Early Neurological Stimulation (ENS): Implications for canine

Veterinary Medicine

purdue.edu/vet/vth

Authors: Grace Boone,

Aynsley Romaniuk,

Candace Croney,

Purdue College of

Veterinary Medicine

VA-24-W

Early Neurological Stimulation

(ENS): Implications for canine

welfare and management

Introduction

In discussions of how to best support

puppy development and welfare, factors

such as the puppy’s growth or time

spent with its mother and littermates

are often considered. Recently, the

amount and type of environmental

enrichment provided to puppies in the

form of toys, walks or playtime outdoors,

and interactions with humans and other

animals have also become important

considerations. Simple interactions

early in a puppy’s life may additionally

increase its ability to learn and cope

successfully with stress later on, thus

leading to better welfare outcomes.

Early Neurological Stimulation (ENS),

which involves applying gentle

stressors to a very young animal for

short periods of time, is thought to

improve their stress responses later in

life. The stressors—which often include

removing animals from their litters for

short periods, very briey exposing

them to cool temperatures, holding

them in dierent positions, and gently

touching parts of their bodies—are

applied for a few seconds, once a day,

for at least 10 days.

Eects of ENS

The link between stress and activation

of the endocrine system is well known.

The release of glucocorticoids (a class

of stress hormones) from the adrenal

cortex following stress aects many

processes in the body. These changes

are the basis for the body’s “ght or

VA-24-W Early Neurological Stimulation (ENS): Implications for canine welfare and management

ight” response. The eects of short-term, mild stress

can be benecial, creating “robustness” in the body

and preparing it to deal more eectively with stressors

later in life (Levine, 1960; and reviewed in Meaney,

2001; Pryce and Feldon, 2003). However, not all stress

is equal. High-intensity or long-term stress is often

detrimental, either because of overwhelming the

body’s ability to respond, or leading to negative side

eects from a sustained “ght-or-ight” process, which

depletes energy and the ability to resist disease (Selye,

1956).

Studies of ENS began with rat pups, and currently,

most of the published work in this area is rodent-

focused. Rat pups handled early in life were much

less fearful when exposed to an auditory stimulus

(Schaefer, 1963), had lower corticosterone levels

when restrained by a person (Plotsky and Meaney,

1993), and were less resistant to being captured after

stress (Núñez et al., 1996). These ndings have since

generated interest in exploring the eects of ENS in

other species, including dogs.

Applications and eects of ENS on

puppy development

As is the case for rodents, it is believed that ENS

may provide stimulation to the developing puppy’s

endocrine system and cause him/her to develop more

ability to deal with stressful events later in life. This

may lead to better learning and an improved ability to

cope with adversity. Though some of this belief stems

from the benets of ENS shown in other species, it has

also been advanced by unpublished work conducted

as part of a US Military Working Dog (MWD) training

program called “Bio Sensor,” later discussed by Battaglia

(2009). Specic claims on the eects of “Bio Sensor”

listed in Battaglia’s discussion include “improved”

heart rate, “stronger” heartbeats and adrenal glands,

and increased stress tolerance and disease resistance

(Battaglia, 2009), although how these eects were

measured was not specied. The “Bio Sensor” program

exercises included the following:

1. Tactile Stimulation: the puppy is “tickled” between

the foot pads on any one foot with a Q-Tip (3-5

seconds)

2. Head Erect: the puppy is held perpendicular to the

ground with both hands, orienting its head above its

tail (3-5 seconds)

3. Head Down: the puppy is held perpendicular to the

ground with both hands, orienting its tail above its

head (3-5 seconds)

4. Supine: the puppy rests with its back in the palms of

both hands, with its nose oriented toward the ceiling

(3-5 seconds)

5. Thermal Stimulation: a damp towel is placed in

fridge for at least 5 minutes; place puppy on towel

on all fours and do not restrain movement (3-5

seconds)

To date, only a few studies have been conducted on

ENS in dogs using various handling exercises, and

these have shown variable results. For example, a study

by Fox and Stelzner (1966) applied an ENS treatment

that included exposure to light and sound, movement,

cold, swimming, grooming, and a check of the puppy’s

reexes. The entire ENS treatment took one hour per

puppy and was done daily from day one to 5 weeks

of age. After three weeks, 10 minutes of play with the

researcher was added in. Puppies were weighed and

their heart rates were measured weekly. They were

then behaviorally tested at 5 weeks, and the body

weights, heart rates, and reexes of ENS puppies

were compared with those who did not receive ENS

treatment. Handled puppies explored more, were

more social toward humans and more condent when

engaged in a social situation with other dogs. They also

were better at problem-solving. They had increased

heart rates compared to puppies that did not receive

ENS, but there were no dierences in their weights or

reexes (Fox and Stelzner, 1966).

