what is the olfactory bulb in dogs

The Olfactory Bulb

is a bulb of neural tissue within the dog’s brain. It is located in the fore-brain and is responsible for processing scents detected by cells in the nasal cavity. It is approximately 40 times larger in dogs than in humans, relative to total brain size.

Full Answer

Where is the olfactory bulb located in a dog?

The Olfactory Bulb is a bulb of neural tissue within the dog’s brain. It is located in the fore-brain and is responsible for processing scents detected by cells in the nasal cavity. It is approximately 40 times largerin dogs than in humans, relative to total brain size.

How does the canine olfactory system recognize smells?

The canine olfactory system can recognize more smells than it has receptors for scent molecules, but olfactory receptors can have specific cross-reactions, building unique systems of patterns connected to different smells [ 4 ].

How many olfactory cells are in a dog's brain?

(This compares with estimates of human numbers that are in the 5- to 10-million-cell range.) In addition, the dog has devoted a tremendous amount of his brain tissue to olfactory cells. (Some estimates allocate one-third of the dog’s brain to the chore of scenting.)

What is Canine Olfaction?

Anatomy and Physiology of Canine Olfaction The canine olfactory system can recognize more smells than it has receptors for scent molecules, but olfactory receptors can have specific cross-reactions, building unique systems of patterns connected to different smells [ 4 ].

What is the olfactory bulb in animals?

olfactory bulb, structure located in the forebrain of vertebrates that receives neural input about odours detected by cells in the nasal cavity. The axons of olfactory receptor (smell receptor) cells extend directly into the highly organized olfactory bulb, where information about odours is processed.

How does the olfactory system work in dogs?

During sniffing, the inhaled air in the dog's nostrils separates into two distinct pathways. The upper flow path, approximately 12–13% of each breath [8], goes straight to the olfactory region, where odor molecules are deposited and accumulate, preventing them from being exhaled.

How big is olfactory bulb in dogs?

The width of the bulb was greatest (p< 0.05) in dogs (10.80± 1.64mm) compared to goats (8.25± 0.96mm) and humans (5.50± 0.71mm), and accounted for a hemisphere breadth of 42.91%, 29.73% and 8.94% respectively.

How dogs develop large olfactory bulb?

With the growth of dogs, the weight of the olfactory bulb increased. The quantity of mitral cells and granule cells decreased but they increased in size. All of these suggested that the olfactory bulb developed with the growth of the dog.

What happens if a dog loses its sense of smell?

When a dog loses their sense of smell, it is as if they are losing their sense of sight! Without being able to detect or interpret scents, dogs can find themselves unable to function properly in their surroundings, causing them to become afraid and anxious.

Why is the olfactory bulb important?

The olfactory bulb transmits smell information from the nose to the brain, and is thus necessary for a proper sense of smell. Scent molecules activate olfactory receptors and signals travel up the olfactory nerves to the olfactory bulb, and then on to the rest of the brain via the olfactory tract.

Why Can dogs smell so well?

Dogs devote lots of brain power to interpreting smells. They have more than 100 million sensory receptor sites in the nasal cavity compared to 6 million in people, and the area of the canine brain devoted to analyzing odors is about 40 times larger than the comparable part of the human brain.

Can dogs smell arousal?

There is no evidence thus far that dogs actually understand what is happening when two people have sex. They likely recognize the smell of pheromones when people become aroused and other scents associated with people engaging in intimacy.

How far can a dog smell?

Dogs can smell things up to 40 feet underground. Dogs can even smell human fingerprints that are a week old! Part of the reason dogs have an excellent sense of smell is the moist leathery surface of the nose determines the direction of air currents.

Why do dogs sniff your face?

Some dog owners misinterpret their dog's greeting as their desire for wanting to smell their breath. However, face and mouth sniffing is one common way canines greet one another, as well as humans they consider members of their pack.

How long do dogs remember your scent?

Dogs will remember a human days, weeks, months or even YEARS. When a pup combines their ability to remember scents, facial recognition, and voice recognition- even after one meeting- it is quite extensive. We have clients that only book every 6 months- and those pups are SO happy to see their pet sitter.

Why do puppies smell so good?

“Their breath has that sweet mother's milk smell because their mouths are clean and haven't yet developed any bacteria or plaque, which typically causes odors.” He adds that some people may not experience this sweet smell because of their puppy's health or particular habits.

Do dogs have olfactory receptors?

