Unit 4 - Equine Skin and FAD Flashcards
Corynebacterium pseudotuberculosis var. equi is a natural inhabitant of what?
the soil
How is Corynebacterium pseudotuberculosis var. equi transmitted?
Via any break in the skin or biting insects
What are the three forms of disease/clinical signs caused by Corynebacterium pseudotuberculosis var. equi?
External abscesses (Pigeon fever)
Internal abscesses
Ulcerative lymphangitis
What age group of horses are predisposed to pigeon fever?
young
What lesions are associated with pigeon fever?
Large pectoral abscesses and on the ventral abdomen
Where do internal abscesses due to Corynebacterium pseudotuberculosis var. equi typically localize?
On the liver, lung, spleen, and kidney
Ulcerative lymphangitis is characterized by what?
Severe cellulitis of one or more limbs
How is Corynebacterium pseudotuberculosis var. equi diagnosed?
Bacterial culture of lesions, peritoneal fluid, or draining tracts
Evidence of chronic infection on CBC
Synergistic hemolysis inhibition
How are the external abscesses caused by Corynebacterium pseudotuberculosis var. equi treated?
Surgical drainage ofmature abscesses
Many abscesses will rupture and heal on their own
Antibiotics only in complicated cases
T/F: There is a low chance of recovery associated with pigeon fever.
False - it is high
How are internal abscesses and ulcerative lymphangitis caused by Corynebacterium pseudotuberculosis var. equi treated?
Long term (minimum 4-6 weeks) of antibiotic therapy
How is Corynebacterium pseudotuberculosis var. equi prevented and controlled?
Isolate infected animals
Contain abscess drainage
Fly control
Vaccination
What is the etiology of sporothricosis?
Sporothrix schenckii
What does sporothricosis present similarily to?
ulcerative lymphangitis
Where does Sporothrix schenckii grow?
In organic material - silvers and thorns
How is sporothricosis introduced?
Via trauma
What clinical signs are associated with sporothricosis?
Multiple abscesses along lymphatic vessels
Typically affects a single limb
How is Sporothricosis diagnosed?
Cytology
Culture
Lack of response to antibiotic therapy
What will you see on cytology in patients with sporothricosis?
Cigar bodies - elongated yeast cells
How is sporothricosis treated?
Sodium iodide with Ketoconazole (or similar drugs) OR amphoteracin B
What are the infectious causes of folliculitis/dermatitis?
Dermatophilosis
Dermatophytosis
Bacterial pyoderma
Parasitic - chorioptic and psoroptic mange
What are the most common etiologic agents of dermatophytosis?
Trichophyton equinum
T. mentagrophytes
Microsporum gypseum
What are the common etiologic agents of dermatophytosis if there is interaction with other infected animals?
T. verrucosum
M. canis
How does dermatophytosis colonize?
It requires some abrasion to skin to allow entry
What clinical signs are associated with dermatophytosis?
Regions of alopecia, frequently round, erythemic, crusted margins
Located on the head, neck, forelimbs, under saddle/girth
How is dermatophytosis diagnosed?
Culture is the best bet
How is dermatophytosis treated?
Most cases are self-limiting Can treat topically with antifungals or lime sulfur \+/- systemic therapy Separate from herd Disinfect equipment
What is the etiologic agent of dermatophilosis?
Dermatophilus congolensis
How does Dermatophilus congolensis enter the body?
Skin abrasion and moisture
T/F: The crusts from dermatophilus infected individuals are contagious
True
What is another name for dermatophilosis?
Rain rot
What lesions are associated with dermatophilosis?
Papules that progress to thick crusts with an erosive underside (paint brush lesions)
How is dermatophilosis diagnosed?
Direct examination of crusts
Giemsa stain
How is dermatophilosis treated?
Dry environment
Crust removal
Topical chlorhexidine
+/- systemic therapy with abx
What is the etiologic agent of vesicualr stomatitis?
Vesicular stomatitis virus
Where is vesicular stomatitis endemic?
In North, Central, and South America
During what time of year is vesicular stomatitis common?
Spring to summer months - waterways
How is vesicular stomatitis transmitted?
Via biting insects and direct contact once on property
T/F: Vesicular stomatitis is zoonotic..
True
What clinical signs are associated with vesicular stomatitis?
Excessive salivation with vesicles on the inner surface of the lips, gums, and tongue - occasional crusting on muzzle, lips, nostrils, ears, coronary band, sheath, ventral abdomen
How is vesicular stomatitis diagnosed?
