Hair loss in dogs, also known scientifically as alopecia, is a disease in which the dog’s hair falls out en masse. However, we have to make an important distinction between alopecia and the hair loss that occurs during, for example, the transition from puppy to hair growth.
The hair grows according to certain cycle phases, which are divided into a growth phase (anagen phase), a transition phase (catagen phase) and a resting phase (telogen phase). These different phases are regulated by growth hormones, which are produced in the thyroid gland or adrenal cortex (adrenal gland), among others.
This is one of the reasons why hormonal diseases can lead to hair loss. However, hair loss in dogs can also be the result of other conditions, which is why a division of the various causes into various categories is useful.
So we can distinguish between itch-related and non-itch-related causes:
Hair loss in dogs, the causes:
Itching can be caused by various stimuli or conditions and in most cases leads to alopecia (hair loss). That’s because the scratching and licking causes the hair to break off rather than falling out completely.
The itchy causes include allergic reactions such as ectoparasites and bacteria and fungal infections.
Accessories , such as harnesses , coats, and collars, can make your dog scratch more. These are accessories that often rub the skin and coat, making it itchy.
But the most common causes include parasites such as ear mites , fleas or hair follicle mites .
A bacterial infection, also known as pyoderma, can quickly be caused by Mirco injuries and subsequent scratching. The most common types of purulent (suppurative) bacteria are staphylococci and streptococci and the most common fungi are Malassezia and dermatophytes.
Non-itch related causes:
This category can be further divided into non-inflammatory and inflammatory causes (inflammatory means associated with inflammation).
The non-inflammatory causes include functional or structural disorders of the hair roots, which can also be caused by various hereditary disorders. An example of this is the so-called follicular dysplasia, which disrupts the formation of the hair follicle in dogs.
But also hormonal conditions such as hyperadrenocorticism (Cushing’s syndrome, adrenal hyperactivity) or hypothyroidism (thyroid hormone deficiency) often play a role. In addition, tumultuous changes such as a Sertoli cell tumor can also lead to more hair loss.
Although deep bacterial skin infections (pyoderma) and fungal infections can lead to itching, they can also occur without itching and only lead to hair loss through inflammation. Demodicosis, caused by the hair follicle mite, can also go without itching at first.
Hair Loss Symptoms in Dogs
Depending on the cause, hair loss can occur in varying degrees and in different parts of the body. Affected dogs occasionally exhibit severe itching, excessive licking and scratching more than usual. Symmetrically bald patches on either side of the body, in the neck or bridge of the nose, are usually signs of a hormonal disorder.
Hypothyroidism is one of the most common hormonal disorders and is often associated with debilitation, weight gain, and neurological and dermatological problems. Cushing’s syndrome is commonly observed in older small dogs breeds and, in addition to hair loss, is manifested in weakening, increased drinking, urination and obesity.
If there are wounds with purulent discharge on the affected skin areas, then there is a high probability that bacteria are involved. If dogs start scratching and licking more, it can in severe cases lead to pain, deep skin infections and blood poisoning with fever. Moreover, this can also lead to a lack of movement and listlessness.
To find out the underlying problem of alopecia, the vet must do an examination. It is very important to report any information about behavioral and dietary changes and the like to the vet. This allows the vet to assess whether it is a hormone disorder or an allergy. An allergy can be determined by means of an allergy test. Often they test this through the blood or with a biopsy of the skin.
Special hormone tests are performed for hormonal disorders. For example, if hyperadrenocorticism is suspected, an ACTH stimulation test is performed.
After a simple conversation, the vet will examine the dog’s bald areas. Inflammatory symptoms such as swelling and redness, or even ectoparasites such as fleas, may already be visible. Incidentally, a distinction must also be made whether the hair falls out completely or whether it only becomes duller and therefore breaks off more often.
If the cause cannot be determined from the outside, other laboratory tests may be used. For example, a Trichogramma can be used to assess the hair cycle by examining individual hairs under a microscope for certain features of the hair anatomy. Furthermore, a biopsy can be performed by removing several pieces of skin with hair using a biopsy punch.
Therapy for hair loss in dogs
The therapy focuses mainly on itch-related causes.
Cortisone preparations can be used for allergic reactions, however, to treat hypothyroidism, you must administer thyroid hormones for life. If there is damage in the adrenal gland, it can be compensated by the administration of steroids. When it comes to a bacterial infection, the emphasis is on regular cleaning of the wound using disinfectant solutions and anti-inflammatory shampoos.
If therapy does not improve, a resistance test should be performed. The results of the research ensure targeted and effective antibiotics and this can prevent antibiotic resistance. In the case of tumors, treatment depends on the type of cell. Depending on the various factors, radiation, chemotherapy or surgery may lead to success.
As with therapy, the prognosis of hair loss depends on the cause and severity of the situation. Whether the next hair cycle can proceed normally depends on the extent of the hair follicle damage and of course the therapeutic success.
Prevention of alopecia
Collars or Spot Ons can be used against itch-related hair loss. These are equipped with a pyrethroid to prevent fleas, but also ticks and mites in dogs. In addition, regular coat care ensures healthy skin. There are hardly any options for tumors and hormone diseases, but in some cases, the risk can be reduced by a conscious diet and exercise!