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Improving the health of dogs: what if it's not genetic?

5/11/2026

By Carol Beuchat PhD

Every trait of an animal must be the result of two things: genetics and environment. In this context "environment" includes anything and everything that is not genetic. So, if there is a particular trait or disorder in a dog, we can do some pedigree or labratory research to determine if it is caused by a genes.

When affordable canine DNA testing appeared on the scene about a decade ago, there was a flood of studies identifying the normal genetic variants or mutations associated with particular traits and disorders and traits. We quickly identified a slew of single-gene causes for all sorts of things, and for a short time it was like picking the low-hanging fruit off a tree.

Then the new discoveries started to dry up. More studies identified not one but many potentially-associated variants, none of which was simply causal, and breeders were left without clear answers and the inability to select against traits based on presence of absence of a single gene. Identification of new mutations slowed, and breeders were left with tough choices - remove an animal from the breeding pool if it's afflicted with a disorder, along with its parents, offspring, and relatives, or cross your fingers and breed to an (apparently) unaffected dog. There are many problems that fall into this category - epilepsy, cancer, renal dysplasia, neurological and heart disorders, and many more. These are often tragic, expensive to treat, and result in death at a young age.

But the genetic studies continue and fuel hope of identifying a gene breeders can test for, despite the fact that we already suspect a polygenic basis.

We know that a trait or disease must be the consequence of genes, environment (non-genetic factors), or both. The heritability of a trait or disease can be computed from a pedigree database; this tells us the fraction of variation in a trait that can be accounted for by genetics and, from our simple relationship described above, the rest of the variation in a trait must be due to environment.

When we fail to find a strong genetic basis for a trait or disorder, step two should be identifying the potential environmental factors that are causing variation.

Unfortunately, we rarely do this. In fact, we rarely estimate heritability, which would tell us something about the relative contributions of genes and environment. If 20% of the variation in a trait is accounted for by genetics, we know that something other than genetics is accounts for the rest of the variation. Many, many health disorders have relatively low heritability, on the order of 10% to 35%.

Maybe we should focus on identifying the some of the environmental factors that account for a huge chunk - 70-90% - of the variation among animals in a trait?

We have lots of ideas about what non-genetic factors could be responsible for the many disorders in dogs that lack a good genetic explanation. Environmental toxins, flea and tick treatments, highly processed kibble, and many more things have been proposed but rarely pan out as the cause of a problem. We are left empty handed continue to cope with health issues that we are powerless to solve.

I've been worrying about this problem for long time, and I didn't have any better ideas than anybody else.

But as part of a project, I monitored the whelping of dozens of litters of puppies of all breeds, and I was stuck by what I considered an astonishing number of puppies that were perfectly formed but dead on arrival, as well as the many that were extremely distressed at birth, often with fluid in the airways, including some with no signs of life - not breathing, no heartbeat - but were brought back to life with vigorous efforts by the breeder.

This seemed to be a "normal" thing experienced by many breeders, and attributed to bad luck, or maybe a virus, or something that remained unidentifies.

My thought as a biologist trying to make sense of the outrageous levels of morbitity and mortality in perinatal puppies was that this couldn't possibly be how "the dog" produced puppies, with high mortality that appears to be the result of an event that occurs in the short period of time between detachment of the placenta and expelling from the birth canal. I needed to figure out what was going on here.

A puppy that is still enclosed in a fluid-filled sack and only partially expelled from the birth canal.

A few years later, I think I have an answer that, surprisingly, was hiding in plain sight.

A 2001 PhD thesis looked at causes of mortality in newborn puppies and found that the puppies simply run out of oxygen before they make it into the real world. Once the placenta detaches from the uterus, the oxygen supply for the puppy is limited. If the puppy is not born before its oxygen is depleted, it becomes hypoxic (low blood oxygen concentration), and simply suffocates. The result is stillborn puppies, or puppies that try to breathe before they are born and instead of air, inhale fluid.

But why are they running out of air? Because birth is too slow.

As every breeder knows, whelping can be quick, with new puppies appearing every few minutes. Or it can take many hours, sometimes with hours between births. There can be lots of straining by the bitch yet puppies are produed very slowly, sometimes even with a puppy making a partial appearance, still encased by membranes and fluid, when the contraction wasn't strong enough to expel the puppy completely.

Slow whelping is caused by uterine inertia, in which the strength of uterine contractions are not strong enough to expel the puppies. Several studies have looked for a cause for uterine inertia, suggesting things like age or pariety of the bitch, litter size either too large or too small, even exhaustion of the bitch. But none of these was an adequate explanation.

