Abortion, Miscarriage or pregnancy loss (malabsorption) may be caused by problems with the foetus or the bitch.

The causes of abortion in dogs include:

There ae main reasons for a bitch to reabsorb puppies, including not giving off enough of the correct hormones at the time the puppies would be attaching to the uterus, infection, a bitch getting too hot or cold, and too many eggs fertilising at the same time.

Other causes include...........

• Infectious causes, such as Brucella canis, canine herpes virus, Toxoplasma, Escherichia coli, Streptococcus
• Uterine causes, such as infection of the uterus (pyometra) 
• Trauma 
• Cancer 
• Drugs, such as chemotherapeutic drugs, chloramphenicol, oestrogen, high dose steroids, or prostaglandins 
• Hormonal problems, such as hypothyroidism (inadequate production of thyroid hormone by the thyroid gland) or insufficient progesterone production 
• Foetal defects 
• Difficult birth (dystocia) caused by the foetus, such as abnormal position of the foetus, excessively large size of the foetus, or breed-related delivery problems (seen in bulldogs, where the large head size of the puppy compared to the size of the bitch's pelvis leads to difficulty in delivery) 
• Difficult birth (dystocia) caused by maternal (bitch) problems, such as a small pelvis, lack of strong uterine contractions, twisting or malformation of the uterus, or medical conditions leading to weakness or fatigue 

The possibility of a bitch losing puppies in the womb and the cause is a common topic at seminars on breeding and is a subject that has been affected by the development of the ultrasound scanner, as before its development and use in pregnancy diagnosis the possibility of reabsorption was treated by some with scepticism.

However a scan makes it possible to demonstrate that puppies can exist at four weeks of pregnancy but are no longer present closer to the due date.

The reabsorption of the dead foetus is a useful economy for the pregnant bitch. Where foetal death occurs in the early stages of pregnancy it is more usually resorbed. Until roughly 45 days, when bone starts to develop, the foetus is soft tissue and cartilage and it is therefore relatively easy for this to be broken down and taken back into the body stores.The bitch’s body actually absorbs the fetal and placental tissue, leaving no sign that puppies ever were present. Reabsorption can happen even after a pregnancy has been confirmed by an abdominal ultrasound. When puppies are reabsorbed, they literally just disappear. No fetuses or fetal or placental tissues are ever expelled through the birth canal. For this reason, a lot of ultrasound scanners prefer to wait until at least day 35 to confirm pregnancy.

Even after the 45th day much of the soft tissue can still be reabsorbed leaving a mummified foetus remnant, consisting chiefly of bone and hair, to be expelled during birth. It is only where pups die very late in pregnancy that abortion becomes more common. 

There are many infections that can cause foetal death, herpes virus, bacteria such as Streptococcus, E coli and Staphylococcus are all common suspects. Another possibility is for other viral diseases to increase foetal mortality simply because of the fever they produce.

However non-infectious factors exist and one example is determined by the ability of a foetus to implant itself into the cells lining the womb. Implantation yields the development of a placenta and it is this that maintains the essential supply of oxygen and nutrients and removes the waste products of foetal metabolism and so the placenta is vital to maintain a viable foetus. If a placenta is less than fully efficient then the foetus may reach a point where it dies simply because it can no longer gain sufficient energy, nutrient and oxygen to grow further.

Another example might be a lethal gene defect that limits the viability of the foetus. Therefore resorption occurs naturally and frequently in healthy bitches.

To this end, do not take any indication of litter size estimates too seriously as it is not unusual for them to be wrong.

If your bitch has been scanned and shown to have puppies, if you are in any doubt, get her re scanned again.

MISCARRIAGE

If a miscarriage occurs closer to the due date, a fetus will be aborted and you may see a vaginal discharge, contractions, or expelled placental or sometimes just fetal tissue. It is quite normal that a dog owner doesn’t realize that the bitch has miscarried, as she may eat any expelled tissue before it is discovered.

A dog who has suffered a miscarriage may be lethargic or depressed and may become dehydrated if she is refusing to eat or drink, but she may not exhibit any signs. You should however monitor for any discharge, and signs of infection.

There are many different reasons a pregnant dog may miscarry one or more of her puppies. These include: Infection, such as brucellosis, herpes, or toxoplasmosis, Low progesterone levels, Nutritional deficiencies, Fetal defects, Endocrine disorders, such as Cushing’s disease, Genetic defects, and as a response to medication

Depending on the cause of the miscarriage, certain breeds of dogs may be more susceptible than others.

Read more at: https://wagwalking.com/condition/miscarriage

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