The transition from fetus to neonate is physiologically strenuous for a puppy. Like an astronaut at the space station, working outside the station requires a transition from an environment with the adequate air pressure and oxygen for normal respiration, to one completely lacking these things. To survive a space walk outside the vehicle, the astronaut needs a suit that can be pressurized and provides oxygen. A failure of those systems to work properly is catastrophic.

A puppy faces similar challenges in its transition from fetus, where the placenta is its lifeline and supplies all of its needs, to a world in which its own physiological systems need to take over all of the processes necessary for life. The complexity of this transition is not physiologically trivial.

One of the techniques that has been used to remove the fluid from lungs of a puppy immediately after birth involves holding the puppy in the hand with arm extended and "swinging" the puppy, head down, in an arc. This will often successfully clear the fluid in the lungs so the pup can begin to breathe normally. I have seen many breeders do this, and there are videos and instructions online for those unfamiliar.

But swinging puppies to clear the airways is a really, really bad idea.

I have to confess that the first time I saw this done, it literally took my breath away (not a pun). Swinging might move the fluid out of the lungs, but it causes ALL of the fluids in the body to move towards the head of the puppy - blood, cerebrospinal fluids, stomach contents, and any other fluids in the body. This is NOT a good thing, and I will explain why.

Perhaps you have seen how astronauts are trained to tolerate the g-forces produced in space flight. They use a huge centrifuge with a capsule at the end of a long arm. The test subject is in the capsule, and as the centrifuge rotates, the g-force experienced by the human in the capsule increases; the faster the rotation, the greater the force.  

Take a few minutes to watch this video of the human centrifuge in action.

 

The expressions on that fellow's face tell you something about what you look like when the force of gravity is higher than your body is designed to tolerate. There is great pressure on the body, making it difficult to breathe, but, perhaps worse, the body fluid want to rush to the head. In an adult humans (and dogs), the physiological systems that control blood pressure kick in immediately to try to maintain normal fluid pressures in the organs and vessels.

Now think about the puppy with fluid in the lungs. (In a newborn, this will ilkely be amniotic fluid, but it can also be milk that is aspirated when nursing or being hand fed.) A newborn puppy is not a small version of an adult dog. Many of the organs are not mature at birth (e.g. eyes, kidneys), nor are the systems that control blood flow and regulation of blood pressure. In the newborn puppy, the circulatory system has a much lower pressure than in the adult dog, and the immature nervous system has very limited ability to control it (Grundy et al 2009).

Your body does a good job of regulating your blood pressure by changing the diameter of blood vessels (constrict or dilate) and increasing or decreasing the heart rate to keep blood pressure from going too high or too low. If you have ever stood up quickly and started to black out, this is your body momentarily failing to maintain the blood pressure in your head; in just a second or two, everything will return to normal as your body automatically adjusts blood pressure and heart rate to restore adequate oxygen delivery to your brain.

The systems to control blood pressure and tissue perfusion in the dog are essentially the same as your own, but they are not fully functional in the newborn puppy. A puppy is more like a premature human infant at birth, with organs systems and regulation not yet fully developed. Because of this, insults that would be handled easily by an adult dog can be much more challenging to the newborn puppy. Control of blood pressure is one of these.

This is a real problem if the puppy is swung in an arc to remove fluid from the lungs. Watch this fellow (a veterinarian, apparently) demonstrate.
​

 
Raise your hand if you gasped when you watched this. Or maybe you even stopped breathing. Think about that astronaut in the centrifuge. Try to imagine what would be happening inside the body of a tiny puppy.  That puppy is being swung HARD.

Yes, swinging might help remove fluid from the lungs of a newborn puppy. But it can also cause brain damage.

What happens to the brain of a puppy that has been swung to clear its airways?

The puppy might have no obvious signs of physical trauma; there are no surface lesions and few behavioral changes (after all, the puppies only have two activities, nurse and sleep). There can be seizures, which might be the only significant outward evidence of serious damage (Grundy et al 2009). However, examination of the brain tissues will reveal evidence of trauma manifested as subdural and intracerebral hemorrhage.

REFERENCES

Grundy SA, 2009. Clinically relevant physiology of the neonate. Vet. Clin. Small Anim. 36: 443-459.

Grundy et al 2009. Intracranial trauma in a dog due to being "swung" at birth. Topics in companion animal medicine 24: 100-103.
​

Back in the good old days, before the development of fancy scientific gadgets that can measure anything to the fifth decimal place, scientists did a lot of good science using very simple, familiar tools. A clever scientist could design experiments that provided information about the neurological basis of body temperature control in animals with nothing more than a heat lamp like the ones you use in your whelping box, and a fan and some water. Ingenuity, creativity, and keen powers of observation were traits of the most successful scientists, much as they still are today in a very different, highly technological context. ​I love reading these old studies. People these days tend to dismiss them because they seem primitive and simple-minded, but a lot of things we know now and take for granted were based on simple experiments cleverly done decades ago.

A good example of one of these was a study by Welker (1959) to learn how puppies are able to stay in contact with their most important heat sources, their mother and their littermates.

The reason you keep a heat source in your whelping box is because newborn puppies are altricial (not fully developed) at birth. Eyes and ears are closed, and they have only two useful senses (temperature and touch). A physiologist would describe a puppy as a "very simple system".

 One consequence of their relative prematurity at birth is that they are unable to generate metabolic heat to control their own body temperature. Although this ability develops over the first few weeks, at birth the puppy behaves pretty much like a water balloon, heating at about the same rate under a heat lamp, and cooling at about the same rate in the cold. Puppies are about 80% water, so the similarity is not surprising.

