Pruritis Basics: (Mechanisms)
The skin contains a vast network of nerve fibers of various types that deal with sensation, such as pruritis, pain, temperature and touch. The exact type of nerves that result in pruritis, and their association with other portions of the nervous system is poorly appreciated at this time. However, suffice it to say that the activities of these nerves are stimulated by chemical mediators (derived from undesirable immune system reactions to allergens), some of which are present in the membranes of skin cells and other cell types that are found in close association in the skin. Suggested mediator types are proteolytic (protein-degrading)enzymes (from microorganisms and from other cell types), prostaglandins and leukotrienes; the latter two are derived from the breakdown of cell membrane via pathways involving arachadonic acid cyclooxygenase and lipooxygenase (these are often sites at which medication to inhibit pruritis are targeted). Modulation of sensory input (worsening of itch intensity) from other factors...,humidity (dry skin is often itchier than moist skin) boredom, pain, temperature and touch can and do occur, though mechanism(s) are not understood.

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Priniples:

Decrease the magnitude of pruritis by depleting or removing pruritic mediators, and/or removing the cause; if more than one cause of pruritis is present removing one or more or these may decrease the sensation and intensity of the itch to below an "itch-threshhold"....effectively stopping the itch even though not all contributors to the itch are eliminated

Substitute a different sensation for pruritis e.g cold/ice, or heat for extended duration (play "mindgames" with the brain..by confusing it!)

Modulate or block inflammatory mediator... activity or synthesis

· Pharmacological Intervention

1. Topicals

Shampoos with topical anti-inflammatory medications, humectants (moisturizers), oatmeal-based, also help to remove environmental irritants (allergens) from the surface of skin


Conditioners with long-lasting moisturizers, anti-inflammatory medications


Ointments and creams...with antibiotics, antifungal medications, anti-inflammatory medications


Hydrotherapy (whirlpools)...loosen dry skin, moisturize, remove environmental irritants (allergens) from the surface

2. Systemic

Antihistamines:

Remember, histamine was one of the mediators listed for pruritis; antihistamines prevent the release of histamine from the stimulated source cells or the binding of histamine to a site that, in turn results in the release of histamine. Hence anti-histamines work best before the histamine release has been triggered (i.e as a preventative)

There are many different antihistamine products...some may work better than others in some animals. Sometimes more than one must be tried for several weeks before going to another

Antihistamines are often used in conjunction with other antipruritics

Some tricyclic antidepressant medications, such as doxepin, contain potent antihistamine activivity and are occasionally useful in the control of itch

"Good" Prostaglandins:

Inflammatory intermediates include some of the prostaglandins and leukotrienes... classes of molecules derived from the breakdown of cell membranes (arachadonic pathways) . However, certain prostaglandins behave as anti-inflammatory (anti-itch) mediators

An example is misoprostil (Cytotec®) a synthetic prostaglandin E₁ analogue (often used to treat gastritis/ gastric ulcers)

Phophodiesterase Inhibitors:

An example is pentoxifylline (Trental® )

Inhibits some pro-inflammatory mediators (TNF- and IL-1 and IL-6)

No side effects reported in the dog

Antidepressants

There is evidence that certain tri-cyclic antidepressant medications are efficacious in controlling pruritis in dogs

Examples are Doxepin and Fluoxetine

Omega Fatty Acids

Certain fat-derived molecules, fatty acids, are rich in anti-inflammatory properties

The breakdown of fat to fatty acids results in the synthesis of particular classes of fatty acids known as omega fatty acids. The fatty acids with the most anti-pruritic properties are of the omega-3 class.

Sources of antipruritic fatty acids include marine (fish), flaxseed and primrose oils.

