Q & A: Desmopressin No Longer Controlling Diabetes Insipidus?

I have a female-spayed 14-year-old, mixed-breed dog in which I diagnosed diabetes insipidus (DI) 4 years ago. The diagnosis of DI was based on signs of intense polyuria and polydipsia (PU/PD) and her response to desmopressin (DDAVP). She has been on desmopressin drops (0.1mg/ml), a the dosage of 3 drops in each eye twice daily. She had been doing very well on the drops, but the owners have noticed, especially in the evenings, frequent urination and increased water drinking once again. 

A repeat complete blood count, serum chemistry panel, and complete urinalysis with culture are all normal. I am planning to have the owners increase the dose to 4 drops in each eye twice daily.

Can dogs with DI become resistance to the desmopressin drops? Any other suggestions?

My Response:

Are you using brand name, generic, or compounded desmopressin product? Any recent change in desmopressin formulation or brand?

Other than reevaluating for other problems such a Cushing's disease (much more common in a 14-year-old dog than DI), I don't see why the signs would worsen on the same desmopressin product.

I've found that desmopressin administered by subcutaneous injection to be most effective route of administration. You might want to try that, starting at a dose of 2 to 4 ug BID, and evaluate the effect. If no improvement, then I'd definitely work up the dog for another cause of polyuria and polydipsia.

For more information, see my previous blog posts that discuss workup of polyuria and polydipsia and treatment of DI with desmopressin.