So here's the mystery. We have hundreds of heath disorders in dogs for which we have no clear genetic explanation. We also have a high attrition rate of newborn puppies attributed to uterine inertia. Could these things be related? What environmental factor (again, meaning non-genetic) could explain these things that would also be common to dogs of many breeds from all over the world, and that affected dogs produced by millions of breeders? It was a real puzzle.

Digging around in the pediatric literature, I finally connected the dots. The strength of uterine contractions during childbirth depends on the presence of the hormone melatonin, which interacts with oxytocin to increase the strength of uterine contraction. As you might know, melatonin is called the "sleep hormone" because it is secreted only at night. Secretion in the daytime is blocked by light, so your melatonin levels are low during the daytime and rise at night.

So, if you were going to give birth to a baby - or a litter of puppies - the most likely time for it to happen is in the darkness of night. Indeed, most infants are born between 1:00 AM and 7:00 AM, with the peak at about 4:00 AM.

Connecting these dots was easy. Uterine inertia in dogs could be caused by inadequate melatonin. If the whelping box is set up in the house where there is adequate light for the breeder to keep an eye on things, the bitch's melatonin would likely be suppressed, resulting in uterine inertia and puppies that run out of oxygen before they are born. If breeders are monitoring the progress of labor, the ambient light will block the secretion of melatonin, resulting in puppies that are hypoxic or even stillborn.

Breeders closely monitor whelping so they can assist when necessary and make sure the newborns are all breathing and connecting to the food supply. But it's probably the lights that are causing the stillbirths and distress of the newborns. Mom's melatonin secretion depends on nighttime darkness. When we turn on the lights, we block the very hormone necessary for strong contractions that will expell puppies quickly.

The connections among the dots here are compelling and offer a sensible explanation for the uterine inertia and high attrition of newborn puppies. I'm beginning a study working with breeders that want to do what I'm calling "dark whelping", for which we eliminate ALL light from the whelping room and document the whelping of the puppies and behavior of the dam. By trial and error, we have found that even a very - VERY - tiny bit of light will shut down uterine contractions, so we are whelping in total darkness. With infrared video cameras, we can watch from outside the room and not miss a thing. And surprisingly, the maternal behavior of the dam seems better in total darkness; no growling or nipping at puppies, no reluctance to nurse or stay in the box, none of the issues with mom that can be a nightmare for the exhausted breeder to manage. In the dark, mom handles everthing competently with no assistance needed. After the video is set up, the breeder and I can settle down with wine and cheese and just watch the show on a phone or tablet.

If you're expecting a itter and are interested in participating in this project, just drop me a note and we can arrange it!

But we haven't settled the other problem we were worrying about - the high rate of apparently non-genetic disorders in dogs. We needed to find an environmental cause that wouldn't be limited to a narrow group of dogs, like a particular brand of flea treatment or kibble. We needed something that is probably "global".

I think the cause could be the way we are whelping our puppies - under lights for observation, instead of in the dark or at night, which results in uterine inertia and slow whelping. What's the connection here?

We can reasonably expect that inadequate oxygen during birth is going to be a problem for dogs. We certainly know that babies that are deprived of adequate oxygen during birth, even very briefly, can be left with a long list of deficiencies and disorders, many of which can compromise health over the lifetime, and some of which are fatal. This is well-documented in the pediatric literature.

These tables list some of the disorders associated with free radical damage cause by oxygen stress during birth in humans, both in newborns and over the lifespan. Some of these are problems in dogs as well - arthritis, cancer, cataracts, heart failure, inflammatory bowel disease, neurological disorders, and a variety of ther things.

Although we should expect that oxygen deprivation during birth could result in similar deficits in dogs, this has received surprisingly little attention. Oxygen deprivation during birth is exactly the sort of non-genetic insult we are looking for to account for the non-genetic sources of health issues is dogs. It is not breed-specific, not limited to only some areas in the world, and - most importantly - not identified by breeders as problem during whelping that can have health consequences not just in the neonata puppy, but for over a lifetime. It's a cause of a huge problem that is literally hiding in plain sight.

Stillborn puppies and pups that are distressed at birth are attributed to bad luck and accepted as a part of the normal emotional burden of being a breeder. But if we undertstand the biology of melatonin and its critical role in the process of whelping, we would recognize this as an exestential problem of our own making and one that is relatively easy to solve.

