Title: Equine Dermatology
1 Equine Dermatology
2What are the major causes of Nodules?
3What are the major causes of Nodules?
- Inflammatory
- Parasites
- Collagenolytic Granulomas/Eosinophilic Granulomas
- Habronema
- Hypoderma
- Tick bite granulomas
- Infections (Fungal/Fungal-like)
- Sporotrichosis
- Phaeophymycosis
- Eumycotic mycetomas
- Zygomycosis
- Other mycoses (dermatophyte kerion, blasto,
crypto) - Pythiosis
4What are the major causes of Nodules?
- Inflammatory
- Infections (Bacterial)
- Furunculosis
- Dermatophilosis
- Ulcerative lymphangitis (Corynebacterium
pseudotuberculosis) - Actinomycosis
- Nocardiosis
- Abscesses
- Mycobacterial infections (TB)
- Glanders
5What are the major causes of Nodules?
- Inflammatory
- Viral
- Vaccinia
- Immunologic
- Urticaria
- Erythema multiforme
- Amyloidosis
6What are the major causes of Nodules?
- Inflammatory
- Miscellaneous
- Dermoid/follicular cysts
- Eosinophilic granulomas
- Axillary nodular necrosis
- Unilateral papular dermatosis
- Exuberant granulation tissue
- Panniculitis
- Hematoma
- Foreign body granulomas
7What are the major causes of Nodules?
- Neoplastic
- Papilloma
- Aural plaque
- Squamous cell carcinoma
- Sarcoid
- Melanoma/melanocytoma
- Mast cell tumor
- Basal cell tumor
- Fibroma/fibrosarcoma
- Hemangioma/hemangiosarcoma
- Lipoma
- Lymphoma
- Malignant fibrous histiocytoma
8What are the basics of diagnosis?
9What are the basics of diagnosis?
- Signalment
- History
- Location and progression of the lesions(s)
- Cytology/FNA
- Biopsy (histopath, bacterial fungal culture)
1023 yr Percheron Gelding
11chief complaint nodules on penis and prepuce
12Differential diagnosis?
13Differential diagnosis
- Melanomas
- Inflammatory granulomas
14Diagnostic Plan
- Fine Needle Aspirate
- Biopsy
- Abdominal palpation/ultrasound exam for evidence
of metastasis
15Clinical Management
- Observation
- Cimetidine 5 mg/kg q 12 hrs for gt 3 months
- ? intratumoral chemotherapy with cisplatin
- ? immunotherapy with BCG
166 yr AQHA Mare Ulcerated nodule at medial canthus
17 Differential diagnosis?
18 Differential diagnosis
- Inflammatory
- Habronema
- Fungal (histo, sporo)
- Post injury exuberant granulation tissue
- Neoplastic
- Sarcoid
- Squamous cell carcinoma
- Basal cell carcinoma
- Mast cell tumor
19Diagnostic Plan
- Impression smear cytology
- Biopsy
- Histopath
- Fungal bacterial culture
20Results
- Cytology
- Numerous eosinophils and macrophages
- Histopath
- Eosinophilic dermatitis with intralesional larvae
21Clinical Management
- Corticosteroids to decrease inflammation
- 600 mg pred daily x 10 days then 300 mg daily for
another 10-14 days - Fly mask to protect from flies
- Ivermectin orally
- Topical corticosteroid-antibiotic ointment or
cream (ophthalmic)
228 yr AQHA Gelding
23 Differential diagnosis?
24 Differential diagnosis
- Inflammatory
- Habronema
- Fungal (histo, sporo)
- Post injury exuberant granulation tissue
- Neoplastic
- Sarcoid
- Squamous cell carcinoma
- Basal cell carcinoma
- Mast cell tumor
25Diagnostic Plan
- Impression smear cytology
- Biopsy
- Histopath
- Fungal bacterial culture
26Fibroblastic Sarcoid
- Probable viral etiology (related to bovine
papillomaviruses) - Types
- Verrucous (wart-like)
- Fibroblastic (proud flesh-like)
- Mixed
- Occult (flat)
27Management Options
- Cyrosurgery
- CO2 Laser Surgery
- Intralesional cisplatin
- Intralesional BCG
- Topical Imiquimod (Aldara)
- Topical XXTERRA (bloodroot ZnCl)
2814 yr Paso Fino Mare
29Presenting Complaint
- Inspiratory stridor
- Mass in right nostril
- Also has partial alopecia over withers and
thickening of skin in that region
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31Differential diagnosis?
32Differential diagnosis
- Inflammatory
- Bacterial infections
- Fungal infections
- Amyloidosis
- Neoplastic
- Lymphosarcoma
- Fibroma/fibrosarcoma
- Mast cell tumors
33Diagnostic Plan
- Impression smears/FNA
- Biopsies
- Histopath
- Bacterial Fungal Cultures
34Amyloidosis
- May be primary or secondary to chronic infections
- Primary is most likely when the skin and upper
respiratory tract are affected - Fibrils are composed of AL amyloid (monoclonal
immunoglobulin light chains)
35Amyloidosis Clinical Management
- Treat secondary infections
- Surgical excision of nodules interfering with
respiration - ? Topical DMSO (may promote amyloid degradation)
3610 yr AQHA gelding
37Differential Diagnoses?
