Animal Skin and Allergy Clinic Blog
Too Much of a Good Thing: Hormone and Immune-Mediated Skin Problems in Pets
Anyone with a basic understanding of physiology knows that the immune and endocrine (hormone) systems are essential for normal body function. These two systems are carefully regulated by the body, and if not regulated properly, skin or internal disease can develop and lead to trouble.
At the Animal Skin and Allergy Clinic, hormone and immune-mediated skin problems in pets make up a reasonable part of our practice. Luckily, if these issues plague your pet, we know just what to do.
Out of Control Hormones
The endocrine system is a collection of various glands within the body that are responsible for the controlled secretion of hormones. Major players include the pituitary gland, adrenal glands, thyroid gland, testicles, and ovaries. Hormones produced by these glands affect the entire body and can even affect the function of each other. For example, an abnormal secretion by the pituitary gland can affect the skin’s immune function which can result in a suppression of the skin immunity, with subsequent development of skin infections.
An endocrine gland may secrete too much of its hormone, resulting in a “hyper” condition; or too little, resulting in a “hypo” condition.
Hormones are intimately involved in hair follicle regulation, and many hormonal skin problems result in thinning hair. Typically, the hair loss is symmetrical (equal amounts on both sides) and not itchy. Hormonal skin conditions may also cause thinning or thickening of the skin. These hormones can come from inside the body due to disease or from outside in the form of medical treatments.
Some of the more common hormone-related skin conditions that we see in pets include:
- Hypothyroidism (typically dogs)
- Hypoadrenocorticism (low cortisone), more commonly known as Addison’s Disease
- Hyperadrenocorticism (excess cortisone), more commonly known as Cushing’s syndrome
- Testicular tumors (often result in increased estrogen production)
- Sex hormone imbalance (estrogen, progesterone, testosterone, and combinations of these)
- Seasonal flank alopecia (melatonin imbalance)
- External hormone exposure (iatrogentic, i.e. introduced by man)
Skin conditions caused by external hormones are usually due to the overuse of cortico steriods such as prednisone, triamcinolone, dexamethasone, or betamethasone. These steroids, if used improperly, can inhibit hair growth and skin growth, cause skin thinning and development of blackheads, and inhibit skin immune function leading to skin infections.
For instance, if you were prescribed a topical spray to treat your dog’s skin disease, look closely at the ingredients. As a rule, any ingredient that ends with the letters “one,” which are steroids, are bad for the skin if used improperly. If there are any steroids in the spray do not use it for longer than 7 days continuously when treating for simple inflammatory sores.
However, if the sores are caused by an underlying infection these sprays should not be used at all. The inflammation caused by the infection is actually the body’s means of fighting the infection. It may seem like the infection will clear after using a topical steroid, but steroids are actually just shutting down the body’s natural infection fighting abilities, not treating the infection itself. Once the spray is discontinued the skin will flare right back up. Topical or systemic (oral or injectable) steroid use when the skin is infected is contraindicated. If you are being prescribed steroids for skin infections, you might want to seek a referral to a dermatologist or find another veterinarian.
On a related note, a new problem seen today are veterinarians who in the past covered up skin infections by prescribing steroids are now using new allergy drugs to treat skin infections. These drugs, Apoquel® and Cytopoint®, are only for allergy and are not indicated for skin infections. If your dog is being prescribed these medications for their skin infections you should seek a referral to a dermatologist as soon as possible.
The Skin and the Immune System
Clearly, the immune system is a good thing. We rely on it to protect us from disease and other foreign invaders. Sometimes, however, the immune system can be misdirected to attack the body it is supposed to protect. This is called an autoimmune disease. We don’t fully understand all the causes for this, but it does appear that there are some genetic and environmental factors at play.
The main autoimmune skin diseases of pets is a condition called pemphigus. Pemphigus is a condition that results in the blistering of the skin, most commonly on the nose, ears, eyelids, paw pads, armpits, and groin. In rare cases, it can affect the junctions between mucous membranes and skin (lips, eyes vulva, and anus).
There are several forms of pemphigus, including:
- Pemphigus Foliaceus: Most common, which results in crusts, pustules, and ulcers around the eyes, ears, paw pads, groin, and bridge of the nose)
- Pemphigus Erythematosus: red, crusting, depigmentation, and scales that form on the bridge of the nose
- Paraneoplastic Pemphigus: caused by and internal cancer that leads to skin lesions
- Pemphigus Vulgaris: formation of fluid-filled blisters in the mouth, eyelids, lips, nose, or genitals
Bullous pemphigoid is another immune-mediated skin condition that can appear similarly to pemphigus. It results in the formation of ulcers, or fluid-filled vesicles in the mouth, at mucocutaneous junctions, and in the the groin area. Most cases that look like they might be bullous pemphigoid are actually drug-induced immune mediated lesions.
Pets can also suffer from lupus. Systemic lupus erythematosus (SLE) can cause fever, shifting-leg lameness, and lowered cell counts. Systemic lupus is primarily an internal disease and rarely affects the skin. There are two skin variants of lupus that form , lesions on the nasal planum or in the nail beds.
- Discoid lupus erythematosus (DLE): limited to the nose and does not progress to the internal disease. It affects the very outer non-haired end of the nose. This is a less serious condition than pemphigus, but does result in severe inflammation of the end of the nose which, if not treated, can result in complete erosion and loss of the end of the nose. UV radiation plays a contributory role in this disease so, in dogs with this disease, sun screen and sun avoidance is important in control of the disease.
- Symmetric lupoid onychodystrophy: Affects the claws. This condition typically is seen as a shedding of a few to all of the claws. Also, as with the nasal form, it does not progress into the internal form of systemic lupus.
Other immune- mediated diseases are drug induced. These most often look like an autoimmune disease, but are caused by drugs or vaccines.
Who to See: Specialist vs. Generalist
Skin conditions can be tricky to diagnose but are usually manageable once the cause is determined. Dermatologists are trained to recognize these skin diseases and can get to the resolution of the problem sooner. With a dermatologist, you will find there is less testing and time needed, which results in less time for the pet to endure the effects of the disease. If your pet has been having repeated “bouts” of a skin condition, or is having a chronic ongoing problem, and there is seemingly no definitive answer you should seek a referral to a dermatologist.
Immune-related skin conditions can be difficult to differentiate from one another and from many other skin diseases that look alike. Because of this, examination, and diagnostics for these types of skin disease, are best if done by a dermatologist. Dermatologists are often able to make a diagnosis by history and physical examinations in some cases further diagnostics may be needed. If additional diagnostics are needed you will find more definitive answers and quicker answers if all of this is done by a dermatologist. Taking your pet to a dermatologist instead of a general veterinarian may appear to be more expensive. However, since the dermatologist will run fewer diagnostics, and there will be fewer examinations, it will result in faster results and less cost overall.
Taming Hormone and Immune-Mediated Skin Problems in Pets
Pet skin diseases of any type can be both frustrating and challenging to diagnose and manage. In particular, hormone and immune-mediated skin problems in pets require some additional expertise to get your pet feeling their best quickly. Thankfully, we are here at Animal Skin and Allergy Clinic to do just that.
No matter what the skin condition, there are many instances where blood tests, biopsies, and specific dermatologic diagnostics are needed to get to the bottom of the issue. Our veterinary dermatologists have the expertise to help your pet heal as fast as possible. Most conditions can be managed with veterinary medications, although prognosis varies.
No matter the diagnosis, you can rest assured that your pet is in good hands! Please call us with questions or to schedule an appointment.