limejellyhead....most complications are short term for anal gland removal surgery(sacculectomy)-reduced anal tone due to bruising, infection on the surgery site etc so most resolve before the stitches come out....there is a low risk of incontinance long term but its actually very rare with a simple gland removal.I've never met a vet who's seen it yet post op.Its a known risk....but thankfully a rare one.Clinicians brief has a paper on it if you google.
Its a tricky operation and shouldn't be done as a first line defence....but compared to a life of painful recurrent infections or in a dog that finds expressions stressful/painful its a very good option to have.
Regards food trials it very much depends on the dog and how bad they are! Generally a food trial will depend on what the owner wants to do-homemade or commercial. one protein they have never had before-especially avoiding beef lamb chicken-usually talking crocodile kangaroo duck venison etc and one carb source again new-sweet potato potato generally if you want to go homemade is where we start and then rotate and see what works each for 8 to 12 week trials,
hills z/d if you would prefer kibble (z/d has a lab synthesised protein instead of an animal based one so low risk of reaction especially if other intolerances are severe) are my go to,
no treats no bones no flavoured drugs-wormers etc no rawhide etc just the one food source.
Main thing is to retest and challenge at the 12 week mark if there is an improvement. Most dogs can return to normal food after once the proteins they are reactive to are ruled out...or if food intolerance is ruled out as these dogs just don't improve on the exclusion diets.
Rebecca with the good hair..non seasonal would mean unlikely to be pollen related. Tricky :( might be worth doing a derm panel(injecting known likely allergens under the skin and checking degree of the reaction) to see if you can get answers. If its certain thing allergens they can make a type of immunotherapy style vaccinations to try and help. Tends to be done at the specialists though so tends to be pricey sadly.
Apoquels another option but not ideal either.... and if steriods arent helping it may not help.
Skin and allergy issues are quite possibly the most frustrating thing to get to the root of in pets :(