Canine Atopic Dermatitis (CAD) is a common skin condition in dogs, characterized by lesions observed mainly on the face, ear pinnae, abdomen, groin, armpits, flexural surfaces of the elbow, and paws.
Breed predisposition and lesion distribution can vary in atopic dogs, leading to diverse and race-specific clinical presentations. Preferred dog breeds may vary from country to country, leading to geographical differences in the breeds selected for CAD studies. This study aims to analyze the prevalence and distribution of CAD lesions in common breeds in Korea, focusing on race-specific characteristics.
Introduction
Canine Atopic Dermatitis (CAD) is a common chronic inflammatory skin condition, influenced by genetic and environmental factors. Its prevalence and clinical presentation can vary significantly from breed to breed. In Asia, and particularly in Korea, small and medium-sized dogs are more popular than large breeds, unlike Western countries where CAD studies often focus on large breeds such as the Golden Retriever or Labrador. This popularity of small breeds in Korea highlights the need for a specific study on the prevalence and distribution of CAD lesions in these dogs.
Previous studies have shown that certain breeds are more predisposed to CAD, with specific lesion sites associated with these breeds. For example, studies in Switzerland have highlighted breed predispositions in the Boxer, Bull Terrier, Vizsla, and Basset Hound. An Australian study revealed an increased risk of CAD in the Beagle, Bulldog, Bull Mastiff, Great Dane, Labrador Retriever, Shar-Pei, and Staffordshire Terrier. A data analysis from 15 countries also identified more frequent lesion areas in the Boxer, Dalmatian, German Shepherd, Shar-Pei, French Bulldog, and West Highland White Terrier (WHWT).
Given the predominance of small and medium-sized dogs in Korea, this study aims to determine the prevalence of CAD in these breeds and identify breeds with a higher prevalence compared to the registered canine population. In addition, the study analyzes breed-specific associations with particular body sites, using an exhaustive dataset collected from photographs of skin lesions. The objective is to provide valuable information to practicing veterinarians in Korea, enabling them to improve the diagnosis and management of CAD in small and medium-sized dogs.
Materials and Methods
This study was conducted in compliance with a strict ethical protocol, ensuring animal welfare and owner data confidentiality.
Ethical Considerations
Written informed consent was obtained from all dog owners participating in the study. This consent included permission to use patient information and clinical data for research purposes. Only photographs of skin lesions were taken for lesion distribution analysis, and no identifiable patient images were used to preserve their anonymity.
Study Design
Data were collected from multiple sources: the Dermatology Department of Seoul National University Veterinary Teaching Hospital and three private veterinary clinics in Korea (ORIGIN Veterinary Dermatology Clinic in Busan, Ilsan Animal Medical Center in Gyeonggi-do, and Green Animal Medical Center in Gyeonggi-do). The collection period extended from January 2023 to November 2023. Lesion locations were recorded from photographs using specific software designed to annotate body sites.
An analysis of the canine population registered with the Ministry of Agriculture, Food and Rural Affairs of Korea was performed, allowing comparison of CAD prevalence in different breeds relative to their representation in the general population.
Of a total of 331 dogs of 42 different breeds included in the study, only small and medium-sized breeds representing 77% of the total CAD group were selected for final analysis. These breeds were: Maltese, Miniature/Toy Poodle, Shih Tzu, Bichon Frise, Cocker Spaniel, Pomeranian, French Bulldog, Yorkshire Terrier, and Dachshund.
Inclusion Criteria
Dogs included in the study had to have a diagnosis of CAD based on history and clinical signs, and satisfy at least five previously established criteria. All dogs underwent adequate parasite control to exclude flea bite hypersensitivity. Ectoparasitic infestations and dermatophytosis were excluded by skin scrapings and hair examination (Wood’s lamp and fungal culture). Only patients who did not show improvement after a 6-8 week elimination diet trial with commercial hydrolyzed foods were included. Dogs with concurrent secondary bacterial or yeast infections were also included.
