Allergies in animals are multifactorial and complex diseases and the symptoms vary highly between species, as well as between different types of allergic disorders. The pathogenesis is, as far as is known, similar to that in humans. In contrast to the deep knowledge in human allergology, the veterinary field lags far behind. However, there is a rising field of interest in comparative and veterinary allergology. While in humans big data are available, no central databases are accessible for animal allergies, which is the biggest limitation in the veterinary field. No big cohort studies are published allowing conclusions on the impact of the gender, breed, or regional differences on the disease. Another aspect to be noted is sterilization surgery in pet animals, which is regularly done in dogs and cats, as well as in male horses. This may explain why there isless impact of sexual hormones on allergies, but this impact is difficult to analyze. In this review article, the few interesting findings regarding gender aspects in companion animals were extracted from current literature. This could be of potential interest for animal owners, as well as for allergic patients who are interested in human-animal comparisons.. To summarize, however, there is still a lack of studies investigating gender predisposition for allergies in cats, dogs or horses.