Fatty acid supplements are often used synergistically with antihistamines and other antipruritic agents

Antimicrobials

Anti bacterial and anti-fungal agents are important in the relief of pruritis in which there is an infectious component (remember...microbial proteolytic enzymes are proponents of pruritis)

Corticosteroid

Corticosteroids are potent inhibitors of pruritic intermediates. When used judiciously they are important components of the phamacological arsenal in dealing with severe pruritis

Keep in mind that overuse, misuse and abuse of corticosteroids can compromise health (see Corticosteroids)

Cyclosporine: an immune system modulator/suppressor with less systemic side effects than corticosteroids. Atopica^® (Novartis) has been approved for the treatment of canine allergic dermatitis (Atopy)

Lumps and bumps are smooth or irregular, raised, flat or depressed, soft or firm discrete areas within or just beneath the skin. The link, descriptions and definitions describes some of these. These include papules, pustules, vesicles, comedones, cysts, nevi, keratoses, horn, tumors/neoplasia , abcesses, granulomas, warts, ulcers, and excoriations. Each of these can be further subdivided into specific type, whether benign or malignant including grade of malignancy, histological appearance, and cause. This page will discuss selected examples...ones that you are most likely to experience with your pet.

Tumors

Malignant:



Mast Cell Tumor: Mast cells are normal inflammatory cells that are found in many areas of skin and other tissues throughout the body. Normal mast cells vary in biochemical characteristics and appearance, depending on the region from which they are derived. Tumors derived from these likewise vary in appearance and behavior.  

They can occur in any age, any gender and breed of dog, though there is a natural (genetic? ("oncogene", viral) ) predilection in certain breeds, especially Boxers, Bulldogs and Boston Terriers. Other overpresented breeds are Weimeraners, Fox Terriers and Golden Retrievers.  

Tumors may arise from the epidermal, dermal or subcutaneous regions of the skin of any region of the body, but mostly the trunk, around and near the skin in the vicinity of the anus, and the limbs. In the dog tumors of the groin, around the anus, and the prepuce (male dog sheath) tend to be more aggressive..and metastasize (spread), usually to regional lymph nodes, the spleen, liver, occasionally to the bone marrow. It is uncommon to find mast cell tumors in the lungs. In the cat, skin tumors are more likely discovered on the head and neck. It is more common to find mast cell tumors in other organs in cats than in dogs. In Siamese breeds of cats younger than 4yrs a histiocytic form of mast cell tumor is seen..these are most often benign. The predictative value of tumor location and metastasis in the cat is not so clear. Most visceral mast cell tumors in the cat are bad..but information and clear studies are lacking in the cat.

Gross appearance is highly variable....pedunculated (hanging from stem) or nodular, soft or firm, smoothe or ulcerated, swollen, white to red to black.

The biological behavior varies in part with the location of the tumor (because there is natural variation in behavior characteristics of the normal (parent) mast cell in each region of the body)..i.e. the cell from which the tumor is derived. Most mast cells contain histamine, heparin and proteolytic (degrading of proteins) enzymes. Tumors are dangerous because they contain large quantities of these components in a relatively concentration area.

Histamine: histamine is a neurotransmitter as well as a vasoactive substance that affects blood vessel tone, and the sequence of events and clinical signs responsible for acute reactions to foreign substances (it is released from mast cells during an allergic reaction, for example). Histamine is one of the neurotransmitters responsible for the release of hydrochloric acid in the stomach. Excess histamine release by mast cell tumors frequently is responsible for gastric ulcers in affected animals. When release of massive quantities of histamine occurs, the vasoactive (dilation of blood vessels) properties results is massive pooling of blood in target organs (in the dog it is primarily the liver; in the cat it is the lungs); this results in acute hypotension (low blood pressure), with compromised circulation to all vital organs in a short amount of time. The consequences of this phenomenon...known as Anaphylactic Shock....is often death.

Heparin &Proteolytic Enzymes: release of these results in altered coagulation properties, with potential for local hemorrhage, wound dehiscence (not healing due to degradative enzymes), and systemically,... hemorrhage, shock, and resulting multiple organ dysfunctions.

