Epigenetics is the circumstance that determines whether genes are turned on or off. Epigenetics is like the operating system of the genes. In metaphorical terms to clarify: Where heredity is the 'gun', epigenetics is the trigger that determines whether or not the gun goes off.
As breeders, we all know how important heredity is in your breeding program. By excluding unhealthy cats from breeding, testing the cats well, taking COI% into account, making smart combinations and by good selection, we as a breeder have an influence on the health of the kittens that are born with us. But heredity and our breeding program are not the only things that play a role. Epigenetics also plays a very important role in which kitten survives and which does not. There are various environmental factors that can play a role in the health of newborn kittens. As a breeder, you do not have influence on everything, but there are things you can do to increase the chances of survival of the kittens, starting with awareness.
The pregnancy
The mother already provide the kittens with information about the conditions of the outside world in her womb. Is there danger, is there enough food, is it cold? Nature is so ingenious that it prepares the kittens well in her womb for what awaits them after birth. This gives the kittens an optimal chance of survival.
Cold
In nature, kittens born in a cold environment are already prepared for this in her womb. They will have a thicker coat than kittens born in a warm summer. Nature also ensures that kittens are born in the kitten season when the chances of survival are as high as possible, usually from March to October, depending on the geographical location.
Of course, this is different when pregnant cats live mainly indoors in a well-heated house. The circadian rhythm of nature in our catteries is disrupted by artificial light and central heating, which is why cats also consider our winters safe enough to have kittens. As breeders, we also know that melatonin supplementation can counteract the cat's heat cycle. In fact, we simulate a winter period, where the melatonin level rises due to the lack of daylight early in the day.
Stress
When the mother produces a lot of stress hormones during pregnancy, her kittens are already prepared in the womb for a world full of danger. The stress hormones also end up in the fetuses, which develop the receptors for stress hormones well in their cells. This also gives the kittens a greater chance of being alert to danger and threats and to be able to anticipate, by for example avoiding it. A stressful pregnancy of the mother also gives a greater chance of kittens that are sensitive to stress.
Scarcity
When the mother cat experiences continuous hunger during pregnancy, the kittens are prepared for a world with scarcity. The bodies of the kittens adapt to this, so that they deal with the food they receive as efficiently as possible. These kittens are therefore more likely to become fat, when they suddenly end up in a world with an abundance of food. You see this, for example, with a pregnant stray cat where the kittens are adopted into a good home. But you also see it with very large litters where the kittens literally have to fight to get enough milk.
Optimal conditions for a successful pregnancy
What can you do as a breeder to optimize the conditions for the future mother cat? We do not have influence on everything, but there are certainly important measures that we as a breeder can take to optimize the conditions in order to ensure a successful pregnancy and birth.
Make sure that your cat is healthy and in good condition when you have her mated. Of course, this also applies to the stud cat.
Provide a stress-free environment. If she does not tolerate other cats around her or gets stressed by (some of) them, keep her separate as much as possible during the pregnancy, or keep her together with the cat(s) she is good friends with.
I myself once experienced that one of my cats had a very stressful pregnancy due to tension in the house from fighting cats, in which she was also involved a few times. The result was that several empty amniotic sacs and a mini placenta were born from resorbed or undeveloped fetuses. Fortunately, two healthy kittens were born as well. There was also a kitten born 20 hours later who had already died in the womb, and which she could not get out on her own due to fatigue/weakness of contractions (she gave birth to it only after an oxytocin injection).
Listen carefully to what your female needs. Every cat is different and has different needs. When you notice that she is restless or not feeling well, without there being a medical cause, try to find out what she needs. This could be a quiet place, more attention, more food or something else.
Give her lots of attention and cuddles. Pregnancy is a period in which your bond can deepen and strengthen enormously. The cat will then also trust you to help with the birth and kittens if necessary, which can be life-saving.
