1. Identify the signalment
Signalment is only slightly helpful in separating an allergic patient from one with an endocrinopathy. In general, patients
presenting with an endocrinopathy are older than the typical allergic patient. Purebred and several breeds of dogs are more
likely than others to develop both allergies and endocrinopathies.
Although any animal may be affected, breeds more likely to develop hypothyroidism include golden retrievers, Doberman pinschers,
dachshunds, Irish setters, Labrador retrievers, miniature schnauzers, Great Danes, poodles, cocker spaniels, shelties and
Dogs most prone to hyperadrenocorticism include poodles, dachshunds, German shepherds, beagles, Boston terriers and other
2. Determine the chief complaint
In general, a dog with an endocrinopathy will be nonpruritic except when the skin is infected. Metabolic changes are common,
especially in hypothyroidism, and owners may complain that the pet has decreased energy, increased weakness or acts old. Body
shape and conformation may change with weight gain, fat deposition and the development of a distended abdomen. The owner will
often mistakenly attribute these changes to normal aging.
3. Get the medical history
The medical team should focus on key elements that may suggest a more severe systemic disease. Some key questions to ask the
How is the pet's energy level? Are you aware of changes such as lethargy or dull or sluggish behavior by the pet? These changes can be subtle and progressive, and the owner may not volunteer this information until asked specifically.
Is there an overall problem with or change in the animal's weight? Both hypothyroidism and hyperadrenocorticism can cause weight gain. Hypothyroid animals have a lower metabolic rate, so weight
may increase even without an increase in calorie intake. Cushingoid patients may have a pendulous abdomen that can make the
pet appear fat.
Has the animal's coat changed? Hypothyroid dogs are incorrectly assumed to shed excessively. In fact most hairs remain in the telogen phase and, in essence,
stop growing. Over time, the coat can appear dull, bleached out and worn, especially at sites of friction created while the
animal lies down, sits or wears a collar or harness. The alopecia may be more dramatic or complete on the trunk with hyperadrenocorticism.
Does the pet have a history of ear infections? Hypothyroid animals can have chronic sustained ear infections, secondary to alterations in keratinization, sebum formation
and cutaneous immunity. Remember, though, that most patients with otitis are allergic and not suffering from an endocrinopathy.
Has there been an increase in water consumption (polydipsia) or urination (polyuria)? With hyperadrenocorticism, there can be a sudden or gradual increase in both.
4. Perform a dermatologic evaluation
Most patients with an endocrinopathy won't show signs of inflammation or erythema of the skin; instead, it may appear cool,
especially with hypothyroidism. The trunk is often the site most notably affected, with a symmetrical alopecia of the dorsal
trunk or tail (Photo 3A). However, large dogs are known to have alopecia develop at points of wear, including their extremities.
Common notable skin changes can include:
Photo 3A: A patient with loss of hair over its tail ("rat tail"), suggestive of an endocrinopathy.
• Symmetrical truncal and tail hair loss, with normal coat on the head and distal legs
• Retention of the fuzzy "puppy coat"
• Hyperpigmentation (Photo 3B)
Photo 3B: A patient with hyperpigmentation of the ventrum, suggestive of an endocrinopathy.
• Excessive shedding or easily epilated hair (Photo 3C)
Photo 3C: A patient with increased regions of hair loss and skin thickening (lichenification), suggestive of an endocrinopathy.
• Cool, thin skin that bruises easily
• Myxedema that affects facial skin folds resulting in a "tragic" expression (Photos 3D and 3E),
Photo 3D and 3E: Patients with excessive thickening of the facial folds ("tragic" expression), suggestive of an endocrinopathy.
• Recurrent or chronic skin infection (e.g., bacterial, Demodex species or dermatophyte)
• Variable coat color changes—notably, bleaching due to slower hair cycle and slower turnover of hair
• Nonpruritic skin (unless there's a secondary infection evident)
• Alopecia on the extremities or distal limbs of larger dogs, especially at the sites of wear or friction
• Thin or atrophic skin
• Comedone formation
• Hard erythematous papules and plaques from calcinosis cutis
• Circumanal gland hyperplasia.