Survey of otitis externa in American Cocker Spaniels in Finland

Background: American Cocker Spaniels are overrepresented among breeds that require surgery as a treatment of end-stage otitis externa. However, the prevalence of otitis externa (OE) in this breed remains unknown. We reviewed the year 2010 medical records of 55 private veterinary clinics in Finland to determine the prevalence of OE in American Cocker Spaniels compared with English Cocker and English and Welsh Springer Spaniels. An American Cocker Spaniel owner questionnaire was designed to identify potential risk factors for end-stage OE. Results: From the medical records of 98,736 dogs, the prevalence of OE was highest in Welsh Springer Spaniels (149 out of 468, 31.8%, [95% confidence interval 27.6-36.0]), followed by American Cocker (89/329, 27.0%, [22.2-31.7]), English Springer (96/491, 19.6%, [16.1-23.1]) and English Cocker Spaniels (231/1467, 15.7%, [13.8-17.6]). The mean number of OE episodes in ear-diseased dogs and the number of ear surgeries were highest in American Cocker Spaniels. Owner questionnaires were received for 151 American Cocker Spaniels, 85 (56%) of which had suffered from OE. In 47% (40/85) of these dogs, OE occurred without concurrent skin lesions, 46% (33/72) displayed the first signs of OE before 1 year of age. In 24% (20/85) of the dogs, the signs of OE recurred within 1 month or continued despite treatment, 16% (14/85) required surgery (n = 11) or were euthanized (n = 5; 2 of the operated dogs and 3 others) due to severe OE. The onset of OE before the age of 1 year significantly increased the risk (OR 3.8, 95% CI 1.1-13.6) of end-stage OE. Conclusions: The prevalence of OE in American Cocker Spaniels in Finland was higher than previously reported in Cocker Spaniels, but the highest prevalence of OE was found in Welsh Springer Spaniels. Compared to the other Spaniels, OE was more often recurrent and more frequently surgically managed in American Cocker Spaniels. Based on the questionnaire, early onset (<1 year) of OE increased the risk of end-stage OE. In American Cocker Spaniels, OE requires an intensive approach from the first treatment, and prevention of recurrence should be emphasised. The causes and treatment of OE in this breed warrant further study.Peer reviewe

Aural CT characteristics of American Cocker Spaniels have features of both mesaticephalic and brachycephalic breeds

Otitis externa and otitis media are common in American Cocker Spaniels, however breed-specific aural CT descriptions are currently lacking. This prospective and retrospective, observational, analytical study aimed to describe quantitative CT characteristics of the horizontal ear canal and the tympanic bulla in American Cocker Spaniels versus similar-sized mesaticephalic dogs. We prospectively performed clinical examinations and aural CT scanning for 38 American Cocker Spaniels. Computed tomographic transverse area of the osseous horizontal ear canal (TA1), transverse area of the widest air-filled part of the cartilaginous horizontal ear canal (TA2), tympanic bulla volume, and tympanic bulla wall thickness were measured. The TA1 and TA2 measurements were compared with those of 23 retrospectively recruited, similar-sized mesaticephalic dogs that had undergone CT-scanning of the head for non-ear-related reasons. The TA1 and TA2 did not differ for healthy American Cocker Spaniels and mesaticephalic dogs. Severely affected American Cocker Spaniels had significantly smaller TA2 (P <.001). The intraclass correlation coefficient for intraobserver and interobserver repeatability was 0.972 and 0.983 for TA1 and 0.994 and 0.998 for TA2, respectively. Variation between individuals was subjectively noted in healthy and affected American Cocker Spaniels, but mean tympanic bulla volume was slightly smaller in relation to body weight, and the tympanic bulla wall was thicker than in previous reports for mesaticephalic dogs. The tympanic bulla wall appeared thicker rostro-ventrally than caudo-ventrally in 44% of the dogs. Our results imply that a relatively thick tympanic bulla wall may be a normal CT variation and should be interpreted cautiously in this breed.Peer reviewe

Clinical and Genetic Findings in 28 American Cocker Spaniels with Aural Ceruminous Gland Hyperplasia and Ectasia

