Paw & Nail Disorders
This condition, which is suspected to be immune mediated, causes nail loss. It is uncommon to rare in dogs, with the highest incidence report in young adult to middle-aged dogs. German shepherds and rottweilers may be predisposed. Usually, an acute onset of nail loss occurs. Initially, 1 to 2 nails are lost, but over the course of a few weeks to several months, all nails slough. Replacement claws are misshapen, soft or brittle, discolored, and friable and usually slough again. Affected paws are often painful and pruritic.
- Diagnosis- Rule out other differentials such as fungal and bacterial nailbed infection, food allergy autoimmune skin disorders, drug eruption and vasculitis.
- Treatment- Systemic antibiotics for at lest 6 weeks if secondary infection present. New nails should be trimmed frequently (approx every 2 weeks), daily oral fatty acid supplementation. Sometimes other drugs are required. Prognosis for nail regrowth is good, although some nails may remain deformed or friable. In some dogs, therapy can be successfully discontinued after 6 months. In others, long-term maintenance therapy is necessary to maintain remission.
Bacterial & Fungal (yeast) Infections
Bacterial Claw Infections
Are almost always secondary to an underlying cause. When one claw is affected, previous trauma should be suspected. When many claws are infected, underlying conditions to be ruled out include hypothyroidism, cushings, allergies, autoimmune disorders, symmetrical lupoid onchyodystrophy, and neoplasm. Affected claws are often fractured and oozing with associated paronychia, toe swelling, and pain.
- Diagnosis- Ususally based on history, clinical findings, and ruling out other differentials. Cytology, culture and occasionally x-rays.
- Treatment- Underlying cause should be identified and corrected. Any loose nails or fractured portions of traumatized nails should be removed. Long term antibiotics should be continued at least 2 weeks beyond complete clinical resolution. Antibiotic selection should be based on culture results. Topical foot scrubs or soaks may be recommended. Prognosis for nail regrowth is good.
Fungal Nail Infections
Are usually caused by dermatophytes, although isolated cases of nail infection from other fungi have been reported. Typically only one or two nails are affected. These infections are rare in dogs and cats. Secondary yeast paronychia is common in allergic dogs.
- Diagnosis- Rule out other differentials, fungal cultures, biopsy.
- Treatment- Any loose or sloughing nails should be removed. For true nail infections long term antifungal therapy should be administered at least 1-3 months beyond complete nail regrowth. Frequent nail trims should be performed to remove infected portions. Trimmings should be submitted for follow up fungal cultures and treatment continued until culture results are negative. Foot soaks and topical treatments may be recommended. Prognosis is guarded to fair. Many dogs have incomplete resolution in spite of aggressive antifungal therapy. In these cases, amputation or long-term, low dose therapy with antifungals may be needed.
Acral Lick Dermatitis (Acral Lick Granulomas)
Is first noted as excessive, compulsive licking at a focal area on a limb, resulting in a firm, proliferative, ulcerative, alopecic lesion. The causes of the licking are multifactoria, and, although environmental stress (eg, boredom, confinement, loneliness, separation anxiety) may be a contributor, other factors are usually more important. Such as, hypersensitivity (food and environment), fleas, trauma (cut, bruise), foreign body reaction, infection, demodicosis, hypothyroidism, neuropathy, osteopathy & arthritis. The lesion usually begins as a small area of dermatitis that slowly enlarges because of persistent licking. The affected area becomes alopecic, firm, raised, thickened, and plaque like to nodular, and it may be eroded or ulcerated. With chronicity, extensive fibrosis, hyperpigmentation, and secondary infection are common. Lesions are usually single but may be multiple and are most often found on the lower leg.
- Diagnosis- Usually based on history, clinical findings and ruling out other differentials. Biopsy and cultures are often helpful tools.
- Treatment- Underlying causes should be identified and corrected. Treat secondary infections with long term antibiotics for minimum 6-8 weeks and as long as 4-6 months in some dogs. Mechanical barriers such as wire muzzles, and Elizabethan collars may be helpful. When no underlying cause can be found, treatment with behavior-modifying drugs may be beneficial to some dogs. Surgery is not recommended because postoperative complications, especially wound dehiscence (re-opening) are common. Prognosis is variable, chronic lesions that re unresponsive or extensively fibrotic and those for which no underlying cause can be found have a poor prognosis for resolution. Although this disease is rarely life threatening, its course may be intractable(hard to treat, relieve, or cure).
