What Is a Flehmen Response in Dogs? A Complete Guide

Dogs are fascinating creatures with extraordinary sensory abilities, especially their sense of smell. One remarkable behaviour linked to this is the Flehmen response, which, although less common in dogs than some other species, reveals how dogs interpret and engage with their environment through scent. This comprehensive guide will explain the Flehmen response, the role of the vomeronasal organ, and how scent plays a vital role in canine behaviour and wellbeing.

1. Understanding the Flehmen Response in Dogs

The Flehmen response is a distinct behaviour exhibited by dogs when they encounter interesting or significant scents, such as the scent markings or urine of other animals. During this response, a dog curls back its upper lip, exposing its front teeth, and inhales deeply, often with nostrils partially closed. This grimace is not just a quirky expression but serves the essential function of directing scent molecules to a specialized organ in the dog's mouth known as the vomeronasal organ (VNO) or Jacobson's organ.

Through this action, dogs can detect chemical messages, pheromones, and other olfactory cues that provide information about social status, reproductive status, age, sex, and emotional state of other animals.

2. The Vomeronasal Organ: Dogs’ Secret Scent Sensor

The VNO is located just above the roof of a dog’s mouth, near the front teeth. It houses specialized olfactory receptor cells that differ slightly from those in the main olfactory system but tie directly into the limbic system, the part of the brain governing emotion and social behaviour.

When performing the Flehmen response, a dog’s lip curl and mouth movements help channel scent particles through ducts to the VNO, enhancing the dog’s ability to analyse pheromones. Interestingly, dogs’ olfactory bulbs are about the size of a plum—significantly larger than a human’s—contributing to their incredibly acute sense of smell, which is estimated to be 10,000 times more sensitive than that of humans.

3. Why Dogs Display the Flehmen Response Less Often Than Other Animals

While animals such as cats and horses exhibit the Flehmen response frequently and conspicuously, dogs show this behaviour less often and often more subtly. This difference is partly due to variations in the role and development of the VNO among species.

Dogs may flick their tongues, smack their lips, or briefly lick the air as part of the Flehmen response, often when investigating urine or scent marks left by other dogs or animals. Though brief, this behaviour can be a window into their complex chemical communication and social understanding.

4. The Vital Role of Scent in a Dog’s Life

Scent is fundamental to a dog’s perception of the world, influencing behaviour, social interactions, and emotional wellbeing. Dogs use scent to navigate their environment, recognise familiar individuals, and assess the presence of other animals or potential threats.

Owners can enhance their dog’s quality of life by incorporating scent enrichment into their routines. This includes scent games that stimulate natural abilities, such as hiding treats for dogs to find by smell. Additionally, reputable breeders often emphasise early scent exposure as part of puppy socialisation.

5. Creating a Scent-Enriched Environment for Dogs

Enhancing a dog's environment with pleasing scents can provide mental stimulation and reduce anxiety. Products such as dog appeasing pheromone (DAP) diffusers release synthetic pheromones that help dogs feel secure and relaxed, especially when introduced to new homes or stressful situations.

Strategically placed essential oils and safe scent sources can assist dogs with visual impairments to navigate their surroundings, such as leading them to food and water bowls or exits. Responsible use of scents should always consider the dog's health and preferences.

6. Making Walks More Engaging With Sniffing Time

Exercise is crucial for physical health, but allowing dogs ample time to sniff during walks provides essential mental exercise. Visiting locations where dogs can encounter a wide variety of scents—such as parks frequented by other dogs—enables them to read scent messages like social media posts. This helps satisfy their natural instincts and can trigger multiple Flehmen responses as they absorb information.

Providing off-lead opportunities in safe areas where dogs can explore these scent trails enriches their daily experiences and supports emotional balance.

Conclusion

The Flehmen response in dogs is a fascinating behavioural expression rooted in their extraordinary olfactory abilities. Although less frequent than in other animals, it underscores the importance of scent to dogs’ communication and understanding of their world. Responsible owners can support their pets by appreciating these behaviours, enriching their environments with scent-based activities, and promoting mental as well as physical wellbeing.

Understanding and observing the Flehmen response not only deepens our bond with our canine friends but also encourages a more empathetic and informed approach to their care and enrichment.