The most common occurrence of incontinence is in the older spayed female.
Most often this is because of a hormonal imbalance and as such is easily treated with medication:
- The traditional way is with doses of DES (estrogen). Typically, the dosage is varied until the incontinence stops, and often the dosage can be later reduced altogether.
- Another method of treatment is with phenylpropanolamine (PPA, brand name Dexatrim), which tightens all the muscles.
DES replaces the hormones, restoring the hormonal balance. PPA works independently of the hormones and as such, may introduce new problems.
Both drugs are known to cause problems and side effects, although typically, the level of dosage that DES is administered at for incontinence will not cause problems. At high dosages, DES is thought to be linked with breast cancer and obesity. Because PPA tightens all muscles in the body, it can potentially cause serious side effects, especially with the heart.
There is speculation that PPA is often prescribed at dosages too high for dogs. In humans, PPA is not advised when thyroid levels are low; this might also be a problem with dogs.
Which drug is safer for your particular spayed dog depends on the particular animal and her particular veterinary history. What’s best for one dog might be bad for another, depending on what other veterinary conditions or susceptibilities she has.