Prevalence of otitis externa in stray cats in northern Italy

Abstract

Feline otitis externa is a dermatological disorder that has not been evaluated much in stray cats. One hundred and eighty-seven stray cats were randomly selected during a trap–neuter–release programme to investigate the prevalence of otitis externa in stray cat colonies in northern Italy. Swabs for cytological examination were obtained from the external ear canal of each cat. A direct otoscopic assessment of the external ear canal was made in 86/187 cats. Cytological evidence of otitis externa was present in 55.1% of cats. The influence on otitis of age, gender, habitat and season of sampling was tested, but no risk factors were found. Otodectes cynotis (as a sole agent or in combination) was the primary cause of otitis in 53.3% of cats. Cocci and rods, either alone or in combination with other agents, were perpetuating factors in 71.8% and 29.1% of cats, respectively. Pregnancy status was a risk factor for otitis caused by coccal infections. Malassezia species, alone or in combination, was the perpetuating factor in 50.5% of cats with otitis. Urban habitat and winter season were risk factors for otitis associated with Malassezia species. Demodex cati was identified as an incidental finding in two cats. There was good agreement between otoscopy and cytology with regard to the diagnosis of otitis externa. The results of this study show a high prevalence of otitis externa in stray colony cats and provide information on causal factors for feline otitis externa.

Introduction

Otitis externa is a multifactorial and aetiologically complex disorder of the ear canal in domestic animals, including the cat.¹ Diagnosis is usually by means of direct otoscopic examination and cytology of otic exudates.^2,3 There is a paucity of published data on the prevalence or incidence of feline otitis. A few older studies report prevalence in pet cats to be between 2% and 10%.^4–6 More recently, a study of pet cats in the UK⁷ reported a prevalence of 19%, although no information about the diagnostic methods used or the size of the study population was reported. A Romanian study⁸ reported a prevalence of 2% in a population of 4572 domestic cats. However, neither study considered the aetiology and/or the microorganisms involved in the development of otitis externa.

Not much information is available about otitis externa in stray cats. Although it is considered the principal primary cause of feline otitis externa,¹ there are surprisingly little data on the prevalence of Otodectes cynotis in stray cats and the prevalence reported varies between 0.6% and 37.0%.^9–12

To our knowledge there are no studies about the prevalence of Malassezia species in the external ear canal of either healthy stray cats or those with otitis, while the bacteria most commonly isolated by culture from the ears of feral cats are coagulase-negative staphylococci (with Staphylococcus felis/Staphylococcus simulans the most common) and Bacillus species.¹³ However, in that study, conducted in Grenada, neither ear cytology nor otoscopic evaluation were performed, and therefore the presence or absence of otitis externa could not be confirmed.

Evaluation of the health status of free-roaming stray cats is important for the improvement of animal welfare¹⁴ and to obtain information about regional pathogens and diseases, regardless of their infectivity. Data on diseases in stray cat populations are needed to define their role in the transmission of some pathogenic agents such as O cynotis, to other susceptible animals and domestic cats that have access to the outdoors.^11,15–17

The aim of this study was to assess the prevalence of otitis externa in a population of stray cats of northern Italy and to evaluate the concordance of cytology and direct otoscopic examination as means of diagnosis of otitis externa. The study also characterises risk factors for feline otitis externa, including gender, age, habitat, season of sampling and microorganism identified at the ear cytology.

Material and methods

Sampling and data collection

Cases included 187 short haired stray cats from colonies in the Lombardy region of northern Italy, regardless of the presence/absence of signs of otitis externa. The cats were trapped by volunteers between 2008 and 2010, during a trap–neuter–return (TNR) programme approved by the city council, as previously described.^15,16 Swabs were obtained from the external ear canal of each cat for cytological examination.

The gender and habitat of each cat were recorded together with the data obtained from cytological ear evaluation. Age was estimated by dentition and animals were classified as young (≤6 months of age) or adult (≥6 months of age). To evaluate seasonal trends the samples were categorised according to the sampling period: spring samples (from March to May), summer samples (from June to August), autumn samples (from September to November) and winter samples (from December to February).

For technical reasons, direct otoscopic assessment of the external ear canal was made in 86/187 cats, all from urban colonies. Evaluation included alterations of quantity and/or quality of ear wax (characterised grossly as normal or abundant and clear, yellow, brown or typically black with the presence of mites) and ear canal alterations (erythema, stenosis, ulceration).

