Close this window to return to IVIS www.ivis.org Proceeding of the LAVC Latin American Veterinary Conference Oct. 16-19, 2009 Lima, Peru Reprinted in the IVIS website with the permission of the LAVC http://www.ivis.org/
Dr. Peter J. Ihrke SKIN MANIFESTATIONS OF ADVERSE REACTIONS TO FOOD IN THE DOG & CAT FLEA ALLERGY DERMATITIS: STILL THE MOST COMMON SMALL ANIMAL DISEASE ON THE PLANET! DEMODICOSIS: WHAT WE KNOW IN BOTH THE DOG & THE CAT CANINE PYODERMA: THE MOST COMMON CANINE INFECTIOUS SKIN DISEASE MALASSEZIA DERMATITIS : THE OTHER COMMON INFECTIOUS SKIN DISEASE DERMATOPHYTOSIS: STILL UNDERDIAGNOSED & OVERDIAGNOSED! Página 34
CANINE PYODERMA: THE MOST COMMON CANINE INFECTIOUS SKIN DISEASE A.Introduction and General Information 1. Definition - Cutaneous pyogenic or pus-producing bacterial infection 2. Pyoderma - Second only to flea allergy dermatitis in North America, among the most common diseases seen in small animal practice worldwide 3.Frequency of pyoderma in the dog - Much greater than in any other species! a.canine stratum corneum - less efficient barrier to bacteria invasion? b.lack of ostial plug in entrance to canine hair follicle? (Mason) B.Etiology and Pathogenesis 1.Pathogens a.staphylococcus intermedius - Only common primary cutaneous canine bacterial pathogen b.staphylococcus schleiferi Uncommon, can be methicillin & fluoroquinolone resistant c.occasionally secondary colonization by Proteus, Pseudomonas, Escherichia coli, other coliforms d.mixed infections - gram negative organisms colonize areas already invaded by S. intermedius 2.Staphylococcus intermedius - Source of organism a.normal canine hair - contaminant b.normal canine skin - Contaminant or transient, restricted, local colonist c.nares and perianal region - Sites of carriage for Staphylococcus intermedius d.skin - Seeded with Staphylococcus intermedius from the nares and perianal region by grooming behavior in the normal dog and licking in the pruritic dog Página 69
3.Staphylococcus intermedius - Evaluation as a pathogen a.does not possess requisite virulence factors to be a potent pathogen b.therefore, most canine pyoderma is probably associated with underlying disease or other predisposing host factors 4.Predisposing Factors a.pruritus - from any cause b.inflammation - from any cause c.diseases of the hair follicle d.disorders or Cornification e.endocrine diseases - hypothyroidism, hyperglucocorticoidism (naturally occurring and iatrogenic) f Poor grooming - especially in long coated dogs g. Immunologic defects - especially T-lymphocyte function 5.Negative Prognostic Factors a.coexisting diseases (especially follicular) 1.Seborrhea/cornification defects 2.Hypothyroidism and other endocrine disorders 3.Pruritic diseases - flea allergy dermatitis, atopy, food allergy, etc. 4.Coexisting diseases that require chronic corticosteroid or cytotoxic therapy - Autoimmune diseases (lupus erythematosus, bullous diseases), neoplasia b.pruritus Primary or Secondary? 1.Presence or absence of pruritus is a key feature in the prioritization and differentiation of underlying causes of recurrent pyoderma 2.Key determining feature - pruritus remains or disappears after antibiotic therapy. If pruritus remains, look for underlying pruritic skin disease. c.immunologic incompetence Página 70
d.improper initial antibiotic therapy - improper choice, dosage, duration C.Pyoderma Site Predilections 1.Intertriginous areas - groin, axilla, interdigital 2.Pressure points (calluses)- stifle, elbow, hocks 3.Anatomic defects - skin folds D.Classification of Canine Pyoderma by Depth of Involvement most useful clinically since the deeper the level of infection, the more likely underlying causes are present, and the more aggressive the clinician must be both diagnostically and therapeutically 1.Surface pyoderma a.acute moist dermatitis (hotspots, pyotraumatic dermatitis) b.intertrigo (skin fold pyoderma) 1. Lip fold 3. Vulvar fold 5. Obesity fold 2. Facial fold 4. Tail fold 6. Generalized c. Mucocutaneous pyoderma 2. Superficial pyoderma a. Impetigo (non-follicular pustules) b. Superficial folliculitis (follicular pustules) c. Superficial spreading pyoderma (intra-corneal splitting) 3. Deep pyoderma a. Deep folliculitis and furunculosis - many clinical subgroupings: canine acne, callus pyoderma, interdigital pyoderma, generalized deep folliculitis & furunculosis b. Cellulitis Página 71