Clinical Signs: The most common clinical signs associated with mast cell tumors are gastrointestinal (vomiting, diarrhea, ulcers..bleeding or not), pruritis, non-healing wounds, bleeding problems, edema (due to leakage of fluid or blood within tissues), and in acute or peracute situations, symptoms of impending or ongoing shock. Sometimes infiltration of major organs such as liver and spleen may result in clinical signs associated with dysfunctions of those particular organs. In addition, cutaneous mast cell tumors may be pruritic and infected secondary to trauma from biting or scratching. Besides the specific consequences related to mast cell tumors, there are other, ubiquitous signs of cancer , such as suppression of the bone marrow, weakened immune system, weight loss and increased incidence of infections.

Diagnosis:  This is often easily determined by fine needle aspiration and cytological evaluation. Many mast cell tumors can be identified by characteristic granules (containing the active biochemicals...histamine, heparin and proteolytic enzymes). Histopathology is also diagnostic. Tumors are "graded" on degree of malignancy with potential to metastasize. It is important to sample regional lymph nodes...if tumor cells are found in these then the tumor is considered to have metaztasized. Examination of "buffy coats" (containing the white blood cells) from centrifuged blood for mast cells used to be considered a good indicator of whether mast cell neoplasia is present system-wide; that is no longer true. Increased numbers of circulating mast cells can be found in the absence of mast cell neoplasia...e.g. with a simple dermatitis (inflammation of the skin). Finding large numbers of mast cell tumor cells in the bone marrow is diagnostic for systemic mast cell neoplasia.

Treatment: Herein there is controversy. In part, how aggressively a mast cell tumor is treated depends upon the grade, the location (no matter what the histological evaluation-because tumors located in certain locations are, historically, more aggressive, as described above) and the overall health of the animal. In general, the following discussion pertains to mast cell tumors in dogs...(treatment in cats is less clear)...

Surgery: All cutaneous (skin) mast cell tumors should be excised. To be sure that all abnormal tissues are removed, a wide (2-3 cm beyond the grossly visible margin) excision is necessary. Pre-treating with a potent antihistamine is customary, should handling of the tumor cause release of large quantities of the potent and potentially dangerous quantities of histamine from the granules in tumor cells. Regional lymph nodes should also be biopsied. There was a report that treating the surgical site with deionized water after excision was somehow toxic to few remaining (but microscopic) mast cells. Sometimes, chemotherapy may precede surgery in order to reduce the size of tumor...allowing excision AND leaving enough normal skin to close the incision without incurring tension on the suture line. Surgery alone results in greater than 50% recurrence...this is unacceptable.

Radiation Treatment: A daily radiation treatment for several weeks is beneficial, but has the best positive affect if begun as soon as possible after surgery.

Chemotherapy: Usually after surgery, but if tumor is huge, presurgery treatment to reduce size is then followed by surgery. Much controversy here, as well. Many animals are placed on large doses of corticosteroids to reduce the growth of these tumors....but in truth, corticosteroid treatment alone is beneficial in less than 20% of of all instances. Likewise, other chemotherapeutic agents, when used alone, are relatively ineffective but when used in specific combinations, can be beneficial in about 1/4 to 1/3 of affected animals . An exception is discussed in a promising study in which Lomustine, as a single agent, may be significantly beneficial in up to 41% of these cases

Other: There has been anecdotal information that DHEA (dehydroepiandosterone), a hormonal precursor, may afford some benefit. There does not appear to be any controlled studies proving this...yet.

Malignant Melanoma: These tumors arise from the pigment-producing cells of the skin are most commonly seen in older (average age 9 yrs dog; 10yrs cat) animals. In cats, lesions are mostly found on the head, especially the lip, eyelid, as well on on the neck. Lesions on dogs are also found on the head, including the mouth...but also the trunk, feet and scrotum. Gross appearance varies greatly (well or poorly circumscribed, dome, or plaque in shape, gray, brown or black, 0.5cm to 10cm (4 cm in cat) diameter). Metastasis is common. Diagnosis is by excision biopsy. Treatment is wide excision. There is little data indicating efficacy of radiation or chemotherapy as adjunct treatment to surgery alone. Prognosis is worst for oral tumors or large tumors (at time of excision).