Cytological evaluation

Samples for cytological evaluation were obtained with two sterile cotton swabs (one per ear) inserted into the lumen of the ear canal and swabbed against the surface of the vertical canal. Each cotton swab was rolled onto two clean microscope slides, evenly distributing a thin layer of material.

One slide per ear was unstained, suspended with mineral oil and mounted with a cover slip, and one slide per ear was heat-fixed, stained with modified Wright’s rapid stain (Quick Panoptic Kit; Pokler Italia), suspended with mineral oil and mounted with a cover slip.² Both slides were examined immediately.

The unstained slide was scanned at low power (100×) for the presence of O cynotis, and the total number of mites was recorded. The detection of a single mite in at least one ear indicated the presence of infection in the cat.¹⁸

The stained slide was evaluated first at low power (100×) (to identify the areas of interest) and then under high power (400×) to evaluate the presence and number of microorganisms morphologically identifiable as Malassezia species and/or bacteria. As both bacteria and Malassezia species are common inhabitants of the normal feline external ear canal, a cytological score for the presence/absence of otitis in each cat was developed based on the average of the different values previously reported in the literature (Table 1).^19–21 Briefly, each parameter evaluated microscopically (presence of cocci, rods and Malassezia species) was given a score from 0 (normal) to 2 (pathological) based on the mean number of detected microorganisms seen in 10 high-power dry fields (400×). Higher-power oil immersion fields (1000×) were chosen by scanning at low power until staining was visualised; by focusing on areas of staining, different kinds of bacteria (cocci or rods) were identified. A value score equal to 1 (or grey zone) is a cytological transitional zone proposed by previous authors²⁰ in which other clinical criteria, including signs of otitis, are taken into account to make a diagnosis of otitis. Animals with a score in the grey zone were classified as normal because the number of microrganisms was lower than the clinically significant limit²⁰ and clinical examination of the ears was not always possible.

Table 1

Cytological score based on the mean number of microorganisms identified in 10 different high-power dry fields (× 400)

		Score
	0(Normal)	1(Grey zone)*	2(Pathological)
Malassezia species (n)	≤2	>2 to <12	≥12
Cocci (n)	≤4	>4 to <15	≥15
Rods (n)	0	–	≥1

Ginel et al²⁰

Cats were considered to be suffering from otitis externa when at least one of the evaluated parameters (cocci, rods and Malassezia species) had a cytological score of 2 in at least one ear.

Statistical analysis

Overall prevalence was defined as the percentage of cats diagnosed with otitis based on cytological examination of ear swabs. Prevalence data were regrouped according to age (young/adult), gender (male/female), pregnancy status (yes/no), habitat (urban/rural), season of sampling (spring/summer/autumn/winter), type of otitis based on microorganisms detected using ear cytology (Malassezia species/cocci/rods/Otodectes species). Univariate analysis of the categorical data was performed using the χ² test for association between otitis externa, type of otitis and independent variable (age, gender, pregnancy status, habitat and season). Any parameters statically linked to otitis externa were used in a logistic regression model to test for risk factors associated with the feline otitis externa. The statistical evaluations were repeated with the subset of cats where both otoscopy and cytology results were available.

Concordance between the results of ear cytology and the direct otoscopic examination was calculated by unweighted kappa statistic. Statistical significance was defined as P <0.01. All data were analysed using commercial software (MedCalc, v. 12.3.0).

Results

Epidemiological data of the 187 stray cats enrolled are reported in Table 2.

Table 2

Tests for a relationship between otitis externa and risk variables using the χ² test with P value, odds ratio (OR) and 95% confidence interval (CI) for each risk variable considered in 187 stray cats

