Once question the things of the detection work?!:
It's often like this. Some things in dog training we have learned or copied at some point and somewhere and then used and automated for our own work with the dog.
Often, we do this without giving it much thought. Maybe because it simply works, or maybe because it seems logical to us.
Sometimes it is also smart to look behind the scenes and to question one or the other.
Often, we are surprised by the result and the explanation for what our dog does is often different than what we want to see in it.
This article does not claim to be completely accurate from a veterinary point of view. I have tried to pick out the most important information from veterinary medicine and science and
make it clear for us practical dog handlers.
I have marked many passages in my article with the sources of studies. So, if you want to have scientifically detailed information, you are welcome to browse through these studies.
The saliva and the salivary glands - effects on the detection work?
As active dog handlers, we recognize and notice how the dog forms saliva, and how it literally runs out of his muzzle, when we show him his favorite toy and we start playing together with him.
This process, the "playing on", I perform as a detection dog handler before any detection work, whether in a real situation or in a training situation.
Until some time ago I believed this game, this ritual before the beginning of the detection work, only serves to make the dog attentive and to direct his concentration to the search for his toy. A "warm up," so to speak."
But that somehow has never been enough of an explanation for me.
The salivation as a visual and physical effect during playing together, had to have another cause and task according to my good feeling.
To do this, I first had to break down the overall process of salivating, and I started with anatomy.
Saliva is a mixture of secretions from the three major salivary glands - parotid glandula, mandibular glandula, and sublingual glandula -, and the minor salivary glands – labial glandula et buccales - and the numerous mucus-producing glands of the oral cavity (Lehmann and Hellwig, 1998; Nickel et al., 1987; Young et al., 1994).
Because the dog hardly chews its food, its salivary glands are weaklier developed than those of humans (Nickel et al., 1987).
The confluence of many small excretory ducts forms a common excretory duct, the parotid duct, which in dogs opens at the level of the maxillary P3/P4 premolar (Nickel et al., 1987) (parotid gland).
In the dog, the mandibular gland is located, usually hidden by the parotid gland, in the area between the atlas wing and the basihyoid of the hyoid bone; in the latter, it is larger than the parotid gland. Its excretory duct, the ductus mandibularis, passes medially by the sublingual gland and opens under the tongue on the caruncula sublingualis into the oral cavity (Nickel et al., 1987; Rohen, 1994).
Beneath the mucosa of the lateral surfaces of the tongue lie the glandula sublinguales (sublingual glands). In dogs and humans, they consist of a complex of small individual glands, the glandula sublinguales minores seu polystomatica, whose excretory ducts open in the area of the floor of the oral cavity, and the more compact glandula sublingualis major seumonostomatica, whose excretory duct runs parallel to the ductus mandibularis and opens
laterally with it on the caruncula sublingualis into the oral cavity (Benninghoff, 1985; Nickel et al., 1987).
Tasks/function of saliva:
Saliva has various tasks, which can be divided into primary digestive and secondary functional groups.
Primary function group:
In all mammals, the first group, digestive physiological functions, includes self-cleaning of the oral cavity by rinsing away food debris, protection of the oral mucosa and teeth from dehydration and acid exposure, and prevention of the spread of infectious germs.
All this is achieved by the constant rinsing of the mouth and teeth (rinsing saliva).
Saliva regulates the fluid balance of the body. Another function is to soak and dilute food (diluting saliva) to make it slippery (lubricating saliva) and enable swallowing.
By releasing flavoring substances during feeding, saliva also intensifies flavor development.
Human saliva, unlike that of dogs, also contains the digestive enzyme a-amylase (digestive saliva), whereby enzymatic carbohydrate digestion is already initiated in the mouth.
Canine saliva lacks digestive enzymes (Breves et al., 2000; Ewe and Karbach, 1993; Lehmann and Hellwig, 1998; Nickel et al., 1987; Young et al., 1994).
Secondary functional group:
The group of secondary salivary functions includes the bactericidal action of saliva. Through its constituent’s lysozyme, peroxidase, and immunoglobulin A, saliva acquires a certain antibacterial effect (Breves et al., 2000; Ewe and Karbach, 1993; Young et al., 1994).
However, saliva also induces plaque formation; it provides an optimal culture medium for the microorganisms of the normal oral flora (Williams et al., 1992).
In dogs, saliva also has a thermoregulatory function; panting releases heat via evaporation of saliva (Breves et al., 2000; Young et al., 1994).
Furthermore, saliva is not only secretion but also excretion.
In renal insufficiency, for example, urea and other uremic substances are excreted via saliva, and some drugs are also eliminated via saliva (Gürtler, 1980; Lehmann and Hellwig, 1998).
Salivary secretion is triggered by various stimuli and, as Pavlov already demonstrated, occurs reflexively by unconditional and conditional reflexes.
The unconditional reflexes are innate; they are triggered by the mechanical and chemical stimuli produced by direct contact of the food with the mucous membrane of the mouth.
