The Real Reasons Dogs Eat Grass, Chase Tails, and Do Other Puzzling Things

A widely cited survey of dog owners found that fewer than 25% of grass-eating dogs appeared ill before eating grass, and only around 22% vomited regularly afterward — suggesting vomiting is the exception, not the purpose. Researchers believe grass consumption may be a retained ancestral behavior, a response to minor gastrointestinal discomfort, a source of dietary fiber, or simply something dogs find appealing. Occasional grass eating in an otherwise healthy dog is generally not cause for concern. However, if your dog is eating grass compulsively or vomiting frequently, a vet visit is warranted to rule out gastrointestinal issues. Also ensure any grass your dog accesses hasn't been treated with herbicides or pesticides, which can be harmful. For a deeper look at what your dog's diet actually provides, see our guide on reading a dog food label the way a vet nutritionist would.

Veterinary behaviorists classify repetitive, hard-to-interrupt tail chasing as a compulsive disorder — similar in mechanism to obsessive-compulsive disorder in humans — particularly when it escalates over time or causes the dog visible distress. Certain breeds, including Bull Terriers, appear genetically predisposed. Physical causes such as skin irritation, flea allergy, or anal gland discomfort can also trigger tail-directed behaviors. If tail chasing is brief, easily interrupted, and happens mainly during play, it's almost certainly benign. If it occurs daily, is difficult to stop, or results in self-injury, consult a veterinarian or a board-certified veterinary behaviorist.

Wild canids circled sleeping areas to pat down grass, check for hidden threats, and position themselves relative to wind direction. Domestic dogs retain this behavior as a vestigial instinct even on cushioned beds with no grass in sight. In healthy dogs, this circling is brief and resolves once the dog settles. Prolonged, repeated circling — especially combined with disorientation, difficulty lying down, or apparent pain — is a different matter and can indicate orthopedic discomfort (especially in older dogs), vestibular disease, or neurological changes. A vet evaluation is appropriate when circling looks effortful rather than ritualistic.

A dog's anal glands — two small sacs located on either side of the anus — need to express naturally during bowel movements. When they become full, impacted, or infected, they cause significant discomfort, and dogs scoot to relieve the pressure. This is the most common cause of scooting seen by vets. Intestinal parasites such as tapeworms can also cause anal irritation and are worth ruling out, particularly if your dog has been exposed to fleas or raw prey. For a practical overview of parasite prevention, see our reference on heartworm, fleas, ticks, and intestinal parasites. Recurring scooting should always prompt a vet visit rather than a home remedy.

Mother dogs routinely consume their puppies' feces to keep the den clean — an instinct puppies sometimes carry into adulthood. Other documented drivers include nutritional deficiencies, boredom, anxiety, learned behavior from observing other dogs, and in some cases, medical conditions affecting nutrient absorption. Assigning spite or malice to the behavior misreads how dogs understand cause and effect. If a dog in your household is eating feces regularly, discuss it with your vet to rule out underlying health contributors before focusing on behavioral management strategies.