E.Appropriate Initial Management of Canine Pyoderma 1.Preliminary investigation for obvious predisposing factors 2.Systemic antibiotic therapy - required for successful management of most pyoderma 3.In deep pyoderma, or if immunodeficiency is suspected or confirmed as an underlying cause of disease - the selection of a bactericidal is indicated. 4.Topical antibacterial shampoo therapy - beneficial adjunct 5.Antibacterial whirlpools or soaks - deep pyoderma F.Investigation for Obvious Predisposing Factors 1.History & Physical Examination Can all of the history and clinical features be explained just by pyoderma alone? 2.Pruritus Present or absent? If present, is the pruritus due to an underlying disease or is it caused by the pyoderma? 3.Is there any clinical evidence of underlying disease? G.Diseases That Most Commonly Predispose to Pyoderma 1.Non-parasitic allergic diseases - (canine atopic dermatitis, food allergy) 2.Parasitic allergic diseases - (flea allergy dermatitis, scabies, cheyletiellosis) 3.Demodicosis 4.Endocrine diseases - (hypothyroidism, hyperglucocorticoidism - primary or iatrogenic) 5.Diseases of Cornification - (primary keratinization defects, secondary "seborrhea") 6.Other infectious skin diseases - (Malassezia dermatitis, dermatophytosis) 7.Genodermatoses - follicular dysplasia, color dilution alopecia, sebaceous adenitis) 8.Occult neoplasia - (solar-induced squamous cell carcinoma Página 72
H.Principles of Effective Systemic Antibiotic Therapy 1.Choice of the proper antibiotic 2.Establishment of an effective dosage 3.Maintenance of the therapy for long enough to insure cure I.Antibiotics - Culture & Sensitivity Studies 1.Multiple studies world-wide - Documented sensitivity and resistance patterns of Staphylococcus intermedius 2. Antibiotics - resistance frequent - penicillin, ampicillin, amoxicillin, tetracycline and non potentiated sulfonamides (North America, European community) 3. Studies (England) - Multi-resistant Staphylococcus intermedius and gram-negative isolates seen more commonly in referral practices than in general practice, resistant bacterial populations most frequently in deep pyoderma (Noble & Kent) J.Antibiotic Selection - Personal Preferences 1. Basis - perceived efficacy, spectrum of activity, drug distribution, safety, lack of side effects, cost, route of administration and required dosing frequency 2.Preferred narrow spectrum antibiotics - erythromycin, lincomycin and oxacillin 3.Preferred broader spectrum antibiotics - cephalexin, enrofloxacin, marbofloxacin, cefpodoxime, cefadroxil, ormetroprim-potentiated sulfonamides 4.Owner compliance - not well studied in veterinary medicine, drugs that need only be given once or twice daily have distinct advantages, enrofloxacin, marbofloxacin, cefpodoxime, ormetoprim-potentiated sulfadimethoxine, clindamycin (once daily antibiotics); cephalexin, cefadroxil, lincomycin, amoxicillin with clavulanate? (twice daily antibiotics) K.-Empirical Narrow Spectrum Drugs of Choice Isoxazolyl penicillins - Oxacillin, (others - cloxacillin, dicloxacillin, nafcillin) Lincosamide group - Lincomycin (Lincocin R ),(others - Clindamycin - Antirobe R [SID]) Macrolide group - Erythromycin (others - tylosin) Página 73
