This is the finding of the latest survey of the American pet food market by the market research institute Packaged Facts. It reports that the five leading pet food manufacturers in the USA account for a market share of 80 per cent. The five companies are Nestlé Purina, Mars, Procter & Gamble (Iams and other brands), Del Monte (Natural Balance and others) and Colgate-Palmolive (Hill's and others). Nestlé Purina continues to lead the US market with a share of 36 per cent, followed by Mars with a market share of 16 per cent. The market share of the "big five" has remained relatively stable over the last few years.Sales channelsThe concentration process is especially intense with regard to pet food in the mass-market sales channels. In supermarkets, drugstores and mass merchandisers, Nestlé Purina has a market share of 49 per cent, followed by Del Monte (14 per cent) and Mars (13 per cent). Only two other companies have secured a market share of over 1 per cent in these sales channels: Procter & Gamble (7 per cent) and Ainsworth Pet Nutrition (2 per cent).The situation in the pet speciality channel is rather more fragmented. There are many players in this field, above all in the growth segment of natural, organic, holistic pet food products. In its survey, Packaged Facts names Diamond Pet Foods as the best-selling brand of dog food. This was named as the market leader in the pet speciality channel by 16 per cent of the retailers surveyed, and by as many as 18 per cent with regard to cat food. Champion Petfoods and Hill's also feature high in the rankings, and the dominant players in the mass-market sales channels are present in force in the speciality channel too.It is estimated that mass channels account for two-thirds of the sales of pet products, while the speciality trade covers roughly a third. PetSmart plays a prominent role in the speciality trade and claims 30 per cent of US pet owners as shoppers, followed by Petco at 23 per cent and independent pet stores at 11 per cent. While supermarkets lost ground among sole purchasers in the last two years, according to Packaged Facts, dropping from 35 per cent (2010) to 31 per cent (2012), pet stores have caught up from 24 per cent to 30 per cent in the sole purchaser category in the same period. Their overall percentage increased nevertheless only by 1 per cent.PetSmart and Petco on the upPackaged Facts puts the combined turnover of PetSmart and Petco at $10.2 bn for 2012. Their collective sales grew…