Canine food hypersensitivity is an adverse reaction to a food or food additive. It can occur at any age, from recently weaned puppies to elderly dogs that have been eating the same food for years. Approximately 30% of dogs diagnosed with food allergy are younger than 1 year of age. It is common in dogs. Canine food hypersensitivity is characterized by nonseasonal pruritus that may or may not respond to steroid therapy. This pruritus (itching) may be regional or generalized and usually involves the feet, ears, inguinal or axillary areas, face, neck and perineum. Affected skin is often Erythematous, and popular rash may be present. Secondary superficial Pyoderma (skin infections), yeast dermatitis, and Otitis externa are common. Other symptoms that may be seen are acral lick dermatitis, chronic seborrhea, and recurring pyotraumatic dermatitis. Some dogs are minimally pruritic, with only symptom being recurrent infection with Pyoderma, yeast infections or Otitis. In these cases, the pruritus is present only when secondary infections are left untreated. Concurrent gastrointestinal signs (frequent bowel movements, vomiting, diarrhea, gas are reported in 20-30% of cases).
- Diagnosis- Intradermal or serologic (blood) allergy testing is not recommended because test results are unreliable. Response to hypoallergenic diet trial, symptoms improve within 10-12 weeks of initiation of a strict home-cooked or commercially prepared restricted diet (one protein and one carbohydrate). The hypoallergenic diet should not contain food ingredients previously administered in dog food, treats, or table scraps. Nor should flavored heartworm preventative, flavored mediations, nutritional supplements, or chewable treats (pigs ears, cows hooves, rawhides, dog biscuits, table food such as cheese or peanut butter to hide pills in) be used during trial.
- Treatment- Any secondary infections (bacterial, yeast), Otitis externa should be treated Controlling secondary infection is an essential component of managing food allergic dogs. A flea-control program should be instituted to prevent flea bites from aggravating the pruritus. Food trial identifying offending substances to avoid. Prognosis is good. In dogs that are poorly controlled, owner noncompliance should be ruled out, along with development of hypersensitivity to an ingredient in hypoallergenic diet, secondary infection, scabies, demodicosis, atopy, flea allergy, dermatisis, and contact hypersensitivity.
Thickening of Paws
Zinc Responsive Dermatosis
Is a zinc deficiency induced disorder of keratinization. An inherent diminished ability to absorb zinc from the intestinal tract, a diet low in absolute zinc concentration, or mineral antagonisms that prevent zinc absorption from the food can cause zinc deficiency. Crusting, scaling, erythema, and alopecia typically develop around the eyes and mouth; the muzzle, nasal planum, ear flaps, and genitalia may also be involved. Hyperkeratotic or thick, crusty plaques may be present on the elbows, stifles, and other pressure points, and at sites of trauma. The footpads may be hyperkeratotic and fissured. Lesions may be asymmetrical and mildly to moderately pruritic in some dogs. Secondary bacterial and yeast skin infections are common. Concurrent depression, anorexia, lymphadenomegaly, and pitting edema of the distal extremities may be seen. Severely affected puppies may have stunted growth.
- Diagnosis- Rule out other causes, biopsy and of course response to zinc therapy.
- Treatment- Any secondary infections should be treated with appropriate therapy. Dog with diet induced zinc deficiency, the dietary imbalance should be identified and corrected. Zinc supplementation may be needed in some dogs, either initially for the first few weeks of the dietary change, or lifelong if there is a diminished ability to absorb zinc. Concurrent symptomatic therapy with warm water soaks, antiseborrheic shampoos and topical applications of ointments on the lesions may be helpful. Intact females who are not well controlled with zinc supplementation should be spayed because estrus may exacerbate the disease. Prognosis is good for most dogs, although life long zinc supplementation is sometimes needed.
Is a unique skin disease in animals that have chronic liver disease or glucagons-secreting pancreatic tumors. The exact pathogenesis is unknown, it is uncommon in dogs and rare in cats, with the highest incidence in older animals. Among dogs, shetland sheep dogs, West Highland White Terriers, cocker spaniels, and Scottish terriers may be predisposed. Skin lesions are characterized by minimally to intensely pruritic, bilaterally symmetrical erythema, scaling, crusting, erosions, and ulcers on the distal limbs and around the mouth and eyes. Lesions may also involve the ear pinnae, elbows, hocks, external genitalia, ventrum, and oral cavity. The footpads are usually mildly to markedly hyperkeratotic, fissured, and ulcerated. Lameness secondary to footpad lesions may be evident. Increase in drinking and urination may be present if there is concurrent diabetes mellitus. Otherwise, system signs of underlying metabolic disease are rarely evident at initial presentation but usually become apparent a few to several months later.
- Diagnosis- Blood testing looking for anemia may be present, liver failure, hyperglycemia Ultrasound of abdomen looking for evidence of liver disease, biopsy of liver, skin biopsy.