Data Collection and Analysis
Software specifically designed for lesion annotation and marking (Lime Research; Lime Solution Corp.) was used to record the location of lesions observed in photographs. Multiple photographs were taken for dogs with lesions in multiple locations. Each photograph of the 44 body sites was examined by referral veterinarians. The list of body sites is presented in Table S1 of the supplementary information.
Statistical Analysis
Breed-specific proportions in the registered canine population were compared to those in the CAD group to determine the prevalence of CAD. Lesion distributions by breed were compared to determine which body sites were most frequently affected in the nine CAD-affected breeds selected in this study.
Statistical analyses were performed using the chi-square test or Fisher’s exact test to identify significant differences. Odds ratios (OR) with 95% confidence intervals (CI) were calculated to determine the strength and precision of these associations. All statistical analyses were performed using R software (version 4.4.0; R Foundation for Statistical Computing), with a statistical significance threshold set at p < 0.05 for all tests.
Results
Data analysis reveals varying CAD prevalence across the studied breeds, as well as breed-specific lesion distributions.
Breed-Specific CAD Prevalence
Shih Tzu (p=0.001, OR=1.78, CI=1.25–2.52), Cocker Spaniel (p<0.001, OR=5.22, CI=3.47–7.84) and French Bulldog (p<0.001, OR=4.07, CI=2.23–7.42) breeds represented a significantly higher proportion of dogs with CAD compared to the registered canine population.
The number and proportion of dogs of each breed are presented in Table 1. The CAD group and the registered canine population are presented. Breeds with a significantly higher proportion of CAD than the registered canine population are highlighted.
Breed-Specific Lesion Distribution
French Bulldog, Shih Tzu, and Dachshund breeds showed statistically significant differences in lesion distribution compared to other selected breeds in this study.
The French Bulldog showed a significantly higher prevalence of lesions in several regions, including the peri-labial (inferior) area, dorsal tail, left front paws (dorsal and ventral), right front paws (dorsal and ventral), and left hind paws (dorsal and ventral).
The Shih Tzu showed a significantly high prevalence of lesions at specific sites, including the right ventral and dorsal neck, caudal aspect of the right forelimb, left elbow fold, ventral trunk, left and right armpits, forehead, and dorsal aspect of the right forepaw.
Compared to other breeds, Dachshunds were significantly more affected at the left and right dorsal thorax.
Discussion
This study highlights the specificities of CAD in small and medium-sized dogs in Korea, emphasizing the importance of considering breed predispositions and lesion distribution for accurate diagnosis and management.
Unlike Western studies focusing on large breeds, this research focuses on small and medium-sized breeds, which represent a significant portion of the canine population in Korea. The classification of dog breeds by size is based on weight, with small and medium-sized breeds generally defined as those weighing less than 25 kg. In this classification, small and medium-sized breeds accounted for a large proportion of the registered canine population. As a result, 93% of the 331 dogs with CAD in this study were small and medium-sized breeds. In contrast, the predominant large breeds in previous studies, such as Golden Retriever, Labrador Retriever, and Boxer, accounted for only 1.8% of the total number of CAD-affected dogs in the present study. This breed distribution is significantly different from that reported in previous studies which focused mainly on medium to large sized dog breeds.
The results reveal that Shih Tzu, Cocker Spaniel, and French Bulldog breeds exhibit a high prevalence of CAD, confirming previous observations in other regions. Although Maltese, Poodle, and Yorkshire Terrier are common in Korea, these breeds did not show a significant difference in CAD prevalence compared to the registered canine population. Although a direct analysis of CAD prevalence was not performed, a study on dogs undergoing an allergen intradermal test in Thailand included a significant number of Poodles and Shih Tzus. Furthermore, previous studies have shown that French Bulldogs are predisposed to CAD in countries such as Switzerland and Germany. Another study conducted in Korea revealed an increased prevalence of CAD in Cocker Spaniel, Pug, and Fox Terrier breeds. This result was consistent with our findings in Cocker Spaniels. In the present study, the Bichon Frise showed no significant difference in CAD prevalence, while a study conducted in Australia reported an increased risk of CAD in this breed.
