# Comparison of Key Nutrient Content of Commercial Puppy Foods with Canine Dietary Requirements
## 1 Introduction  
The annual report from the European Pet Food Industry Federation [1] showed that pet ownership across Europe remained at a high level, with an estimated 90 million households in the European Union (46% of all households) owning at least one pet, of which 25% owned at least one dog. European pet owners spent more than EUR 20 billion on pet food, supplies and services in 2021. Sales growth in the European pet food market was largely influenced by increased awareness of ingredients, customized food products and grain-free and organic foods. The dog food industry has undergone a significant transformation. Recognition of the critical role that a balanced diet plays in promoting the health and well-being of dogs has been the catalyst for this change. Dogs are now considered as not just pets, but integral members of the household in the current environment [2]. The increased awareness of animal well-being has led to a wider variety of pet food products becoming available. The pet food market has grown dramatically in the last decades and offers a huge number of products that differ for dogs' physical form, composition of nutrients needed and physiological and pathological conditions. But the most popular are maintenance (complete) pet foods, referred to as over the counter diets (OTC). Complete and balanced pet food means pet food which, by reason of its composition, is sufficient for a daily ration [3]. The nutritional quality of commercial pet foods is of paramount importance tothe animal's health as, nowadays, these foods are the sole source of nutrients and energy for most dogs [4; 5; 6]. In European countries, recommended nutrient profiles are published by the European Pet Food Industry Federation (FEDIAF). The FEDIAF [7] is a crucial contributor to the regulatory framework for the formulation, production, labeling and safety of complete pet food products. The oversight ensures that complete products provide the minimum recommended levels (MRL) of key nutrients. The nutritional guidelines focus on the dietary needs of both adult dogs and puppies. Nutritional deficiencies in puppies are crucial and can affect their overall development. For growing dogs, the FEDIAF nutritional guidelines specify that in addition to major nutrients, five polyunsaturated fatty acids (PUFAs) should be included in their diet: alpha-linolenic acid (ALA, C18:3 \(n-3\)), linoleic acid (LA, C18:2 \(n-6\)), arachidonic acid (ARA, C20:4 \(n-6\)), docosahexaenoicenoic acid (DHA, C22:6 \(n-3\)) and eicosapentaenoic acid (EPA, C20:5 \(n-3\)). According to nutritional guidelines [7], after reaching maturity, only linoleic acid remains essential. Several health benefits, like the reduction in cardiovascular diseases and the development of visual and cognitive functions in growing puppies, are associated with \(n-3\) PUFA [8; 9; 10]. DHA is crucial during fetal and growing body development because it is a component of cell membranes, but it also contributes to brain structure [11; 12]. Its impact extends to the nature and number of receptors present in cell membranes. A study on rats suggests that a low intake of \(n-3\) fatty acids during pregnancy and lactation can lead to anxiety in these animals [13]. Long-chain (LC) \(n-3\) PUFA-EPA and DHA-appear to have a much stronger effect than the shorter chain \(n-3\) PUFA ALA. The conversion of polyunsaturated fatty acids into longer-chain fatty acids occurs through the involvement of specific enzymes. The formation of fatty acids such as EPA and DHA are achieved through desaturation, elongation and \(\beta-\)oxidation processes (Figure 1). Nonetheless, in dogs, the enzymatic activity involved in these processes is inadequate, requiring the provision of EPA and DHA fatty acids through the diet [14]. Hence, DHA and EPA fatty acids are essential fatty acids (EFAs) in the diet of growing dogs. Research studies have shown the crucial functions of DHA and EPA in numerous physiological processes in dogs [10; 17; 18; 19; 20].