The mechanical stimuli have the greater importance in domestic mammals, dry food causes greater salivary secretion. In the case of rapid food intake, however, such as the ingestion of a water-rich, mushy food, they play a minor role.
Conditioned reflexes are not innate; they are acquired through experience during life.
The cerebrum is involved in their formation. They cause a "psychic" secretion - triggered by sensory stimuli.
Thus, salivary secretion is already stimulated by smelling or seeing the food; sounds or actions associated with feeding preparation can also trigger secretion (Breves et al., 2000; Gürtler, 1980; Hill, 1976; Meyer, 1983).
There is another functional group, but it is conditioned by the harmful events or diseases, among others:
Dogs can quickly become too warm. Especially breeds with a short snout (e.g., pug or bulldog) start to salivate quickly at higher temperatures. In this case, it is important not to expose your four-legged friend to the warm rays of the sun for longer than necessary and to give him enough water to drink.
Fear and stress
During anxiety, excitement, nervousness and stress, animals also tend to increase saliva production. If your dog's heavy salivation occurs while driving, for example, the situation is most likely causing him anxiety or stress. Animals should generally be accustomed to driving slowly. For example, you can put your dog in the car more often without driving off. This allows him to get used to the environment and the excitement gradually decreases. If your four-legged friend salivates a lot when playing with other dogs, this can also cause him stress or excitement.
Foreign body in the muzzle
One of the most common causes of heavy salivation in dogs and cats are small pieces of bone, wood, fish bones, or the like that have become lodged between the teeth. Check the mouth for foreign objects and remove them carefully. If you are concerned about hurting or injuring your pet in the process, have a veterinarian remove the foreign objects.
"Obstructions" in the oral cavity.
These include swellings or tumors. These prevent the animal from swallowing saliva. The secretion therefore accumulates in the oral cavity and eventually runs out of the mouth. If you notice swellings and the like in your pet's mouth, you should consult a veterinarian.
Problems with teeth and gums All discrepancies with the tooth and gums automatically trigger increased salivation. These include inflamed gums and break, lose or rotten teeth. Take a close look at your four-legged friend's mouth. Other symptoms besides increased salivation in dogs and cats include strong bad breath and refusal to eat due to pain.
Does your dog or cat need to take medication? Increased salivation in dogs is a common side effect of various medications. Read the package inserts carefully or ask your veterinarian.
When dogs and cats have a cold, they exhibit increased salivation. This is a normal reaction of
Increased salivary secretion often accompanies nausea and vomiting.
Inflammation of the salivary glands Salivary glands are stimulated to produce additional saliva during inflammation. This is where a veterinarian should examine your dog or cat.
Increased salivary secretion occurs as a symptom of poisoning. If, in addition to salivation, vomiting, tremors, convulsions or even unconsciousness occur, you should visit a veterinarian's office immediately. Give advance notice of your arrival by telephone so that treatment measures can be prepared in time.
Salivation as a fight or flight response
When the body is preparing for what is called a "fight or flight" response, the flow of saliva for digestion is interrupted. This is clear and fluid. Only the formation of so-called mucous (viscous)
saliva is stimulated.
There are reasons for excessive saliva production
There are, of course, other causes of excessive saliva production.
The result is that the saliva no longer drips, i.e., the dog's mouth no longer waters, but the saliva hangs in gel-like strings. With additional panting, the gel is broken down like egg whites and becomes foam.
We humans therefore tend to have a dry mouth when we are stressed.
Sticky, gel-like drool is therefore an important indication of stress, while dripping water is more indicative of an expectation to feed!
Saliva secretion is not constant because the individual glands do not secrete (secrete) evenly.
As already mentioned above, the minor salivary glands and the other glands of the oral cavity are in a state of constant secretion; they have predominantly a local function and keep the oral cavity moist.
In contrast, the major salivary glands secrete (but secrete) only during food intake (Breves et al., 2000; Gürtler, 1980; Hill, 1976; Nickel et al., 1987).
In humans, approximately 1-1.5 l of saliva is secreted daily (Breves et al., 2000; Ewe and Karbach, 1993; Lehmann and Hellwig, 1998).
In dogs, the amount of saliva varies greatly and is particularly dependent on breed or size and stress (panting); basal secretion is usually low. The average amount of secretion given by Meyer (1983) is 20-40 ml/kg/day, whereas Breves et al. (2000) give saliva volumes of 0.1-0.2 l/day.
On average, approximately 90% of saliva is produced by the secretions of the parotid and mandibular glands, with half of the remaining 10% produced by the sublingual and minor salivary glands (Breves et al., 2000).
Water intake or fluid balance of the body is important for salivary secretion; thirsty animals produce less saliva (Hill, 1976).
Furthermore, the amount of food intake, the physical condition, and the dry matter content of the food also influence the volume of secretion (Gürtler, 1980).
Innervation (supply of nerves to tissues) of the salivary glands of both humans and dogs, occurs via parasympathetic fibers (calming fibers) from the facial nerve and glossopharyngeal nerve, and sympathetic fibers (excitatory fibers) from the first three thoracic segments (Breves et al., 2000; Young et al., 1994).