The study also highlights breed-specific lesion distributions. Shih Tzus with CAD primarily presented with lesions on the ventral neck, joint folds, stomach, and armpits. The characteristic lesion distribution in atopic Shih Tzus has not been reported previously. Malassezia dermatitis can occur secondarily to CAD, and its risk is notoriously high in Shih Tzus. The distribution of Malassezia dermatitis lesions primarily affects the ventral neck and armpits. The higher risk of secondary Malassezia dermatitis in atopic Shih Tzus can be attributed not only to their skin folds on the ventral neck and armpits, which structurally predispose these regions to Malassezia overgrowth, but also to the characteristic distribution of atopic lesions on the uncovered belly found in the present study.
Lesions were particularly frequent in the labial and tail folds of French Bulldogs affected by CAD. One study reported a predisposition to facial lesions in atopic French Bulldogs, although specific facial areas were not further detailed. Another study, which analyzed more detailed sites, found that atopic lesions in French Bulldogs were mainly located on the eyelids, armpits, and flexor surfaces of the limbs. Although this study and the present study observed differences in the specific facial areas affected, both showed a tendency for facial lesions. The wrinkled skin in this breed predisposes them to intertriginous dermatitis. In addition, we found that the French Bulldog more frequently developed lesions on the distal extremities. The paws are generally known to be a commonly affected area in CAD, yet our results showed that the prevalence of paw lesions was more concentrated in the French Bulldog compared to other breeds.
In the present study, CAD-affected Dachshunds had lesions on the dorsal thorax, significantly more than other breeds. However, further research is needed due to the small sample size of Dachshunds (n=7) in this study. In general, the dorsolateral area is not a frequently affected site for atopic lesions in dogs. However, one study reported that Shar-Peis and WHWTs with CAD frequently have lesions in the dorsolateral area. Thus, not all breeds frequently develop lesions in the dorsolateral area.
The present study showed that the prevalence of ear lesions in Cocker Spaniels did not differ significantly from that in other breeds. The Cocker Spaniel is predisposed to developing otitis externa and is commonly affected by CAD. Nevertheless, the Cocker Spaniels involved in this study did not show a distinct pattern of atopic lesions concentrated in the ear concha compared to other breeds.
Maltese, Pomeranian, Bichon Frise, and Yorkshire Terrier did not show a significantly higher prevalence of atopic lesions at specific sites than other breeds. According to a previous study, atopic lesions in Maltese were frequently observed on the abdomen and paws. Nevertheless, no study has analyzed the distribution of atopic lesions in Pomeranians, Bichon Frises, and Yorkshire Terriers.
Limitations of this study include the small number of dogs with CAD, including French Bulldogs (n = 11), Yorkshire Terriers (n = 11), and Dachshunds (n = 7). Due to the lack of data on disease duration and medication administration, lesion distribution in this study was limited to the condition at the time of imaging. Therefore, additional studies with larger sample sizes and more detailed clinical histories are needed.
Conclusions
In summary, this study identified significant differences in the prevalence and distribution of CAD lesions in small and medium-sized dogs in Korea. Shih Tzu, Cocker Spaniel, and French Bulldog breeds show a higher prevalence of CAD, with breed-specific lesion patterns.
These results underscore the importance of a personalized approach to the diagnosis and management of CAD, taking into account breed predispositions and lesion distribution to optimize therapeutic strategies and improve the quality of life of affected animals.
Ryu J-H, Kang J-H, Kang Y-H, Kim M-S, Kim H-J, Huh E-A, et al. Prevalence and lesion distribution of atopic dermatitis in small-to-medium breed dogs in Korea. Vet Dermatol. 2025;36:186–195. https://doi.org/10.1111/vde.13329