38Differential Diagnoses
- Inflammatory
- Bacterial granulomas
- Dermatophyte kerions
- Warbles
- Tick bite granulomas
- Erythema multiforme
- Dermoid/follicular cysts
- Eosinophilic granulomas
- Collagenolytic granulomas
- Panniculitis
39Differential Diagnoses
- Neoplastic
- Basal cell tumors
- Hair follicle tumors
- Mast cell tumors
40Diagnostic Plan
- FNA
- Biopsy
- Histopath
- Bacterial fungal cultures
41Histopath
- Multiple foci of collagenolysis
- Inflammatory infiltrate is predominantly
eosinophilic - No larval fragments
42Collagenolytic Granulomas/Eosinophilic Granulomas
- Most common in spring summer
- Most common on back, withers and neck
- Not painful or pruritic
- Likely a consequence of fly or mosquito bites
43Clinical Management
- Observation
- Surgical excision
- Sublesional injections of triamcinolone acetonide
(3-5 mg/lesion) repeated q 2 wks for max of 3
times - Fly mosquito control (fly sheets/repellants)
4424 yr AQHA gelding
45Differential Diagnosis?
46Differential Diagnoses
- Inflammatory
- Bacterial granulomas (dermatophilosis)
- Dermatophyte kerions
- Warbles
- Tick bite granulomas
- Erythema multiforme
- Dermoid/follicular cysts
- Eosinophilic granulomas
- Collagenolytic granulomas
- Panniculitis
47Differential Diagnoses
- Neoplastic
- Basal cell tumors
- Hair follicle tumors
- Mast cell tumors
- Sarcoids
-
48Diagnostic plan
- Impression smears/FNA
- Biopsies
- histopathology
- Fungal and bacterial culture
49Cytology
50Dermatophilosis Clinical Management
- Keep dry
- Remove crusts (2-4 chlorhexidine shampoo)
- Chlorhexidine cream or spray daily
- If does not resolve with topical treatment
systemic penicillin or oral TMS until lesions
resolve
5112 yr Clydesdale gelding
52Differential Diagnosis?
53Differential Diagnoses
- Inflammatory
- Bacterial granulomas
- Fungal granulomas/dermatophyte kerions
- Tick bite granulomas
- Eosinophilic/collagenolytic granulomas
54Differential Diagnoses
- Neoplastic
- melanocytomas
- lymphosarcoma
- Basal cell tumors
- Hair follicle tumors
- Mast cell tumors
55Diagnostic Plan
- Cytology/FNA
- Biopsies
- Histopathology
- Bacterial and fungal cultures
56Sporotrichosis
- Iodides
- NaI 20-40 mg/kg IV for 2-5 days then orally until
cured - KI 1-2 mg/kg PO daily for 1 wk then 0.5-1 mg/kg
daily until cured - Iodism scaling, alopecia, depression, anorexia,
lacrimation, salivation - Itraconazole
- 5 mg/kg PO daily
579 yr TB mare
58Differential Diagnoses?
59Differential Diagnoses
- Inflammatory
- Infectious bacterial, fungal, parasitic,
pythiosis - Post traumaticexuberant granulation tissue
- Parasitichabronema, hypoderma
- Neoplastic
- Squamous cell, sarcoid, mast cell tumor,
malignant fibrous histiocytoma
60Diagnostic Plan
- Cytology
- Biopsy
- Histopathology
- Bacterial fungal cultures
61Fistulous Withers
- Inflammation of the supraspinous bursae
- Ruptures and drains a clear or purulent fluid
- Occasionally associated with Brucella abortus or
occasionally B suis infection - Run an agglutination titer for Brucella
62Fistulous withers clinical management
- Surgical debridement (remove infected bursa)
- Systemic antibiotics based on CS
- ?? Vaccinate with strain 19 brucella SQ or IV ??
634 yr old Belgian gelding
64Differential diagnoses?
65Differential Diagnoses
- Inflammatory
- Bacterial (especially Corynebacterium
pseudotuberculosis) - Fungal (especially Basidiobolomycosis)
- Pythiosis
- Exuberant granulation tissue
- Neoplastic
- Fibroma/fibrosarcoma
- Sarcoid
- Squamous cell carcinoma
66Diagnostic Plan
- Cytology
- Biopsy
- Histopathology
- Bacterial fungal cultures
67Pythiosis
68Pythiosis Clinical management
- Surgical excision/debulking (laser?)
- Immunotherapy with vaccine prepared from Pythium
hyphal extract (2 ml SQ weekly for at least 3
treatments) - Itraconazole Terbinafine are effective in
20 of dogs but - Do not allow horses to stand in ponds!
69Ventral Midline of 14 yr Tennessee Walker gelding
70Differential Diagnoses?
71Differential Diagnoses
- Horn fly hypersensitivity
- Culicoides hypersensitivity
- Dermatophilosis
- Dermatophytosis
- Pelodera dermatitis
- Onchocerciasis (? Usually dorsal)
- Contact dermatitis
- Bacterial pyoderma
72Diagnostic Plan
- Cytology
- Skin scrapings
- Biopsy
- Histopathology
- Bacterial fungal cultures
- Intradermal skin testing for hypersenstivity to
Culicoides and Horn Flies (Haemotobia irritans)
73Results
- Eosinophilic Dermatitis
- 4 reaction to Culicoides
74Ventral Midline Dermatitis Management
- Topical corticosteroids /- antibiotics
- Protect from gnats and flies
- Check stable hygiene (remove straw bedding if
diagnose Pelodera)
75Culicoides Preventative strategies
- Stable dusk to dawn
- Fans in stalls
- 32 mesh screens
- Insecticides and repellants
- Eliminate standing water (breeding areas for the
gnats)
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