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The vast majority of dogs that see their veterinarians for a hair loss issues do not have Alopecia X. Their problems are much simpler - or at least more straightforward. Things like fleas, hot spots, ringworm, allergies, mange and anxiety; or more serious problems like Cushing’s disease and hypothyroidism. Even testicular tumors can cause dogs to loose hair. (ref) I discuss all those problems in other articles on this website.
The key points in all of the not-so-simple hair loss causes is that hair loss is more or less identical (symmetrical) on both sides of your dog’s body and that the skin there is not itchy or inflamed. That tells your veterinarian that the source of the problem is within your pet’s body – not within its skin.
Alopecia X is one of those internally generated problems. Alopecia just means thinning or no hair. X stands for cause unknown. The problem has also been called “Post-clipping Alopecia”, “Growth Hormone Responsive Alopecia”, “Adult Onset Growth Hormone Deficiency”, “Castration Responsive Alopecia”, “Hair Cycle Arrest”. It shares some similarities with what is sometimes called "Atypical Cushing's Disease" but is not the same thing. (ref) Pomeranian breeders have referred to Alopecia X as “Black Skin Disease”, malamute breeders as “Cold Funk” and Husky breeders as “Follicular Dysplasia”. Some breeders just say that their dogs have "blown their coats". Post-clipping alopecia sometimes occurs when a dog's fur is shaved close to the skin. It may not grow back for very long periods. Each term reflects a little snippet of information we know about the condition, Alopecia X.
Although most veterinary dermatologists now call it Alopecia X, I believe that it is actually many diseases – each reflecting a defect at one point in the very complex command process that occurs whenever a hair on your dog begins or stops growing. Every year we learn a little bit more about how very complex the hair growth cycle really is. Most of that research progress is driven by human male vanity. Men do not relish growing bald.
Alopecia X can affect either male or female dogs. Both neutered and un-neutered dogs develop it - male dogs it a bit more frequently than females. The hair loss can begin before the pet reaches one year of age or much later in life. Occasionally, dogs with Alopecia X will regrow their hair with no treatment. That can occur suddenly – or up to several years after the problem began. Some dogs temporarily get better on their own; only to relapse at a later date.
Alopecia X affects breeds of dogs with very thick hair coats – those are the breeds adapted to living in very cold climates. So breeds referred to as “Nordic” or “Arctic” dogs all have a tendency toward this hair loss problem. I believe that all of these breeds originate from, or share genetics with, the primordial spitz dogs of Germany. (ref) Even little Pomeranians, Asian breeds like chow chows and Akitas, and Siberian breeds such as Samoyeds share a great deal of the spitz's genetics that appears to underlie Alopecia X. That genetics favors a hair coat that has a soft dense undercoat of hair and a striking long topcoat of coarser guard hairs. These 2 layers blend into each other. Another genetic trait that favors the Alopecia X problem is a tendency to have two heavy sheds a year when exposed to natural sunlight. That is an important genetic survival trait shared by all animals that inhabit the arctic (of those 8 species, only polar bears don't have a complete fall hair coat molt).
Toy and miniature poodles are said to occasionally develop Alopecia X as well. When they do, I believe that the genetic and hormonal mechanisms underlying their hair loss problem are different than those underlying the problem when it occurs in the Nordic breeds.
Veterinarians have known for a long time that each of your dog’s hair follicles cycle through active and quiescent (quiet) phases. The hair's growing phase is called anagen. Anagen is the phase where the hair within the individual hair follicle is continuously being formed and moves upward through the follicle. The hairs themselves form under the influence of stem cells that are always present deep within the hair follicles. (ref) In wolves, the wild predecessors or dogs, that active hair follicle stage lasts 8-10 months. Once its ends, their hair follicles enter a resting stage culminating in loss of their entire hair coat between April and May. In wolves and foxes, it is called their shed or molt (moult). The process is similar in arctic fox except that they have a second molt at the end of summer in order to turn white to match the snow. One of Nature's great miracles.
Hair growth in all canines, wild and domestic, is under the control of the pineal gland, a small endocrine gland at the base of the dog's brain that is linked to special light receptors in its eyes (retinas). The pineal gland senses the length of daylight in each 24-hour day (the photoperiod). It also senses the time of day. In response to the time of day, the pineal gland varies its pulsed nighttime secretion of the hormone, melatonin. In response to seasonal changes in the length of days, the pineal also varies its pulsed night time secretions of melatonin. (ref) The amount of melatonin the pineal gland produces is inversely proportional to day length. (ref)
The melatonin produced acts as a cue or signal to your dog’s pituitary gland to produce or cease producing a variety of sex hormones (prolactin, FSH, LH, testosterone, estrogen, and progesterone). These hormone fluctuations have been best confirmed in the fox fur industry (ref1, ref2) It is believed that in addition to beginning and ending breeding cycles, it is changes in the levels of those hormones that turn on and turn off hair growth. The mechanisms by which they do that remain unknown. Human studies indicate that prolactin can act directly on hair follicle stem cells to stimulates hair growth. (ref) Other than prolactin, how and when the rest of these hormones might act directly on the hair follicles of your dog also remains unknown.