Thus, the composition and quantity of saliva depend not only on the volume, physical composition, and water content of the food, but also, and especially, on the concentration of the transmitter’s norepinephrine and acetylcholine, respectively, in the vicinity of the glandular cells!
A stimulation of the sympathetic nervous system (autonomic nervous system) leads to a decrease in the amount of saliva as well as to the secretion of a more viscous (more viscous), water-deficient saliva by vasoconstriction (constriction of blood vessels) and contraction (contraction) of the basket cells of the glandular endings.
Parasympathetic stimulation, on the other hand, causes vasodilation and a large increase in salivary secretion, primarily through increased secretion of the gluteal parotid gland with production of a serous saliva (Breves et al., 2000; Gürtler, 1980; Hill, 1976; Young et al., 1994).
The saliva is 99% water, and the dry matter content depends on the consistency of the feed (Meyer, 1983). Included in the dry matter are inorganic and organic compounds as well as exfoliated epithelial cells, microorganisms, and leukocytes.
The organic components in saliva make up about 60-70% of the dry matter. They consist of proteins (albumins, globulins, various enzymes), amino acids, vitamins and hormones produced by the serous and mucous glands.
The secretion of the mucous glands also contains mucin, a glycoprotein that conditions the viscosity of saliva and facilitates the chewing and swallowing of solid food.
The main inorganic substances are chlorides, phosphates, and bicarbonates, as well as the cations sodium, potassium, calcium and magnesium, and traces of sulfates, nitrates, ammonia, and iron salts. Due to the content of bicarbonate, free CO and protein, saliva also plays a role as a buffer for the whole organism (Gürtler, 1980; Hill, 1976; Lehmann and Hellwig, 1998; Meyer, 1983; Young et al., 1994).
Salivation during play and effect on detection work:
The salivation is caused by the physical and mental tension and expectation, by the excitement and joy, at different triggers.
So also, during our "playing on" before the detection work!
Briefly said, salivation occurs through:
1. the small salivary gland. It has the task to keep the oral cavity moist.
2. the large salivary gland has the task to digest the food.
But why does the dog salivate so much when playing together? There is apparently no food intake here.
The dogs are in a heightened emotional state during play, which they can hardly control, and the excitement and anticipation is shown by the increased saliva production in the mouth.
(See above: (Sounds and actions: Breves et al., 2000; Gürtler, 1980; Hill, 1976; Meyer, 1983).
Play in itself, is again as an action a chasing and struggling after prey. In nature, chasing the prey results in the prey being eaten.
Therefore, the answer to this question is simple because this salivating is based in the game also again instinctively on an expected food intake, since here the chasing/playing is linked with a food intake.
The saliva itself does not have the function here that is required for a food intake. The trigger is the same.
Here the saliva contains, among other things, adrenaline. Adrenaline (epinephrine) is a hormone that is produced in the adrenal glands and released into the blood in greater quantities during stress. It mobilizes the energy reserves in the body and increases the willingness to perform. The heart beats faster, blood pressure rises.
Some of the adrenaline is also released through saliva. (Cooper et. al. 1989).
Likewise, saliva contains norepinephrine, which is also formed in the adrenal glands and is also released in small amounts in saliva.
These neurotransmitters have a direct effect on salivation as it regulates the release of corticotropin releasing hormone (CRH). From this, heart rate and blood pressure increase, and it increases or decreases energy levels.
In addition, saliva contains cortisol!
According to LADEWIG (1994), stressors that acutely affect the body lead to a significant increase in cortisol levels.
Several scientists claim that measuring cortisol levels provides evidence of stress (Morberg 2000; Kirschbaum u. Hellhammer 1994; Vincent u. Michell 1992). Morberg (2000) emphasizes that the prerequisite for this must be good experimental conditions.
Meanwhile, the measurement of salivary cortisol is a widely used test method to determine stress in farm animals and dogs (KOBELT et al. 2003).
In practice, one often observes not a playful struggle for the play object with the dog handler, but an almost combative confrontation by actively threatening the dog handler, accompanied by physical impacts (jamming the dog, pushing it away with the knee, etc.) All this leads to a massively increased cortisol level. Measurable in the dog's saliva. And measurable in negative results in detection work!
As studies also show, besides cortisol, hormones of the renal cortex are also metabolized in the salivary glands (degradation of substances by an enzyme), (BOTZEN, 1989) or excreted in free form with the saliva (COOPER et al. 1989).
So, in summary, saliva production is an important indication that our dog is well prepared for detection work, if we avoid the cortisol surge in the process!
All biochemical and psychological processes are set in motion by the game and the dog is well prepared for its task.
Maybe we compare it with a high-performance athlete. This also does not start with a hurdle race without warming up first. When warming up, all important bodily functions are stimulated, and he gets a feeling for his task.
That is why it is important to warm up dogs by playing together and prepare them for the detection work.