1
Q
Most relevant fly genus in equine IBH
A
Culicoides
Simulium are also important
2
Q
Predominant feeding site of Culicoides pulicaris
A
Along the dorsal aspects of horses where lesions of IBH are common
3
Q
Flying insects known to bite horse
A
- Culicoides (midges),
- Simulium (blackfly)
- Tabanidae (horse flies)
- Stomoxidae (stable flies),
- Culicidae (mosquitoes)
- Phlebotominae (sandflies)
4
Q
Main feeding times of Culicoides
A
Dawn and dusk
5
Q
Nine Culicoides antigens have
been identified as ‘major allergens’ in IBH
horses through studies focusing on IgE
binding from sera of affected horses - what are 8 of them?
A
Cul n 1 - 5
Cul o 1 -3
Other source: Cul o 1P, Cul o 2P, Cul o 3, Cul o 5, Cul o 7, Cul o 8 Cul o 9, Cul o 10, Cul o 11
6
Q
Risk factors for the development of IBH
A
- exposure later in life
- warm, humid climates
- close proximity to bodies of water
7
Q
What types of hypersensitivity reactions have been implicated in IBH?
A
- Type I (immediate, IgE mediated)
- Type IVb (delayed, T-cell mediated)
8
Q
Key cytokine group involved in IBH
A
Th2 cytokines
9
Q
Histologically, IBH is characterized by infiltration of which inflammatory cells?
A
Mast cells and eosinophils
some texts say lymphocytes > mast cells
10
Q
What cells and inflammatory mediators are increased in the lesional skin of IBH horses
A
- CD5+ and CD4+ T lymphocytes
- Langerhans’ cells
- Mast cells
- TSLP
- LTB4 and LTD4 (leukotrienes)
11
Q
Which immunoglobulins have roles in IBH
A
IgE and IgG (5 and 1)
12
Q
What transcription factor is reduced in IBH skin?
A
FOXP3
FOXP3 is regulatory - less regulation => more reaction
13
Q
Target of monoclonal antibody therapy for horses with IBH
A
IL-5
14
Q
Is early life or later in life exposure to Cullicoides associated with a greater predisposition to IBH
A
Later in life exposure
15
Q
IBH lesion distribution
A
face (jaw, ears), neck, ventrum, inguinal region, mane, tail,
limbs
16
Q
Primary therapeutic strategy for IBH
A
- Use of insect repellents (pyrethrins, Neem oil)
- Fly sheets
- stabling at dawn and dusk
- removal of standing water
- industrial fans
17
Q
Risk factors for the development of IBH
A
- exposure later in life
- warm, humid climates
- close proximity to bodies of water
18
Q
Strategies to reduce Culicoides exposure
A
- Use of fans (weak flyers)
- Moving horses away from standing water
- Stabling at night (when Culicoides are most active)
- Physical barriers (fly sheets/masks)
- Permethrin based fly sprays
19
Q
Horse breeds more commonly affected by atopic dermatitis
A
- Arabians
- Finn horses
- Thoroughbreds
20
Q
Th2 cytokines upregulated in equine AD
A
IL-4, IL-5, IL-6 and IL-13 and IL-31
21
Q
Recommended medication withdrawal times prior to IDST in horses
A
minimum withdrawal times are:
14 days for oral glucocorticoids and
7 days for oral antihistamines
22
Q
Main types of steroids used in equine AD management
A
- prednisolone (0.5-1 mg/kg/d typically, but doses up to double that have been reported)
- dexamethasone (0.02–0.1mg/kg once daily, which may be followed by an oral maintenance dosage of 0.01–0.02mg/kg every two to three days)
23
Q
Antihistamines most commonly used in the management of equine AD
A
- hydroxyzine
- cetirizine (active metabolite of hydroxyzine)
- chrlorpheniramines
24
Q
Pentoxyfilline is sometimes used in combination with glucocorticoids for the management of equine AD. Proposed MOA in allergic skin conditions
A
- Inhibition of T- and B-cell activation and proliferation
- Increased leucocyte deformability and chemotaxis
- Increased production of IL-10 and prostaglandin (PG)E2,
- Decreased leucocyte adhesion and aggregation, neutrophil superoxide release, neutrophil degranulation,
monocyte TNF-alpha production, leucocyte response to TNF-alpha, lymphotoxin and interferon-gamma production, leucocyte response to IL-1 and IL-12, and natural killer cell activity
25
Most common cause of cutaneous vasculitis in horses? Type of hypersensitivity?