Light has many effects on reproduction processes, even beyond the ones described here for melatonin. Breeders are largely unaware of these, so they are overlooked while we tend to focus on identifying genetic causes for health problems. It is critical that we broaden our perspective when trying to address health issues, and breeders should be encouraged to expand their education to include understand the many ways non-genetic factors could be responsible for some of the health problems in dogs.

READ THIS!

There is no research documenting the effects of administered melatonin in pregnant dogs and nothing about dosage or timing.

DO NOT GIVE YOUR PREGNANT BITCH MELATONIN EXCEPT UNDER THE SUPERVISION OF A VETERINARIAN FAMILIAR WITH ITS ROLE IN WHELPING!!

To this end, I am deveoping a program to evaluate whelping in total darkness with the cooperation of breeders that are expecting a litter soon. If you would like to contribute to the project, please join the Facebook group for the project at -
https://www.facebook.com/groups/uterineinertiaindogs

You can also enroll in the NEW ICB Course about dark whelping and other effects of light on canine physiology: "From Breeding To Weaning: The Critical Role Of Light". The course starts on 13 May with recorded live lectures that you can access at any time.

You can learn more about the course and register here -
https://www.instituteofcaninebiology.org/breedingtoweaning.html

You can learn more about the genetics of dogs in 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

What does jet lag have to do with whelping puppies?

5/8/2026

By Carol Beuchat PhD

If you've done much travel by air, you've probably experienced jet lag, that awful feeling of fatigue, disorientation, and brain fog that leaves you feeling like crap just before a job interview or your best friend's wedding. You're hungry at the wrong time, can't sleep, and try to self-medicate with coffee or donuts or chocolate.

You probably know jet lag has something to do with your internal clock being out of phase with the time zone you're in, and that things will be better in few days. (Ugh, just in time for you to fly home to a different time zone).

Jet lag is definitely physiological. Your body expects things to happen at a certain time of day, and your internal (circadian) clock monitors whether it's light or dark outside to keep everything running on time.

A key player in keeping the parts of your body in sync is a hormone called melatonin. When melatonin levels are high, your body knows it nighttime. Melatonin secretion is suppressed by light, so you know it's daytime when melatonin levels are low. The cycle of light from daytime to nighttime is called your photoperiod.

This isn't just a clever way for people to keep track of time when they travel. It turns out that all animals and even plants take their cues from the photoperiod to know not just when to sleep and when to wake up, but also when to molt, migrate, hibernate, and all the other things that need to happen at a particular time or season.

This video from Khan Academy about photoperiods talks about plants, but the basics apply just as well to animals (and dogs, and you), so it's worth watching. Especially pay attention to the effects of light at the wrong time of day, like a blast of light when your body is expecting nighttime. (At about 7 minutes it starts talking about mRNA and gets geeky fast, so you can skip the end.)

(Khan Academy video: Watch from beginning to about 7 minutes.)

A critical point here is that light at a time when your body is expecting it to be nighttime really messes things up. In essence, that period of light - even very short, very dim light - throws everything out of whack. When your body gets that blast of light, it decides it must be daytime and adjusts the internal clocks to synchronize with that new time. All the things in your body that run by the clock will be messed up until there are several days of a normal photoperiod that your body can sync to.

This blast of light at the wrong time is just like what happens in jet lag. Your internal clock is on the wrong schedule, and the consequences are predictable and not pleasant. This is also why you're not supposed to check your email in the middle of the night; the brightly lit screen of your phone resets your internal clock, leaving you feeling not your very best the next morning.

What does jet lag have to do with whelping puppies?

Dogs rely on external light cues to keep track of day and night, just like you (and plants) do. If you keep a fairly regular schedule, your dog knows when you will be home from work, when it's time for dinner, and when it's time to get up in the morning.

Dogs tend to go into labor and whelp their puppies in the middle of the night, but not always. For the daytime whelpers, it's likely that they haven't had a reliable photoperiod in the days and weeks coming up to the end of gestation. They whelp during the daytime because their circadian clock isn't synchronized to the real photoperiod.

There are two problems with whelping in the daytime.

First, the bitch's melatonin will be suppressed by light unless she's in a very dark room. The strong uterine contractions needed to expel the puppies depend on the interaction of melatonin with oxytocin. Without melatonin, the uterine contractions aren't strong enough to expel the puppies quickly, the classic case of uterine inertia. (How do you know if your whelping room dark enough?)