Squamous Cell Carcinoma (see picture)(See Picture).  These tumors arise from the keratinocyte layer (stratum spinosum) of epidermis (see "Layers"). The causes are not clear but there may be a correlation with exposure to sunlight. Characteristic benign changes in the epidermis related to sunlight (actinic keratosis) sometimes progress to malignancy (sqamous cell carcinoma). Evidence suggesting a viral component in the development of these malignancies has been postulated for dogs....but not for cats. Dogs may be affected at any age (average 9yrs) with a breed predispositions for Scottish terriers, Pekingese, Boxers, Poodles and Norwegian Elkhounds. Tumors of the clawbed are most likely seen in black breeds (Labrador Retriever, Bouvier des Flanders, Giant Schnauzer, Dachshund). Short-coated, light-skinned breeds (Dalmatian, American Stafforshire Terrier, Bull Terrier and Beagle) have the highest incidence of solar-induced squamous cell carcinoma. Depigmentation of the nose and ears also predisposes to actinic (solar) damage...and the risk of squamous cell carcinoma. In cats, white and orange cats have increased incidences of squamous cell carcinomas, compared to other colorations.
Additionally:

Lesions are commonly found on the trunk, limbs, digits/feet, scrotum, lips and nose in dogs and on the face (nose, lips and ears), neck and digits in cats. In addition, oral forms of squamous cell carcinoma are sometimes seen in the cat (and rarely in the dog).

Multicentric Squamous Cell Carcinoma in Situ..is a rare variant in cats and dogs that is probably of viral origin...unrelated to sunlight exposure. In cats lesions are found most often on the head, neck shoulder and forelimb; in dogs, the mouth and genitals are most likely sites. Histologically, these tumors do not invade the dermis, unlike the standard, common squamous cell carcinomas.

Lesions are usually solitary (one tumor at one site) in dogs and are often (about one-half of the cases) multiple in cats.

In dogs and cats, gross appearance of tumors is either proliferative (cauliflower-like growth) or ulcerative (easily damaged, with crators and blood present)

Tumors do not ordinarily metastasize (spread) but they tend to be locally aggressive, invading and disrupting adjacent tissues...this can impede or destroy function, and create considerable pain.

Diagnosis: by excision biopsy. In cats, tumors can be graded and prognosis depends on the histoligcal appearance...not always the location (as in Mast Cell Tunors in dogs) except that lesions of the claws/digits in both dogs and cats are, historically, associated with a poorer outcome.

Treatment: Surgical excision followed by either chemotherapy, cryoptherapy, hyperthermia therapy and/or radiation therapy. Choice of post-operative treatment depends on the histological appearance and, sometimes (e.g. digital tumors) the location. The treatment of Multicentric Squamous Cell Carcinoma in Situ is different. Studies have shown that Imidoquod (Aldara ®), an immune response modifier used to treat genital warts, has potent antitumor and antiviral actions. It comes as a cream and is applied to the affected lesion once daily. Some report complete resolution of lesions in 7-15 days!



Fibrosarcoma These tumors arise from connective tissue cells within the dermis and subcutis. They are more common in cats than in dogs..occuring more frequently in younger (<5yrs old) animals. They may also be more common in FelineLeukemia (felv) positive animals. Most importantly, there is considerable evidence for vaccine-induced fibrosarcomas in cats. Indeed, there is significant correlation between the appearanece of these tumors at sites of vaccination and repeated vaccination with felv and rabies vaccines. The tumors can be large (up to 15-20cm!) rapidly growing, locally invasive, nodular, fleshy and hairless, sometimes raw, often ulcerated growths associated with sites of vaccination, the trunk, feet and ears. While they rarely spread to other locations, they are locally aggressive and surgical excision is associated with a high incidence of recurrence. It is for this reason that the American Association of Feline Practitioners (AAFP) now advocates giving the vaccines  (Felv and Rabies) in the hindlimbs. At the worst, amputation of the affected limb is a life-sparing salvage option in afflicted animals.