Make sure that you are at home from day 60 of the pregnancy and that you are present when she delivers the kittens. The cat should do everything herself, but sometimes intervention is necessary and life-saving. Also after she gave birth, I advise not to leave the kittens alone for the first week and also to sleep in the same room at night. When something is wrong, the situation can deteriorate very quickly, both with a kitten and the mother cat. It is important to monitor them continuously. The first ten days, the little ones and the mother cat are very vulnerable.
Also make sure that you are well prepared for the birth. It is important that you have everything at home to be able to act quickly in various scenarios. What is also important is that you have sufficient knowledge of how to act in certain situations. Take a course in bottle feeding kittens beforehand, read up, watch videos and talk to many breeders about their experiences. Your knowledge and skills can be life-saving. Also make sure that you have arranged helplines in advance, such as your vet, the number of the emergency vet, your mentor and possibly befriended breeders or family members who can help in an emergency.
Make sure that you know the blood group of both parents. If the future mother cat has blood group B, it is essential to know this before she gives birth, in connection with kitten mortality due to a possible mismatch with the blood group of the kittens and the mother. If the mother cat has blood group B (b/b) and the tomcat has blood group A (N/N or N/b), the kittens should not drink from their mother for the first 18 hours to prevent a high chance of death. The colostrum could be lethal for these kittens because it contains antibodies against their own blood group.
Preventing birth defects
Sometimes kittens are born with a birth defect, such as a heart defects, cleft palate or umbilical hernia. According to a study from 1978 of various cat breeds, 6.8% of all 3,468 kittens were born with a birth defect (5). A more recent study in the UK from 2005 speaks of 14.9% of kittens having a birth defect (6). In a study of stray kittens, autopsy showed that 40% of kittens that died young had a birth defect. This study also suggests that infectious diseases and living conditions can play a major role.
The same study indicates that birth defects can arise from a variety of factors. Some arise unpredictably without an identifiable cause, while others manifest as visible signs of genetic disorders or are the result of the mother's exposure to harmful substances during pregnancy. Certain drugs with teratogenic potential, including griseofulvin, corticosteroids, and metronidazole, can increase the risk of birth defects. In addition, maternal factors such as malnutrition can contribute to these defects, as can maternal diseases such as FIP, panleukopenia, and toxoplasmosis. For example, megaesophagus (dilated esophagus) can be associated with infectious causes such as viral infections and toxoplasmosis. In addition, conditions such as hydranencephaly (waterhead) and cerebellar hypoplasia have been associated with panleukopenia due to natural infection or vaccination with a modified live virus vaccine.
I have personally had a few kittens with birth defects, in a couple of my litters, presumably due to a bacterial infection that infected my queens via the tomcat. After a course of antibiotics, a change of food, and folic acid supplementation during pregnancy, I have fortunately not experienced this again.
Because environmental factors and circumstances (epigenetics) can play a major role, this is also something that we as a breeder can influence. For example, we can take the following measures to prevent birth defects:
Provide sufficient food and of premium quality. Pregnant cats eat much more and need more than normal. Also consider sufficient folic acid and taurine. Some brands have special food for pregnant cats, enriched with folic acid. If you do not provide this, make sure you supplement with folic acid. Just like in humans, folic acid prevents the chance of kittens with spina bifida, cleft palate and other closure defects.
Do not use medication for the mother cat if it is not urgently necessary. I would personally never vaccinate, preventively deworm or deflea during pregnancy, but at least 3 weeks before mating (if necessary at all).
Do not use toxic cleaning agents, such as Dettol. Also consider weed killers, green deposit cleaners for the garden, these products are very toxic to cats and unborn kittens. But also consider air fresheners, scented candles/sticks and certain essential oils or incense. Cigarette smoke can also cause developmental defects in kittens.