Purpura hemorrhagica; Type III
26
Purpura hemorrhagica is an immune-mediated response to what?
infection (most often Strep equi - Strangles) or vaccination
27
Bacteria other than Strep Equi tha are associated with Purpura Hemorrhagica in horses
Corynebacterium pseudotuberculosis
28
Clinical signs of purpura hemorrhagica in horses
edema of the head and limbs, leukocytoclastic vasculitis, petechial hemorrhages in mucosae, musculature, and viscera, and sometimes glomerulonephritis
29
Two conditions in horses in which leukocytoclastic vasculitis may be appreciated histologically
- Purpura hemorrhagica
- Pastern leukocytoclastic vasculitis
*lesions of purpura hemorrhagica are not restricted to the distal limbs and are associated with systemic illness*
30
Vasculitic, likely photo-activated disease of horses that only affects unpigmented distal extremities (pasterns)
Pastern leukocytoclastic vasculitis
*typically limited to one leg even though several extremities may lack pigment*
31
Clinical signs of leukocytoclastic vasculitis in horses
erythema, oozing, and crusting that may progress to erosion and superficial ulceration on a non-pigmented distal extremity/pastern
32
Recommendations for clinical management of leukocytoclastic vasculitis
- prevent further UV exposure
- systemic corticosteroids
33
Clinical signs of hairy vetch toxicosis in horses
*rare in horses, much more common in cattle*
- generalized dermatitis
- alopecia
- crusting and scaling (mostly over the face)
- blepharitis, conjunctivitis
- lymphadenomegaly
- dependent edema
- diarrhea, and wasting
34
CoNs of horses
S. epidermidis, S. hemolyticus, Staphylococcus sciuri, and S. auriculari, S. xylosus, S. lentus, S. capitis
*can be pathogenic but are more frequently found on healthy skin*
35
Common pathogenic Staph sp seen in horses
Staphylococcus aureus, S. pseudintermedius, S. hyicus, and S. delphini
36
Causative agent of Glanders
Burkholderia mallei
37
What Cullicoides sp tend to preferentially feed on the ventrum of horses?
C. chiopterus, C. punctatus, and C. obsoletus/scoticus
38
Preferred feeding site of Haemaobia irritans (Horn flies)
Ventral/focal umbilical
39
What Cullicoides sp tend to preferentially feed on the dorsum of horses?
C. dewulfi and C. pulicaris
40
Biting insects that tend to have a ventral feeding distribution
- Simulium
- Haematobia irritans (umbilical area)
- C. chiopterus, C. punctatus, and C. obsoletus/scoticus
41
Insects that prefer to feed over the caudal-lateral aspects of the limbs
- Stomoxys calcitrans (Stable flies)
- Aedes (Mosquitoes)
42
Horse louse that prefers to feed at the mane, tail, and fetlocks (also back and thighs)
Haematopinus asini
43
Horse louse that prefers to feed at the head, mane, shoulder, tail base, dorsolateral trunk
Damalinia/Werneckiella equi
44
Vector for Onchocerca cervicalis
Cullicoides
45
Short demodex of horses typically found over the body
D. equi
46
Long demodex of horses that is most often found over the eyelids and muzzle
D. caballi
47
Potential causes of head tossing in horses
allergies, middle ear disorders, ear mites, rider ineptitude (lolz), auditory tube diverticulum (guttural pouch) mycosis, periapical dental osteitis, equine protozoal myeloencephalitis (EPM) and vasomotor rhinitis
48
Histologic findings in allergic horses
mixed eosinophilic perivascular infiltrates with variable degrees of surface crusting, erosions and ulcerations. Other features seen could include spongiosis, exocytosis and patchy areas of hyper and parakeratosis.
*eosinophilic folliculitis and eosinophilic granulomas are seen more often in insect hypersensitivity*
49
Trannquilization with what type of drug should be avoided for IDT testing in horses as it may interfere with the results
Phenothiazines
50
Sedative that can be used for IDT in horses
xylazine or dexmedetomidine
51
Insects that tend to feed during the day time
Tabanus, Chrysops, Haematobia irritans, and Stomoxys calcitrans
52
Fly genus that favors/breeds in moving water
Simulium or black flies
53
Biting insect that breeds in standing water and wet manure
Cullicoides
54
For what fly species can the use of fans be a helpful strategy?