Basal Cell Carcinoma this tumor, possibly a result of exposure to excessive ultraviolet light (sunlight)...at least in cats, is more common in the cat than the dog, and arises from the least differentiated cells within the basal layer of the epidermis. Dog breeds with a predeliction for this tumor type include Cocker Spaniels, Kerry Blue Terriers, Shetland Sheepdogs, Huskies, English Springer Spaniels and Poodles. In the dog, the tumor is most likely to be found on the head, neck and chest while in the cat, the nose and eyelids are more common. Grossly, tumors can be tiny or huge, pigmented or not, firm to soft (cystic?) and ulcerated. Basal Cell Carcinomas are considered to be of low grade malignancy. Diagnosis is by needle or excisional biopsy. Treatment is surgical excision.

Benign (or rarely neoplastic)

Lipoma this is a fluctuant ( or firm if mixed with fibrous tissue) tumor of unknown cause arising from subcutaneous (under the skin) fat, mostly in any breed of older dogs (though there may be some breed predilections) and some cats (e.g. in Siamese). The lipoma may occur anywhere, singly or in multiple locations concurrently. Diagnosis is by needle or excisional biopsy  Treatment (surgical excision) is usual not undertaken unless there is pain or discomfort.

Benign Feline Basal Cell Tumor this firm, round, elevated, sometimes pigmented usually solitary, 1/4 to 3/4 inch mass (see figure) arises from the basal cell layer of the epidermis and usually is found on the head, neck, limbs or back of cats (Himalayan and Persian cats may be predisposed). Diagnosis is via needle or excisional biopsy. Treatment is surgical excision...or no treatment at all

Hair Follicle Tumors

Trichoepithelioma this is a fairly uncommon (and technically malignant) neoplasm in dogs and cats (Persians are over represented) older than five years arising from the most superficial layers of the hair follicle. The cause(s) is unknown. In dogs the most common sites are the back, head and neck. In cats, tumors are found on the head, limbs and the tail. Grossly (see picture), tumors are tiny or huge, single or lobulated-multiple, hairless and sometimes ulcerated. Diagnosis is via needle or excisional biopsy... and despite histological appearance of malignancy..they are NOT invasive and do not spread. Treatment is via surgical excision

Trichoblastoma like the trichoepithelioma, this is a rare,benign tumor of middle aged or older dogs and cats that originates in fairly primitive hair germinal cells (the cells that will differentiate and become hair). Grossly, 1/2-1 inch tumors are likely found on the head, neck and the base of ears in dogs and anywhere on the front half of the trunk in cats. Diagnosis and Treatment are the same as for Trichoepithelioma



Sebaceous Gland Tumors Sebaceous gland tumors are fairly common occurences in middle aged to older dogs. The cause is unknown. They are well defined, raised, smooth, sometimes lobulated, sometimes cauliflower-like, pink to orange (some are melanotic...black!), small (millimeters) to large (centimeters) in size. Most often they are seen on the limbs, trunk and eyelids/head.

Sebaceous adenomas: Adenoma are benign tumors of epithelial glandular derivation or morphology. These are more common in the dog than the cat and occur most frequently on the head, neck legs and anus. Growths are up to 3cm in diameter, are discrete, hairless lobulated and sometimes ulcerated (due to trauma).

Sebaceous carcinoma: Carcinomas are malignant variations (based upon histological cellular morphology ) of sebaceous tumors that are rare in the dog and the cat, are locally invasive...but do not usually spread to other regions of the body. The tumors are frequently ulcerated (not due to trauma) and surrounding areas are also inflamed

Nodular sebaceous hyperplasia This is the most common manifestation of sebaceous gland tumors, about 53%. Sebaceous gland cells simply grow to resemble nodular/cauliflower like projections above the skin with characteristics described above (Sebaceous Gland Tumors)

Sebaceous epithelioma These tumors are actually derived from basal cells that have metamorphed (differentiated) to a sebaceous gland appearance. They account for more than a third of all sebaceous gland tumors and are most common in Shih Tzus, Lhasas, Huskies,Malamutes and Irish Setters. These growths are most commonly found on the head...ususally the eyelids. Some are melanotic (black)

