Hair loss, technically called “alopecia,” is broadly defined as partial or complete lack of hairs in areas where they are normally present. Alopecia doesn’t refer only to hair loss; it also includes coat defects from failure of hair to grow. Many medical conditions involve hair loss, including colour dilution alopecia, seasonal flank alopecia, alopecia X, acanthosis nigricans, follicular dysplasia, congenital hypotrichosis, pattern baldness and pituitary dwarfism. Some have a genetic component. External parasites, fungal and bacterial skin infections, certain drugs, hormonal/endocrine imbalances such as Cushing’s disease, Addison’s disease, hypothyroidism, hyperthyroidism, allergies, stress, poor nutrition, lactation and cancer can all cause hair loss, with or without redness, itchiness, scabbing, scaling or bleeding. Hair loss is typically associated with an underlying medical disorder, annual veterinary examinations can help identify and manage the problem before it becomes out of hand.
How Does Dog and Cat Hair Grow?
Hair begins growth within a little pocket called a follicle where it is nourished by proteins and other materials in the blood. Blood also carries hormones, such as epidermal growth factor, that determine the growing, resting, regressing, and shedding phases. Hormones that control hair growth are influenced by sunlight and temperature, so that many pets have major growing and shedding cycles each spring and fall. With more pets kept indoors in a controlled climate, marked growing and shedding cycles are less frequent, and many pets appear to shed more evenly throughout the year. There are some dogs that do not shed very much at all. These dogs have hair that grows constantly and can become very long. Poodles and Shih Tzus are good examples of dogs with constantly growing hair. Although these pets don't shed, their coats require care, usually clipping every 4-6 weeks. Hairs over the body don't move through the phases at the same rate. For example, hair over the back and hips grows more slowly than hair on the chest. The rate at which hair grows is influenced by hormones and by blood supply. A good blood supply brings nutrients and a normal concentration of hormones so that the area experiences healthy hair growth. Areas with a poor blood supply do not have healthy hair growth. Unlike humans who have one of a few hairs growing in each follicle, most dogs and cats have many hairs in each follicle. With so much hair in a follicle, when follicles go through the shedding phase there is lots of hair to clean up.
Causes of Canine Alopecia
There is no particular age or sex predisposition to the development of alopecia, although certain dog breeds do seem at increased risk for certain kinds of alopecia. All pets are susceptible to hair loss, but the following breeds often have their own particular problems. For example, Dachshunds have a breed predilection for thinning over the ears, abdomen, and neck. Hair loss due to hypothyroid disease affects the Afghan hound, Airedale, Boxer, Chow Chow, Cocker Spaniel, Dachshund, Doberman Pinscher, English Bulldog, Golden Retriever, Great Dane, Irish Setter, Irish wolfhound, Miniature and Giant Schnauzer, Newfoundland, Poodle, Scottish Deerhound, and Shetland Sheepdogs. Hair loss due to hyperthyroid disease affects many breeds of cats, but is uncommon in Siamese and Himalayan cats. Hair loss due to hyper-adrenocorticism ( Cushing's disease) affects these dog breeds: Beagle, Boston Terrier, Boxer, Dachshund, and Poodle. These breeds grow hair very slowly after being clipped: Siberian Huskies, Alaskan Malamutes, Chow Chows and mixed breed dogs with Northern genetics. Doberman pinschers and many other breeds are prone to developing colour dilution alopecia. Recurrent seasonal flank alopecia tends to occur inBoxers,Bulldogs, and Airedale terriers. Alopecia X (also called adrenal reproductive hormone imbalance and sometimes called “black skin disease”) occurs more commonly in plush-coated breeds such as the Pomeranian,Chow chow, Keeshond, and Miniature poodle.
Some of the more common causes of alopecia in dogs are described below.
External parasites are notorious for causing alopecia in dogs. Fleas, ticks, lice and mites can all cause intense itching and scratching which leads to hair loss. Parasites can also physically damage the hair follicles, and allergic reactions to the parasites can cause hair loss as well. Demodectic mange causes localized to generalized hair loss with redness and mild scaling.
Fungal infections of the skin (called “dermatophytosis”) can cause partial to complete alopecia with scaling and with or without associated redness. Some fungal infections are zoonotic, which means that they have the potential to cause skin lesions in people.
Bacterial skin infections – especially those caused by Staphylococcal species – can cause alopecia with redness, crusting and circular patterns of hair loss. Bacterial folliculitis is the most common cause of multifocal alopecia in dogs.