Variable	Category	Total n (%) of subject	n (%) of cats with otitis	P value and OR (95% CI )
Gender (n = 187)
	Female	106/187 (56.7)	50/106 (47.2)	P = 0.019 OR = 0.49 (0.27–0.89)
	Male	46/187 (24.6)	32/46 (69.6)	P = 0.023 OR = 2.25 (1.11–4.58)
	Pregnant female	35/187 (18.7)	21/35 (60)	P = 0.516 OR = 1.28 (0.61–2.70)
Age (n = 187)
	Young	80/187 (42.8)	45/80 (56.3)	P = 0.897 OR = 1.09 (0.60–1.95)
	Adult	107/187 (57.2)	58/107 (54.2)	P = 0.897 OR = 0.92 (0.51–1.65)
Habitat (n = 187)
	Rural	100/187 (53.5)	59/100 (59)	P = 0.314 OR = 1.41 (0.79–2.51)
	Urban	87/187 (46.5)	44/87 (50.6)	P = 0.314 OR = 0.71 (0.40–1.27)
Season of sampling (n = 187)
	Spring	35/187 (18.7)	14/35 (40)	P = 0.05 OR = 0.47 (0.22–1.00)
	Summer	42/187 (22.5)	23/42 (54.8)	P = 0.962 OR = 0.98 (0.49–1.96)
	Autumn	68/187 (36.4)	39/68 (57.4)	P = 0.637 OR = 1.16 (063–2.11)
	Winter	42/187 (22.5)	27/42 (64.3)	P = 0.173 OR = 1.63 (0.80–3.33)
Otoscopic alterations of ear canal (n = 86)	Yes	46/86 (53.5)	37/46 (80.4)	P <0.00001(<0.0001)*OR = 23.30 (7.50–72.34)
	No	40/86 (46.5)	6/40 (15)	P <0.00001 (<0.0001)*OR = 0.04 (0.01–0.13)

P values <0.05 are in bold

Data from logistic regression

Cytological evaluation

The evaluation of cytological samples revealed the presence of otitis externa in 103/187 cats, with a prevalence of 55.1%. Epidemiological data of these 103 cats are reported in Table 2.

Unilateral otitis was present in 4/103 cats (3.9%) and bilateral otitis in 99/103 cats (96.1%). Only 13/99 cats (13.1%) with bilateral otitis had different cytological scores for their left and right ears. There was no correlation between gender, age, habitat and season of sampling and feline otitis externa.

The microorganisms and the associations of microorganisms detected on ear cytology in cats with otitis are reported in Table 3. Malassezia species, alone or in association with other microorganisms, were present in 52/103 (50.5%) cats, cocci — alone or in combination — in 74/103 (71.8%) cats, rods in 30/103 (29.1%) cats (always with other microorganisms) and, finally, O cynotis — alone or in combination — in 55/103 (53.3%) cats. Data classified according to the type of otitis are reported in Tables 4 and 5. Positive correlations were detected between otitis externa with Malassezia species and urban habitat and winter season (Table 4), and confirmed by logistic regression analysis [odds ratio (OR) 4.68, 95% confidence interval (CI) 2.02–10.85, P = 0.0002 and OR 5.08, 95% CI 1.84–14.04, P = 0.0007, respectively). A factor significantly associated with the presence of otitis externa with cocci was pregnancy status (Table 5), and this correlation was confirmed by logistic regression analysis (OR 9.68, 95% CI 1.23–76.03, P = 0.0038). In otitis externa associated with rods a positive correlation was detected with winter season, but not confirmed by logistic regression analysis (Table 5).

Table 3

Microorganisms isolated in 103 stray cats with otitis externa (cytological score ≥2)

Microorganism	Number (%)
Malassezia species	6 (5.8)
Cocci	22 (21.4)
Cocci + rods	10 (9.7)
Otodectes cynotis	14 (13.6)
Malassezia species + cocci	5 (4.8)
Malassezia species + O cynotis	9 (8.7)
Malassezia species + cocci + rods	5 (4.9)
Malassezia species + cocci +O cynotis	14 (13.6)
Malassezia species + cocci + rods + O cynotis	13 (12.6)
Cocci + O cynotis	3 (2.9)
Cocci + rods + O cynotis	2 (1.9)

Table 4

Prevalence of Malassezia species and Otodectes cynotis in 103 stray cats with otitis, in relation to the epidemiological data and P value of the χ² test and odds ratio (OR) for each risk factor considered. Each cat may have more than one type of microorganism at the same time

