Potbellied pigs were one of the first types of miniature pigs to become popular in the US pet market. First introduced in 1985, the potbellied pig has a short to medium wrinkled snout; small, erect ears; large jowls in proportion to the head; a short neck; a pronounced potbelly; a swayed back; and a straight tail with a switch at the end. As the potbellied pig gained popularity, less cautious breeding resulted in potbellied pigs being mixed with other breeds of miniature swine and even larger commercial swine. Thus, the pet pigs of today, although miniature in comparison to commercial swine bred for food production, vary much more in size and shape than did the original potbellied pigs.
The Con and Lea lines of potbellied pigs at 1 year old should not be > 46 cm at the withers (ideal height is ≤36 cm) or weigh > 43.2 kg (ideal weight is ≤ 22.7 kg). Nevertheless, miniature pet pigs commonly weigh 45.5–68.2 kg, and they can weigh more. These higher weights can be due to overfeeding and morbid obesity, but in some cases, it is due to interbreeding with other varieties of pigs.
The lifespan of a miniature pig is ~8–20 years (typically ~10–15 years). Very small or obese miniature pigs are likely have a shortened life span. For hematologic and serum biochemical reference ranges, see the Hematologic Reference Interval Hematologic Reference Ranges in Ferretsa and Serum Biochemical Reference Ranges Serum Biochemical Analysis Reference Ranges tables.
The term teacup pig has no strict definition. An educated guess of mature size is difficult without knowledge of the size of the fully grown parents and grandparents. Miniature pigs rarely reach their full size until they are 2–3 years old. Given that pigs can be bred as early as 3 months old, unscrupulous breeders can point to the small size of the mother and suggest that the offspring will grow no larger than the mother, when in fact the mother is not yet fully grown herself. Mature size is also heavily influenced by adequate nutrition. In general, when pigs are selected for smaller size, in addition to nutritional stunting many other genetic problems of pigs may be magnified, including hypoglycemia, idiopathic seizures, musculoskeletal deformities, heart disease, cleft palate, atresia ani, and reproductive problems such as dystocia and agalactia.