Allergic pets have itchy skin, and in response they scratch or chew out their hair. Pets can be allergic to:
- Inhaled allergens
- Materials their skin contacts
Hair requires a constant supply of nutrients to remain anchored in the skin. Nutrients that support healthy hair are the same as those that support healthy skin: vitamins, minerals, antioxidants, and Omega 3 and Omega 6 fatty acids. Hair that doesn't receive a balanced supply of nutrients becomes dull, loosens, and falls out. For example, pets on starvation diets have thin, dull coats. Hair loss due to poor nutrition often involves the whole pet, but may be most obvious over areas that are easily worn and over the back and hips where hair follicles have shorter growth cycles and longer inactive periods. Some Northern dog breeds, such as the Siberian Husky, have a genetic tendency to zinc deficiency that leads to skin and coat problems. The problem is in the pet's inability to absorb zinc, which is usually present in adequate amounts in the diet. The medical term is Alopecia X of the Northern breeds.
Abnormal Organ Function
Because the kidneys, liver, intestines, and other organs regulate the nutrients in the blood, diseases and drugs affecting these organs directly influence hair loss. For example, pets with inflammatory bowel disease, cancer or on chemotherapy often have dull, thinning hair throughout. Pets with kidney failure often have bedraggled, dull coats and may have a strong smell of urine from their skin. Pets with liver failure have orange-yellow skin (jaundice), and nails that grow long but are weak and flaky.
Hair is a living element anchored in the follicle and nourished by blood for most of its cycle. When the blood doesn't circulate, hair will not grow well. Pets with weak hearts, low blood pressure, and chronic anaemia may have cool skin and dull coats.
Excessive or Deficient Hormone Levels
Many hormones influence hair growth, including testosterone, estrogen, melatonin, growth hormone, thyroxin, and cortisol. Abnormal levels of these hormones cause hair to be too thin or to be too thick. Thyroxin increases the rate that cells grow and multiply because it stimulates the cell's nuclear machinery. Hair follicles and skin cells are as strongly influenced by thyroxin. With normal thyroxin levels, hair growth is normal. With insufficient thyroxin, which usually occurs in dogs (hypothyroidism), hair growth is thin, especially over the back. With excess thyroxin, which usually occurs in cats ( hyperthyroidism), the coat is poorly groomed and matted over oily clumps of skin cells. Cortisol is a hormone released from the adrenals that is carried by the blood and influences most cells in the body. When cortisol levels are too high–due to Cushing's disease or cortisol medication overload–hair thins over the back all down the tail, leaving tuft of hairs at the very end (rat tail). If hair is clipped anywhere on the body, it grows back very slowly.
Several oral, topical and injected medications cause hair loss. For example, high doses or long-term use of oral, topical, or injected steroids can cause hair follicles to shrink and hair to fall out. Hair regrowth is delayed until follicles are no longer influenced by high steroid levels. Some topically applied flea medications cause hair loss at the area of application.
Behaviour (Excessive Grooming and Anxiety)
Pets can develop hair loss because they have behavioural problems. For example, dogs with a separation anxiety behaviour disorder lick patches of hair off their legs. This is called acral lick dermatitis. With acral lick dermatitis, dogs can lick so adamantly that their skin breaks down and becomes infected. What began as anxiety turns into a bacterial and yeast infection that is difficult to cure because the pet licks it whenever left alone. The areas normally involved are the front legs just above the wrist (carpus) and back legs near the ankle (tarsus). Cats can also over groom or barber themselves until bald spots spread over abdomen and thighs. When over grooming is causing bald spots, the hairs will be broken or chewed off and the only involved areas will be where the pet can reach so the back, head and neck are never involved.
Some types of alopecia have a genetic basis. These include: Acanthosis nigricans, Alopecia X, follicular dysplasia, colour dilution mutant alopecia, congenital hypotrichosis, pattern baldness and pituitary dwarfism, among others.
How Alopecia Affects Dogs
Alopecia is one of the more common complaints of dog owners. How alopecia affects a dog depends upon the underlying cause of the condition. Hair loss (or failure to grow) can occur anywhere on the body of a dog of any age, breed or gender, including face, around the eyes, on the back, near the base of the tail or on the flank. Alternatively, the absence of hair may be accompanied by scratching, redness, pustules or other skin changes. Alopecia can appear symmetrically in discrete but well distributed patches, or it can have no pattern at all.
