Once a female reaches puberty uteruses an unfertilized egg along with the blank

Once a female she begins to create eggs meaning she is now able to conceive/carry children but when not impregnated the egg will line the uterus and blood is a cushion for the egg or baby and when the egg is old or not being used for a week at least a female will shed the blood lining and reproduce a new egg

Explanation:

if you think your dog may have been exposed to a toxin, the best thing to do is to check the label of the item you think your pet ingested. read the information about toxicity. often, but not always, the information on packaging regarding children is relevant to dogs and some manufacturers even discuss dog toxicity. if there is an 800 number on the package – call them! it’s also recommended that you call your veterinarian to confirm the recommendations. if you go to your veterinarian, take all packaging and any information you have on the product.