Ensure that the infection pressure in your cattery is low. The best and also most difficult way is to limit the number of cats in the house to a small group. The more cats in the house, the greater the infection pressure. If you have more than 5 cats, you could reduce the infection pressure in the house by splitting the group into several small groups that live together. The second measure you can take is not to plan two or more litters at the same time. The large number of kittens greatly increases the infection pressure in the group, making kittens more vulnerable and when they pick something up, it can spread very quickly throughout your entire group. Calici, Herpes disease and other viruses, or parasites and ringworm thrive in a cattery with high infection pressure and are much more difficult to control.
Ensure a clean house and good litter box hygiene protocol. Also think about hygiene protocols for visitors, such as removing shoes and washing hands or avoiding visitors altogether to reduce the chance that your pregnant cat gets an infection that you know can be harmful to the kittens if treated.
Do not visit shows during this period, unless you are extremely careful and take strict hygiene measures. Think about a quarantine period for the shown cats when they return home and change clothes and shower yourself when you return home.
Is there a kitten with a birth defect that dies? Then consider having an autopsy done on the kitten. If the kitten is alive and otherwise healthy, you can also have the placenta examined to see if you are dealing with a bacterial or viral infection. This way you may find out the cause so that you can also treat it and prevent it in the future.
Observations during birth
How the birth and the born kittens provide information about their chances for a good start in life.
Giving birth
With a smooth birth, the kittens are born in quick succession. How much time is there between two kittens? An interval of 30 minutes is average. When lots of time passes before the next kitten is born, there is a greater risk that this kitten will be stillborn. In the study that was done with puppies, it appeared that the chances of survival are significantly lower if two hours have passed since the birth of the previous puppy. In another study with Maine Coons (7), a total interval of 6 hours was found between the birth of the first and the last kitten in 99.3% of the 52 monitored births. Of all kittens born, 12.5% were stillborn. Another study indicates that in 13% of the born litters of Maine Coons, at least 1 kitten was stillborn.
I myself have witnessed three deliveries where the last kitten was delayed for more than two hours. In one cat, the 10th kitten was born 4 hours after number 9, and it was stillborn. In another cat, the third kitten was born 20 hours later and unfortunately already died in the womb. In another cat's first litter, the last kitten was born about 4 hours later and fortunately he was healthy.
As a breeder, you have influence on making the circumstances of the birth as optimal as possible. The most important thing is that the mother feels safe when giving birth (but also during the pregnancy). It is nice if she has approved her place to give birth. As a breeder, you ensure that this is ready well before the delivery starts, so that this gives her some peace.
Giving birth in the dark
There are also indications that light influences the duration of the birth. The presence of light can influence the strength and frequency of contractions in humans and mammals. For example, you can see in the graph below that when the light is turned on, the frequency of the number of contractions in a woman per hour decreases. A birth can take longer and stagnate due to the presence of (artificial) light. Carol Beuchat is conducting a study in dogs on how giving birth in the dark increases the chance of a successful birth (3). She is currently working on a protocol for dog breeders. Her recommendations are to make the room pitch black and to monitor it via a camera. Even the light from a mobile phone can be disturbing. It is possible that red light offers a solution so that we as breeders can observe and help better, without delaying or disrupting the birth.
Caesarean section
If your cat unexpectedly needs a caesarean section, it is not without risks. A (small) study (8) shows that kittens born via caesarean section have a lower chance of survival than kittens born naturally. The kittens born via caesarean section were less vital and often needed extra support or medical intervention to increase their chances of survival. The study shows that kittens born via caesarean section had significantly lower Apgar scores. These kittens had higher blood sugar levels, lower oxygen saturation, reduced reflexes and a lower respiratory rate. In the study of 32 born kittens, of which 13 were born via caesarean section, 12.5% (4 kittens) of the kittens born via caesarean section died, compared to 5% (1 kitten) of the kittens born naturally.
At the time of writing, I have experienced a caesarean section once. One of the eight kittens born died within a few hours in the ICU because breathing did not start properly. The ICU where the caesarean section was performed was not very knowledgeable and experienced in dealing with new born kittens, and how to provide that extra care for them. Read more about what a vet or yourself can do in this situation in this study 8.