Symptoms of Alopecia
One of the most baffling things about alopecia is the vast number of ways that it can present. It can occur acutely or be slowly progressive. It can happen in isolation or with localized or generalized hair loss but no other clinical signs. The skin may appear normal, and the dog may act completely normal as well. Some cases of alopecia never progress. The affected dog simply loses hair, and the hair does not grow back. In other cases, hair loss may spread across the body and become generalized, or it may become patchy.
Symptoms In Addition to Hair Loss
Hair loss is accompanied by other clinical signs, like itching, scratching, chewing which changes the appearance or condition of the skin. In many cases, the affected skin becomes crusty, thickened, and raised sometimes, it can also become thinner. Sometimes, the skin becomes oily and greasy, and pustules or other skin lesions can develop. In severe cases, dogs can develop blisters, weeping sores and hot spots, which are prone to developing secondary bacterial infections.
Which clinical signs a particular dog develops depends upon the underlying cause of the alopecia. The specific signs are important to help the veterinarian establish a correct diagnosis.
An accurate diagnosis of the cause of alopecia requires a careful history and physical examination. Key points in the history include recognition of breed predispositions for congenital or hereditary alopecia; the duration and progression of lesions; and the presence or absence of pruritus, evidence of contagion, or non dermatologic problems, eg, polyuria and polydipsia. On physical examination, the distribution of lesions should be noted (focal, multifocal, symmetric, generalized), and the hairs examined to determine whether they are being shed from the hair follicle or broken off—the latter suggesting pruritus. Signs of secondary skin infections or ectoparasites should be noted, and a careful non dermatologic examination should be performed.
Initial diagnostic tests include skin scrapings for ectoparasites (particularly Demodex mites); combing of the hair coat for fleas, mites, and lice; impression smears of the skin for evidence of bacterial or yeast infections; fungal cultures for identification of dermatophytosis; and examination of plucked hairs, looking at both the shaft and the ends for evidence of dermatophytosis or that the hairs were chewed off.
If these tests do not identify or suggest an underlying cause, a skin biopsy may be indicated to evaluate hair follicle structures, numbers, and anagen/telogen ratios and to look for evidence of bacterial, fungal, or parasitic skin infections. In addition, skin biopsies are often needed to confirm congenital causes of hair loss and to identify inflammatory or neoplastic causes of hair loss. Skin biopsies from normal and abnormal sites should be submitted for evaluation. CBC, serum chemistry panels, and urinalyses are generally only helpful when an endocrinopathy is suspected. Specific endocrine function tests can be performed based on findings of routine laboratory work or clinical signs.
Alopecia is usually a sign of an underlying disorder, which must be diagnosed accurately in order for effective treatment to begin. If the hair loss is accompanied by scratching, pustules, hot spots or other lesions, it may be appropriate to apply topical medications to manage and hopefully alleviate the discomfort caused by these conditions even before the actual cause of the alopecia is determined. The veterinarian may prescribe suitable treatment along with ointments, creams, lotions, shampoos or other soothing treatments to calm any inflammation associated with alopecia.
There are a number of topical medications to treat alopecia caused by external parasites. Flea and tick control, and shampoos or other products that kill mites, lice or fungi, are generally quite effective in resolving parasitic alopecia, although it can take weeks to months for the hair to grow back completely.
Alopecia Due to Endocrine Disorders or Hormonal Imbalance
Alopecia caused by endocrine or hormonal abnormalities is managed by treating the underlying disorders. For example, alopecia associated with hyperthyroidism or pituitary dwarfism can be treated with lifelong hormone replacement medication. Spaying and neutering can be successful treatments for hair loss caused by certain other hormonal imbalances, or even stress.
There are a number of treatment options for alopecia caused by immune-mediated reactions. These include medicated shampoos, topical and oral anti-inflammatories and antihistamines, and corticosteroid therapy. Of course, if a veterinarian can identify the cause of the reaction and remove the allergen from the dog’s environment, allergic alopecia should resolve in short order.
Essential fatty-acids, Vitamin D, and oral melatonin supplementation have been found to be safe and variably effective in stimulating hair regrowth and improving overall coat condition in dogs.
The prognosis for recovery from alopecia is good in most cases, if the underlying cause of hair loss is identified and treated. If the skin has suffered extensive scarring, hair regrowth will be more limited.
