Here’s all the latest research on canine cystine stones, I’ve condensed into this article so you can get the best understanding of what cystine stones are, how they form, why they form and how to use nutrition to help treat them.
The great news is, you don’t only have to use a processed low quality veterinary diet.
What are cystine stones?
Canine cystinuria is caused by a malfunctioning within the tubes or transporter channels in the kidneys, (part of the urinary tract) specifically when it comes absorption of cystine and other types of amino acids.
This leads to the formation of rock-like formations of minerals that form in the urinary tract, specifically bladder.
To understand a little more about how and why they form, you need to understand the urinary tract.
What does the urinary tract do?
The urinary tract is a waste removal system. When your dog eats, the body takes nutrients from the food and they go into the blood through the digestive process. Not everything taken into the blood is needed or in fact healthy, and some of what the body has used needs removing from the body, the waste. The kidneys and urinary system help the body to eliminate the waste.
Sometimes there’s too much waste or not enough of the right stuff, or the kidneys struggle to absorb and nutrient and it causes an imbalance. This makes the urinary tract more susceptible to encountering issues, like infections or types of stones or both.
What are the symptoms of a cystine stones in dogs?
- Bloody and/or cloudy urine
- Straining or whimpering during urination
- Accidents in the house
- Needing to be let outside more frequently
- Licking around the urinary opening
What causes Cystine Stones? (Too much cystine)
- Altered intestinal transport of cystine (1)
- A high urine specific gravity suggests an increase in concentration of urolithic precursors. (1)
- Certain mutations in genes predispose dogs for cysteine stones. A classification model developed in 2013 indicates four types of genetic defects that can lead to cystine urolithiasis, from which one type is sex-linked to intact male dogs (2)
- Cystine uroliths form typically in acidic urine, however the solubility of cystine is about 250 mg/ L at 6.5pH, meaning they do dissolve in acidic urine. This solubility increases as the urine becomes more alkaline. For example, 500 mg of cystine will dissolve in a litre of urine at a pH of 7.5. But this increased pH this brings an increased risk of other health issues. (3)
If stones are present, an initial high alkaline diet with the inclusion of potassium citrate is recommended to increase the speed in which the stones dissolve (4) , however this is not recommended or necessary for the maintenance cystine stones, as long term high alkaline diets will present other issues.
Dietary management of cystine stones is designed around maintaining a urine pH 6.5 – 6.75. This is done by having a slightly more alkaline diet than is normally prescribed for a dog.
Also decreasing the urine specific gravity (promoting urine dilution) this is best achieved by feeding high-moisture diets (5). Raw food diets have a moisture content of around 70%.
There is little evidence to support dietary restriction of protein, however the restriction of methionine contain foods like broccoli, mushrooms, cauliflower, potato’s is recommended. Also the vegetables used should have a high in organic anion content (6)
You need to restrict salt intake. No more snacking on leftovers that have human levels of salt.
The inclusion of Alpha Lipoic Acid is a safe and well tolerated food supplement that has been remarkably effective in a mouse model of cystinuria. (7)
Selenium supplementation has also been shown to reduce cystine volume (8)
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- Bartges, J.W. and Callens, A.J., 2015. Urolithiasis. Veterinary Clinics: Small Animal Practice, 45(4), pp.747-768.
- Burggraaf, N.D., Westgeest, D.B. and Corbee, R.J., 2021. Analysis of 7866 feline and canine uroliths submitted between 2014 and 2020 in the Netherlands. Research in Veterinary Science, 137, pp.86-93.
- Leslie, S.W., Sajjad, H. and Nazzal, L., 2020. Cystinuria. In StatPearls [Internet]. StatPearls Publishing.
- Lulich, J.P., Berent, A.C., Adams, L.G., Westropp, J.L., Bartges, J.W. and Osborne, C.A., 2016. ACVIM small animal consensus recommendations on the treatment and prevention of uroliths in dogs and cats. Journal of veterinary internal medicine, 30(5), pp.1564-1574.
- Queau, Y., 2019. Nutritional management of urolithiasis. Veterinary Clinics: Small Animal Practice, 49(2), pp.175-186.