Perianal Gland Adenoma These arise in dogs from specialized glands (circumanal or perianal) which are present in the vicinity of the anus/anal sacs; tumors most commonly are found in this area but can occasionally occur on the tail, prepuce and on the back (rump area). The occurence of these benign masses may be under the influence of sex hormones, being more common in male dogs. Malignant variations (carcinomas) are more common in female dogs. Other tumors found in this area derived from the apocrine (sweat-like) tissues of the anal sac can be malignant and aggressive, spreading to other regions of the body (about 30% of cases)...also more likely in female dogs. Diagnosis is via biopsy; Treatment is surgical excision; chemotherapy if needed (carcinoma).

Hemangiopericytoma These are medium to humongous locally invasive masses that arise from cells associated with skin blood vessels (pericytes) usually in male or female middle-age or older dogs (7-10yrs). The cause is...unknown. Diagnosis is via excision biopsy. Treatment is wide surgical excision or appendage amputation, if indicated. The problem with these neoplasms is that though metastasis is rare, the rate of recurrence is high: for example, about 30% recurr within 4 months to four years of excision...and the rare of recurrence does not improve with post-operative radiaton therapy.



Histiocytoma These are fairly common, benign neoplasms within the dermis and subcutis derived from histiocytes...(a type of inflammatory cell residing in the skin). These growths occur most commonly in young dogs (more than 50% in dogs <2yrs), though older dogs may also be affected. They are usually solitary, red, smooth and are mostly found on the head, ears and limbs.The cause is unknown . Diagnosis is by needle or excision biopsy. NOTE...to the untrained pathologist (e.g. the non-veterinarian) the histological appearance of the tumor appears to meet the criteria for true malignancy. However, it is benign! Treatment is either nothing (many will regress spontaneously) or surgical excision.

Other causes of alopecia include:

Alopecia areata: this is a disorder manifest as patches of non-inflammatory alopecia of unknown cause, though an immune-mediated etiology is suspected. The exposed underlying skin is normal. Lesions can occur anywhere. Alopecia appears grossly the same as focal alopecia from other causes,so the diagnosis is based on the results of procedures ruling out other causes and histopathology of biopsied specimen. There is no know treatment. Hair may or may not regrow.

Anagen defluvion: Anagen refers to active phase of follicular hair growth. Disruption of this process can occur secondary to stressors, such as infectious or metabolic diseases (e.g. hypothyroidism). This is characterized by sudden hair loss

Telogen defluvion: Telogen refers to the inactive, resting or dormant phase of follicular hair production. The base (bulb ) of the hair follicle is clubbed, reflecting this lack of activity and hair that is present is not growing . Stressors, such as those described for anagen defluvion, result in abrupt cessation of growth of many anagen hairs, and the synchronization of these many hairs in telogen over a period of days and weeks. Later, when follicles return to active (anagen) state, the massive numbers of telogen hairs are shed (pushed out of the follicles) by young, emerging anagen hairs

Genetic

Pattern Balding: Affected areas are pinnae( external ears), base of pinnae, ventral (underside) neck, belly tail and thigh . All can, ultimately, be diagnosed via skin biopsy.These begin in young animals, and are classified thusly:

Pinnal Alopecia: Is a genetically transmitted trait, particularly (but not exclusively) in certain breeds, such as Dachshunds, Minpinchers, Manchesters Terriers and Chihuahuas. There is hair loss on ears beginning about 6months of age that progresses to naked ears by 8 or 9 years of age. Exposed skin is (or becomes) dark/black. The rest of the coat is normal. Neutering or spaying has no effect on this. Some advocate Melatonin to subvert progression...(no proven effect, however).

Pattern Baldness of American Water Spaniels and Portuguese Water Spaniels: This occurs in animals of affected breeds who are under one years old . There is clearly a genetic predisposition. Animals begin to develop bald areas at about 6 months of age that are restricted to the neck, back and inside regions of the thighs, the tail and the underside of the belly.