Cullicoides
55
Are Simulium (black flies) strong or weak fliers?
Strong
56
Peak feeding times for Cullicoides midges and Simulium (black flies)
Dusk and dawn
57
Antihistamines that may be useful in horses
chlorpheniramine, cetirizine, hydroxyzine, diphenhydramine, doxepin
58
What kind of drug is doxepin?
TCA with antihistaminic properties
59
Non-antihistamine medication that may be helpful for both pruritus and urticaria in horses
Pentoxifylline
60
Most common species causing dermatophytosis in horses
T. equinum (and then T mentagrophytes)
*Nannizzia gypsea (formerly Microsporum gypseum), M canis, and T verrucosum have also been isolated*
61
What needs to be added to culture medium (SDA > DTM) to facilitate the growth of T. equinum on culture?
Niacin
62
Common clinical signs of dermatophytosis in horses
Hair loss with associated scale and crusting is the most common
63
What systemic antifungal medication can be used to treat dermatophytosis if topical therapies are not successful/practical?
- Griseofulvin (do not use in stallions - teratogenic)
- Itraconazole
*Keto is ineffective*
64
Most common site of pruritus associated with Malassezia dermatitis in horses
- Caudal inter-mammary area and tail head in mares
- Preputial area in males
65
Topical therapies for dermatophyosis and Malassezia dermatitis in horses
- lime sulfur
- enilconazole
- 2% miconazole/2% chlorhexidine shampoo
- povidone-iodine
- sodium hypochlorite
66
Risk factors for the development of MRSA infections in horses
- Hospitalization (esp NICU and non-surgical services)
- presence of colonized horses on the farm
- antimicrobial administration within 30 days
67
Topical therapies for MRS in horses
2-4% chlorhexidine, dilute lime sulfur dip, dilute bleach
(Vetericyn® VF products), 10% povidone iodine products, silver products, mupirocin 2%, fusidic acid
68
Class of antibiotics NEVER to use in horses
Macrolides
*can cause fatal colitis in adults*
69
Antibiotic for Staph in horses (culture for the ones you should culture for)
- TMS
- Doxycycline
- Cephalexin
- Ceftiofur
- Penicillin
- Gentamicin
- Enro (culture)
- Chloramphenicol
70
Most common skin tumor of horses
Sarcoids
71
6 classes of equine sarcoids
- occult
- verrucose
- nodular
- fibroblastic
- mixed
- malignant
72
Viruses implicated in the pathogeness of equine sarcoids
BPV 1, 2, and 13
73
Dysregulation in the functioning of matrix metalloproteinases (MMPs) is associated with what quality of equine sarcoids
Invasiveness
*MMPs, a family of zinc-dependent endopepdidases, exhibit higher expression during cancer invasion*
74
Horse breeds that seem more prone to sarcoids
Quarter horses and Franches-Montagnes
*medium rates in Thoroughbred, low in Standardbred*
75
Why might certain equine leukocyte antigen/MHC antigen haplotypes influence rates of sarcoid developement?
Some ELA haplotyes are associated with impaired elimination of the virus-induced tumor cells and impaired cell-mediated immunity at the level of epitope recognition
*BUT susceptibilty to equine sarcoids is polygenic rather than dependent upon a single gene*
76
Potential routes of BPV infection in horses
- direct contact with infected cattle or other horses carrying BPV
- insect bites
77
Sarcoids are benign tumors that develop from what type of tissue?
Fibrous tissue
*though they are technically benign, they can be locally aggressive and they have high rates of recurrence*
78
Sites most commonly affected by sarcoids
Head, ventral abdomen, and limbs
79
What is the mildest, most stable, and most superficial form of equine sarcoid?
Occult
80
Type of sarcoid that is slow growing and presents as a rough, hyperkeratotic appearance with variable degrees of flaking and scaling over limited or wider areas of the body. Most commonly seen over face, trunk, and groin/ sheath areas.
Verrucous
81
Type of sarcoid with the following characteristics:
- typically SC
- displays moderate growth
- Accidental or intentional interference can agitate these sarcoids leading to rapid growth and possible transformation into the more ominous forms of sarcoid (esp fibroblastic)
Nodular
82
Type of sarcoid with the following appearance: fleshy, ulcerated, aggressive appearance
Fibroblastic
83
Typical behavior and prognosis of fibroblastic sarcoids
- do not metastasize but can spread by local invasion into the dermis
- may carry a very poor prognosis
84
Common sites of fibroblastic sarcoids
- groin, eyelid, lower limbs, and coronary band
- sites of skin wounds
- sites of any other types of sarcoid subjected to trauma or insult
85
Type of sarcoid that can have a complex mixture of any sarcoid types
Mixed...nailed it
86
Most severe type of equine sarcoid.