L.Empirical Broad Spectrum Drugs of Choice Diaminopyrimidine-potentiated sulfonamides - a.trimethoprim-potentiated sulfonamides - (diaminopyrimidine-potentiated sulfonamides using trimethoprim - SDZ/TMP, (veterinary Tribrissen R ), SMX/TMP (human Bactrim R, Septra R ) b.ormetroprim-potentiated sulfonamides - (diaminopyrimidine-potentiated sulfonamide using ormetoprim - SDM/OMP (vet. Primor R ) c.bacquiloprim-potentiated sulfadimethoxine (vet. Zaquilan R ) Aminopenicillin and B-lactamase inhibitor - Clavulanic acid-potentiated amoxicillin (Clavamox R ) First generation (group two) oral Cephalosporins - (cephalexin, cefadroxil (veterinary - Cefa-tabs R available in some countries), cephradine) Third generation (group five) oral Cephalosporins - (cefpodoxime - Simplicef TM ) Fluoroquinolones - (veterinary - enrofloxacin (Baytril R ), marbofloxacin (Zeniquin R, Marbocyl R ), orbifloxacin (Orbax R ), difloxacin (Dicural R ) M.Antibiotics Usually Ineffective in Empirical Treatment 1.Penicillin 2.Ampicillin 3.Tetracycline 4.Sulfonamides 5.Amoxicillin N.Establishment of an Effective Antibiotic Dosage 1.All dogs should be weighed 2.Older antibiotics Many dosages are empirical 3.New flexible dosage ranges Very useful Página 74
4.Required dosages vary between superficial and deep pyoderma. Deep pyoderma can require much higher dosages. O.Maintain Therapy for Long Enough to Insure Cure 1.Superficial pyoderma Minimum of 3 weeks, at least one week beyond clinical cure 2.Deep pyoderma Minimum of 6 weeks, at least 2 weeks beyond apparent clinical cure. 3.Remember that in deep pyoderma, surface lesions heal before deep lesions! P.Antibacterial Shampoo Therapy 1.Antibacterial Shampoo - alternative to systemic antibiotics in some surface pyoderma and as an adjunct in the management of superficial and deep pyoderma 2.Additional benefits - simple cleansing, removal of inflammatory products and other debris, may reduce pain and pruritus, improvement in patient attitude and owner encouragement 3.Minimum of 10 minutes of shampoo contact time. 4.Frequency - minimum of once weekly, twice weekly is advantageous but time consuming 5. Deep pyoderma - in conjunction with clipping and whirlpools or soaks 6. Active agents - benzoyl peroxide, benzoyl peroxide and sulfur, chlorhexidine, ethyl lactate or triclosan Q.Antibacterial Soaks and Whirlpools 1.Especially beneficial for deep pyoderma - cleansing and gentle debridement 2.Dogs should be close clipped and shampooed and then either soaked or whirlpooled in warm water containing antibacterials such as povidone-iodine or chlorhexidine 3.Foot soaks - pedal folliculitis and furunculosis 4. Whirlpool - agitation provided by a whirlpool is superior to simple soaking (if feasible) 5.Labor intensive - hospitalized dogs benefit from daily or twice daily treatment for 15 to 30 minutes R.Compliance Página 75
1.The study of recommended therapy versus delivered therapy 2.Compliance is well studied in human medicine and poorly studied in veterinary medicine. 3. One study in human medicine indicated that 40% of prescriptions are never filled! 4.Another study in human medicine indicated that up to 40% of prescriptions are taken incorrectly! 5.Client education increases compliance S.Assessment of Response to Therapy 1.All dogs receiving systemic antibiotics should be re-evaluated within 14 to 21 days 2.If substantial improvement is not noted - clinician should re-evaluate therapy and various factors complicating management (owner compliance, inadequate dosage through vomition, inactivation by food or malabsorption) 3.If owner compliance or patient factors have not led to drug failure - the clinician should reevaluate the choice of the antibiotic 4. If the causes of treatment failure are not found, the clinician should address factors that can complicate successful management and re-evaluate the possibility of underlying disease 5.Clinicians should always maintain the flexibility to consider the possibility that their initial diagnosis of pyoderma was incorrect! 6.- Referral to a veterinary dermatologist should be considered as an option each time that clinical failure occurs T.Treatment Failure in Pyoderma 1.Inadequate antibiotic dosages 2.Inadequate duration of therapy 3.Choice of the wrong antibiotic 4.Inadequate owner compliance 5.Failure to diagnose underlying disease 6.Failure to successfully address underlying disease 7.Incorrect diagnosis! Página 76
