De behoefte voor vitD bij honden wordt volgens dit artikel bepaald door de verhouding Ca en Fosfor
https://www.dsm.com/markets/anh/en_US/C ... min_D.html
Cats and dogs have low vitamin D requirements when calcium, phosphorus and the ratio of the minerals are correct. The need for vitamin D depends to a large extent on the ratio of calcium to phosphorus. As this ratio becomes either wider or narrower than the optimum, the requirement for vitamin D increases, but no amount will compensate for severe deficiencies of either calcium or phosphorus. A calcium to phosphorus ratio of 1.2:1 is suggested for dogs with no optimum ratio yet established for cats (NRC, 2006).Amounts of dietary calcium and phosphorus and the physical and chemical forms in which they are presented must be considered when determining requirements for vitamin D. High dietary calcium concentrations can precipitate phosphates as insoluble calcium phosphate. Soluble calcium salts are more readily absorbed, and oxalates tend to interfere with absorption, but some of this interference can be overcome by dietary vitamin D. Correspondingly, while the phosphorus of inorganic orthophosphate tends to be well absorbed, other factors being favorable, that of phytic acid, which is the predominant phosphorus compound of unprocessed cereal grains and oilseeds, seems to be poorly available to monogastric species. Phosphorus absorption is mostly independent of vitamin D intake, with the inefficient absorption in rickets being secondary to failure of calcium absorption, and the improvement upon vitamin administration being a result of improved calcium absorption.
En even verderop;
Michaud and Elvehjem (1944) concluded that, with a dietary calcium:phosphorus ratio of 1.2:1, daily intakes of 10 to 20 IU vitamin D per kg (4.5 to 9.1 IU per lb) of body weight were adequate, even for large breeds.The current NRC (2006) vitamin D recommendations for dogs is 13.8 µg of vitamin D3 per kg of diet (6.3 µg per lb) for all classes of dogs. The AAFCO (2007) recommendation is 500 IU per kg (227 IU per lb) of diet.
Maaarrrrrrr deze adviezen zijn m.n. gebaseerd op onderzoek naar het voorkomen van botafwijkingen bij Puppies.
Ik weet dat bij mensen met osteoporose een probleem kan ontstaan als je te lang bisfosfanaten calcium en vitD geeft dat de botten te hard worden en dat dit kan leiden tot meer gewrichtsklachten.
Deze lijkt me interessant maar ik kan er nog niet bij;
https://www.ncbi.nlm.nih.gov/pubmed/27171904
Ik quote even de samenvatting; However, there are important differences in vitamin D intake and metabolism between humans and dogs that should be accounted for. The understanding of basic vitamin D metabolism and the relationship between vitamin D intake and vitamin D status in dogs remains even more limited than current knowledge in humans
Ik denk dat de benadering van Spikkelneus zo gek nog niet is