It may not be all about the diet
https://www.merckvetmanual.com/dog-owners/digestive-disorders-of-dogs/disorders-of-the-rectum-and-anus-in-dogs
Your veterinarian can often squeeze out impacted anal sacs by hand. If the material in the sacs is too hard or dry, the veterinarian may inject a softening agent into the sac. If infection is present, antibiotics might be prescribed. Your veterinarian might recommend applying hot compresses if an abscess (infection) is present. Supplemental fiber may be recommended to increase fecal bulk, which facilitates anal sac compression and emptying. If treatment is ineffective, the condition keeps coming back, or a tumor is present, the anal sac can be surgically removed. A common complication from this surgery is fecal incontinence.
Anal sacs may become clogged (impacted), infected, abscessed, or cancerous. There are several common causes of clogged anal sacs, including failure of the sacs to be squeezed out during defecation, poor muscle tone in obese dogs, and excessive secretion of the gland. When the clogged gland contents are not periodically squeezed out, this can make the glands susceptible to bacterial overgrowth, infection, and inflammation.
