Congenital hypothyroidism with goiter (Spanish water dog type) (CHG) is an inherited condition known to affect dogs. Affected dogs lack an Enzyme important for proper thyroid function and the production of thyroid hormone. Thyroid hormone is necessary for a dog’s normal development and metabolism. Around 2 weeks of age, dogs with CHG are generally noted to have reduced movement and are smaller when compared to their littermates. Enlarged thyroid glands (goiter) are often noticeable as a swelling on the neck. Affected puppies may exhibit dwarfism with short legs, large heads, and fluffy hair coats absent of guard hairs. In addition, affected dogs may develop a wide variety of neurological and neuromuscular deficits. The condition progresses to failure to thrive and death. Most symptoms can be prevented or will regress if the condition is diagnosed early and affected dogs are treated. However, the thyroid glands may continue to enlarge over time, despite treatment, and may create complications such as airway obstruction.