Some important information about the fetus and the newborn puppy

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1 Some important information about the fetus and the newborn puppy Dr. Harmon Rogers Veterinary Teaching Hospital Washington State University Here are a few interesting medical details about fetuses and newborn puppies. Knowing them may help an owner understand some of what happens during this critical time of life and possibly take steps to reduce the chance of still births and neonatal puppy deaths. Puppies are called neonatal from the time of birth until they are two weeks old. This is a critical period when there is transition from support of all their bodily functions within the uterus to full independence in the cold cruel world. At birth the puppy no longer gets nutrition from the mother s blood supply. Energy must come from digestion and metabolism of the milk it consumes. The puppy must get oxygen from its own lungs, and it must discharge all the waste products to its kidneys. To do this there are important things which happen with circulation. One is the umbilical vessels are cut off at birth. The blood vessels in the body respond to that by expanding to allow greater blood to flow through the stomach, intestines, kidneys, and other organs. Second, a bypass connection in the veins near the liver closes so that blood from the gastrointestinal vessels starts flowing through the liver. Third, a connection in the arteries near the heart closes so that blood from the right side of the heart which bypassed the lungs while the puppy was in the mother is directed to the lungs. At birth the puppy becomes chilled and its CO2 level rises. That stimulates the respiratory center in the brain and makes the puppy start breathing. When the puppy starts to breath the airspaces in the lung expand and the blood flowing through the lung tissue exchanges oxygen and carbon dioxide. From the standpoint of the effort required the very first breath the puppy takes is the hardest. After it is born a puppy has about 10 minutes to start breathing. So if it isn t breathing right away don t give up on it too soon. Have a rubber bulb syringe with a soft flexible tip and use that to repeatedly clear fluid from the back of the mouth and from the nose. Having a couple of these bulb syringes handy and some extra help is important if two puppies are delivered one right after the other. 1

2 Rubber bulb syringe Suctioning the airway with a soft rubber catheter As the airway is repeatedly cleared with suction, turn the puppy from side to side and rub it vigorously all over with a small dry towel. That will further stimulate it and get breathing going. Don t press hard on its chest, though. It needs to take a breath. Don t go flinging it around either. It could slip out of your hands, and centrifugal force puts pressure against the diaphragm and chest at a time when inflation must happen. It is the exact opposite of what is needed. Some owners will do mouth to mouth resuscitation. The puppy passed by the rear end of the mother when it was born and is likely covered with bad bacteria. For the health of the person mouth to mouth isn t a great idea. Devices which are supposed to inflate puppy lungs can be purchased, but they may not help very much. Keep suctioning and stimulating by turning side to side and rubbing with the towel. 2

3 Fetal aspirator and respirator In a medical environment a skilled person can pass an endotracheal tube and then breathe for the puppy. Doing that is very difficult and not something most owners can do. Medications used in older animals to stimulate breathing do not work on puppies because their nervous system is not developed to respond to them. Before birth there is very little need for the fetus to increase or decrease its blood pressure. After all, it isn t running anywhere. Fetal and neonatal blood pressure is low and stays low all the time. Because the blood pressure is low the heart must beat very fast to circulate blood through the body. At the time it is born the heart rate in a normal puppy is easily 200 beats per minute or faster. In an adult dog a resting heart rate of 80 to 100 beats per minute means the dog is healthy and well-conditioned. In the fetus a slow heart rate means that there is a serious problem. It is really hard to check fetal heart rates accurately with a stethoscope or fetal heart monitor. A veterinarian may use ultrasound to check fetal heart rate before and during labor. A fetus with a heart rate above 200 beats per minutes is doing ok. One with a heart rate of 100 beats per minute 3

4 is in extreme stress and could die before it can be born. Fetal heart rates which consistently are less than 180 beats per minute indicate whelping is not going well and Caesarean surgery is needed. Because of low blood pressure the neonate is very sensitive to cool environmental temperature. Body temperature is maintained by a combination of muscle activity generating heat and constriction of blood vessels in the skin to conserve heat. Neonates don t generate a lot of heat from muscle activity and their blood vessels are dilated all the time. They lose body heat easily, and they can become hypothermic. Also, because blood pressure is low and a puppy s skin is very thin the circulation through the skin located on the downside of the neonatal puppy can be blocked by the puppy s weight on it when it is not moving. Most puppies move around so this isn t a problem. A hypothermic neonate may not move very much at all and circulation through the skin can be persistently obstructed. This can lead to further problems. If a hypothermic puppy is placed on a heating pad or warm water bottle the relatively low heat of the pad or bottle might burn the skin. This can happen with pads and warmers only a few degrees above normal body temperature. Do not put neonatal puppies on heating pads or warm water bottles. It is better to warm the air around them. Warming of air is easily done with just a plain incandescent light bulb suspended above a box. Put the puppy on a towel in the box, put a thermometer to measure air temperature by the puppy, and warm the air by the puppy to around 90 degrees Fahrenheit. The light bulb can be raised and lowered to adjust the temperature. The goal is to slowly warm the puppy over an hour or so to its normal rectal temperature of 98 degrees. The more the puppy moves around on its own the more easily it is warmed back to normal. 4

5 Here is another note of caution about hypothermic neonates. When their body temperature drops to 94 degrees Fahrenheit or less the normal movements of the stomach and intestines stop. Puppies which are hypothermic must not be given any thing by mouth. If that is done, milk or other fluid will get to the stomach, but then it will passively flow back up esophagus into the mouth while the puppy is lying. When the puppy takes a breath the fluid in the mouth will be inhaled into the lungs and the puppy will get pneumonia or inhale so much that it dies right away. From a standpoint of body functions there are four big killers of neonatal puppies. In addition to hypothermia, they are lack of oxygen, lack of energy, and dehydration. In the hospital putting a critical neonatal puppy may be placed in an incubator with supplemental oxygen. There may not be much an owner can do about lack of oxygen. Supplemental oxygen in an incubator A lack of energy and dehydration is addressed by supplemental feeding with a properly balanced commercial canine orphan formula. A newborn puppy should nurse or be fed at least once every two hours. It is really hard and very time consuming to hand feeding enough milk with a nursing bottle. A better way is to learn how to tube feed with a soft rubber feeding tube. It looks much harder than it is. A veterinarian or veterinary technician can teach any owner how to do this easily and safely. When you are feeding a litter of 10 puppies every two hours it makes a huge difference. Again, do not feed puppies which are hypothermic. Warm them first. 5

6 Checking distance from nose to stomach for feeding tube length Feeding with syringe and feeding tube 6