Als ik erop zoek, kunnen honden vit D2 opnemen en omzetten.
Wellicht zit de D2 in een gistextract?
https://www.ncbi.nlm.nih.gov/pmc/articl ... s-10-00496
En
https://avmajournals.avma.org/view/jour ... 1.1259.xml
Zoals ik dit artikel scan/lees zijn de aanbevolen waardes per 1000 kcal niet zozeer gebaseerd op wat optimaal is maar meer op wat er Max in brok mag zitten om overdosering te voorkomen….
Quote:
According to the Association of American Feed Control Officials, the minimum vitamin D recommendation for canine adult maintenance is to provide 125 U/1,000 kcal. The Association of American Feed Control Officials recommends that the maximum amount allowed in commercial dog foods is 750 U/kcal.55 For example, a 20-kg (44-lb) dog eating a maintenance energy requirement (1.6 × resting energy requirement) of approximately 1,000 kcal/d could theoretically ingest a range of 125 to 750 U of cholecalciferol/d. On the basis of the 2010 adjustment to adequate intake for humans, it is possible that optimal dietary intake in canine and feline subjects might need adjustment in the future. However, one cannot necessarily predict a dog's serum 25(OH)D concentration on the basis of its cholecalciferol intake.’
En over vitD en kanker:
Neoplasia
Decreased 25(OH)D concentrations have been linked to increased risk of numerous neoplasms in humans, and 1,25(OH)2D has been found to have antineoplastic activity.77,78 Concentrations of circulating vitamin D metabolites have been measured in dogs with various neoplasms. Serum 25(OH)D concentrations are significantly lower for various neoplastic conditions, including dogs with neoplasia and hemoabdomen,36 cutaneous mast cell tumor,44 and lymphoma.40
Serum 25(OH)D concentrations in dogs and cats prior to the development of neoplasia have not been evaluated. Thus, it is not clear whether dogs develop hypovitaminosis D secondary to neoplasia or whether hypovitaminosis D is actually a risk factor for development of cancer. Dogs with neoplasia are often ill; this puts them at risk of developing hypovitaminosis D as a result of a reduced appetite, which leads to reduced cholecalciferol intake, and potentially from decreased intestinal absorption of cholecalciferol.
Serum 1,25(OH)2D concentrations have been measured in populations of dogs with lymphoma, both with and without hypercalcemia, with wide differences in findings.37,38,40 In the earliest study,37 both hypercalcemic and normocalcemic dogs had significantly lower 1,25(OH)2D concentrations than did healthy control dogs. Most of the hypercalcemic dogs had 1,25(OH)2D concentrations lower than the limit of detection, which is an appropriate response in the face of hypercalcemia.37 In a later study,38 hypercalcemic dogs with lymphoma had a higher mean 1,25(OH)2D concentration than did control dogs, but the normocalcemic dogs with lymphoma had a lower mean 1,25(OH)2D concentration than did control dogs, although these results were not compared with a statistical assessment. Mean 1,25(OH)2D concentrations were within reference limits for both hypercalcemic and normocalcemic dogs with lymphoma.38 Finally, in the most recent study,40 median 1,25(OH)2D concentration was significantly lower in dogs with lymphoma (110.0 pmol/L) than in control dogs (157.5 pmol/L); however, there was a wide range of concentrations that extended below the low end and above the high end of the reference range.40 The 1,25(OH)2D concentrations in dogs with anal sac adenocarcinoma (with both hypercalcemia and normocalcemia) were not significantly different from 1,25(OH)2D concentrations in control dogs.38,58
From an antineoplastic standpoint, calcitriol can have in vitro activity against osteosarcoma,79 squamous cell carcinoma,80 prostatic epithelial,81 anal sac adenocarcinoma,82 mammary gland cancer,83 and mast cell tumor84 canine cell lines.79–84 One in vivo study83 revealed a synergistic effect of administration of calcitriol with cisplatin against various tumors (eg, osteosarcoma and chondrosarcoma) in dogs. Investigators of another in vivo study84 found that calcitriol treatment could induce remission of mast cell tumors; however, the trial was discontinued because of the high rate of toxic events (ie, hypercalcemia and azotemia) observed.
Kortom, lijkt alsof het helemaal nog niet zo duidelijk is allemaal ?