Another disadvantage of a caesarean section is that the mother cat can be upset after the operation, can be in pain and might not feel safe. This can manifest itself in dragging the kittens around. It can also take a while before she realizes that the kittens are hers and she wants to take care of them. Sometimes the pain can be so overwhelming that she completely abandons the kittens to their fate. Provide (limited and short-term) pain medication after the birth. Summarized, having a caesarean section performed on your queen can cause a lot of stress and make the kittens more vulnerable. Of course, a caesarean section cannot always be prevented and this can be a life-saving procedure for the kittens and mother cat. As a breeder, it helps to be well prepared for these situations and to stay calm.
Newborn kittens
How does the kitten behave immediately after birth? Is it lively and active in search of a nipple, or does it lie still? What is the color of the kitten, is the mucous membrane a nice pink color? Are the paw pads of the feet dark pink, showing a good blood flow in their limbs? Does the kitten breathe normally? Does the kitten cry after birth (airways are clear)? Can it drink independently from the nipple? Does it have normal shaped legs? You can also check the kitten for birth defects by looking at whether the palate is closed inside the roof of their mouths, if the umbilical looks normal (no protrusion), if it does not have a kinked tail and if the chest is normally formed (no flat chest).
There is a method in which you test the newborn kittens on various factors, immediately after birth and again at one hour after birth, where you give each outcome a score. This is called the Apgar score, and it helps to identify vulnerable kittens, so that you are more alert with them and can intervene more quickly. This method is used for both puppies and kittens. See source 8 for those who want to read more about this.
Birth weight
What does the birth weight say about a kitten? A kitten with a much lower birth weight has a lower chance of survival than littermates that are heavier. However, a very heavy kitten has a higher risk of being stillborn. Heavier kittens can take a longer time to be born, which can cause it to suffocate in the process.
In the graph below (9) you can see that Maine Coon kittens with a birth weight of less than 75 grams (category a - very light birth weight) have a 50% chance of surviving the first 8 weeks. Maine Coon kittens with a birth weight of less than 81 grams (category b - low birth weight) have an 83.5% chance of surviving the first 8 weeks. Kittens with a normal birth weight (category c - normal birth weight) have a 95.5% chance of surviving the first 8 weeks. These are kittens that are heavier than 81 grams and have an average birth weight of 119 grams. The thresholds are different for each breed. In the study (9) you can find the different weights per breed.
I myself have had 4 kittens that were born in category a, all four of which survived without intervention being necessary. This also applies to 1 kitten in category b. I once had a premature litter of 8 kittens with a birth weight between 72 and 80 grams. They were not yet developed enough to be viable on day 55 of pregnancy and did not survive.
Weigh the kittens twice a day for the first week, until they all gain weight, after which you weigh them once a day. With bottle-fed kittens or vulnerable kittens, it is sometimes necessary to weigh them more often to check whether they have gained weight after a feeding. Find a balance between necessity and rest. Their weight is an important indication of their health and gives you a signal if something is going on. The weight is often the first thing you can notice that something is not quite right. After birth, it is normal for the kittens to lose a few grams on the first day. Adjusting to the new environment and finding and drinking milk often costs more energy on the first day than it takes in. Sometimes it also takes a few days for a kitten to really get going. Research on puppies showed that if a puppy has not yet exceeded its birth weight on day four, it has a small chance of survival (2).
What is the colour, shape and structure of the placenta? Were there as many placentas born as kittens? The placenta provides the kitten with oxygen during delivery. A placenta that is not well supplied with blood and is of an abnormal colour (blue) can indicate a lack of oxygen during the delivery of the kitten. A placenta can also provide information about possible infectious diseases that may be present. You can have a placenta tested on this, so don't throw them away right after birth if the mother doesn't eat them.