Another study looked at the eects of ENS on dogs

being raised in homes and those kept in professional

breeding kennels. The ENS consisted of a 5-minute

gentle whole-body massage with the puppy lying

both on its back and on its stomach (Gazzano et al.,

2008). This was done daily for days 3-21 of life. The

puppies were later behaviorally tested at 8 weeks

of age. Handled and unhandled puppies from both

the kennels and the homes were compared. In an

isolation test, all handled puppies regardless of

housing explored the environment more. There were

no dierences between any groups in their heart rates

or reactions to dierent objects and an unfamiliar

environment and person (Gazzano et al., 2008).

VA-24-W Early Neurological Stimulation (ENS): Implications for canine welfare and management

Other studies have found no signicant eects of

using ENS in dogs. For instance, Schoon and Berntsen

(2011) observed that when puppies bred for mine-

detection underwent “Bio Sensor” in addition to

their normal socialization program, there were no

dierences in their performance on a test intended

to measure search behavior, responses to novel

people, environments, and objects. There were also no

dierences in any of their developmental benchmarks

(Schoon and Berntsen, 2011). However, the high level

of socialization the puppies were already receiving

could have masked any eects of the ENS. ENS eects

might be clearer when used with puppies raised in a

less stimulating environment.

Overall, because of the variety of test processes

used and the small number of studies that exist, it is

currently impossible to say if some types of ENS are

more eective than others. More research is needed

to determine what sorts of ENS intervention might be

most benecial to dogs.

Limitations of ENS

For those choosing to use ENS in hopes of improving

puppy welfare, caution is needed to avoid

inadvertently creating problems. For example, it can

be easy to accidentally overstress puppies when

providing ENS. As previously mentioned, little research

has been done on ENS in dogs, which makes it unclear

as to how much stimulation is needed to achieve

any benets. This is problematic because there is no

threshold for under- or over-stimulation (Battaglia,

2009). Separating young animals from their mothers

is commonly a part of ENS, but a review of many

studies has found that separation for a prolonged

period produces long-term negative eects on brain

chemistry and stress responses in puppies (Anand and

Scalzo, 2000). The duration of separation needed to

achieve benets rather than negative eects is unclear.

Further, following Schaefer’s (1963) suggestion that a

temperature change may be the only factor needed for

eective ENS, a slight, brief temperature change might

be useful to incorporate into puppy ENS programs.

However, a prolonged or severe change in temperature

may be harmful to the puppy’s health. Therefore,

anyone including cold stress in their ENS protocols

must be careful not to expose puppies to very cold

temperatures, and puppies should not be exposed to

cooler surfaces or ambient air temperatures for more

than a few seconds at a time. Regardless of which ENS

procedures are used, puppies must be continuously

monitored for signs of distress, as these would indicate

a need to stop the ENS treatment immediately.

Conclusions

There is some evidence to suggest that ENS may help

dogs cope better with stress later in life. Several of the

suggested ENS stimulation techniques take little time

to do, are low cost, and may provide crucial long-

term behavioral benets to dogs. The techniques are

relatively easy for breeders to incorporate into their

practices, and, if eective, could potentially improve

the overall health and welfare of puppies, potentially

improving owner satisfaction. Breeders should

therefore be educated about the potential benets of

ENS and how to implement it without over-stressing

puppies. More research is needed to determine the

most eective methods of ENS, so that both dogs and

breeders receive the greatest benets from utilizing

this intervention.

Photo by Croney Lab, Purdue University.

VA-24-W Early Neurological Stimulation (ENS): Implications for canine welfare and management

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January 2020

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