Prolonged whelping times result in oxygen stress in the puppies as the store of oxygen in the placenta and blood of the fetus is depleted. The result is stillbirths and puppies that have had inadequate oxygen (hypoxia) and are born with airways full of fluid because breathing was stimulated while still in the amniotic sac.

The second problem when melatonin is suppressed in the bitch during whelping is that uterine inertia is likely to result in oxidative stress, when fetal metabolism produces free radicals that can damage tissue and DNA.

Antioxidants produced by the body and in the diet typically mop up excess free radicals to prevent damage, but the newborn puppy does not produce its own yet and relies on mother's milk to supply what it needs. But melatonin is one of the most effective antioxidants, and its secretion is blocked when the bitch is whelping when there is light. So newborn puppies are likely to have a free radical load and inadequate antioxidants to prevent damage.

The result is that newborn puppies that experience hypoxia during birth might suffer tissue and DNA damage as soon as they enter the world. We know a lot about the effects of inadequate oxygen during birth in human infants. These can be severe and also last a lifetime. If inadequate oxygen has similar effects on a puppy during birth, we should expect some serious consequences to the health of a puppy as well. (Consequences to puppies of inadequate oxygen during birth)

While uterine inertia and its consequences for stillbirths and distressed puppies are well-documented in dogs, very little is known about the consequences to health, either short or long term. We should certainly expect to see some of the same disorders in dogs that occur in humans. In fact, several health problems in dogs could very well be a consequence of exposure to hypoxia at birth, but research has focused on identifying genetic associations with little success. Renal dysplasia, seizures, and cancer are three obvious candidates for disorders that are likely linked to perinatal stress. (Key things you should know about whelping that you probably don't)

The point here is that we might think the effects of turning the lights on and off are inconsequential, there could be profound effects on the physiology of a bitch during gestation and whelping, and we might never connect the light scheme with the short and long term health of her puppies.

There are some simple fixes for this. Just like you have a regular "bedtime" for your toddler, after which lights are out, we can establish similar routines for our dogs, especially the breeding females.

We can avoid the suppression of melatonin during whelping with a bit of planning ahead of time to set up the whelping room to be completely dark and invest in a few inexpensive infrared video camera so we can keep an eye on things. In my experience, bitches whelping in total darkness give birth to their puppies quickly, with no stillbirths or even puppies that are distressed. The time between puppies is 10-20 minutes, so even a large litter can be whelped in an hour or two.

Most of us have personal experience with the significant effects of travel that disrupt our circadian timing. We can appreciate how a disrupted schedule might wreck havoc on her physiology of a pregnant bitch as well. To prevent this, we can put our household lights on timers to provide a predictable day and nighttime schedule. We can also provide a very dark room for whelping so melatonin can play its essential role in the control of uterine contractions during whelping.

To learn more about the important effects of light during pregnancy and whelping, check out ICB's live-lecture course,

"From Breeding to Weaning: The Critical Importance of Light".

Also visit our Facebook Group,
ICB Uterine Inertia and Neonatal Mortality in Dogs.

How do you know if your whelping room dark enough?

5/1/2026

By Carol Beuchat PhD

If light inhibits the hormone that increases the strength of uterine contractions during labor, you want to whelp in a dark room to prevent uterine inertia and reduce the risk of stillborn or distressed puppies.

But how dark is dark enough?

You can't trust your eyes to tell this. First of all, you know that our eyes can slowly adapt to darkness, so you can't trust your eyes to assess light levels.

It's the light that interacts with the receptors in the dam's eyes that matters. Photons that reach her receptors for light intensity (not rods or cones) signal to her brain whether it is light or dark where she is, and this information controls the secretion of the hormone melatonin. It's photons interacting with the receptors in the eye that matter here, not what she (or you) can see.

Melatonin interacts with oxytocin during labor to produce the strong contractions necessary to expel the puppies during labor. Light blocks melatonin secretion by the pineal in the brain. So if the room isn't dark enough, the hormone that is critical for expelling the puppies during labor is inadequate, and the result is uterine inertia.

We need to know the relationship between the number of photons reaching her light receptors and the secretion of melatonin. In bright light, melatonin secretion by the pineal is blocked. How low does the light level need to be to eliminate suppression of melatonin?

How dark is dark enough?

A "dim" room is roughly 20-50 lux. At night with a full moon, the light level is about 0.1 lux. Starlight at night is about 0.001 lux.

We know that the light sensors in the eyes of diurnal mammals are extremely sensitive. Studies of the effects of dim light at night use light levels of 2-5 lux. Starlight blocks melatonin secretion in diurnal mammals.

