When taking a cortisol-lowering medication such as Vetoryl, dogs are always in danger of their cortisol levels dropping too low. This is especially true if the dose is too high or if a dog’s adrenal glands have become over suppressed by the medication. Dogs need cortisol to survive, so a significant drop in cortisol can rapidly lead to a life-threatening emergency called an Addisonian crisis. That’s why it’s important to withdraw the medication according to protocol and seek veterinary care as soon as possible if your dog exhibits any adverse effects or signs of being unwell.
According to the package insert and prescribing information for Vetoryl, a dog owner should immediately withdraw the medication and consult a veterinarian in the following scenarios:
(1) if an ACTH stim test shows that post-ACTH cortisol is below 1.45 ug/dL (40 nmol),
(2) if a Pre-Vetoryl Cortisol test shows that cortisol is below 1.5 ug/dL (41.37 nmol), or
(3) if a dog shows any signs of being unwell, such as lack of appetite, extreme lethargy, vomiting, diarrhea, collapsing, or shaking.
In these circumstances, Vetoryl should not be given to the dog again until (1) at least 7 days have gone by, (2) side effects subside and the primary Cushing’s symptoms that the dog had prior to starting Vetoryl return, and (3) an ACTH stim test shows that cortisol levels have returned to normal. Once all of this happens, it’s normally safe to restart the medication at a lower dose.
Please note, it can sometimes take much longer than 7 days for cortisol levels to rise again. If a dog doesn’t appear to be getting better or has worsening side effects after withdrawing Vetoryl, steroids and IV fluids might be needed to revive the adrenal glands.
Remember: you are your dog’s best advocate.