Reduce Shedding With Regular Grooming
To control or reduce the amount of hair your pet is losing, regular and proper grooming is the key. Grooming your dog regularly will control their hair loss. In addition to brushing/combing your dog, a bath helps to remove loose hair and dander. Bathing once or twice a month should be enough, although if you or someone else in your family has an allergy to dog hair, bathing weekly may be better as long as it doesn't irritate the dogs' skin.
Always use a very mild shampoo or hypoallergenic formula (no medicated or highly-scented ones please). Dander Control Shampoo can really help reduce the dog dander that's the number one trigger for sneezing, itching and other common dog allergy symptoms.
Here's a quick look at the best tools to use when you're trying to keep dog shedding to a minimum in different breeds:
Dogs with thick 'double coats:
They need to be groomed daily if possible, failing that at least 3 times a week.
Dogs with long, silky hair:
You'll need a metal grooming comb and a dog slicker brush (the wide-flat type with bent-wire 'teeth') to take care of these breeds (for example the Yorkshire Terrier, Maltese, Setters, Spaniels etc.), who are pretty high-maintenance in terms of grooming. Care should be taken while using the slicker brush, as it would hurt the delicate skin under that beautiful flowing hair.
Dogs with short, wiry coats:
Many terriers (such as the Cairn Terrier, Jack Russell Terrier, wire-haired Fox terrier) and other breeds such as the Irish Wolfhound, have a soft undercoat and a tough, wiry top coat. To reduce dog shedding in these breeds you'll need a steel comb and a 'pin' brush to remove all the loose hair. They also need 'stripping' or 'plucking' and bathing every 3 months or so, and it's best to have this done by a professional groomer.
Dogs with smooth, short coats:
These are the easiest ones to groom and the least labor-intensive breeds in that respect. This group includes breeds such as the Boxer, Bulldogs, certain Hounds such as short-coated Dachshund and the Weimaraner, Doberman, Pinschers and many others. They are groomed once weekly with a bristle brush is enough to keep them neat and tidy and keep dog shedding to a minimum.
Tips of Home Remedies for Dog Hair Loss
One of the best ways to reduce excessive shedding in dogs is to start with a healthy diet. Feed your dog with a homemade mix of fully-cooked rice, cooked vegetables and boiled chicken. This home food remedy may reduce the allergies caused by food to your dog and helps in reducing the hair fall.
Another home remedy for hair shedding in dogs is to mix a small amount of flaxseed oil in your dog’s food. Flaxseed oil contains high amounts of Omega 3, an excellent natural treatment for dog hair loss. After a few weeks you would see the change in your dog’s hair fall. It is good for other health benefits too.
Olive oil is a good home remedy to apply on dog’s coat and skin. It will help moisturize as well as pacify any pain caused by severe itching. Another benefit of olive oil is that it will choke mites, if those fleas are the cause of dog’s hair loss. Olive oil is said to give the dog a fine and healthy coat with an amazing shine.
Lemon juice has natural antibacterial properties that can be used to treat excessive hair shedding in dogs. Introduce a slice of lemon in warm water and leave for five hours. Strain afterward and apply the lemon juice mixture as a rinse or as a spot treatment.
An additional home remedy to follow is to pat your dog in the backyard after the bath and then brush him down. By this way, all the unwanted hair on the dog’s coat is removed. Regular baths encourage loose hair to fall out in the tub (or outside) instead of on your furniture. However over-bathing can cause dry skin, which causes fur to fall out.
Give your dog access to clean, fresh water.
Dehydration can lead to dry skin, which can cause excessive shedding and even illness. Make sure your dog always has access to as much clean, fresh water as it wants to drink. The water intake for your dog can also be increased by incorporating moist foods into its diet. Wet dog food contains up to 78% moisture, compared to 10% for dry food, and can be a good way to make sure your dog stays hydrated.
Give your dog regular baths.
Regular baths encourage loose hair to fall out in the tub (or outside) instead of on your furniture. However, over-bathing can cause dry skin, which causes fur to fall out. Research your dog's breed to learn about the suggested bathing schedule, or ask your veterinarian. Blow-drying after a bath can be helpful if your dog has a long coat. Use only the lowest heat setting (or a cool setting, if there is one). Towel-dry your dog first, then use the blow dryer to help remove loose fur.
Control fleas . Dogs with flea problems scratch incessantly, which causes hair to fall out. Keeping your dog free of fleas will prevent irritated skin, dandruff and excessive fur shedding.
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About Author / Additional Info:
I am PhD Scholar at National Dairy Research Institute in Animal Nutrition Division. Currently I am doing my research work of my PhD. I have worked one for treatment of animals at village level.