Variable	Category	n (%)of subjects with otitis	n of cats with Malassezia species otitis	P value and OR(95% CI)	n of cats with Otodectes cynotis otitis	P value and OR (95% CI)
Gender
	Female	50/103 (49)	26/52	P = 0.7652 OR = 1.13 (0.52–2.44)	29/55	P = 0.3632 OR = 1.43 (0.66–3.12)
	Male	32/103 (31)	18/52	P = 0.4321 OR = 1.40 (0.60–3.24)	19/55	P = 0.4143 OR = 1.42 (0.61–3.31)
	Pregnant female	21/103 (20)	8/52	P = 0.2031 OR = 0.53 (0.20–1.42)	7/55	P = 0.0388 OR = 0.35 (0.13–0.97)
Age
	Young	45/103 (44)	20/52	P = 0.2801 OR = 0.65 (0.30–1.42)	21/55	P = 0.2277 OR = 0.62 (0.28–1.35)
	Adult	58/103 (56)	32/52	P = 0.2801 OR = 1.54 (0.70– 3.37)	34/55	P = 0.2277 OR = 1.62 (0.74–3.55)
Habitat
	Rural	59/103 (57)	20/52	P = 0.0001 (0.0002)*OR = 0.19 (0.08–0.45)	25/55	P = 0.6449 OR = 0.83 (0.38–1.81)
	Urban	44/103 (43)	32/52	P = 0.0001 (0.0002)*OR = 5.20 (2.21–12.23)	30/55	P = 0.6449 OR = 1.20 (0.55–2.61)
Season
	Spring	14/103 (14)	9/52	P = 0.2666 OR = 1.93 (CI = 0.6-6.20)	8/55	P = 0.7625 OR = 1.19 (CI = 0.38–3.72)
	Summer	23/103 (22)	6/52	P = 0.008 (0.0007)*OR = 0.26 (0.09–0.73)	8/55	P = 0.0423 OR = 0.37 (0.14–0.98)
	Autumn	39/103 (38)	16/52	P = 0.13 39 OR = 0.54 (0.24–1.21)	20/55	P = 0.7368 OR = 0.87 (0.39–1.94)
	Winter	27/103 (26)	21/52	P = 0.001 (0.0007)*OR = 5.08 (1.84–14.03)	19/55	P = 0.0396 OR = 2.64 (1.03–6.76)

CI = confidence interval

P values <0.01 are in bold

Data from logistic regression

Table 5

Prevalence of cocci and rods in 103 stray cats with otitis in relation to the epidemiological data and P value of the χ² test and odds ratio (OR) for each risk factor considered. Each cat may have more than one type of bacteria at the same time

Variable	Category	Number (%) with otitis	Number with otitis with cocci	P value and OR (95% CI)	Number with otitis with rods	P value and OR(95% CI)
Gender
	Female	50/103 (49)	35/74	P = 0.6860 OR = 0.84 (0.35–1.98)	16/30	P = 0.5330 OR = 1.31 (0.56–3.07)
	Male	32/103 (31)	19/74	P = 0.0589 OR = 0.43 (0.17–1.04)	9/30	P = 0.8807 OR = 0.93 (0.37–2.35)
	Pregnant female	21/103 (20)	20/74	P = 0.0076 (0.0038)*OR = 10.37 (1.32–81.33)	5/30	P = 0.5478 OR = 0.71 (0.24–2.16)
Age
	Young	45/103 (44)	32/74	P = 0.8841 OR = 0.94 (0.40–2.23)	8/30	P = 0.0256 OR = 0.35 (0.14–0.90)
	Adult	58/103 (56)	42/74	P = 0.8841 OR = 1.07 (0.45–2.53)	22/30	P = 0.0256 OR = 2.83 (1.11–7.17)
Habitat
	Rural	59/103 (57)	39/74	P = 0.2171 OR = 0.57 (0.24–1.39)	15/30	P = 0.3382 OR = 0.66 (0.28–1.55)
	Urban	44/103 (43)	34/74	P = 0.2171 OD = 1.74 (0.72–4.24)	15/30	P = 0.3382 OR = 1.52 (0.64–3.57)
Season
	Spring	14/103 (14)	13/74	P = 0.06 OR = 5.97 (0.74–47.89)	4/30	P = 0.9608 OR = 0.97 (0.28–3.37)
	Summer	23/103 (22)	19/74	P = 0.1928 OR = 2.16 (0.67–7.01)	5/30	P = 0.3763 OR = 0.61 (0.20–1.83)
	Autumn	39/103 (38)	20/74	P = 0.0003 (0.003)*OR = 0.19 (0.08–0.49)	7/30	P = 0.0513 OR = 0.39 (0.15–1.02)
	Winter	27/103 (26)	22/74	P = 0.1949 OR = 2.03 (0.69–6.01)	14/30	P = 0.0025 OR = 4.04 (1.59–10.29)

CI = confidence interval

P values <0.01 are in bold

Data from logistic regression

There was no difference in results when evaluating the subset of 86 cats with otoscopy and cytology available (data not reported).