U.Recurrent Pyoderma 1.- A pyoderma that responds completely to appropriate therapy leaving the dog either normal or apparently normal, and then recurs.. 2.- Recurrent pyoderma can be extremely frustrating and challenging - Always consider the option of early referral! 3.- Many similarities exist between recurrent pyoderma and recurrent Malassezia dermatitis. V.General References DeBoer DJ: Management of chronic and recurrent pyoderma in the dog. In: Bonagura JD (ed): Kirk's Current Veterinary Therapy XII. Philadelphia, WB Saunders, 1995, pp 611-617. Ihrke PJ: Bacterial infections of the skin. In: Greene CE (ed): Infectious Diseases of the Dog and Cat, Third Edition, Philadelphia, WB Saunders Co, 2006, 807-815. Ihrke PJ: Bacterial Skin Disease in the Dog: A Guide to Canine Pyoderma. Veterinary Learning Systems. 1996, pp 1-97. Mason I, Moriello K: Management of infectious disorders. In: Moriello K, Mason I (eds): Handbook of Small Animal Dermatology. Pergamon, 1995, pp 287-294. Scott DW, Miller WH, Griffin CE: Muller and Kirk's Small Animal Dermatology. 6th edition, W. B. Saunders Company, Philadelphia, 2001, pp 274-308. Gross TL, Ihrke PJ, Walder EJ, Affolter VK: Skin Diseases of the Dog and Cat: Clinical and Histopathologic Diagnosis. Blackwell, Oxford, pp 222-225, 4-9, 406-410, 420-435, 2005. Página 77
ORAL ANTIBIOTICS USEFUL IN CANINE DERMATOLOGY 2009 Peter J. Ihrke Drug Name Advantages Disadvantages Assessment Dose mg/kg Erythromycin inexpensive, cross Rz with lincomycin older empirical (10-15 mg q8h) narrow spectrum vomiting & diarrhea common, choice, 3x daily too many GI signs Lincomycin 2x daily, cross Rz with erythromycin reasonable first (22 mg q12h) narrow spectrum relatively expensive empirical choice, especially if need q12h drug Ormetoprim - 1x daily, relatively expensive, good empirical sulfadimethoxine broad spectrum, side effects - kerato- choice esp. if need (27.5 mg q24h) useful for MRSA conjunctivitis sicca, q24h drug, MRSA suppressed thyroid function, cutaneous drug reactions Cephalexin, 2x daily, cefadroxil - expensive excellent choice, Cefadroxil broad spectrum, all pyoderma, (22-33 mg q12h) resistance is uncommon, q12h drug good tissue penetration Enrofloxacin 1x daily, broad spectrum, expensive, excellent choices, (5 15+ mg q24h) rapidly absorbed, cannot use in growing dogs refractory/recurrent Marbofloxacin excellent tissue penetration deep pyoderma, (3 10 mg q24h) Pseudomonas otitis q24h drug Cefpodoxime 1x daily, broad spectrum somewhat expensive excellent choice, 5-10mg q24h rapidly absorbed all pyoderma q24h drug Oxacillin narrow spectrum, very expensive, 3x daily, good choice for (22 mg q8h) resistance uncommon, food interferes with absorption deep pyoderma side effects rare give 1 hour before feeding Amoxicillin-clavulanate broad spectrum, expensive, moisture efficacy does not (12.5-20mg q12 or 8h?) side effects rare sensitive. In vivo effect warrant expense? not as good as would be deep pyoderma predicted?, slow response? Trimethoprim - inexpensive, 2x daily side effects - kerato- good for MRSA sulfonamides broad spectrum conjunctivitis sicca, concern about (22 mg q12h) useful for MRSA severe cutaneous drug drug reactions reactions (E.M., T.E.N.), Chloramphenicol inexpensive, resurgence idiosyncratic aplastic anemia good for MRSA, (45mg q8h) of interest - MRSA in humans diminished use, caution owners gastrointestinal side-effects hepatic necrosis, suppressed Página 78