Genetic predisposition to obesity and increased appetite in the Labrador Retriever and the Flat-Coated Retriever, commercially described as an "adiposity" (ADI) test. A 14-bp deletion in the POMC gene alters the production of the neuropeptides β-MSH and β-endorphin, central regulators of energy balance. Carrier dogs show greater food motivation and greater weight and adiposity; the effect is additive (each mutant allele adds ~0.33 SD of weight). It does not cause clinical disease by itself, but it substantially modifies the risk of obesity.

Labrador Retriever (allele frequency ~12 %) and Flat-Coated Retriever (allele frequency ~60 % in samples examined). Absent in 38 breeds screened. There are no reliable figures by country for the European breeding population (limited data in the accessible literature).

- Greater food motivation (behavioural hyperphagia)
- Increased body weight and greater body condition (BCS)
- Increased adiposity
- Enhanced response to food reward
- No clinical signs as such: a weight-modifying effect

The association between POMC and canine obesity was described by Raffan and colleagues in 2016 (Cell Metabolism), after sequencing candidate genes of the melanocortin pathway in obese and lean Labradors. The 14-bp deletion was found with an allele frequency of 12 % in the Labrador and, among the breeds screened, also appeared only in the Flat-Coated Retriever (FCR), related through the St. John's water dog. Subsequent studies have confirmed that the variant is more frequent in Labradors selected as assistance dogs than in companion dogs, suggesting a behavioural advantage for food-reward work.

- Genotype breeding animals before mating, especially in working lines with food reward
- A carrier may be bred to a clear animal, progressively replacing the allele
- Avoid mating two carriers: 25 % homozygotes and 50 % carriers
- It is not advisable to select breeding animals solely by POMC status: obesity is multifactorial
- Inform the buyer of the status and reinforce feeding and exercise guidelines
- The test is useful, not deterministic: weight control depends mainly on management

The POMC variant is a genetic modifier of weight, not a disease. It must be distinguished from endocrine obesities (hypothyroidism, hypercortisolism) and from purely environmental obesity. In homozygous dogs, strict control of intake and exercise can maintain a normal weight. The greater food motivation is used positively in assistance dog lines.

1. Raffan E et al. 2016. A deletion in the canine POMC gene is associated with weight and appetite in obesity-prone Labrador retriever dogs. Cell Metab 23:893-900. PMID: 27157046
2. OMIA:001258-9615 - Obesity (POMC). https://omia.org/OMIA001258/9615/