Dermatophytosis, commonly known as ringworm, is a superficial fungal infection frequently encountered in pets and humans. Although this pathology is regularly reported by Portuguese veterinary practitioners, detailed epidemiological data concerning the relative importance of the different dermatophyte species involved and the observed variations according to animal species, breed, sex, and age have so far remained scarce.
This study aims to fill this gap by providing an in-depth epidemiological analysis of dermatophytosis in dogs and cats in Portugal over a 12-year period.
Materials and Methods
Data Collection and Diagnostic Procedures
Between 2012 and 2023, hair and scale samples were collected from dogs and cats with a clinical suspicion of dermatophytosis in 355 veterinary centers across mainland Portugal. In total, 4716 samples were analyzed, of which 271 were excluded due to fungal contamination.
Samples were inoculated on DERM agar medium, incubated at 25°C for a maximum of 4 weeks, and periodically examined for fungal growth. Dermatophyte identification was performed by macroscopic and microscopic examination of colonies.
Statistical Analysis
Data were processed using JMP® and MedCalc® software. Non-parametric tests were used to study differences between observed and expected frequencies. Logistic regression with Tikhonov regularization was used to identify predisposed breeds.
Results
Prevalence and Geographical Distribution
Of the 4445 samples analyzed, 568 (12.8%) tested positive for dermatophytes. The majority of samples came from the North (44.6%) and Central (28.4%) regions of Portugal. The regions with the highest frequency of positive cases were the Central (14.6%) and North (13.8%) regions.
Animal Species and Breeds
Cats showed a significantly higher frequency of dermatophytosis (17.4%) compared to dogs (9.1%) (p<0.001).
In dogs, Yorkshire Terrier, West Highland White Terrier, Miniature Pinscher, Dalmatian, and Miniature Schnauzer breeds showed a significant predisposition to dermatophytosis (p<0.05). In cats, Persian and Scottish Fold breeds were significantly predisposed (p<0.05).
Severe ringworm in a Yorkshire terrier
Sex and Age
No significant difference was observed between sexes (p>0.05). A weak but significant negative correlation was found between age and the frequency of dermatophytosis, both in dogs (r=-0.05, p=0.018) and cats (r=-0.14, p<0.001).
Dermatophyte Species
Microsporum canis was the most frequently isolated species (63.9%), followed by Trichophyton spp. (20.3%) and Nannizzia gypsea (formerly Microsporum gypseum) (8.1%). M. canis was significantly more frequent in cats (68.6%) than in dogs (31.4%).
Discussion
This study provides the first in-depth epidemiological analysis of dermatophytosis in companion animals in Portugal. The overall prevalence of 12.8% is at the lower end of the range reported in other European countries, where it typically varies from 20% to 30%.
The predominance of M. canis (63.9% of isolates) corroborates literature data, which report that this species is responsible for 81.8% to 97% of dermatophytosis cases in companion animals. The higher frequency in cats (17.4%) compared to dogs (9.1%) also confirms observations from other studies.
The geographical distribution of cases, with a predominance in the North and Central regions, could be explained by climatic conditions more favorable to the development of dermatophytes, particularly higher humidity. However, the presence of cases in all regions of Portugal highlights the ubiquity of these infections and the need for constant vigilance, even in areas considered less favorable.
The identification of predisposed breeds, in both dogs and cats, provides valuable information for clinical practice. This data will allow veterinarians to be more vigilant when examining these at-risk breeds, without neglecting the possibility of dermatophytosis in other breeds.
The negative correlation between age and the frequency of dermatophytosis suggests a greater vulnerability of young animals, probably due to the immaturity of their immune system. This observation highlights the importance of particular attention during the examination of puppies and kittens, without ruling out the possibility of infection in older animals.
Conclusion
This 12-year retrospective study provides valuable epidemiological data on dermatophytosis in companion animals in Portugal. It highlights the importance of M. canis as the main etiological agent, the predisposition of certain breeds, and the increased vulnerability of young animals. These results emphasize the need for continued vigilance against this zoonotic and contagious affection, which represents a growing public health issue.
Veterinary practitioners should integrate this information into their diagnostic and therapeutic approach, paying particular attention to breeds identified as predisposed and to young animals, without neglecting the possibility of dermatophytosis in other categories of animals.
Future research could focus on the environmental and genetic factors underlying the predisposition of certain breeds, as well as prevention and control strategies adapted to the epidemiological specificities identified in this study.
Lopes R, Garcês A, Silva A, Brilhante-Simões P, Martins Â, Cardoso L, Duarte EL, Coelho AC. Dermatophytosis in Companion Animals in Portugal: A Comprehensive Epidemiological Retrospective Study of 12 Years (2012-2023). Microorganisms. 2024 Aug 22;12(8):1727. doi: 10.3390
Related Searches
cat ringworm, cat, ringworm in cats, ringworm in cats, treatment, ringworm in, dog, animal, veterinarian, skin, symptoms, disease, treating ringworm, fungus, fungi, wood’s lamp, surface, how to treat ringworm, lesions, reading, scabs, risks, mycosis, mammals, skin lesions, hair loss, dandruff, causes, human, redness, hair loss, ringworm treatment, appointment, itching, ears, external environment, tail, head, limbs, skin surface, ringworm diagnosis, herpes circinata, culture, other, environment, contamination, parasite, ringworms, preventing ringworm, in humans, clinical signs, Persians, spores, times, ringworm symptoms, contagion, contact
