As you may be aware, ACTH stimulation testing is the way that cortisol levels are typically monitored in dogs being medically treated for Cushing’s disease. What you may not know is that there’s an alternative testing method that can potentially save you hundreds of dollars. This method is called Pre-Vetoryl Cortisol (PVC) testing and applies to dogs being treated with either Vetoryl or compounded trilostane.
As the name implies, PVC testing involves collecting a blood sample at a dog's usual Vetoryl dosing time, but medication is withheld until after the test. This method was developed by Professor Ian Ramsey at the University of Glasgow and announced by Dechra, the manufacturer of Vetoryl, in 2018. According to Dechra, “Pre-Vetoryl Cortisol monitoring is a reliable alternative to traditional ACTH stimulation tests for several reasons. It predicts clinical signs better, gives more consistent results, is less expensive and is easier to perform.”
Veterinarians in the UK and European Union have widely adopted the PVC test. Unfortunately, many vets in the United States haven’t even been informed of it. But there's no reason that they can't adopt the new method, as long as they take time to thoroughly review the protocol so that testing can be done correctly.
If your vet isn't aware of PVC testing, it’s worth having a discussion to determine if they’re open to it. It can save a lot of money and time, since it only requires one blood draw and a shorter office visit than the ACTH stim test. Feel free to review the references below and provide them to your vet.
References
Pre-Vetoryl Cortisol protocol (ug/dL)
Pre-Pill Cortisol for Dogs on Vetoryl, by the University of Glasgow
Dechra launches improved monitoring method for Cushingoid dogs (press release)
Pre-trilostane and three-hour post-trilostane cortisol to monitor trilostane therapy in dogs, Vet Rec. 2016 Dec 10
Trilostane Dosing and Monitoring in Dogs, by Douglas Brum, DVM