About how big will the puppy be?

So my fiance got a puppy from the shelter. The vet says that she's about 4 months old. We think she's a Rottweiler/German Shepherd mix, but recently we've noticed a bit of Australian Cattle Dog. Although, she's a shelter dog, so we can never be sure. At about 4 months old, she's currently 20 lbs and on the lean side. About how many pounds do you think she might be as an adult?

40-50 its not going to be a big dog by the way you descibe it.

Awhile back my family had a Rottie/GSD mix that grew to be 80lbs although with mixed breeds you can never really tell which breed the dog will favor. Your vet can usually help with predicting the weight of your dog as she gets older.x Kharis

It really depends on how much he grows per month. For instance if he gains a massive 10+ pounds every month for the next few months, then you know you are going to have a huge dog. If he gains like 5 pounds per month, then you will have a medium sized dog, most likely. Don't go based on how much weight he gains this month because he is probably underweight from living at a shelter in a highly stressful environment. Now that he is in a stable home and being fed enough food he will probably put on quite a few pounds over the next few weeks. I adopted a 6 month old lab mix three months ago. He came to me at 32lbs. Three months later he is about 50lbs. That's about 6 pounds give or take per month. I doubt he will grow past 60-65lbs based on his slowed rate of growth in the past month.

Right now, your puppy's age/weight (4 months and 20 lbs.) is running as follows:- Approximately slightly less than 1/2 of a full breed Rott. (43 to 50 lbs @ 4 mos.) with average weight at 1 year of 90 to 105 lbs.- Approximately 1/2 of a full breed GSD (36 to 41 lbs @ 4 mos.) with average weight at 1 year of 65 to 76 lbs.- Approximately 1/2 for a full breed Australian Cattle Dog at 1 year (35 to 45 lbs.)Based on the above, my guess would be that if you have a Rott/GSD mix only, be prepared for 70 to 85 lbs. If she also turns out to have some ACD in her, she will likely be less than that -- maybe 65 to 75 lbs.She's still got quite awhile till she fills out completely and reaches her full stature.Enjoy your new family member!