The Miniature Pinscher has a short and smooth coat and you can only find them in black and tan or red color. No other color is acceptable. On the other hand, the Chihuahua can be in almost any color. So if you will see a dog and you will not be sure if it is a Miniature Pinscher or a Chihuahua, than you can first check out its color. If the dog is white or for example blue merle, than you can be sure, that this is not the Min Pin. Chihuahua can also have a long fluffy coat, which makes it even easier to recognize it apart.
But what if the Chihuahua is short coated with red or black and tan color? Then there are some other differences in the appearance. You can look at the ears. The Miniature Pinscher ears are set very high on the head and they can be folded in half, although very often they are erect. The Chihuahua ears are set at a 45 degree angle and there is a bigger gap between them.
Another difference are the eyes. Chihuahua eyes are much larger, more expressive and rounder. Miniature Pinscher eyes are oval shaped.
Then we have the size and body. As you probably know, the Chihuahua is the smallest of all dogs, with average height between 15-25 cm, which is 6-10 inch and weight between 1,5-3 kg, which is 4-6 pounds. Miniature Pinscher is bigger and heavier with height between 10-13 inches or 25-32 cm and weight between 8-10 pounds, which is 4-5 kg.
One last important difference is the gait. Especially the Miniature Pinscher has very unique, high stepping gait, which is easy to recognize.
What about the temperament? Both breeds might be small in size, but they definitely have big personalities. Both are active, courageous, fearless, alert and spirited. I think that the Chihuahua is lets say more companion type of a dog, while the Miniature Pinscher is a hunter. Which is a logical, since the Min Pin was bred in Germany to hunt vermin. The Chihuahua origin is unclear, but it is believed that they were developed in Mexico from Techichi dog, which was a companion dog of Toltec civilization.
This also explains, why the Chihuahua does not have a strong hunting instinct, while the Min Pin might have tendencies to follow smaller animals and they are not recommended to household with smaller pets.
Both dogs are affectionate and friendly towards their family and they make good playful partners for older children. They are too fragile to let them alone with young kids who do not know how to act properly around dogs. They can be easily injured. On the other hand, the Chihuahua and the Miniature Pinscher are not the best friends with strangers and other dogs.
Even though the Chihuahua is not a total coach potatoe, it is very easy to meet their exercise needs. Thanks to their small size it can be done with daily indoor exercise. Of course you should still také them on few good walks every day. The Miniature Pinscher activity level is something else. This is a forever on move dog which is always ready for any outdoor adventure. They love long walks or hikes. And you should be prepared for a very playful dog, afterall, their nickname is the King of Toys. So if you are an active person, than the Min Pin is just for you. If you are more laid back, or even a senior, than you should rather consider the Chihuahua.
So to sumarize it, if you are looking for a devoted companion dog, which does not have very high exercise needs and that provides tons of affection, than the Chihuahua is great for you. On the other hand if you are looking for always active, independent and spirited breed, that will always entertain you with its playful nature, than the Miniature Pinscher is the better choice.
Great fact about both dogs is, that they have relatively low grooming needs. Long haired chihuahuas needs frequent brushing, but short coated Chihuahua and Min Pin only need occasional brush to minimize the shedding and to keep the coat in top condition.
The Chihuahua lifespan is very long, up to 20 years. They can suffer from patellar luxation, heart murmur or pulmonic stenosis. The Min Pin life expectancy is little bit shorter, but still very long, it is around 15 years. The major health concerns are legg calve perther disease, cataracts and skeletal deformities.