The most important characteristic of the detection canine is its sense of smell. Olfactory receptors are primarily located on the ethmoturbinates of the nasal cavity. The vomeronasal organ is an additional site of odor detection that detects chemical signals that stimulate behavioral and/or physiological changes.

How many olfactory sensors do dogs have?

What do dog noses have that humans don't? They possess up to 300 million olfactory receptors in their noses, compared to about six million in us. And the part of a dog's brain that is devoted to analyzing smells is about 40 times greater than ours.

How many olfactory receptors cells do dogs have?

220 million olfactory receptorsA dog's sense of smell is said to be a thousand times more sensitive than that of humans. In fact, a dog has more than 220 million olfactory receptors in its nose, while humans have only 5 million.

Where is the olfactory epithelium in dogs?

nasal cavityIn humans, this tissue -- called the olfactory epithelium -- is a single flat sheet lining the roof of the nasal cavity. In dogs, however, the olfactory epithelium forms a complex maze, folding and curling over a number of bony protrusions, called turbinates, that form in the nasal cavity.

What is the olfactory epithelium of a dog called?

The projections are bony structures called turbinates. A recent study explored the development of the canine olfactory epithelium and the turbinates.

Why do dogs have a olfactory lobe?

Canine Olfactory Structures. Dogs have a huge olfactory lobe that helps them process all of the scent-related information that they take in . The size and complexity of this structure in the brain is one reason that dogs have such an amazing sense of smell and can detect bombs, cancer, drugs, lost people and even the tiniest trace ...

What part of the brain is responsible for dogs' ability to smell?

The dog brain is only one part of the anatomy responsible for their extraordinary sniffing abilities. The canine nose also contains key features that contribute to dogs’ superior skill at smelling, but only recently have people studied how the structures in the nose develop.

How many square centimeters does the olfactory epithelium have?

There is a correlation across species between the surface area of the olfactory epithelium and olfactory abilities. Humans have around 10 square centimeters of this tissue lining the roof of the nasal cavity. Dogs have about 170 square centimeters of it.

What part of the olfactory system does a dog have?

In most mammals, including dogs, there are two main parts of the olfactory system: the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). The MOE is located in the usually pigmented part of the mucosa in the caudo-dorsal region of the nasal cavity, and the VNO lies between the nasal and oral cavity, near the vomer bone, just above the roof of the mouth. The nasopalatine duct, which starts behind the upper incisors on the palate, connects the mouth with the VNO, which is a tubular, elongated organ, separated by the nasal septum [ 5, 6, 7 ].

Why does my dog have a bad olfactory sense?

In the case of hyposmia in dogs caused by endocrinological disorders such as hyperadrenocorticism, hypothyroidism, or diabetes, a neural mechanism is probably involved, similar to the anosmia observed in some cases of COVID-19 infection in humans [ 48, 49 ].

Why is olfaction important for dogs?

Olfaction in dogs is crucial for gathering important information about the environment, recognizing individuals , making decisions, and learning. It is far more specialized and sensitive than humans’ sense of smell. Using the strength of dogs’ sense of smell, humans work with dogs for the recognition of different odors, with a precision far exceeding the analytical capabilities of most modern instruments. Due to their extremely sensitive sense of smell, dogs could be used as modern, super-sensitive mobile area scanners, detecting specific chemical signals in real time in various environments outside the laboratory, and then tracking the odor of dynamic targets to their source, also in crowded places. Recent studies show that dogs can detect not only specific scents of drugs or explosives, but also changes in emotions as well as in human cell metabolism during various illnesses, including COVID-19 infection. Here, we provide an overview of canine olfaction, discussing aspects connected with anatomy, physiology, behavioral aspects of sniffing, and factors influencing the olfactory abilities of the domestic dog ( Canis familiaris ).

What nostril do dogs use when sniffing?