- Treatment- Secondary infections should be treated, if the underlying cause is a respectable glucagonoma, surgical excision of the tumor is curative. If the underlying problem is liver disease, its cause should be identified and corrected, to symptomatically improve liver function, with antioxidants may be helpful. Amino Acid supplements may be helpful. Symptomatic topical therapies may help improve skin lesions. Prognosis for animals with chronic hepatic disease or metastatic pancreatic neoplasia is poor, and survivial time after the onset of skin lesions may be only a few months.
Is an autoimmune skin disease that is characterized by the production of autoantibodies that attack the skins ability to stay attached. Pemphigus Foliaceus is probably the most common autoimmune skin disease in dogs and cats. Any age, sex, or breed can be affected. Pemphigus Foliaceus is usually idiopathic, but some cases may be drug induced, or it may occur as a sequela to a chronic inflammatory skin disease. The primary lesions are superficial pustules. However, intact pustules are often difficult to find because they are obscured by trhe hair coat, are fragile and rupture easily. Secondary lesions include superficial erosions, crusts, scales, epidermal collarettes, and alopecia. Lesions on the nasal planum, ear pinnae, and footpads are unique and characteristic of autoimmune skin disease. The disease often begins on the bridge of the nose, around the eyes, and on the ear pinnae, before it becomes generalized. Nasal depigmentation frequently accompanies facial lesions. Skin lesions are variably pruritic and may wax and wane. Footpad hyperkeratosis is common and may be the only symptom in some dogs and cats. With generalized skin disease, concurrent lymphadenomegaly, limb edema, fever, anorexia, and depression may be present.
- Diagnosis- Rule out other differentials. Biopsy is the only way to diagnose the disease.
- Treatment- Symptomatic shampoo therapy to remove crusts may be helpful. Treat any secondary infections. Immunosuppressive drugs are given over a couple of months with a decreasing dosage to get to the lowest possible effective dose. Prognosis is fair to good. Although some animals remain in remission after immunosuppressive therapy is tapered and discontinued, most animals require lifelong therapy to maintain remission. Regular monitoring of clinical signs and blood testing with treatment adjustments as needed is essential. Potential complications of immunosuppressive therapy include unacceptable drug adverse effects and immunosuppression-induced bacterial infection, demodex, or dermatophytosis.
Viral Flat Papilloma (Flat Warts)
Canine papillomavirus is characterized by benign tumors induced by infection of epithelial cells by species-specific DNA papillomaviruses. Viral oncogenes induce host epithelial cell growth and division and cause chromosomal instability and mutations. Papillomaviruses are transmitted by direct and indirect contact, with an incubation period of 1-2 months in the mouth and 6-12 months on the skin before regression occurs. Cellular immunity is key to papilloma regression; immunosuppressive conditions (including feline immunodeficiency virus in cats and immunosuppressive medications may exacerbate and prolong infection). At lest five types of canine papillomavirus and up to eight types of feline papillomavirus have been identified; each has a distinct clinical presentation or site of infection.
Canine Footpad Papilloma (Wart)
This is an infrequently reported disease of adult dogs that has not been consistently demonstrated to have a viral cause. Lesions are firm, hyperkeratotic masses on multiple footpads. Interdigital lesions have been described in Greyhounds. Lameness and secondary bacterial infection may occur.
- Diagnosis- By Biopsy.
- Treatment- Most papillomavirus infections regress spontaneously after development of host cell-mediated immune response. Surgery may be curative for persistent solitary lesions, but care should be taken with tissue handling to avoid seeding the surgical site with viral particles. Cryotherapy and laser ablation are often effective, but they may need to be repeated. Oral medications, subcutaneous injections or topical creams may be prescribed in certain cases. Prognosis is usually good, as most cases will spontaneously regress.
Famillal Footpad Hyperkeratosis
Hyperkeratosis is a familial disorder that results in severe digital hyperkeratosis by 5-6 months of age. It is rare in dogs, with the highest incidence in Irish terriers, Dogues de Bordeaux, and Kerry blue terriers. An autosomal recessive mode of inheritance is suspected in Irish terriers. At birth, the footpads appear to be normal, but by 4-6 months of age, affected dogs begin to develop marked hyperkeratotic, thickened, hard, and cracked footpads. The entire surface of all footpads are involved, and the subsequent information of horny growths, expanding fissures, and secondary bacterial infection usually results in severe, intermittent lameness. No other skin involvement occurs, but concurrent abnormal nail development, characterized by slightly faster growth and round profiles instead of the normal U-shaped ones, may be seen in Irish terriers.
- Diagnosis- Rule out other differentials, and performing biopsy.
