Animals can assign novel odours to a known category.

The ability to identify a novel stimulus as a member of a known category allows an organism to respond appropriately towards it. Categorisation is thus a fundamental component of cognition and an essential tool for processing and responding to unknown stimuli. Therefore, one might expect to observe it throughout the animal kingdom and across sensory domains.

A double-blind placebo-controlled study into the efficacy of a homeopathic remedy for fear of firework noises in the dog (Canis familiaris).

Seventy-five dogs that showed a fear response to fireworks participated in a double-blinded, placebo-controlled clinical trial to assess the efficacy of a homeopathic remedy for the alleviation of their behavioural signs. Dogs were randomly assigned to one of two treatments; the homeopathic treatment or the placebo treatment. At the baseline assessments the owners identified the behavioural signs of fear that their dogs normally displayed in response to fireworks, rated their frequency and intensity, and assessed the global severity of their dog's responses.