Report any suspicious lesions to the state vet
PCR from lesions
Serology
How is vesicular stomatitis treated?
supportive care
How is vesicular stomatitis prevented and controlled?
Quarantine of any identified premises
Isolate any new horses for 21 days
Insect control programs
Individual feeders
What transmits African horse sickness?
Biting midges
What serves as reservoirs for African horse sickness?
Donkeys, mules, zebras, elephants, camels, and dogs
what complicates the prevention of African horse sickness?
The antigenic variants
Where is African horse sickness endemic?
Sub-Saharan Africa
What cell does African horse sickness attack and what does that result in?
Vascular endothelium resulting in edema
What are the forms of African horse sickness?
Pulmonary, cardiac, mixed, mild
What clinical signs are associated with the pulmonary form of African horse sickness?
Severe pulmonary edema, frothing at the nares, high fever, and 95% case fatality rate
What clinical signs are associated with the cardiac form of African horse sickness?
Pronounced edema of the head and neck, hydropericardium, and high case fatality rate
What clinical signs are associated with the mild form of African horse sickness?
Fever only
How is African horse sickness diagnosed?
Clinical signs
Virus isolation
PCR if available
Serology
Is African horse sickness treatable?
Not really - supportive care is the best you can do because it is highly fatal
How is African Horse sickness prevented and controlled?
Strict importation rules
Control biting midges
Screening/netting at night
Vaccination
What is the reservoir of Hendra virus?
fruit bat
How is Hendra virus transmitted between horses?
Direct contact only with respiratory secretions
T/F: Hendra virus is highly fatal and zoonotic
True
What clinical signs are associated with Hendra virus?
Fever, respiratory distress, and death
Severe bilateral pulmonary edema
Potential for neurologic signs
Where does Hendra virus replicate? How does it spread?
Replicates in respiratory epithelium first, then spreads hematogenously to other organs
How is Hendra virus diagnosed?
RNA virus - RT-PCR
Serology
How is Hendra virus treated?
No treatment - euthanized to protect human health
What is the etiologic agent of glanders?
Burkholderia mallei
T/F: Burkolderia mallei lives in the soil and is zoonotic.
False - it is zoonotic but it is an obligate parasite of equidae and dies out in the environment fairly quickly
How is Burkholderia mallei discharged from a horse?
Draining nodules and nasal mucosa
How is glanders transmitted?
Feed, water, and direct contact
What is a key to glanders transmission?
Recovered carriers
What equidae species tend to develop chronic glanders? acute disease?
Chronic - horses
Acute - donkeys and mules
What are the forms of glanders?
Respiratory and cutaneous
What are the respiratory clinical signs of glanders?
Pneumonia
Small nodules on the nasal and pharyngeal mucosa that ulcerate and drain
Ulcers will heal and scars form (stellate scars)
What are the cutaneous clinical signs of glanders?
Nodules on skin, subcutaneous tissues, and lymph nodes
Lymphangitis
What form of glanders do humans get?
Primarily cutaneous but can get respiratory
How is glanders diagnosed in acute cases?
Culture or PCR of lesions
Postmortem lesions and culture
How are carriers of glanders detected?
Serology - CF (official test for import), ELISA, AGID
Mallein intradermal skin test
How is glanders treated?
It is not recommended - don’t want carriers
How is glanders prevented and controlled?
Test and slaughter is preferred - no vaccination
What is the etiologic agent of dourine?
Trypanosoma eqiperdum
T/F: Dourine is common in all hooved species.
False - only in equidae
How is dourine transmitted?
venereally
Where is dourine found?
Central and S. America, N. Africa, and the Middle East
When is the onset of dourine?
Up to 20 weeks
What acute signs are associated with dourine?
Initial low-grade fever and urethral or vaginal discharge
Edema, swelling, and ulceration of external genitalia
Occasional abortion
What chronic signs are associated with dourine?
Peculiar raised plaques in skin of the flank that disappear and are replaced by plaques in other areas (pathognomonic)
CNS signs - incoordination, ataxia, paralysis
Loss of condition and progressive weakness
How is dourine diagnosed?
Clinical signs
Serologic testing
Real-time PCR
How is dourine treated?
Use of trypanosomal drugs is possible… but not practical
How is dourine prevented and controlled?
Slaughter of all CF positive carrier animals