Other Pattern Baldnesses: The most commonly affected animals are Dachshunds, Boston Terriers, Whippets, Greyhounds, Italian Greyhounds, Chihuahuas and Manchester Terriers. The pattern of hair loss is similar to that of the water dog breeds, described above, but also includes areas on the tops of the head, behind the base of the ears. Importantly, affected animals are approximately 6month old and are females. Hair loss is progressive over the next twelve months, until only very fine hairs are present in the near- naked areas. A similar pattern of hair loss that can confuse diagnosis occurs in animals deficient in the hormone estrogen. A trial treatment with estrogen can determine whether that is the case. (Alternatively, because estrogen is potentially dangerous to administer, serum estrogen levels can be ascertained in unspayed dogs.)ears (primarily males) and on belly (primarily females). Loss of hair from ears (pinnal alopecia) begins in puppyhood and progresses for years, to complete baldness.

Color Mutant Alopecia: This is a genetically complex anomaly affecting some dogs with fawn or blue coloring, most commonly recognized in Doberman Pinchers (though others breeds have also been documented. Interestingly, Weimaraners, with naturally occurring blue color are not affected.). There is clumping of pigment granules in the hair and degenerative processes are recognized histologically. Affected animals are either plagued by recurring bacterial folliculitis (infection of the hair follicle) most commonly on the back and flank areas, with papules/pustules present (see definitions) and/ or sparse hair in those regions. Eventually, all affected dogs are sparsely-haired in the affected areas. Dogs with light-blue coloration are affected early (around six months of age); steel-blue colored dogs may not show any clinical signs til they are two or three years old. With time, hair loss may extend to the rest of the body. Thereafter, scaley skin is a common appearance. Diagnosis is by microscopic examination of remnant hair shafts (known as a trichogram) for abnormal clumping pigment granules, and other morphological changes seen with his disease. Treatment involves management of infectious processes with appropriate antibiotics, gentle handling of skin, including avoidance of harsh shampoos and excessive grooming (to retard mechanical damage to fragile hair shafts). It is unlikely that progression of hair loss can be prevented completely, but it may be slowed. Some are trying synthetic vitamin A treatments. However, the specific protocols are not clear and the potentially harmful side effects make this approach somewhat unappealing to this author.

Seasonal Flank Alopecia: This a seasonal (usually June to October OR..in some animals...October to March) and usually symmetrical loss of hair and the concurrent presence of dark pigmentation at the flanks of English Bulldogs, Boxers and Airdales (though other breeds may also be affected). Supposedly, this has something to do with seasonal Growth Hormone variations in these breeds and the resulting, transient form of follicular dysplasia. However ,the occurence and also the recurrence of clinical signs is not predictable for any dog in any given year. When hair growth resumes, several months later, it may result in a normal hair coat or in hair that is different in color, texture...one or both of these. Diagnosis is via skin biopsy. Distinguish this from Follicular Dysplasia. Treatment...is probably not necessary. Lately the use of Melatonin has been shown to be effective in some animals.

Follicular Dysplasia: The various forms of dysplasia are characterized by abnormal hair follicles resulting in aberrant or non-existant hair synthesis. In most instances, the problem is based in genetics; affected dogs usually have clinical signs in puppyhood or as young adults. Patterns of hair loss, and/or abnormal appearance depend on the affected breed. For example:

Siberian Husky and Malamute: By 3 to 4 months of age, guard hairs on the trunk are progressively lost, and remaining hairs may turn red. Also, if remaining hairs are clipped (e.g. for biopsy)..there is no regrowth!



Doberman Pinchers: Black or red dobeys may show signs at 1 to 4 years of age. Hair loss begins at the flanks and progresses to involve the rear one-half of the back and flank regions.

Airdales, Boxers, English Bulldogs, Stafforshire Terriers: Onset may not occur until dog is 2 to 4 years old. Hair loss is restricted to the flank in these animals. This must be distinguished from Seasonal Flank Alopecia, described earlier.