Also for reasons unknown, arctic dog breeds retain more pineal gland sensitivity to the length of daylight than other dog breeds do. We know that this complex interaction of light and sex hormone fluctuations breaks down in dogs with Alopecia X. Once their anagen phase has ended, the dog’s hair follicle stem cells never receive the proper cues to resume their next anagen (hair production) cycle. Not only do those cues have to be of the correct intensity. They also have to be in the correct sequence. To further complicate matters, the proper clue or code sequence to resume hair production varies on different areas of the dog's body. That is why your dog's head never looses its hair. That is a bit similar to why men grow bald on the top of their head but not on the sides. In 2017, a Swiss study found that a group of genes that regulate hair follicle stem cell activity behaved differently in Pomeranians with alopecia X than in those that did not suffer from the problem. So perhaps we are making progress. Read that study here: (ref)
Dogs with Alopecia X develop hair loss symptoms that are gradual and symmetrical (the same on both sides of the body). The problem is usually worse over the torso and the rear sides of the back legs. Hair on the head, neck and front legs is usually spared and the soft undercoat of hair these dogs have is sometimes unaffected as well. It is common for the skin of these pets to turn intensely black. The black pigment is melanin – a compound also produced under the influence of melatonin. (ref)
The first sign can be an abnormal heavy shedding episode without the presence of new hair recruits peeking out. In other dogs, shedding may just stop. Current hairs don't last forever. That is why they need yearly replacement. So with time, those dogs become bald in the typical areas as well. Also because old hairs are not replaces as they should be, the dog’s coat color often fades. Black coats turn reddish brown or gray. They lack luster and appear dry. Tail hairs of your dog take more of a beating than body hair; so the top of the dog’s tail might be the first balding area you notice.
A physical examination of your dog by your veterinarian - as well as its breed, age and history may lead your vet to suspect Alopecia X. To confirm it, the veterinarian will probably order a blood chemistry profile and blood cell examination to rule out other common causes of hair loss. The blood profile will probably include a T-4 value. (ref) That test assesses the health of your dog’s thyroid gland. A urine examination might be performed as well. If these tests come back normal and you wish to pursue the cause further, an adrenal hormone test to rule out Cushing’s Disease (ref) (the ACTH test) and a skin biopsy would probably be suggested.
At this point, some dog owners (more than half) elect not to pursue diagnosis or treatment because their pet seems happy and active. This is a quite legitimate decision – one I would probably make myself. There is no need to feel guilty about it. Not all bald men visit Bosley and dogs are not vain. Another thing to remember is that even if medications work initially, the problem often returns at a later date. An exception is melatonin. Through 2019, I know of no downside to giving it to your dog in moderate doses. (ref1, ref2)
My personal opinion is that animals with Alopecia X (or any of the previously named health issues) should never be bred.
Some cases of Alopecia X resolve when a female pet is spayed or a male dog is neutered. So this is the first step I would pursue if you elect treatment (beyond melatonin) at all. Perhaps a third of Alopecia X cases are said to be surgically curable in this way - but there is no hard data.
Since sex hormones reduced by neuter/spay can have negative as well as positive effects on hair growth, it might be wise to administer one of the GNRH antagonists (such as leuprolide acetate/ Lupron ® or goserelin/ Zoladex ®) which act as a temporary “neuter” to see if the surgical procedure of spay/neuter is likely to be helpful or harmful in your dog’s particular hair loss case. There are also a considerable number of potentially negative health consequences of spay/neutering pets. (ref)
If your dog is already neutered, or if neutering did not solve its problem, oral melatonin or melatonin implants might be helpful. (ref) It is said to be helpful in about one in three dogs. As I mentioned earlier, melatonin is a hormone produced in a small structure adjacent to the brain called the pineal body as well as in other areas of the body including the skin.
Some dogs begin to re-grow their hair within 1-3 month of beginning a melatonin supplement. The larger problem is that veterinarians do not know how to accurately determine the best dose, how frequently to give it or how long to continue giving it. If you want to let other readers know your experiences giving melatonin to your dog, let me know.
