Can brother and sister Shih Tzus breed? What are the health risks?

If you have the two of them together while she is in heat, she may become pregnant. Even if they are from the same litter and are brother/sister, they will still breed if given the chance. Therefore, if you do not want them to breed, it would be best to either separate them completely while she's in heat, or have one or both of them "fixed." At 6 months old, your male dog can be neutered at any time. It would be best to wait until the female is out of heat, because the surgery is a bit more difficult to perform when the female is in heat as there is increased blood flow to the uterus. Thanks for asking Petco Pet Education Center, formerly Petcoach!

You can breed a sister and brother but is is not recommended because this is considered in-breeding and poses the risk of selecting for certain genes that can lead to increased chance of a lot of disease processes and abnormalities.

Yes a black lab can breed with a Shih Tzu but the problem is that the lab is so much bigger than your dog, meaning the puppies will be large. This leads to an increased risk of dystocia (difficulty giving birth) and likely an emergency c-section. There is nothing you can do about the owner of the lab unfortunately. I would have your dog spayed after she has her puppies so you don't have to worry about any unplanned matings in the future. Best of luck.

Yes, unfortunately a lot of people do not get their pets fixed and pets go into their heat cycles before you know it and accidents happen. Dogs do not know the concept so they mate regardless. It can lead to developmental problems and medical problems along with undesirable characteristics in a breed

If Lilly is not spayed it is possible she could become pregnant if the two dogs were alone together at any point. If you suspect a pregnancy, you can have it confirmed with an ultrasound at the vet’s office. Please feel free to ask any further questions here on the forum. Happy to help!

Yes, genetics can go awry when related animals (including humans) mate. It is not recommended that they breed, as you know, but what's done is done at this point. There is not going to be any way for you to know what their genetics are so all you can do is treat them as normally as possible and hope for the best. Sometimes they are just fine. If you see no outward abnormalities that doesn't mean there aren't some internal ones. Again, there is nothing you can do about it at this stage except be aware that some problems may arise and those problems don't always show up early. It may be years down the road before anything is noticed. Try not worry too much and just treat them like normal. Hope this helps. Best wishes!

If you want to breed them together they need to be from different parents. If they are from the same parents you will be inbreeding them and the puppies could potentially be born with potentially life threatening abnormalities.