American Cocker Spaniels (ACSs) develop aural ceruminous gland hyperplasia and ectasia more often than dogs of other breeds. Data on the cause and development of these breed characteristic histopathological changes are lacking. We performed video-otoscopic examinations and dermatological work-up on 28 ACSs, obtained aural biopsies from each dog and assessed the statistical associations between the presence of ceruminous gland hyperplasia and ectasia and disease history, clinical or microbiological findings and underlying cause of otitis externa (OE). Histological lesions of ceruminous gland hyperplasia and ectasia were observed in aural biopsies from 6/13 clinically healthy ears and 13/15 ears with OE from 19/28 examined dogs. Nine of 28 dogs had histologically normal ceruminous glands (odds ratio [OR] 6.2, 95% confidence interval [CI] 1.1-36.6). Bacterial growth in microbiological culture of aural exudate (OR 14.1, 95% CI 2.1-95.3) was associated with ceruminous glandular changes, whereas previous history of OE, cutaneous findings or underlying allergies were not. Pedigree analysis and a genome-wide association study (GWAS) were performed on 18 affected and eight unaffected dogs based on histopathological diagnosis. While the GWAS indicated a tentative, but not statistically significant, association of ceruminous gland hyperplasia and ectasia with chromosome 31, a larger cohort is needed to confirm this preliminary result. Based on our results, ceruminous gland hyperplasia and ectasia may also precede clinical signs of OE in ACSs and a genetic aetiological component is likely Further studies with larger cohorts are warranted to verify our preliminary results. (C) 2021 The Authors. Published by Elsevier Ltd.Peer reviewe

