Sulfur is a structural macroelement in dogs and cats. It does not occur in the body on its own, but as part of sulfur amino acids (methionine, cysteine, taurine), vitamins (B1, biotin) and joint cartilage [1][2]. The proper level of sulfur amino acids is very important. Deficiencies in the diet or the use of compounds for other purposes result in protein synthesis disorders. Sulfur amino acids are precursors of many molecules, i.e. glutathione, H2S and sulfates, therefore they are involved in the methylation of DNA (methionine), the response to oxidative stress, or act as mediators influencing cell metabolism and functions. Research indicates that the appropriate amount of methionine and/or cysteine is important for the detoxification of the body [3]. Sulfur in the form of disulfide bridges that create keratin allows you to maintain strong, healthy fur, hard claws, elastic skin and synovial fluid. Dogs and cats do not absorb sulfur in its pure inorganic form - they must supply it with animal protein in the form of sulfur amino acids [1].
What it contains: Raw egg yolks, muscle meat, fish and offal (liver, hearts, kidneys), broccoli (should be given in small amounts) [2]. For therapeutic purposes on joints: MSM (methylsulfonylmethane - organic sulfur) [5].
Deficiency: Virtually non-existent on a meat diet. When fed with poor quality food (cereals), it causes matting, brittleness and loss of hair, peeling of the skin and joint degeneration, as well as deficiency of synovial fluid and loss of joint elasticity. [1][5].
Excess: Sulfuric amino acids break down into sulfuric acid, lowering the pH of the urine (acidifying it). In cats, this helps prevent struvite. This is also associated with the hypothesis that excessive urine acidification may predispose to insoluble calcium oxalate stones (oxalates) - however, this is a controversial hypothesis and the data are ambiguous: in the study by Bijsmans et al. (2021), urine acidification did not increase calcium oxalate supersaturation [5] [6]. Sulphates, which are a product of methionine breakdown, may burden the kidneys and liver of sick animals.
Sources
- National Research Council (2006). Nutrient Requirements of Dogs and Cats. National Academies Press. https://nap.nationalacademies.org/catalog/10668/nutrient-requirements-of-dogs-and-cats
- Li P, Wu G (2023). Amino acid nutrition and metabolism in domestic cats and dogs. Journal of Animal Science and Biotechnology 14:19. https://doi.org/10.1186/s40104-022-00827-8
- Tesseraud, S., Métayer-Coustard, S., Collin, A., & Seiliez, I. (2009). Role of sulfur amino acids in controlling nutrient metabolism and cell functions: Implications for nutrition. British Journal of Nutrition, 101(8), 1132–1139. https://doi.org/10.1017/S0007114508159025
- Hand MS, Thatcher CD, Remillard RL, Roudebush P, Novotny BJ (2010). Small Animal Clinical Nutrition, 5th Edition. https://www.markmorrisinstitute.org/sacn5.html
- Butawan M, Benjamin RL, Bloomer RJ (2017). Methylsulfonylmethane: Applications and Safety of a Novel Dietary Supplement. Nutrients 9(3):290. https://pmc.ncbi.nlm.nih.gov/articles/PMC5372953/
- Bijsmans ES, Quéau Y, Feugier A, Biourge VC (2021). The effect of urine acidification on calcium oxalate relative supersaturation in cats. https://pubmed.ncbi.nlm.nih.gov/33550588/