Early weaning increases aggression and stereotypic behaviour in cats, shows a new study from Professor Hannes Lohi's research group. Based on the study conducted at the University of Helsinki, the recommended weaning age of 12 weeks should be raised by at least two weeks. Delaying weaning is an easy and cost-efficient way of improving the quality of life of cats.

The cat is the most popular companion animal, and people are increasingly interested in its wellbeing. One of the topics under international debate is the weaning age, i.e., the age at which kittens are separated from their mother and siblings and brought to a new home. In Finland, the recommended minimum age of weaning is 12 weeks, but in many other countries, such as the United States, weaning of kittens as young as 8 weeks is common.

It has previously been thought that the critical period of socialisation in cats ends by 8 weeks of age, after which social experiences have little impact on behaviour.

"We found that positive changes in the cat's behaviour can occur after the currently recommended age of weaning, 12 weeks. I'm a cat lover myself, and this study supports my own previous experiences on the importance of the weaning age on the wellbeing of cats. I think raising the recommended age of weaning would be the animal welfare act of the year," says doctoral student Milla Ahola.

While the detrimental effects of early weaning have been studied in some other animal species, no studies on the topic have been conducted on cats, despite suspicions of its connection to feline behavioural problems.

"We found an easy way to improve cat welfare: we propose that the recommended age of weaning be increased by two weeks. The number of cats in the world is immense, and behavioural problems are very common. This could have a significant positive impact on the wellbeing of both cats and their owners on a global scale," says Professor Hannes Lohi.

The study used the results from the health and behaviour survey Professor Lohi's group had previously conducted on nearly 6,000 cats, currently the most extensive cat behaviour database in the world. According to the survey, many behavioural problems are more common than expected. More than 80% of cats were reported as exhibiting mild behavioural problems, while serious behavioural problems were reported for 25% of all cats. Feline behavioural problems can include shyness, stereotypic wool sucking, excessive grooming and aggression.

"The age of weaning has an impact on the cat's later behaviour. Cats weaned under the age of 8 weeks displayed more aggression and stereotypic behaviour. Cats weaned in adulthood had fewer such problems than other cats. Cats weaned at 14 weeks of age had fewer behavioural problems than cats weaned earlier," explains Ahola.

Studies on other animal species have produced similar results. For example, among rodents, monkeys and minks, early separation from the mother leads to a higher prevalence of stereotypic behaviour and aggression. A similar phenomenon has been found in humans.

"These behavioural changes are also linked. We found that increased aggression correlated with increased stereotypic behaviour. The impacts of early weaning seem to manifest specifically as aggression and stereotypic behaviour, which suggests changes in the neurotransmitters of the basal ganglia," states Professor Lohi.

Professor Hannes Lohi's research group works in the University of Helsinki's Faculty of Veterinary Medicine and Faculty of Medicine as well as at the Folkhälsan Research Centre. Professor Lohi's research has received support from Kissaliitto, the Jane and Aatos Erkko Foundation, and the ERANET-NEURON network under the European Commission.