Dogs eat soap for a variety of medical reasons, including malnutrition and vitamin deficiencies. Dogs who suffer from diabetes, or those with a thyroid disorder, may also eat soap. The presence of parasites is another key factor in why dogs consume soap, according to petMD.
Behavioral problems are another reason dogs may prefer soap. Because of improper training, the dog cannot distinguish between good and bad foods, and becomes curious. "Pica" is the medical term for a dog who craves non-food items, including soap. Bar soaps contain detergent, which can cause gastrointestinal irritation if ingested.
A dog who develops diarrhea or vomits because of eating soap could become dehydrated, a serious medical condition, according to the ASPCA. Ingesting soap containing essential oils, such as lavender, also has an adverse effect on the nervous system. If a large portion of a bar of soap is eaten, the dog's intestinal tract may become completely blocked. The dog may also appear weak or lethargic.
The treatment for a dog who eats soap varies. A veterinarian needs to determine the cause of the behavior and come up with a suitable treatment plan. If the behavior is caused by a medical condition, anything from drug therapy to surgery may be used. Dietary changes may also need to be adjusted. If the dog is exhibiting a behavioral issue, proper training may be required. Abdominal X-rays may need to be performed to determine if there are any abnormalities in the dog's stomach or intestines.