Displays infiltration of lymphatic vessels that results in nodules and cords of palpable tumor.
Malignant
87
Behavior and prognosis of malignant equine sarcoids
- Highly invasive and destructive.
- Can rapidly spread over a wide body area and grows quickly.
- This type of sarcoid is rare, often develops following trauma or failed treatment, and can be ulcerated and bleed
88
Histologic features of equine sarcoids
- increased density of dermal fibroblasts compared to normal skin.
- proliferation of interlacing bundles and whorls of spindle-shaped fibroblasts within the dermis.
- The epidermis is hyperplastic and hyperkeratotic with long rete peg-like extensions into the dermal mass in the majority of cases
- Often at the dermoepidermal junction, there is a characteristic perpendicular orientation of fibroblasts toward the basement membrane, reminiscent of a picket fence
89
Gene responsible for Junctional Epidermolysis Bullosa (JEB) in Belgian, Trait Breton, and Trait Comtois horses
LAMC2
90
Gene responsible for Junctional Epidermolysis Bullosa (JEB) in American Saddlebred horses
LAMA3
91
Clinical signs of JEB in horses
- Ulcers with peripheral collarettes (former vesicles); coronets, mucocutaneous regions, oral cavity, bony prominences/pressure points are most affected
- Enamel hypoplasia may be present
92
HERDA (hereditary acquired regional dermal asthenia) in horses has been reported almost exclusively in Quarter horses and is associated with a mutation in what gene?
cyclophilin B (PPIB)
93
Clinical lesions caused by HERDA are primarily distributed over what area of the body?
Dorsally distributed
94
Clinical signs of HERDA in quarter horses
- hyperextensible, fragile skin
- seromas and haematomas
- ulcers and scarring
95
Environmental factor that contribute to dorsal distribution of HERDA lesions
UV radiation
*limiting sun exposure is helpful for affected horses*
96
UV radiation contributes to the severity and distribution of HERDA lesion through what mechanism?
solar irradiation leads to up-regulation of skin collagenase genes particularly MMP1 (interstitial collagenase) in the dorsal, sun-exposed skin of horses => more collagenase mediated degradation => thinner skin with decreased tensile strength
97
What causes immersion foot syndrome (also called "trench foot")?
prolonged exposure to water
98
Notable PE findings in equids with immersion foot syndrome
- Well-demarcated "water lines"
- Skin distal to the water line may crack, fissure, ulcerate, for crusts, and slough
99
Immersion foot syndrome has profound effects on what structures
dermal vasculature
100
3 stages of immersion foot syndrome
prehyperemic (preinflammatory), hyperemic (inflammatory), and posthyperemic (postinflammatory)
*histologic changes of all of these stages are suspected to result from direct injury to the dermal microvasculature*
101
Key histo findings in immersion foot syndrome
- perivascular lymphoplasmacytic and histiocytic perivascular dermatiti with vasculitis and coagulative necrosis of the epidermis, dermis, and subcutis consistent with ischemia
102
Horse breeds more prone to developing chronic progressive lymphedema
Draft horses (Belgian, Clydesdale, Shire, Cobbs)
103
What are Cross-reactive carbohydrate determinants (CCDs)?
sugar structures found on plant and insect proteins that can cause false-positive results in IgE allergy tests because they trigger a similar immune response to specific protein allergens
104
Blocking of what can improve agreement of serum allergy test results and IDT results?
blocking the anti-CCD IgE
**horses have high levels of anti-CCD IgE**
105
Weird colloquial named for dermatophilosis
Rain Rot, Rain Scald, Mud Fever, Dew Poisoning
106
What type of organism is Dermatophilus congolensis?