Irish Water Spaniels, Portuguese Water Spaniels, Curly-Coated Retrievers: Alopecia is first noticed at about 2yrs of age, up to 4yrs of age...earlier if there is excessive grooming. In these breeds, hair is particularly fragile and alopecia is most often the result of hair fracture from trauma. Initially, there is new hair to replace the damaged and lost ones, but the quality and texture of the regrowth is poor; these are then lost and may or may not then be replaced. The pattern of hair deficiency begins on the rear one-half of the back but then spreads to include the entire trunk (the head and limbs may be spared).

Epidermal Dysplasia of West Highland White Terriers: This is, sadly, a severely debilitating disease of this breed that begins in puppyhood (at or before 6 months of age). It is hereditary...thus not all Westies are stricken. Strictly speaking, it is NOT a genuine form of follicular dysplasia; the epidermis, not the follicle, is abnormal, representing aberrant keratin on the superficial-most portions of skin. This condition predisposes to a severe yeast infection, which leads to a greasy coat, that then precedes to intense pruritis and resulting hair loss from inflammation and self-trauma (scratching). Initially, pruritis is noticed on the face, ears, feet and belly. with time, lesions spread and animal suffering is marked. Diagnosis is by biopsy; treatment is palliative, with focus on aggressively controlling the secondary yeast infection (that is responsible for the brunt of the pruritis). Treatment with antifungal (anti yeast) medications may be required for life! Corticosteroid treatments are not useful in managing this affliction. Due to the expense of treatment and the likely life-long discomfort , many owners opt to euthanize the unfortunate victims. Needless to say, breeding animals harboring the predisposing gene should be neutered or spayed.





Self Mutilation :

Feline Psychogenic Alopecia in cats is a "dermatopathy" that results from constant licking of areas of the skin. The cause is unclear , but is believed to be related to anxiety resulting from perceived alterations in the animal's environment, social position, enhanced competition for choice space, and control of food and elimination areas...or any condition involving some or all of these factors. These perceived stressors alter the levels of stress hormones, and other neurogical moderators, such as endorphins, resulting in the behavior. The is a prediliction for this affliction in the more emotional breeds, e.g. Siamese or Abyssinian. Clinical findings range from complaints of excessive grooming to actual areas of chewed hair and skin..leaving unsightly "nubs". Some animals literally pull their hair out! The most common areas are the inside of the thighs, and nearby abdomen and groin. Exposed skin may or may not be inflamed. In some animals, the back..right along the midline is affected. In these animals. when hair regrows it may be a different (darker) color. It is important to realize that these skin patterns mimic the patterns found in other diseases of skin, such as allergic dermatitis, flea bite dermatitis, ringworm and certain hormonal imbalances. Diagnosis requires eliminating the other mentioned caused of alopecia, trichogram (examine residual hairs microscopically for signs of mutilation; hairs should NOT epilate easily). Treatment is controversial. endorphin blockers, progestational hormones and and anxiolytic (anti-anxiety) medications may be tried, along with attempts at applying principles of behavior modification as appropriate for quelling anxiety.

Tail Sucking occurs most frequently in Siamese cats. The end of the tail is wet from continued mouthing/sucking behavior. The skin is otherwise normal. The cause is not clear but seem to be related to boredom, as stimulation often result in complete resolution of the activity (and the tail again looks normal). Treatment is to provide stimulation and obliterate bordom.

Flank Sucking occurs most commonly in Doberman Pinchers. It is believed that this activity is really a form of seizure...a psychomotor seizure. The sides of the abdomen (the "flanks") are bare or partially alopecic. In some respects the appearance of affected dogs resembles that of Follicular Dysplasia of Doberman Pinchers.

Chemotherapy/Radiation Therapy: Various chemotherapy agents inhibit normal, actively growing tissues, such as bone marrow, gastrointestinal and..for the purpose of this discussion..hair follicle development. In such instances, a defluvion exists, hair falls out and is not replaced during and for a period after chemotherapy treatment.

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