The difference in light levels of what we perceive at a dimly lit room is 4 orders of magnitude - a factor of 1,000x - more light than necessary to block melatonin secretion.

To prevent suppression of melatonin secretion, it must be very, VERY dark. Your own eyes are worthless as light sensors at this level of darkness.

For a bitch on a dark night in an underground den, the light levels must be lower than this or she will not secrete the melatonin necessary for contractions strong enough to expel her puppies.

When we whelp puppies in darkness, we must get the light levels in the room below the level that would suppress melatonin secretion. We don't know that that level is, and we wouldn't be able to measure it without an expensive sensor. So we simply eliminate ALL light in the room.

When we do that, everything about whelping changes. The behavior of the bitch is different, we stop seeing abdominal contractions (because the uterus is pushing the puppies out), the interval between puppies gets very short, and we stop seeing stillborn and distressed puppies.

We live in a world of light. Getting a room this dark is a real trick, and we have found that even the tinest amout of light, even very briefly, shuts down normal uterine contractions, usually for about 2 hours. This can be too long for a puppy already in the birth canal to survive on the oxygenated blood in the placenta and its circulatory system. We have found that this shut-down is very unforgiving. Any light shuts things down for hours.

The trick is to get the room dark enough for whelping, and to prevent ANY light in the room until all of the pups have been born.

When I supervise a whelping, my goal is to use my experience to help breeders get it right in the environment where they whelp their dogs. My other job is to reassure the breeder that we can see quite well what is happing from the video feed, and as long as things are going well, we are simply spectators. Of course, if there is a serious issue the breeder can just enter the room. The goal is 100% survival of normal puppies. In about two dozen dark whelpings, we have had no normal puppies that were stillborn or distressed.

So how do you know if your room is dark enough?

If you can see anything at all, that's way too much light. Certainly you cannot be supervising from inside the whelping room. You wouldn't be useful in her very dark den, either.

Check out this graph showing the mortality rate of puppies as a function of time interval between briths Cornellius et al., 2019). The data for the shortest interval was 0-60 minutes. From the rest of the graph it's clear that we would like to have data for shorter intervals than that, because that's where ight level is low enough for no stillbirths. In the graph, I put the data point halfway between 0 and 60 min as the best we could do with the data provided.

You can use this graph as a very rough guide. If you have a litter of 10 puppies and one is stillborn (10%), that woud correspond to about 30-40 minutes (again, a wild extrapolation of the available data). So 40 minutes - even 30 minutes - between puppies is too long.

Remember, this graph is for stillbirths - puppies that ran out of oxygen and suffocated. Other puppies might also have had experienced inadequate oxygen but were successfully born. Some of these surviving puppies can be expected to suffer from some of the disorders we know to be consequences of hypoxia and oxidative stress in animals and humans. (See Why do newborn puppies die?; and Consequences to puppies of inadequate oxygen during birth)

Also remember that there are other things that might affect the interval between puppies or the risk of stillbirth. We have run into a few of these that were particular to the way the whelping room was set up, so I watch for those when we prepare the whelping room.

If we get everything right, births are 10-20 minutes apart or even less. A litter of seven can whelp in an hour. We have never needed to use calcium between puppies. There are no stillbirths of normal puppies; no puppies needing postnatal assistance. No exhausted mothers.

Now what we need is a cohort of puppies that were whelped without exposure to hypoxia that we can follow through life and record any health issues. The best way to do this is to get a big enough group of breeders together in a single breed so we have enough puppies to be able to compare with those whelped in light.

We have the beginnings of a group for Golden Retrievers, and these puppies will be especially useful because they can be compared to the dogs in the Morris Lifetime Study. If you're a Golden Breeder and want to join, send me a private message.

We welcome any breed where we have enough breeders to produce a decent sample size of puppies for statistics.
.......................................................

If you would like to learn more about whelping in the dark, see the Facebook group for his project at -

https://www.facebook.com/groups/uterineinertiaindogs

I am also teaching a course about the science behing dark whelping that starts 6 May 2026 ("From Breeding To Weaning: The Critical Role Of Light"). If you wish to participate in the breeding project, you should take this course. Learn more about it here -

https://www.instituteofcaninebiology.org/breedingtoweaning.html

You can learn more about the genetics of dogs in ICB's Online Courses.

*** Population Genetics for Dog Breeders ***

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

Improving the health of dogs: what if it's not genetic?

What does jet lag have to do with whelping puppies?

How do you know if your whelping room dark enough?

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