Gram positive, non-acid fast, facultative anaerobe actinomycete
107
Histologic findings associated with dermatophilosis
- stratified or layered crust made up of alternating bands of parakeratotic and/or orthokeratotic keratin and accumulations of degenerating inflammatory cells (horizontal stratification)
108
How is dermatophilosis transmitted?
direct contact, environment (get rid of the crusts that fall off but don't pick them off becuase it freakin hurts), biting insects
109
Predisposing factors for the development of dermatophilosis
rainfall, high humidity, high temperature, trauma to skin,
immuno-compromise, poor nutrition, parasitism
110
Clinical signs of dermatophilosis
tufted papules, crusts, “paintbrush” lesions with underlying erosion/ulceration, annular areas of crust/scale/alopecia (chronic), “scratches” esp over the dorsum, face, neck, and distal limbs
*can also cause photosensitization in white-haired areas*
111
How to diagnose dermatophilosis
- Cytology: neutrophilic inflammation with branching coccoid cells (2-8 parallel rows) “railroad tracks”
*Saline prep of crusts can be helpful*
- Culture: request increased CO2, blood agar
- Histopathology: alternating hyperkeratosis and neutrophils (“palisading” crusts)
112
Topical therapies are typically preferred for management of dermatophilosis. What systemic anti-microbials can be used in severe, generalized, or chronic infections?
- TMS
- Penicillin
113
What nematodes cause "summer sores"
- Habronema muscae (most common)
- Habronema microstoma (majus)
- Draschia megastoma
114
Life cycle of - Habronema muscae, Habronema microstoma (majus), and Draschia megastoma
Adult lives in stomach => Eggs and larvae passed in feces => larvae hatch in GIT or feces => ingested by intermediate host larvae (Musca. domestica and Stomoxys calcitrans) => develop within the fly => Fly bites horse and then L3 larvae can penetrate => Infects skin, lungs (asymptomatic), stomach (probably asymptomatic but maybe ulcers) => Larvae live for <1 month and death can cause more inflammation
115
Clinical habronemiasis may occur in part due a hypersensitivity to what?
The spine of L3 nematode larvae
116
Likely cause of proliferative nodule/nodules with exudate and ulceration and yellow granules that are “rice-like” (necrosis around a larva) occurring in the summer
Habronemiasis
117
Treatment of habronemiasis
*there isn't actually an agreed upon protocal but list some things to do*
- May spontaneously resolve
- Ivermectin (0.2mg/kg) or moxidectin (0.4 mg/kg) given twice, 21 days apart
- Oral steroids (anti-inflammatory dose, see allergy sections)
- Intralesional triamcinolone
- Topicals: Synotic®, Tresaderm®
- Surgical debulk
- Cryotherapy
- Fly control measures must be instituted
- Manure and garbage disposal
- Fly repellants
- Physical barriers
- Regular deworming?
118
Roundworm species that cause onchocerciasis
**Onchocerca cervicalis** microfilaria
Onchocerca reticulata (Europe, Asia), Onchocerca gutturosa (North America, Africa, Australia,
Europe); Onchocerca ralliti (only in donkeys in Africa, adult worm causes disease)
119
Where in a horses body might you find the adult life-stage of Onchocerca
Nuchal ligament in the neck
120
Main vectors of onchocerciasis
Cullicoides spp.
121
Key clinical signs of onchocerciasis in horses
- ventral midline dermatitis
- “bull’s-eye” lesion in center of forehead (fairly pathognomonic)
- sharply demarcated areas of alopecia and crusting, depigmentation
- ocular signs including uveitis
*- cutaneous nodules (O. gutturosa, O. reticulata)
- lameness (O. reticulata)
- severe ulceration of withers and neck (O. raileiti)*
122
Is infection with Onchocerca cervicalis common in the US?
Yes!
Affects 20-100% of a given population
*Huge problem in Africa*
123
Why should you do an ocular exam before initiating treatment for onchocerciasis?
So you don't literally make the horse go blind secondary to inflammation caused by microfilaria die off
*pred is your friend*
124
Cause of leg/tail/foot mange in horses
Chorioptes bovis
125
Horse breed/group predisposed to chorioptes
Draft breeds/horses with feathered limbs
126
Infections with chorioptes bovis are most commonly seen during what time of year?
Why?