- Treatment- No specific treatment is known, but treatments as for idiopathic nasodigital hyperkeratosis may be effective. Symptomatically treat with daily foot soaks prescribed by doctor and frequent filing of the footpads to remove surplus keratin. Significant improvement should be seen within 5 days, but life long maintenance therapy is required for control. For fissured lesions, a cream may be recommended and systemic antibiotics for 3-4 weeks if footpads are secondarily infected. Fast-growing nails should be trimmed frequently. Prognosis for cure is poor, but most dogs enjoy a good quality of life with routine symptomatic therapy. Affected dogs should not be bred.
Idiopathic Nasodigital Hyperkeratosis
Is an idiopathic (unknown cause) condition that is characterized by the excessive formulation of nasal or footpad keratin. It is common in older dogs. Thickened, hard, dry keratin accumulates on the top of the nose, footpads, or both. The accumulated keratin is usually most prominent on the top of the nose and at the edges of the footpads. Nasolacrimal (tear) duct blockage may present a contributing factor. Affected dogs are otherwise healthy and have no other skin signs.
- Diagnosis- Is made by ruling out other medical problems such as Zinc deficiency, distemper, pemphigus foliaceus and discoid lupus and others.
- Treatment- The intensity of therapy depends on the severity of the lesions. Tear ducts should be flushed. For mild, asymptomatic cases, no treatment may be appropriate. For moderate to severe cases, affected areas should be hydrated and a softening agent will be prescribed.
- Prognosis- Is good. Although it is incurable, this is a cosmetic disease that can usually be managed symptomatically.
The etiopathogenesis is unclear, but one hypothesis is that sterile pedal furunculosis is a persistent, immune –mediated, inflammatory response to keratin and triglycerides liberated from ruptured hair follicles, sebaceous glands, and the panniculus. The condition is thought to develop after the initiating cause of the furunculosis (e.g., mechanical, infectious, parasitic, allergic) has been resolved. It is uncommon in dogs, with short-coated breeds possibly predisposed. Canine pedal furunculosis manifests as single to multiple, erythematous papules; firm to fluctuant nodules; or bullae of 1 foot or more that appear in the interdigital areas. The lesions may be painful or pruritic, may ulcerate, may develop draining tracts with serosanguineous or purulent exudates, and , with chronicity, may become fibrotic. Lesions spontaneously resolve, was and wane, or persist indefinitely. Regional lymphadenopathy is common, but no systempic signs of illness are noted. Secondary bacterial and yeast infections are common.
- Diagnosis- Based on history, clinical finding and ruling out other differentials. Cytology (aspirate of nodule or nonruptured bulla), biopsy, cultures.
- Treatment- The clinician should make sure that the initiating cause of the furunculosis (eg, food allergy, wet environment, dirt kennels, friction in short-coated breeds) has been identified and corrected. Secondary infections should be treated with antibiotics or antifungas. For solitary lesions, surgical excision or laser ablation may be curative. Topical ointments may be prescribed. The prognosis is good to fair. Lifelong medical therapy may be needed to maintain remission, and interdigital fibrosis may be a permanent sequela in chronic cases.
Interdigital Deep Pyoderma (Bacterial Pododermatitis-paw infection)
Bacterial Pododermatitis is a deep bacterial infection of the feet that almost always occurs secondary to some underlying factor (Foreign body, parasite, fungus, food allergy, atopy, hypothyroidism, Cushings, trauma from stones, stubble, gravel, sands, autoimmune and immune-mediated skin disorders). It is common in dogs and rare in cats. One or more feet may be affected by interdigital erythema, pustules, papules, nodules, hemmorhagic bullae, fistulae, ulcers, alopecia, or swelling. Pruritus (licking, chewing), pain, or lameness may be present. Regional lymphadenomegaly is common. Occasionally, pitting edema of the associated metatarsus or metacarpus is seen.
- Diagnosis- Rule out other differentials, cytology, biopsy and culture.
- Treatment- Any underlying cause should be identified and corrected. Systemic antibiotics long term, adjunctive topical therapy can be helpful. Foot trauma should be minimized by having the dog confined indoors, leash-walked, and kept away from rough surfaces. Fusion podoplasty, whereby all diseased tissue is removed and digits are fused together, is a radical surgical alternative that is available for severe cases. The prognosis is good to guarded, depending on whether the underlying cause can be identified and corrected. In severe and chornic cases, permanent fibrosis and scarring may contribute to future relapses by predisposing feet to traumatic injury.
Lymphocytic Plasmocytic Pododermatitis
This disease is characterized by swollen paws, usually all four paws are involved. The paws are red, have hair loss, painful with no other areas of the body involved. Skin biopsies reveal a tissue infiltrated with lymphocytes and plasma cells. The cause is unknown, there is no response to antibiotics. There is marked clinical improvement with long term immunosuppressive drug therapy.