Building the Brains of Scent Detection Puppies with Early Scent Introduction

Starting at 3 days of age, we introduce scents of our litters of puppies, and follow the Biosensor (Early Neurological Stimulation) program (1) daily and introduce a new scent daily. This early brain training accelerates development. It kickstarts the olfactory and neurological systems and may result in earlier proficiency and improved performance over what would normally occur without intervention.

This 8 day old puppy’s left nostril moves while he sniffs actively. Photo by Hunter’s Heart

The video above shows our 2018 litter of puppies undergoing Early Neurological Stimulation and Scent Introduction. In the closeup at 0:05 seconds, you can clearly see left nostril moving as the puppy sniffs actively and audibly. The 9 Brittany Spaniel puppies shown in the video are from Hunter’s Heart BB x Boo breeding, shown at about 1 week of age. On day 8, the scent was Madagascar vanilla extract on a cotton pad, and on day 9, the scent was cocktailed Myrrh and Vetiver in a tin. The video documents the introduction of only a few odors, and new odors are used daily, including bed bugs, pseudonarcotics, bird wings nosework target odors. The responses of puppies ranging from avoiding the scent, to approaching the scent, with some neutral responses such as going back to sleep. Entertaining highlights included some licking, barking, growling, and tail wagging. Jager (a full sibling male shown at 9 months of age) allowed an interesting comparison in how he treated the scent, as well as getting more comfortable with the new arrivals in our home. Regardless of the reaction of the puppy to the scents, early stimulation may yield significant results later in life, given only a few minutes a day.

Even before birth, puppies can recognize scent. In one study, researchers fed pregnant bitches food flavored with anise in the last 3 weeks before whelping (3). When tested within 24 hours after birth, the puppies moved towards the smell of anise. When presented with vanilla, which they weren’t exposed to previously, the attraction was not the same. When puppy’s are exposed to a scent both before birth and after birth, an even stronger preference results (4). Prenatal exposure might prime the puppy to be more receptive to smells experienced in the womb. That makes sense, given that learning which foods are safe before birth is likely an evolutionary advantage. Further, early exposure to odors increases cell numbers in both the accessory and main olfactory bulb (10). More cells allow improved olfaction.

Based on a preliminary survey by Avidog, Gayle Watkins reports that early scent introduction may result in earlier proficiency in dogsports involving scent, from tracking to hunting, to handler discrimination and nosework (2). The case for success of Early Neurological Stimulation is sufficiently strong that canines in the US military being considered for scent detection are exposed to early neurological stimulation, to increase their likelihood of successful scent detection performance later in life.

Of course, genetics combines with environment to produce the final adult performance. Not only do we endeavor to genetically engineer better scent dogs over time, but we advocate ongoing socialization from 4-16 weeks, followed by appropriate enrichment and training based on the type of work or sports dogs will do.


Essentially, we are helping to build the brains of the puppies by taking advantage of this sensitive period. Once a day, we handle each puppy separately from it’s mother and its litter. We expose the puppy to several exercises, for 3-5 seconds each, while supporting the puppy so it can’t fall:

  • Place puppy on its stomach on a cold cloth (that was kept in the fridge for 5 minutes)
  • Stimulate the toes of one paw with a cotton swab
  • Head held straight up
  • Head held straight down
  • Resting supported on its back (this is the last step in Early Neurological Stimulation, but we believe an additional step is important)
  • Introduce a new odor 1 inch away from the puppy’s nose, for 3-5 seconds. If the puppy avoids the scent (by moving away), the exercise is over. If the puppy approaches the scent (moving towards it), I allow it to check out the scent for up to 30 seconds, then the exercise is over.


Neuroplasticity is a term used by scientists studying the brain to refer to the brain’s ability to change over time, for better or for worse. You may have heard about utilizing plasticity of the human brain to your advantage, by training with specific brain games to maintain or enhance your mental capabilities as you age. Our brains respond to exercises with physical changes including shrinking or thickening grey matter, forging, refining, weakening or severing connections between nerves. And this results in changes to our abilities over time. For example, when you learn a new dance step, your brain creates new connections between nerve cells (like wires). Therefore, if you want to be a better dancer, it stands to reason that you should practice correctly performing dance steps over time, to strengthen those neural pathways in your brain. Eventually, you don’t even need to think about how you perform a dance, it becomes unconsciously controlled muscle memory.