Characteristics of Otitis Externa in American Cocker Spaniels in Finland

Otitis externa (OE) is one of the most common diseases in dogs with multifactorial aetiology. OE, especially when severe, may cause marked discomfort, pain and hearing loss, substantially reducing animal welfare. American Cocker Spaniels (ACSs) have a breed predisposition to OE. They are over-represented among breeds that suffer from end-stage otitis, in which chronic proliferative changes of the ear canal prevent the resolution of OE. Histologically, in end-stage otitis, fibrosis of the ear canal skin is common in dogs of other breeds, whereas the majority of ACSs show ceruminous gland hyperplasia and ectasia. The reason for this difference remains unknown. This thesis aimed to characterise special features of OE in ACSs with retrospective and prospective methods. We aimed to describe the prevalence of OE in ACSs in Finland and the clinical, histopathological, and computed tomography (CT) characteristics of OE in ACSs. We also aimed to evaluate possible associated factors and genetic predisposition of breed-characteristic ceruminous glandular changes in this breed. A cross-sectional retrospective study exploring patient record data revealed that the prevalence of OE in ACSs, 27%, was higher than previously described for Cocker Spaniels. Compared to other spaniel breeds, OE in ACSs was more often recurrent and severe. Nine per cent of ACSs were treated with surgery compared with 1% of other spaniel breeds. An online questionnaire for ACS owners with 151 responses revealed that the first onset of OE frequently occurred at a young age, in 46% before the age of one year. The early onset of OE significantly increased the risk for end-stage otitis. Thirty-eight ACSs participated in prospective, observational, analytical studies performed at the Veterinary Teaching Hospital of University of Helsinki (VTHUH). The dogs were graded as clinically healthy or having OE based on video-otoscopic examination and scoring of the amount of erythema, oedema, erosions and exudate of the ear canals. Aural CT scanning was performed on 18 clinically healthy ACSs and 20 ACSs with OE, and the results were compared with 23 retrospectively collected healthy mesaticephalic dogs. The transverse area of the osseous and cartilaginous horizontal ear canal of clinically healthy ACSs was comparable to other similar-sized mesaticephalic dogs. In both healthy and otitic ACSs, the tympanic bulla wall was thicker and the tympanic cavity volume smaller in relation to body weight when compared to previous reports of mesaticephalic dogs. The tympanic bulla wall was thicker rostro-ventrally than caudo-ventrally in 44% of the ACSs, which is a typical finding in brachycephalic but not in mesaticephalic breeds. Histological examination of ear canal biopsies was performed on 13 clinically healthy ACSs and 15 ACSs with OE. Ceruminous gland hyperplasia and ectasia appeared in 87% of dogs with OE. A novel finding was that such histological findings appeared also in 46% of clinically healthy ACSs. The presence of OE was significantly associated with the presence of ceruminous gland hyperplasia and ectasia. Age, disease history, the presence of concurrent skin lesions or allergies showed no such associations. Pedigree analysis revealed that many histologically affected dogs were closely related, indicating a likely genetic background for the glandular changes. Genome-wide association study showed a tentative but not a statistically significant association in chromosome 31. Based on our results, the prevalence of OE in ACSs is high in Finland. ACSs have an increased risk for end-stage otitis, especially if the first OE episode occurs before one year of age. The anatomical morphology of the tympanic bulla appears slightly different in ACSs compared to other mesaticephalic dogs. A thick tympanic bulla wall may be a normal variation in this breed, which should be considered when interpreting CT-images. Ceruminous gland hyperplasia and ectasia appear to be a feature common to the breed. The finding that glandular changes may precede clinical signs of OE in this breed points to a possible genetic background for the condition. Further studies with a larger number of dogs are required to verify our genetic results.Ulkokorvantulehdus on koiralla hyvin yleinen, kipua aiheuttava, monitekijäinen sairaus. Kroonistuessaan se heikentää merkittävästi eläimen kuuloa ja hyvinvointia. Amerikancockerspanieleilla on alttius vakavalle, krooniselle ulkokorvantulehdukselle, jossa tulehdusta ylläpitävät tekijät estävät korvatulehduksen paranemisen. Kroonisessa korvatulehduksessa havaittava korvakäytävän ihon korvavahaa tuottavien apokriinisten hikirauhasten voimakas liikakasvu ja laajeneminen on tällä rodulla yleisempää kuin muilla, mutta syytä tähän eroon ei tiedetä. Tämän väitöskirjan tavoitteena oli selvittää ulkokorvantulehduksen esiintyvyyttä ja erityispiirteitä amerikancockerspanieleilla Suomessa. Lisäksi tavoitteena oli selvittää rodulle tyypilliseen korvavaharauhasten liikakasvuun ja liikatoimintaan liittyviä tekijöitä ja mahdollista perinnöllistä alttiutta. Potilastietokantojen retrospektiivisessä tutkimuksessa havaittiin, että korvatulehduksen esiintyvyys Suomen amerikancockerspanieleilla oli 27 %. Esiintyvyys oli korkeampi kuin mitä cockerspanieleilla on aiemmin raportoitu (8–20 %). Muihin spanielirotuihin verrattuna korvatulehdus uusiutui tällä rodulla useammin ja myös kirurginen hoito oli yleisempää. Amerikancockerspanielien omistajille suunnatun kyselytutkimuksen 151 vastauksen perusteella ensimmäinen korvatulehdus esiintyi tällä rodulla usein varhain, 46 %:lla koirista alle yksivuotiaana. Varhainen alkamisikä lisäsi merkittävästi vakavan korvatulehduksen riskiä. Yliopistollisessa Eläinsairaalassa suoritettuun prospektiiviseen ja havainnoivaan tutkimukseen osallistui 18 kliinisesti tervettä ja 20 ulkokorvantulehdusta sairastavaa amerikancockerspanielia. Koirille suoritettiin tietokonetomografiakuvaus (TT) ja tuloksia verrattiin retrospektiivisesti tutkittuihin terveisiin, samankokoisiin, keskipitkäkuonoisiin koiriin (n=23). Vaakasuoran korvakäytävän poikkileikkauksen pinta-alassa ei ollut eroa terveiden amerikancockerpanielien ja kontrollikoirien välillä. Amerikancockerspanieleiden täryontelon tilavuus suhteessa koiran painoon oli pienempi ja täryontelon luisen seinämän paksuus suurempi kuin mitä muilla keskipitkäkuonoisilla koirilla on aikaisemmin raportoitu. Täryontelon seinämän paksuudessa oli piirteitä lyhytkuonoisille koirille tyypillisestä rakenteesta. Korvakäytäväbiopsian histologinen tutkimus suoritettiin 13:lle kliinisesti terveelle ja 15:lle ulkokorvantulehdusta sairastavalle koiralle. Korvavaharauhasten liikakasvu ja laajeneminen todettiin 87 %:lla sairaista koirista. Ulkokorvantulehduksen ja rauhasmuutosten välillä todettiin tilastollisesti merkitsevä yhteys. Koiran ikä, sairaushistoria, iho-oireiden esiintyminen tai allergia eivät vaikuttaneet rauhasmuutosten esiintymiseen. Korvavaharauhasten liikakasvu ja laajeneminen havaittiin myös lähes puolella kliinisesti terveistä koirista. Tätä ei ole aikaisemmin raportoitu. Tulos viittaa siihen, että amerikancockerspanieleilla rauhasmuutoksia voi esiintyä jo ennen korvatulehduksen ilmaantumista. Sukutaulututkimuksessa havaittiin, että moni rauhasmuutos-koirista oli sukua keskenään, mikä viittaa perinnölliseen alttiuteen. Perimänlaajuisessa assosiaatiotutkimuksessa löytyi alustava, ei kuitenkaan tilastollisesti merkitsevä, yhteys kromosomiin 31. Väitöskirjan tulosten perusteella ulkokorvantulehduksen esiintyvyys Suomen amerikancockerspanieleilla on korkea. Rodun yksilöillä on suurentunut riski vakavalle krooniselle ulkokorvantulehdukselle, erityisesti jos ensimmäinen korvatulehdus esiintyy alle vuoden ikäisenä. Amerikancockerspanielilla paksu täryontelon seinämä voi olla normaali löydös, mikä on otettava huomioon TT-kuvien tulkinnassa. Korvavaharauhasten liikakasvu ja laajeneminen on rodulle tyypillistä. Rauhasmuutoksen esiintyminen myös kliinisesti terveillä koirilla viittaa perinnölliseen taustatekijään. Perinnöllisyyden varmentaminen vaatii lisätutkimuksia suuremmalla koiramäärällä