Hair Loss Related to Systemic Disease in Dogs

Systemic disease is a term that indicates a disease that is affecting multiple systems within the body of the patient. This can include autoimmune disorders, bacterial and fungal infections, and hormonal imbalances. There are many systemic diseases that result in the loss of hair, either through damage to the skin or through the weakening of the hair or follicle’s structure. In order to remedy the loss of hair, the underlying condition must first be treated.

Systemic diseases and disorders affect multiple systems in the dog’s body. In some cases, these systemic diseases can affect the skin, causing hair loss to develop.

Because the term “systemic disease” can refer to any disease that attacks more than one body system, the symptoms of the disease itself can vary greatly. Depending on the underlying condition, hair loss may be accompanied by other dermal symptoms such as swelling, itching, welts, rashes, and ulcers. In a few cases, the lack of fur is the only symptom spotted on the skin. 

• Lack of fur
• Swelling
• Itching
• Welts
• Rashes
• Ulcers

Types

Several types of illness can be categorized as systemic, such as: 

• Autoimmune Disorders - Autoimmune disorders are usually the first thing that many people think of when referring to a systemic disease, as most autoimmune disorders affect many body systems at one time; systemic lupus is a systemic illness that is known to frequently cause bald patches due to dermatitis
• Fungal and Bacterial Infections - Fungal infections that enter through a single access point and disseminate throughout the body are known as systemic mycoses, and when bacteria spreads to multiple systems, it is known as sepsis; both conditions can prove difficult to eradicate and many fungal infections cause lesions, plaques, and rashes that prevent the growth of hair
• Hormonal Disease - Hormonal diseases like Cushing’s disease and diabetes are often characterized by the loss of hair

The type of hair loss caused by the disorder will depend on which type of illness is affecting the dog. Some illnesses cause hair loss by weakening the structure of the hair due to chemical and hormonal changes in the dog, while others may be triggered by a deformation or infection of the follicle itself. The loss of hair is most commonly due to the condition of the skin as persistent swelling, itching and scratching can break off fur and temporarily damage the underlying follicle.

As there are many conditions that can affect the skin, there are many techniques and tests that may be utilized to determine the origin of the hair loss. Your veterinarian will generally start with a physical examination, noting the condition of the skin and of the fur. Hairs from the edge of the area of the hair loss may be examined microscopically to determine if there is any thinning or weakness in the structure of the hair itself. 

The examining vet will also typically examine a skin sample from the affected area under the microscope, a technique known as cutaneous cytology; by doing this, they may get visual confirmation of fungal or bacterial infestation that may be present on the surface of the skin. Standard diagnostic tests such as a urinalysis, a biochemical profile and a complete blood count will be evaluated to check the hormonal balance and to check for infections or signs of an overactive immune system. Ultrasounds and x-ray technology may be employed to determine the state of the internal organs and help clarify which underlying systemic condition may be causing the patient’s loss of hair.

Treatment of this condition is dependent on treating the underlying systemic disorder. This can include medications such as antibiotics or antifungals to defeat bacterial or fungal infections, injected or oral corticosteroids or anti-inflammatories to reduce swelling and inflammation, or medications to adjust the patient’s hormones, like insulin injections for dogs with diabetes. Dogs with Cushing’s disorder may even require surgery to remove the tumor before the symptoms, including the loss of hair, have a chance to be reversed. 

Many of these treatments take days or weeks before the underlying illness is eradicated if the loss of hair is accompanied by other dermal symptoms, such as swollen, crusty, painful, or ulcerated skin. These symptoms may be treated with topical medications, but it is important to follow your veterinarian’s instructions on all drugs, whether topical or oral, in order to be certain that medications do not interfere with one another, and that no overdoses occur due to treating with different forms of similar drugs.

The prognosis for dogs with hair loss due to systemic diseases depends on the ability to treat the underlying disorder. Some disorders may be managed in a relatively short amount of time, but others can take weeks or months to be fully eliminated. Additional support measures will need to be utilized until the fur is able to grow back as the bare skin can be particularly susceptible to environmental hazards. In order to properly care for the bare skin, the animal should be bathed and moisturized regularly, and sunscreen should be used whenever the dog is exposed to ultraviolet rays.