Dogs bear their young in litters. The number of puppies in these litters varies considerably, numbering as few as one and as many as 10, sometimes more. Both males and females have eight to twelve undeveloped nipples when they are born; however, male dogs’ teats remain nonfunctioning. Teats don't reflect how many puppies a female can have, but a veterinarian can use several means to estimate the number of puppies in an litter that's coming due.
The canine mammary structure consists of five paired mammary glands laid out in a chain staggered along the midline of the dog’s chest and stomach. Typically, a small- to medium-size dog will have eight teats, and a large to giant-size dog will have 10 teats, regardless of how many puppies she will bear in a litter. Nipples mature and develop functionality when the female dog reaches adolescence. They become fully functional when the female dog has her first puppies. Once a female dog has stopped nursing, her nipples reduce in size until the next time she has puppies to nurse.
The number of puppies a female carries can be estimated starting the fourth week of pregnancy, by having the vet gently palpate her abdomen. Palpating a pregnant dog’s abdomen puts the pregnancy at risk if it is done improperly, so only a veterinarian should perform it. An ultrasound image can be taken of the female dog’s abdomen at approximately four weeks, as well. This test will determine if she is pregnant or not, but not how many puppies she will have. Abdominal X-rays taken at about the end of the eighth week of pregnancy are the most accurate means of determining the number of puppies a female dog carries.
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