At the other extreme is heat, which physiological systems don't cope with very well. Puppies can suffer heat stroke just like an adult dog, causing tissue damage and ultimately shut-down of the physiological systems necessary for life. An adult dog has some ability to prevent heat stroke by increasing heat loss and limiting gain (e.g, panting). But the newborn puppy enters the world with few response options beyond trying to crawl to a suitable place. ​

Of course, the best way of prevent being exposed to a dangerously high or low temperature is for the puppy to avoid it in the first place. We would expect puppies to be pretty good at doing this (after all, the unsuccessful could die), but how?

Back in the 1950s, a scientist named Wexler at the University of Wisconsin did some simple but clever experiments to learn about how newborn puppies can avoid hot and cold to maintain a body temperature suited to their physiology. He used a 250 W infrared heat lamp to produce "warm" and "hot" conditions simply by holding it closer (about 1-2 ft away) or a bit farther away (about 4 ft)  from the puppy. For a cold condition, he moistened the skin of the puppy with water and used a fan to produce evaporative cooling. This was crude; the experimental conditions were subjective and qualitative, and probably not even repeatable. But it was a simple experiment that anyone could do (both then and now) if you had a heat lamp, a glass of water, a fan, and a puppy.

There were several questions Wexler wanted to address.

• Are puppies able to sense their own body temperate? If they can't do this, they can't take actions to regulate it. This would require the puppy to have a central heat sensor that communicates with the physiological systems involved in a response.

 

• Can puppies sense hot and cold objects in their environment? A puppy in a place that's too hot needs to know if it's moving towards a place that is coolerr, and likewise for its response to cold.

 

• Finally all of these must work together to produce the appropriate response by the puppy to get it from a dangerous place to a safe one.

Here's the setup. Wexler worked with 45 mongrel puppies that were 1-3 days old. He had a surface to put one or several puppies on (a table covered with a towel), and the tools for producing hot and cold temperatures (lamp, fan, and water).

The hot and cold conditions were applied until the puppy produced vocal and behavioral responses. The  effects of touching an object just using the fingers applied to various places on the body.

The Puppy Huddle
​
To address the first question about whether puppies can sense their own body temperature, Wexler put a group of 4 puppies on the table. Under cold conditions, the puppies gathered to form a huddle. After some time in the cold, the puppies became agitated and vocalized, but they only moved around within the pile and not away from it. If a heat lamp was directed at the pile of puppies, they became quiet within a few seconds. If the heat lamp was moved closer, vocalizations and movement began again in response to the higher temperature, and the puppies gradually moved apart from the huddle. When the puppies were all separated from each other to avoid the heat from the lamp, the lamp was turned off and activity and vocalizations stopped. The puppies would gradually cool until once again they got cold enough to stimulate  vocalization and movement. This phenomenon worked so well that the puppies could be induced to huddle and disperse over and over, simply by turning the heat lamp on and off. 

This demonstrated two things - first, that the puppies could sense their own body temperature and, second, that they could also moderate their response to body temperature with a skin sensor that could detect both pressure when in contact with littermates, and temperature; that is, whether an object was hot or cold.
​

The Single Puppy

​The behavior of individual puppies in response to heat or cold was even more interesting. 

A lone puppy in the cold sweeps its head from side to side, emitting a cry with each respiration, and occasionally moves forward a short distance. Similar side to side movements of the head occur under hot conditions, again with cries on respiration. While it might take 30 to 60 seconds with the heat lamp turned on to simulate the head movements and vocalizations, both stopped almost immediately when the lamp was turned off. If the lamp was turned on again, the response of the puppy was almost immediate, in contrast to the slower response with the first exposure to heat. This would require thermal sensors on the skin that stimulate a central receptor almost immediately. 

In the trials under hot conditions, the temperature of the fingers mattered. Touching a cool puppy's nose with a warm finger caused the puppy to move forward, while touching both cold and hot puppies with cold fingers stimulated withdrawal and avoidance behavior.

​This response of newborn puppies to touch was remarkably strong. A puppy could travel a distance of 50 yards in 15 minutes, stimulated simply by a bilateral touch on the nose. And perhaps even more remarkably, the puppies seemed to be as strong after this distance than when they started.

The Integrated Puppy

A newborn puppy might look helpless, with eyes closed and limited ability to move around, but it has remarkable sensory abilities that allow it to maintain some control of its body temperature and avoid extremes that would be dangerous or deadly. We know from simple studies like the one described here that puppies can sense their own body temperature, determine whether it is too high or too low, and take actions to move to a more thermally suitable place. The puppy can sense when it touches something and whether it is hot or cold, and it will move forward in response to a touch on the nose, something that might help it stay with its siblings or mother. 

What might look like random, pointless movements of puppies in your whelping box are actually evidence of the actions a newborn puppy takes to keep its body temperature in a suitable range for growth and physiological functions. Over the next days and weeks, the physiology of the puppy will mature and it will be able to generate and retain enough metabolic heat to maintain a stable body temperature, at which time it is able to become more independent.

​You can learn more about the science of dog breeding in my new online course, "The Science of Canine Husbandry", which is available through the Institute of Canine Biology.

REFERENCES
Welker, WI. 1959. Factors influencing aggregation of neonatal puppies. ​J. Comp. Physiol. Psych., 52(3), 376-380. https://doi.org/10.1037/h0047414

To learn more about the genetics of dogs, check out
ICB's online courses

***************************************

Visit our Facebook Groups

ICB Institute of Canine Biology
...the latest canine news and research

ICB Breeding for the Future
...the science of animal breeding
​