Potassium citrate is a dietary supplement used in humans as well as cats and dog diets to prevent the development of urinary stones. It breaks down accumulations of calcium in the organs. There have been no demonstrated serious side effects for use of potassium citrate to prevent calcium stone formation or acidosis in dogs with kidney disease. However there are a few less-serious ones. Potassium citrate is available over the counter at pet supply shops but should be used under veterinary supervision.
According to the label information for generic, over-the-counter potassium citrate supplements (as listed on the Vet Depot website), there have been no documented side effects of potassium citrate use in dogs. This does not necessarily mean that there are none, just that they are not common enough to be documented. It is important to discuss this and any supplement with your veterinarian before beginning a regimen as well as to observe your dog's behaviours after he starts a new medication.
Potassium citrate can cause the development of hyperkalemia in animals, although this has been rare. According to the Cornell University Veterinary website, hyperkalemia is high blood potassium, which may cause death by cardiac arrest in sever cases. Symptoms include muscle weakness, vomiting, diarrhoea and heart arrhythmia. Hyperkalemia also can be asymptomatic, so it is important to communicate with your vet about proper dosage before giving your pet this supplement.
Potassium citrate should never be given to animals with hyperkalemia, kidney failure, Addison's disease or dehydration as it may cause death. Use under veterinary supervision if your pet takes ACE inhibitors such as enalapril, NSAIDs such as carprophen, diuretics such as furosemide or aspirin for other medical conditions.