March 24, 2025 – A new potential treatment for chronic kidney disease (CKD) in dogs, paricalcitol, a synthetic form of vitamin D, could play a pivotal role in the treatment of the disease, according to a new study by Hebrew University researchers at the Koret School of Veterinary Medicine. The new study published in the Journal of Veterinary Internal Medicine highlights the potential benefits of paricalcitol, a second-generation vitamin D analog, in addressing renal secondary hyperparathyroidism (RHPT) and proteinuria—two critical CKD complications.

CKD is a progressive condition in which a dog’s kidneys gradually stop functioning properly. While it primarily affects older dogs, younger dogs can also develop the disease. RHPT, a disorder that occurs when the kidneys fail to regulate essential minerals such as calcium and phosphorus, leads to elevated parathyroid hormone (PTH) levels. This imbalance can cause damage to bones and other organs.

The study investigated whether paricalcitol could effectively reduce RHPT and mitigate other harmful CKD effects.

The randomized, controlled cross-over clinical trial involved 13 client-owned dogs diagnosed with CKD (stages 2-4) according to the International Renal Interest Society (IRIS) guidelines. Over two 12-week study periods, dogs were administered either paricalcitol or a placebo, with a two-week washout phase in between. Throughout the study, researchers closely monitored kidney function, hormone levels, and calcium phosphate concentrations.

Key Findings:

  • Reduction in PTH Levels: A 12-week regimen of paricalcitol led to a significant decrease in PTH concentrations, marking an improvement in mineral balance management for dogs with CKD.
  • Stabilization of Proteinuria: While proteinuria worsened in dogs receiving a placebo, it remained stable in those treated with paricalcitol, suggesting potential renoprotective effects.
  • Mild Side Effects: Mild hypercalcemia was observed in approximately half of the dogs treated. However, dose adjustments successfully mitigated this effect, allowing continued treatment without study withdrawal.
  • Unexpected Increase in FGF-23: A notable rise in fibroblast growth factor-23 (FGF-23) levels was detected, raising questions about the long-term impact of paricalcitol and the need for further investigation.

These findings suggest that paricalcitol could play a pivotal role in managing CKD by reducing RHPT and potentially slowing disease progression. However, given the associated risk of hypercalcemia, veterinarians should carefully monitor calcium and adjust dosages accordingly.

While this study provides encouraging data, further long-term research is necessary to evaluate the long-term effects of paricalcitol on CKD progression, survival rates, and potential risks associated with increased FGF-23 levels.

The research paper titled “Effects of Paricalcitol on Renal Secondary Hyperparathyroidism and Proteinuria in Dogs with Chronic Kidney Disease,” published in the Journal of Veterinary Internal Medicine, can be accessed here.