Otoscopic examination

Alterations in quantity and/or quality of ear wax and/or ear canal abnormalities were identified in 46/86 cats (53.5%). The wax was characterised grossly as abundant in 41/86 (47.7%) cats, dark brown in 40/86 (46.5%) cats, yellow in 1/86 (1.2%) cat and black (typical of ear mite infection) in 28/86 (32.6%) cats. The following ear canal alterations were recorded: erythema in 3/86 (3.4%) cats, stenosis in 1/86 (1.2%) cat and ulcerations in 1/86 (1.2%) cat.

The χ² test showed a statistically significant correlation (P <0.0001) between otitis externa diagnosed by cytology and pathological changes in the external ear canal observed with direct otoscopic examination (Table 2) confirmed by logistic regression analysis (OR 23.3, 95% CI 7.50–72.34, P <0.0001). There was good agreement between findings of direct otoscopic examination and cytological examination in the 86 cats where both were performed (K 0.651, 95% CI 9 0.49–0.81).

Discussion

To our knowledge, this study is the first to analyse the prevalence of otitis externa in a population of stray cats, and for this reason it is difficult to compare our results with the literature, which is mainly concerned with pet cats.

The prevalence of feline otitis externa diagnosed by cytological examination of the ear canal in our study (55.1%) is considerably higher than the values previously reported in pet cats, which range from 2% to 19%.^4,6–8 The high prevalence in this study can be explained by the different population sampled. In fact, the populations studied by Baxter and Lawler,⁴ Baba and Fukata,⁶ Hill et al⁷ and Topală et al⁸ consisted of house cats admitted to a veterinary hospital, while our population is entirely composed of randomly selected urban and rural stray cats. It is likely that this cat population will have a lower health status than privately owned cats, and potentially more contact with other animals, increasing the risk of transmission of some pathogens, such as O cynotis.⁹

In the majority of the cats in this study the otitis externa was bilateral (96.1%). This is in agreement with results reported by Pugh et al²² in pet cats, but there have, to date, been no published reports of disease in stray cats.

In accordance with findings of previous studies in pet cats,^8,22 risk factor analysis showed that gender did not affect the prevalence of feline otitis externa. No differences between the causes of otitis in cats of different ages, habitats and seasons of sampling were observed in this study, although it has previously been reported that there is an increased frequency of otitis in young cats and summer months.⁸ However, that study analysed a population of only 83 pet cats without reporting the method by which otitis was diagnosed or specifying the causal factors involved.

O cynotis was identified in 29.4% of 187 cats in this study and was the primary cause of otitis in 55/103 animals (53.3%). Values reported in this study are very different from the 1% prevalence reported in the study conducted in Australia by Coman et al¹⁰ in 327 feral cats, and from the 2.2% detected by Duarte et al¹¹ in a population of 182 stray cats in Lisbon, Portugal. However, the prevalence reported in our study is quite similar to the 37% reported in a study conducted by Akucewich et al⁹ in central Florida during the summer in a population of 200 feral cats randomly selected for a TNR programme. The great variability in the values reported in the literature indicates the variation in the role of O cynotis in the stray cat population from country to country, probably owing to the different life and sanitary conditions of stray cats in different countries.¹⁴ Demodex cati was isolated from two cats that had no other signs of otitis externa. Considering the low number of mites detected (only one mite in both cases) this finding was considered to have no pathological relevance. However, opinion in the literature is divided on the role of this mite in otitis externa: some reports indicate that feline demodicosis may manifest as cerumious otitis externa,^23–25 while others describe the identification of this mite in large numbers from the ear canal of clinically normal cats.^26,27

Malassezia species may be found in low numbers in normal feline ears,^{20, 21} but this yeast may also become an important perpetuating cause of otitis externa.³ No previous studies have looked at the prevalence of otitis associated with Malassezia species in stray cats. In this study, Malassezia species was detected in 52/103 (50.5%) cats with otitis, which is consistent with previous reports of a prevalence between 28% to 95% in domestic or shelter cats with otitis externa.^28–31

In this study, winter and urban habitat were identified as predisposing factors for Malassezia species otitis; this may be owing to the hot and humid urban microclimate in the winter,^32–34 which may be more favourable to the development of Malassezia species. In a study of pet cats, Cafarchia et al¹⁹ found that the most favourable season for Malassezia species otitis development was autumn; however, both winter and autumn seasons are characterised by a high humidity at the latitudes discussed.³⁵