The answer to the above questions gives an impression of whether the kitten is healthy and has a good chance of survival. As a breeder, it is good to note these things down so that you can keep a closer eye on these kittens if anything is unusual. By being alert and observant, you can intervene earlier and thus increase the chances of survival of the vulnerable kittens.
Colostrum
The most crucial ingredient for a good start in life is colostrum. The first mother's milk. It contains antibodies that prepare the kitten's immune system for defense against diseases. It is the "vaccination" of mother nature that is passed on from mother to child. Everything that the mother cat has overcome in her life in terms of diseases and viruses, antibodies are passed on to the kitten via the colostrum. The mother only produces this substance for the first 12-16 hours after giving birth. Her kittens therefore only have a limited time to drink it.
As a breeder, try to ensure that all kittens receive the colostrum. You can do this by checking whether all nipples are producing milk, and by observing whether all kittens are properly attached to a nipple. If necessary, you can also choose to pump some colostrum from the mother cat, so that you can give it to vulnerable kittens who do not have enough strength to drink themselves. You can also keep the fattest kittens away from the nipples for a while in larger litters to give the vulnerable kittens a chance to get the colostrum. Kittens that have not gotten enough colostrum may not grow as well in the days after birth. In addition, these kittens may be more vulnerable to illnesses and allergies later in life.
Mother dragging her kittens
A mother who drags her kittens does not feel safe. It is possible that she does not find the place safe enough. Give her a sheltered, quiet and dark place. Most cats like it when there are no other cats in the same room, but they do want you to be there all the time. But this also depends on your bond of trust and her character. Some cats want their dearest cat friend with them. The cat indicates when she is stressed, learn to observe well and listen to her signals to see what she needs.
It is also possible that the mother cat sees you as a threat. For example, when you pick up or touch the kittens too much. Leave the kittens alone as much as possible and only pick them up briefly to weigh them or to intervene when necessary. Bottle-feeding the kittens in the presence of the mother cat can also cause her a lot of stress, which makes her want to keep the kittens away from you and constantly hide them from you. In that case, keep the mother cat separate when you have to bottle feed them and make sure she can't hear the sound of the squeaking kittens.
Finally, a medical problem can also be the cause of postnatal stress in the mother. Think of uterine infections from residual tissue. But mammary gland infections can also flare up after the birth and cause a lot of pain and discomfort in the mother. Check the milk packages daily.
Observe the mother cat carefully and try to find out what she needs. A satisfied mother = satisfied kittens and vice versa.
Hopefully this article will give you as a breeder some more guidance and tips that you can apply. Cat fanciers who read along may also gain more insight that breeding is more than "female cat + male cat = kittens" and that nothing is self-evident, a lot can go wrong. A lot of knowledge and expertise is required for the many possible scenarios that you will encounter. You never stop learning. Your knowledge and actions can make the difference between life and death. I therefore advise everyone never to start getting a litter without a good mentor and preparation.
Sources:
Training the Evocircadian Code, completed in 2013. Teacher Leo van der Zijde, and also author of the accompanying books The Evocircadian Code parts 1, 2 and 3.
We can prevent neonatal puppy mortality Carol Beuchat PhD (2023)
Using light to regulate uterine contractions. Olcese J, (2015)
Congenital Defects of Kittens Little (2005)
A questionnaire-based study of gestation, parturition and neonatal mortality in pedigree breeding cats in the UK. Sparkes et al (2005)
Obstetric and newborn parameters in the Maine Coon cats. Socha et al (2019)
Topics in the routine assessment of newborn kitten vitality: Apgar score, reflexes and complementary assessments Yukari Hibaru et al (2022)
Association between Birth Weight and Mortality over the Two First Months after Birth in Feline Species: Definition of Breed-Specific Thresholds. Mugnier et al (2023)
Mortality in Stray Kittens under Eight Weeks Old: Focusing on Congenital Malformations Contreras et al (2024)