sinus
trephination with instillation of a topical antifungal agent, Clotrimazole, withoutconcurrently
administering systemic antifungal drugs (n = 5). This technique involvesusing catheters placed
non-surgically into the sinuses and performing a short flush of 1% Clotrimazole followedby
instillation of a 1% Clotrimazole cream as a depot agent. This technique allowsfor a shorter
duration of anaesthesia when compared withthe alternative 1-hour instillation technique,
avoids potential complications arising from surgically-placed indwelling catheters, and
theoretically provides improved persistence in the frontal sinuses as a result of the instillation
cream’s viscosity (Sissener TR et al. 2006). In one study it was claimed that 92.9% of dogs that
underwent this therapy required only one treatment; however in this study, 83.3% of dogs that
received this topicaltreatment required more than one instillation, 3 weeks apart. Despite this,

6. Megan Work
all cases that underwent this treatment did show an improvement after the initial therapy. This
method of applying a topical antifungal agent was combined with the use of systemic
antifungals in 16.7% of cases (n=2); of these two cases, one required only one topical treatment
while the other dog required two treatments. Both of these dogs required a further 4 weeks of
systemic medication after topicalapplication of Clotrimazole before an acceptable resolution of
clinical signs was reached, withonly intermittent nasal discharge reported at recheck
examination.
In this study, two cases (16.7%) underwent intranasal instillation of topicalantifungal. One of
these dogs was not prescribed any systemic medication alongside the topical treatments, and
required twointranasal instillations before complete resolution of clinical signs. The other case
in which this intranasal option was elected forwas a dog whichhad exhibited evidence of
cribiformplate destruction on CT scan, however after twointranasal topical treatments as well
as twomonths of systemic antifungal medication (Itraconazole),a repeat CT scan and sinuscopy
showed signs consistent of progression of the disease into the frontal sinuses – this dog then
received a third intranasal instillation and a right frontal sinus trephination for topical
treatment.
Twocases underwent rhinotomy for surgical debridement of fungal plaques and necrotic
turbinates, after being unsuccessfully managed on systemic antifungal medication. One of these
cases receivedtopical antifungal treatment, while the other did not; the dog that did not receive
topical treatment relapsed with severe clinical signs within 4 weeks of completing the
medication course, and required a further month of systemic antifungal medication. The case
whichunderwent rhinotomy and topical instillation of Clotrimazole recovered wellwith
complete resolution of clinical signs, aside from occasional unproductive sneezing.
Five cases showed evidence of cribiform plate lysis on CT scan, which carries a guarded
prognosis. This is considered to be a contraindication of utilising topical antifungal therapy due
to the risk of developing neurological signs. Neurological signs can develop in these cases either
as a consequence of antifungal treatment or as a result of intracranial extension of fungal
organisms. Complications associated with destruction of the cribiform plate may arise prior to
intervention, for instance due to fungal disturbance of the dura; or may arise followingsurgical
intervention with topical antifungal treatment – communication between the nasal and
intracranial cavities post-surgery can lead to the patient developing neurological signs such as
seizuring, as a result of the instilled antifungal agent causing irritant-induced
meningoencephalitis. Furthermore, in one study pneumocephalus was reported after surgical
treatment for fungal rhinosinusitis in which there was direct communicationbetween the nasal
and intracranial sinuses (Launcelott ZA et al. 2016).
Of the fivecases with evidence of cribiformplate lysis on CT scan, only 20% were able to be
treated using systemic antifungal medication exclusively. The remaining 80% (n=4) were
treated with systemic antifungal medication but at recheckinvestigations – including repeat CT
and rhinoscopy – evidence of persistent/progressive disease was discovered. These four cases
required more aggressive therapy; one dog received rhinotomy with debridement of fungal
plaques and necrotic turbinates only;one dog received rhinotomy and sinusotomy for
debridement combined with topicalantifungal application; and the remaining two dogs each
underwent sinus trephination with instillation of Clotrimazole. The dog that did not receive any
topical antifungal treatment had a relapse of symptoms 3 months after the surgical procedure,
while the three dogs that did receivetopical treatment showed almost complete resolution of
clinical signs. These findings imply that surgical debridement and systemic antifungal

7. Megan Work
treatment was not sufficient to treat the fungal infection in this study, and concurwith previous
publications that topical infusion with an antifungal agent is associated withgreater success
(Claeys S et al.2006).
Of the three cases with evidence of cribiform plate lysis that received intrasinusal topical
antifungal infusion, 0% developed neurological signs followingtreatment. This is not consistent
with many publications, as it is considered a contraindication to perform topical antifungal
infusion in patients with evidence of destruction of the cribiformplate; however,this finding
could reveal that this risk has previously been over-estimated. Furthermore, cases with
cribiformplate destruction carry a guarded-poor prognosis; it couldbe considered that prompt
intervention with the more efficacioustopical treatment may improve chances of survival when
compared to delayed topical treatment followingunsuccessful systemic medication and
worsening clinicalsigns. When presented witha fungal rhinosinusitis case, however, it is
paramount to educate the owners of all risks associated with the treatments and to gain
informed consent.
Of the twelvedogs included in this study, 75% were prescribed concurrent antibiosis to treat
a secondary bacterial rhinitis. The antibiotic medications prescribed were chosen based upon
culture and sensitivity results from nasal discharge in all cases. Secondary bacterial
complications in nasal disease are frequently reported, and are thought to be a consequence of
extensive nasal turbinate destruction and impaired mucociliary clearance of nasal debris
(Schuller et al. 2004). This factoris important when evaluating clinical improvement following
treatment of fungal rhinosinusitis; many patients that are cured from the disease will exhibit
intermittent sneezing and/or nasal discharge after completion of treatment as a result of this
impaired nasal clearance and nasal turbinate destruction. In this study, one case was
considered a failure of treatment, as after receiving prolonged treatment withsystemic
antifungal medications as well as rhinotomy and surgical debridement of fungal plaques, the
dog had a relapse in clinical symptoms 3 months after completing treatment; this dog had
evidence of cribiform plate lysis. 25% (n=3) of dogs were reported to occasionally sneeze
followingcompletion of treatment but were otherwise clinically well, and 25% (n=3) exhibited
intermittent nasal discharge only post-treatment. The remaining fivecases (41.6%) were
described as being back to normal by their owners, with complete resolution of clinical signs.
With only one case considered a treatment failure, the overall treatment success rate of this
study was 91.7%.
Conclusion:
Based on the findings of this retrospective study, it can be concludedthat fungal
rhinosinusitis is a disease that most commonly affectsdogs of mesaticephalic and
dolichocephalic breeds, and that males are more likely to be affected. Chronic nasal discharge,
sneezing, and nasal pain/head-shyness are commonly reported clinicalsigns, with nasal planum
ulceration/depigmentation less frequently described. Computed tomography and
rhinoscopy/sinuscopy are valuable diagnostic tools in the investigation of nasal disease, and
often facilitateidentification of turbinate destruction and fungal plaques respectively.
Histology, cytology,and fungal culture are more sensitive but less specific in the diagnosis of
fungal rhinosinusitis. There are a variety of therapeutic options available; topical infusion with
an antifungal agent is more efficaciousalthough often requires more than one treatment before
resolution of clinical signs. Informed consent fromowners is essential when considering
treatment of a case with evidence of cribiform plate destruction.

8. Megan Work
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