Subcutaneous melatonin implants are also available from various online sources. (ref) I have no experience using these implants and I know nothing about the legitimacy of these suppliers. If you have used them in your dog's Alopecia X case you can let me know about that too.
Some veterinarians believe that giving too much melatonin or giving it over too long a period can actually make the hair loss problem worse. That might be only an illusion because dogs that are not melatonin-responsive would be loosing more hair in any case. My suggestion is to begin at a low dose and only increase the amount if no response is noted. Since this hormone is designed to pulse and not be continually supplied at high levels, it is probably best not to continue giving it after the hair has returned. If the dog becomes sluggish or shows personality changes, the dose is probably too high. I would not give melatonin to diabetic dogs. Melatonin itself does not grow hair. But in some cases, it appears to trick the body into producing the compounds that stimulate hair follicle stem cells to grow hair. Melatonin also has the ability to lower GnRH hormone levels, the driver of the sex hormone production involved in shedding. (ref1, ref2)
You can consider melatonin administration to your dog as similar to exposing your dog to the shortened daylight hours of fall and winter. (ref)
Dogs that reside in a typical residence do not experience normal exposure to light in a way that encourages normal shedding and hair regrowth. You might attempt to remedy that by providing light to your dog proportional to the natural day length of the season. When dogs are exposed to too much or too little light, their melatonin circadian clock looses track of the seasons (their clock becomes "free running") and the normal endocrine gland cycles that drive haircoat shed and replacement break down. I cannot tell you what color light would be best, nor the intensity because that is unknown. Perhaps the blue light of the afternoon sky (~470 nm) with an intensity of ~18 lx at the cornea or perhaps full spectrum light with the intensity of a sunny day. (ref1, ref2)
Perhaps two months at the shortest daylight hours (that produces the most melatonin) and then two months at the longest daylight hours. If you find that helpful or unhelpful, let me know.
The Veterinary College at the University of Tennessee (and perhaps other institutions) offer an intensive analysis of sex hormones and their building blocks. Their focus has been primarily on the dog’s adrenal glands and the various hormones those glands are capable of producing that might cause “Atypical” Cushing’s disease. (ref) Atypical Cushing’s disease is often accompanied by hair loss similar to Alopecia X. Perhaps their endocrinology consultation service might offer you treatment options based on their findings. Hopefully those options will not include powerful adrenal gland-altering drugs such as mitotane (Lysodren ®), trilostane (Vetoryl ®), selegiline (Anipryl ®) or ketoconazole).
In 2013, veterinarians also at the University of Tennessee, conducted some studies in Pomeranians diagnoses with Alopecia X. The dogs were given injections of Depo-Povera® (medroxyprogesterone acetate [ref]) – the 12-14 week human birth control product. Depo-Povera® mimics progesterone – the hormone of pregnancy and reproduction. Some of the Pomeranians in this small study showed a 40-60% hair regrowth. One showed a 100% hair regrowth. Read their study here: (ref)
The authors of that study attributed the hair regrowth to the synthetic progesterone’s ability to stimulate the production of a particular type of growth hormone (IGF-1). IGF-1 has similar roles to growth hormone. (ref) That IGF-1 has the ability to stimulate hair growth has been confirmed, (ref)
I do not suggest that you give your dog Depo-Povera® in an attempt to alleviate Alopecia X. The drug has too many potential side effects. Those include diabetes, weight gain, pyometra, enhancement of tumor growth, anemia, blood clots and negative effects on the liver.
(ref1, ref2, ref3, ref4, ref5, ref6, ref7, ref8, ref9, ref10, ref11, ref12)
There are a number of companies marketing topical products that claim to contain IGF-1. They are sold as a supposed aid for balding people. Although increased IGF-1 was the explanation given for improved haircoats in the Tennessee pomeranian study, I am doubtful that these creams or lotions contain enough IGF-1 to be helpful. If you have found otherwise, let me know
Another oral medication, tofacitinib (Xeljanz®) marketed for human rheumatoid arthritis and ulcerative colitis apparently encourages hair growth. (ref) Xeljanz is very similar to Apoquel, marketed by Zoetis for allergic skin disease in dogs. I do not suggest your try either in your dog in an attempt to grow hair.
I revised this article in 2019. The previous version listed other hormone products that occasionally appeared to regrow hair in alopecia X cases. I no longer list them because I believe that hair loss does not justify the use of drugs with the known potential to cause health problems considerably more serious than the loss of hair.
I suggest you just manage your dog’s life a bit differently. Dogs with Alopecia X need more protection against the sun and the cold. Sunscreen and a sweater solve those problem better than drugs. Treating their exposed skin with a gentle lanolin-containing cream rinse will help prevent flaking skin.