Lecture 9 2/18/25 Flashcards
What are the three causes of a nodule or draining lesion?
-infectious
-neoplastic
-sterile
What are the basic diagnostics done for nodular diseases?
-aspirate cytology
-surface cytology of draining fluid
-histopathology
-culture from biopsy on macerated tissue culture
What are the characteristics of mycobacteria canine leproid granuloma?
-novel mycobacterial species that do not grow using standard methods
-lesions are restricted to head/pinnae
-diagnosed via PCR or finding acid fast organisms on histopath/cytology
What are the characteristics of atypical mycobacteriosis?
-fast growing mycobacteria; typically Mycobacterium fortuitum complex
-environmental saprophytes enter via trauma
What are the clinical signs of atypical mycobacteriosis?
-multiple draining tracts within subcutaneous tissue of ventral abdomen and groin
-otherwise healthy animal
-may have history of surgical dehiscence
How is atypical mycobacteriosis diagnosed?
-pyogranulomatous inflammation of cytology with no organisms
-pyogranulomatous dermatitis/panniculitis with “holes” +/- filamentous acid-fast bacteria on histology
-culture using Lowenstein-Jensen media
What are the treatment options for atypical mycobacteriosis?
-long term antibiotics
-topical enrofloxacin/DMSO
-steroids may be indicated
-remission maintained with antibiotics, but cure often not achieved
What are the potential fungal causes of nodular disease?
-dermatophytic fungi
-saprophytic fungi
-pythium/lagenidium
-sporotrichosis
-blasto
-histo
-crypto
-coccidioidomycosis
What is a kerion?
furunculosis presentation that is the most common clinical presentation of dermatophytosis in dogs
What are the characteristics of phaeohyphomycosis/eumycotic mycetoma?
-mycetoma = tumefaction + tracts + drains
-want to look for immunosuppression
What are the characteristics of pythiosis/lagenidiosis/paralegenidiosis?
-not true fungi
-saprophytic infection
-found in decaying wood and vegetable matter
-often seen in gulf coast areas
How is pythiosis/lagenidiosis diagnosed?
-cytology that is pyogranulomatous with eosinophils**
-biopsy with silver stain
-culture
-serology
-PCR
-IHC
What are the treatment options for pythiosis/lagenidiosis?
**very difficult
-wide surgical excision
-systemic therapy
-immunotherapy with anti-pythium vx
What are the characteristics of sporotrichosis?
-most often seen in cats
-very contagious
-present as “non-healing” wounds
What are the characteristics of blastomycosis?
-can cause patients to be febrile
-can see swollen digits
-presents with draining, oozing lesions
What are the characteristics of histoplasmosis?
-papular to nodular growths at mucocutaneous junctions
-associated with poultry
What is the main outward-presenting sign of cryptococcosis?
roman nose
What are the characteristics of viral nodular lesions?
-caused by papillomavirus
-seen in young dogs
-often around the oral mucosa
What is the treatment for papillomavirus lesions?
-regression
-azithromycin
-cimetidine
-laser surgery
What are the characteristics of sterile nodules?
-likely an immune-mediated inflammatory response to unknown antigen
-pathogenesis is unknown
What are the characteristics of canine eosinophilic furunculosis?
-like a response to arthropod or insect bite
-sudden onset
-steroid responsive
-recurrence is rare
-should be a top differential when eosinophils are seen on cytology
What are the characteristics of juvenile cellulitis/puppy strangles?
-pustular to nodular disease of young puppies; may occur in adults
-most common in dachshunds, goldens, and pointers
-occasionally develops following recent vx
-have not been able to reproduce disease with vx or virus
Where do the clinical signs of juvenile cellulitis tend to appear?
-face and head around the muzzle and eyes (most common)
-ears
-anus
-prepuce
What is a common clinical sign of juvenile cellulitis in addition to the nodular skin lesions?
large submandibular lymphadenopathy
What are the treatment steps for juvenile cellulitis?
-immunosuppression at high doses
-concurrent antibiotic treatment with doxycycline, niacinamide, or cyclosporine
-slow taper off all meds once in remission
What are the characteristics of sterile nodular panniculitis?
-solitary or multiple subcutaneous nodules that ulcerate and discharge oily, bloody exudate
-lesions can occur anywhere
What are the clinical findings in dogs with sterile nodular panniculitis?
-systemic illness, including anorexia, lethargy, and fever
-elevated serum alkaline phosphatase
What is the treatment for sterile nodular panniculitis?
-immunosuppression
-doxycycline/niacinamide
-cyclosporine
-vitamin E
What are the types of granulomatous dermatoses?
-periadnexal multinodular granulomatous dermatosis
-cutaneous histiocytosis
Where are lesions associated with granulomatous dermatoses often seen?
nasal mucosa; may cause stertorous breathing
How are granulomatous dermatoses diagnosed?
round cells on cytology
What is the treatment for granulomatous dermatoses?
-immunosuppression
-doxycycline/niacinamide
-cyclosporine
-long term treatment
What are the characteristics of perianal fistuals?
-draining lesions around the anus; shallow blind-ended sinuses NOT associated with anal sacs
-predisposed in german shepherds
-very painful
-genetic link identified
-immune-mediated
How are perianal fistulas visually differentiated from cancer?
-cancer comes out toward you
-perianal fistulas ulcerate away from you
How are perianal fistulas diagnosed?
-clinical signs
-cytology
-possible biopsy
-sedated rectal exam
What is the treatment for perianal fistulas?
-cyclosporine
-tacrolimus
-prednisone
-food trial
-antibiotics
-surgery if refractory or with secondary anal sac involvement
How is pyogranulomatous inflammation proven to be sterile rather than infectious?
negative tissue cultures and not seeing organisms on histopath.