This phenomenon has been shown to be similar to auditory and visual perception in dogs [ 11, 12, 13 ]. Dogs have a strong right nostril bias as it is the nostril through which they first start sniffing. Then, if the smell turns out to be a familiar or non-aversive odor such as food, they shift to using the left nostril. However, if the stimuli turn out to be novel, threatening, or arousing, such as adrenaline, the dog continues to use only the right nostril. These findings are consistent with the theory reviewed by Vallortigara et al. [ 14, 15 ], that the right hemisphere controls novel information processing, with the left hemisphere then taking charge of behavioral responses to familiar stimuli and the right hemisphere maintaining dominance over the sympathetic–hypothalamic–pituitary adrenal axis [ 16 ]. Behavioral lateralization directly reflects asymmetries of brain function [ 17 ], which may confer a better understanding of the training process and hence a need for new methods of training for detection dogs. As D’Aniello et al. [ 2] demonstrated, hemispheric specialization and chemo-signaling are also involved in the process of chemical communication between dogs and humans, allowing the transfer of information about emotional states (stress or happiness). Moreover, Webber et al. [ 18] proved the existence of nasal cycles in dogs in their magnetic resonance imaging study of the function of the erectile tissue surrounding the turbinates. The physiological phenomenon of the nasal turbinates’ congestion is caused by the selective activation of the autonomic nervous system by the hypothalamus. It has been hypothesized that this could assist in olfaction detection under conditions of low airflow, allowing some odors to bind to olfactory receptors [ 19 ].

How do drugs affect the sense of smell?

The influence of drugs on the sense of smell could be connected with a loss of acuity [ 52] and/or distortion of function (dysosmia). The mechanisms responsible for those events are thought to be connected with inhibition of odorant receptors. As Henkin [ 52] suggested, this effect can be achieved by inducing abnormal persistence of receptor activity or by blocking receptor activation. Taking into account the number of drugs used in canine veterinary medicine, available studies have tested a less than representative number of substances for effects on canine olfaction. Even though zinc sulfate [ 53] has been used routinely in various studies for destruction of the main olfactory epithelium in many species [ 53 ], Ramaihgari et al. [ 54] found that that zinc nanoparticles could potentially be used to increase canine detection capabilities in environments with very low concentrations of the odorants. Among the drugs used for anesthesia and analgesia in dogs, isoflurane and propofol, as well as fentanyl followed by naloxone, have been investigated in terms of olfaction capability in dogs, but no negative effect on canine olfaction was observed [ 55, 56 ]. Similarly, a study performed in humans revealed no influence of oral hormonal contraceptives on olfaction [ 57 ]. However, some studies have identified medications that had a negative effect on canine olfaction. Jenkins et al. [ 56] found that oral administration of metronidazole (25 mg/kg every 12 h) degraded the ability of working dogs to detect the odors of explosives. Similarly, the use of steroids (dexamethasone or hydrocortisone) caused a significant elevation in the olfactory detection threshold of dogs, without any observable structural alteration of the olfactory tissue using light microscopy [ 58 ].

Why does my dog's olfactory ability decrease with age?

Similar to the other senses, olfactory capabilities can decrease with age due to atrophic changes, with degeneration observed in the olfactory epithelium and fewer olfactory cells in aged dogs [ 42 ]. Moreover, in comparison with juvenile dogs, older individuals may have a much stronger long-term memory of odors and can deal with more complicated odor information [ 43 ].

How does a dog's nose work?

The remainder of the air, in the lower pathway, flows down the pharynx into the lungs. This path is also used for exhalation, thus supporting prolonged exposure of inspired air to the chemoreceptor area of the olfactory epithelium as air flows through the olfactory area of the dog during expiration [ 8, 9 ]. Turbulence in nasal air flow is a consequence of anatomical and physiological factors. These factors influence humidification, warming, and the path of inspired air, guiding a portion of the air towards the olfactory epithelium [ 10 ]. In dogs, as in other species (e.g., human), the mechanism of nasal airflow patterns during inhalation allows the acquisition of separate odor samples in each nostril, allowing bilateral comparison of stimulus intensity and odor source localization [ 8 ].

What happens when a dog inhales?

When a dog inhales the air is diverted into two sections of their nose – one path is for respiration (the regular breathing) and other goes to the canine olfactory system or smelling area. They are literally built to have a better sense of smell.

How does a dog's nose work?

How Your Dog's Nose Works. How a dog's nose works is a subject that has long fascinated mankind. We're probably just jealous, since our noses pick up such a tiny fraction of what our dog's noses easily gather. All mammals have turbinates, which are bony, curly scroll-shaped plates, that air flows over in the breathing process.

What dogs have super powers?

Of course, many dogs were bred specifically for their sniffing abilities; the Bloodhound, Basset Hound, Beagle, Coonhounds, Dachshund, Foxhounds and the Rhodesian Ridgeback, to name a few. But every single dog has sniffing abilities that blow our puny noses away (pun intended).

What is the turbinate in mammals?