There is a wide range in the numbers of bacteria considered to be normal in ear cytology from domestic cats^20,21 and, in the absence of clinical signs, this can make it difficult to make a diagnosis of otitis based on cytological preparations. In our study, 74/103 cats had large numbers of cocci and therefore a cytological score suggestive of otitis externa. The presence of cocci in the ears of cats suffering from otitis has been reported,²⁰ but the prevalence in our study cannot be compared with previous reports because the only report on feral cats was a culture study, without cytological evaluation of specimens.¹³ Pregnancy status seems to be an important risk factor for of otitis with cocci; a possible explanation could be reduction in local immunity during pregnancy, although there are no studies in veterinary medicine to confirm this hypothesis, and in human medicine it is known that it is misleading to consider pregnancy as a condition causing general immune suppression.³⁶ However, it is important to note the wide CI of the OR for this variable, which may limit the validity of the data.

In this study the identification of a single rod was considered sufficient to diagnose rod-based otitis externa, as previously reported by Tater et al²¹ in whose study no rods were detected in the ears of healthy cats. The number of cats with otitis associated with rods (30/187, 16%) was much higher than expected, but we cannot compare the data as no studies of either pet cats or stray cats have previously reported on cytological evaluation of the presence of rods in the ear canal. However, there is a culture study that shows a prevalence of 17% for Bacillus species in the ear canal of a group of stray cats.¹³ Finally, it is interesting to note that rods were never present as the sole organism in cats with otitis, but always in combination with cocci, Malassezia species and/or O cynotis.

Cytology of otic exudates is a very specific diagnostic method in the cat²⁰ that is indispensable for confirming the presence of an ear infection and for evaluating the type of infection.^2,37 It is reported to be more sensitive in the detection of microorganisms than microbial culture.^3,38 In the present study, the χ² test showed a statistically significant association between cytological results and direct otoscopic examination of the external canal, confirmed by logistical regression, and the K statistics showed a good degree of assessment between cytological score and otoscopic canal examination. This positive correlation shows that detection of alterations in the ear wax and/or in the external ear canal may be an accurate indicator of the presence of feline otitis, even if cytological examination is still required to identify aetiological agents. It could, therefore, be concluded that direct otoscopy alone may allow the diagnosis of an ear infection in cats, which may be very useful in TNR programmes where time is limited and additional examinations like ear cytology may not be feasible.

However, in this study, mite movement on typical black wax was not seen on otoscopic examination of the ear canal in all cases of O cynotis infestation. In fact, mites were noted with direct ear otoscopy in only 28/86 cats, while O cynotis was identified on ear cytology in 30 cats. This confirms that the typical black ear discharge with mite movement in the ear canal is not always seen in affected cats¹⁸ and emphasises the importance of ear cytology for exclusion of the presence of O cynotis.

One of the major limitations of this study was the fact that not all cats were examined for signs of otitis externa. This meant that we were unable to objectively interpret the cytological grey zone defined by previous studies. The cats in this study included in the grey zone were classed as unaffected and the prevalence of otitis in our study may have been underestimated. In fact, we know that the cytological limits used in our study to differentiate normal from inflamed external ear canals provide a specificity of 100%, but a low sensitivity.²⁰ In addition, cytological evaluation was made by taking material only from the vertical portion of the external ear canal, and the prevalence of various microorganisms may change at the level of the horizontal canal; however, to make a withdrawal more accurate we needed a cone-sterile otoscope, but we wanted to reproduce a normal clinical situation. A further limitation was the small sample size in some subgroups that limited our ability to perform statistical analyses. Furthermore, some conclusions or associations may be affected by type II error, and culture examination for Malassezia species and bacteria was not performed on ear canals of all cats.

Conclusions

Despite the limitations of our survey, these results demonstrate that otitis externa is a relevant disease in stray cats and confirms that O cynotis is a common parasite in stray colony cats of northern Italy. Also, there is a high prevalence of Malassezia species and bacterial otitis in stray cats. This study adds to the literature on stray cats, which remain poorly investigated, and expands the information on feline otitis in general.

Footnotes

Funding

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors

Conflict of interest

The authors do not have any potential conflicts of interest to declare.

Accepted: 14 October 2013

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