A recent study has found that cats are the only type of pet linked to an increased risk of mental health problems in children, according to research based on data from the INMA Project (Infancia y Medio Ambiente, or "Children and Environment"). The study included about 1,900 households in Spain, located in the regions of Asturias, Gipuzkoa (in the Basque Country), Sabadell (near Barcelona), and Valencia. Nearly half of the families (52.3%) had or had previously had a pet. Among them, 19.1% had dogs, 8.7% had cats, 14.8% had birds, and 28.6% had other types of pets such as hamsters, rabbits, turtles, or fish. The study looked at how the presence of pets affects children's mental health, classifying issues into two categories: internalising (like depression, anxiety, and physical symptoms related to stress) and externalising (such as aggression or breaking rules). Children who had never had a pet showed the most positive mental health outcomes. While some trends suggested slightly worse outcomes for children who had always lived with pets, these were not statistically significant. However, children who had pets only occasionally were more likely to have mental health issues, and this was most clearly seen in those who had cats. After adjusting for factors like social class, gender, age, and birth year, no significant differences were found between children who had never had pets and those who had them consistently or only sometimes. This was true for all types of pets, including dogs and birds. The most notable finding was that having a cat between the ages of 4 and 5 was linked to a higher risk of mental health problems in children. Other pets, such as hamsters, rabbits, turtles, or fish, appeared to have a protective effect when present consistently throughout early childhood. These pets are generally easier to care for and provide stable, regular interaction, which may help children develop responsibility, empathy, and self-control. In contrast, the study found no clear mental health benefits or risks from having dogs or birds, possibly because the bond with these pets is less consistent or not fully developed in early childhood. The study also notes that factors not considered in the research could have influenced the results. The study suggests that cats may affect children differently due to their more independent nature, which may limit emotional bonding. Some families might choose cats for pets if their children have emotional needs, or because cats are easier to care for. Additionally, cats are more likely to carry Toxoplasma gondii, a parasite that can cause toxoplasmosis in humans, which has been linked to behavioral issues and serious mental disorders like bipolar disorder and schizophrenia. Meanwhile, pets like fish, turtles, and hamsters, when kept consistently, seem to offer more mental health benefits, possibly due to the regular, stable interaction they provide. The study highlights the need for further research on how pets affect children's mental health as they grow older.