All mammals have turbinates, which are bony, curly scroll-shaped plates, that air flows over in the breathing process. This consists of a thick, spongy membrane that houses most of the scent-detecting cells and the partner nerves that send info to the brain. As mentioned in the list above, the odor analyzer is about one square inch in people and 60 square inches in dogs! Think postage stamp compared to piece of paper.

Can humans sniff like dogs?

Unfortunately there’s no way for a mere human to get inside this highly detailed world. Even if we get down on the ground and sniff, we cannot do it like a dog. When we sniff we are sporadically blind to scent as we breathe in and out through the same holes. A 2009 study of the fluid dynamics of the dog’s sniff showed that their system is far more complex.

Where do dogs smell?

Once in the olfactory bulb, scents are transported to the frontal cortex for recognition as well as to other regions of the brain that include the brain’s centers for emotions, memory, and pleasure. There are many interconnections between all these centers, with the result that a simple smell, detected by a dog, likely has an entire set of meanings, memories, and emotional ties that only that dog can know and interpret.

How do dogs collect scents?

The dog collects scents by air-scenting (sni ffing volatile oils that are traveling in the air) and sniffing the ground. A dog’s nose is ideally made for sniffing – the outer nares are mobile and allow for expansion on inspiration and contraction to prevent the entry of unwanted objects.

What is the nose of a dog?

The dog’s nose consists of a bony nasal cavity that is divided into two separate chambers by a bony and cartilaginous nasal septum. Within each of the cavities are the turbinate bones (conchae) and the paranasal sinuses.

How does aromatherapy work on dogs?

Aromatherapy is directly applied through the animal’s ability to sense odors that in turn are directed to various parts of the brain. The effects on the brain centers depends on the flower essence used, and an entire repertory has been developed to help the practitioner and a dog’s caretaker decide which aroma may be beneficial for the condition.

How many sensory cells does a dog have?

But we do know that dogs have much more surface area within their nasal cavities, and this area is well supplied with sensory cells – estimates of the total number of these cells vary and depend on the breed, but they have been cited as somewhere between 125 million and several times that.

Can dogs smell humans?

We know, for example, that animals (and humans) prefer to mingle with the scent of members within their own pack or herd (or, in the case of humans, in their own culture), and horses and dogs can detect the human scent of fear. Also, shortly after birth, mothers are able to pick out their own offspring by smell, and puppies quickly learn the smell of their mother’s milk . . . and before long, the smell of a preferred teat.

Does the sense of smell extend to other realms?

The nose and the sense of smell are vastly expanded by Jacobson’s Organ, but an animal’s ability to smell extends into many other realms as well. Since smelling is hooked into the most primitive areas of an animal’s brain, there is reason to believe that smell is also linked to sensations created long before the animal was actually born.

Why do dogs have a sense of smell?

dog's sensory experience of the world is guided largely by its nose. Unlike upright humans who have evolved to depend on high acuity vision, the macrosmatic dog relies heavily on a highly developed olfactory system to detect environmental information relevant for survival. A dog's sense of smell is many orders of magnitude more sensitive than a human's. This is largely due to anatomical, physiological and genetic differences that allows dogs to more effectively collect, sample and cognitively process chemosensory information from their environment. The dog's partnership with humans evolved in part because man wanted to take advantage of the dog's keen sense of smell to aid his own needs for tracking and hunting. The modern working dog continues to provide odor detection for human directed tasks at a level of sensitivity that has yet to be replicated or surpassed by man-made instruments.

How does air enter a dog's nasal cavity?

Air enters the dog's nasal cavities through two external nostrils or "nares." The dog has bilateral, symmetrical nasal cavities separated by the nasal septum. Inside the nasal cavity lie the turbinate bones and the paranasal sinuses. The turbinate bones (or conchae) are convoluted folds of bone covered in a mucous membrane containing the olfactory epithelium. The turbinates in macrosmatic animals (animals with higher olfactory acuity compared to low acuity microsmatic animals, such as humans) dramatically increase the surface area of the olfactory epithelium. The surface area containing olfactory cells in a human is roughly 5 cm2 compared to 150-170 cm2 in a dog. Inhaled air is first exposed to the maxilloturbinates where it is warmed, moistened and cleaned by specialized ciliated epithelium and support cells. The inspired air then continues to flow into the more posterior ethmoturbinates and the frontal, maxillary and sphenoid sinuses. The majority of odor processing is accomplished by the main olfactory epithelium (MOE) lining the ethmoturbinates and frontal sinuses; the mucosa of the maxilloturbinates contains only a small number of olfactory sensory neurons. (See Figure 1)