Returning to scent training, Wilson and Stevenson (8) suggested that plasticity of the neurons in the brain is enhanced by experience with many, diverse (simple or complex) odorants in a variety of conditions, including other distraction odors. Therefore, olfactory development of young puppies represents a unique window opportunity that only happens once. Even if you perceive young puppies as silent, and you think not much is going on, this period is critically important to development of their brains, bodies and minds. Since puppies are born blind and deaf, they are forced to rely on scent (touch and taste) to survive. Unless a human is bottle feeding, that’s how they find the mom’s nipple, nursing every hour of their first few days. Young puppies are scenting. And you can help shape their future potential by offering them a variety of novel scents, allowing them the opportunity to start developing their detection capability.


Olfaction is the primary scent by which dogs explore and experience the world. And that olfactory experience begins in the womb, when the puppy’s mother is exposed to scents in her environment, notably target odors in scent detection. Check out this previous blog post to learn more about prenatal and neonatal scenting: What Do Sperm and Puppies Have in Common?

Jenkins et al commented “Canines learn odor starting in the prenatal period, due to the influence of maternal diet on the composition of the amniotic fluid, but the learned odor memory appears to dissipate by 10 weeks of age” (4). Then the puppy’s developing olfactory system takes over. Throughout a canine’s life, olfactory neurons only live for 1-2 months, and unlike other cells, olfactory receptor cells constantly regenerate (2). But olfactory receptor cells aren’t just replaced with nonspecific cells. The more an animal smells a scent, the more his body responds by producing olfactory receptors for that specific scent.

That’s one physiological reason why, even once detector dogs are fully trained, and deployed in the field, maintenance training is expected to maintain that degree of proficiency. Wang et al (5) and Youngentob and Kent (6) showed that dogs develop more olfactory receptors for target scents from their detection training. Gerritsen and Hank (8) also reported that olfactory cell turnover is not static: the type of new replacement odor receptor cells is triggered by familiar scents.

Early neurological development in response to novel stimulation is free and easy. Just a few simple, daily exercises with each puppy in a litter not only helps to get to know the puppies better but will hopefully accelerate their development and increase their performance in future.


  1. Battaglia, Carmen, Early Neurological Stimulation.
  2. Watkins, Gayle. Why not start your puppies on Early Scent Introduction?
  3. Wells, DL and Hepper, PG, Prenatal olfactory learning in the domestic dog. Anim Behav Vol, 72(3), Sept. 2006, pages 681 – 686
  4. Deborah Wells and Peter Hepper, “Prenatal olfactory learning in the domestic dog, Animal Behaviour 72 (2006): 681-686.
  5. Jenkins, EK, DeChant MT and Perry EB, When the Nose Doesn’t Know: Canine Olfactory Function Associated with Health, Management, and Potential Links to Microbiota. Front. Vet. Sci., 29 March 2018.
  6. Wang HW, Wysocki CJ, Gold GH. Induction of olfactory receptor sensitivity in mice. Science (1993) 260:998–1000. doi:10.1126/science.8493539
  7. Youngentob SL, Kent PF. Enhancement of odorant-induced mucosal activity patterns in rats trained on an odorant identification task. Brain Res (1995) 670:82–8. doi:10.1016/0006-8993(94)01275-M
  8. Gerritsen R, Hank R. K9 Scent Training: A Manual for Training Your Identification, Tracking, and Detection Dog. Vancouver, BC: Brush Education, Inc (2015).
  9. Wilson DA, Stevenson RJ. The fundamental role of memory in olfactory perception. Trends Neurosci (2003) 26:243–7. doi:10.1016/S0166-2236(03)00076-6
  10. Rosselli-Austin, L. and Williams, J. (1990) Enriched neonatal odor exposure leads to increased numbers of olfactory bulb mitral and granule cells. Dev. Brain Res., 51, 135–137


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