- Winter
- Hot and dry climates are unfavorable
127
Treatment recommendations for chorioptes bovis
- lime sulfur
- fipronil
- ivermectin
- clip, clean, pasture rotation, environmental cleaning
128
Preferred feeding sites of Damalinia equi
head, mane, tail base, lateral flanks
129
Predisposing factors to pediculosis in horses
- overcrowding
- cold temperatures (ie winter)
- poor nutrition
- stress
130
Treatment of pediculosis in horses (biting/chewing vs sucking)
- Biting/chewing: topical lime sulfur, Ultra-Boss Pour-On, or pyrethrin/permethrin
- Sucking: systemic ivermectin
- Consider clipping
- Clean barn and equipment
131
Equine equivalent of Cushing's disease
Pituitary pars intermedia dysfunction
132
A dopaminergic neurodegenerative disease that causes hirsutism and and muscleloss in horses
PPID
*In horses with PPID, a lack of dopamine disrupts regulation of ACTH. As a result, the pituitary gland overproduces ACTH, which then stimulates the adrenal glands to produce excessive amounts of cortisol*
133
Types of horses at an increased risk of developing PPID
- Horses of 15yo
- Ponies
- Morgans
134
Horses with PPID have increase levels of what hormones/peptides
- POMC-derived peptides including ACTH, alpha and beta LPH
- Cortisol
135
Consequences of chronic hypercortisolism due to PPID in horses
Insulin resistance, dyslipidemia, laminitis
136
Clinical signs of PPID in horses (signs often wax and wane)
- Hypertrichosis/hirsutism
- increased susceptibility to skin infections
- weight loss, muscle atropthy (pot-belly and sway back)
- PU/PD (associated with DM or DI)
- behavioral changes
- laminitis
- hyperhidrosis (d/t pressure of pituitary gland on thermoregulatory areas of the hypothalamus)
137
CBC/Chem/UA changes common in horses with PPID
insulin resistant hyperglycemia, glucosuria, steroid leukogram, low plasma insulin, low T4 and T3, USG is normal to low; may have ELE, lipemia, hypercholesterolemia, hypertriglyceridemia
138
Specific tests that may be useful for PPID diagnoses
- ACTH stim + Plasma ACTH concentrations
- Overnight DST
139
Main medical therapy used for management of PPID
Pergolide mesylate
140
MOA of pergolide
Dopamine receptor agonist => inhibits the excessive release of adrenocorticotropic hormone (ACTH), beta-endorphin and melanocyte stimulating hormone as well as their intermediates
141
Drugs other than pergolide that are sometimes used to manage PPID
- Cyproheptadine (serotonin agonist)
- Trilostane (3B hydroxysteroid dehydrogenase inhibitor)
142
Deficiency in what mineral can cause coat fading and leukotrichia in horses?
Copper (needed for conversion of tyrosine to melanin)
143
Deficiency in what mineral d/t feeding of low quality forage with excessive light exposure can lead to a rough, dull haircoat, alopecia, scaling, hyperkeratosis, coronitis, and in some cases night blindness and reproductive issues
Vitamin A deficiency (can also see skin signs with vit A excess)
144
Weird hair morphology thing that both Golden's and horses seem to get that can cause hypotrichosis
Trichorrhexis nodosa
*Appears along the hairshaft as small, beaded swellings (may be visible with the naked eye) composed of frayed cortical fibers*
145
Horse breed predisposed to linear alopecia/linear keratosis
Quarter horses
146
Is linear alopecia/keratosis curable?
Nope - but it can be managed with corticosteroids and keratolytic shampoos
147
Contact photosensitization can occur in horses grazing in pasture containing what type of plant?
Clover
148
Lethal white foal/overo syndrome primarily reported in what breed of horse?
Paints
149
A mutation in what gene is responsible for lethal white foal syndrome?
EdnrB
*It is caused by the same mutation that causes the frame overo white spotting patterns*
*same gene affected in Type IV Wardenberg syndrome in dogs and cats*
150
Clinical signs of lethal white foal/overo syndrome (homozygous)
- all white coat color
- pink skin
- blue eyes
- deafness (sometimes)
- difficulty passing manure => abdominal pain => colic => death within a few days :(
151
Mutation to what gene causes equine graying with age?
STX17
*autosomal dominant*
152
The STX17 mutation that causes graying in horses is a major predisposing factor for what neoplasm?
Melanoma
*prognosis is guarded for this reason*
153
Lethal lavender foal syndrome is fatal in affected Arabian horses (neuro and skin signs). It occurs due to a genetic mutation in what gene?
MYO5A (myosin-Va plays an important role in melanosome transfer from melanocytes to keratinocytes)
154
Leukoderma seems most common in what horse breed?
Arabians - also called Arabian fading syndrome or pinky syndrome (congenital autoimmune disease)
155
Clinical signs/skin areas most commonly impacted in Arabian fading syndrome
White splotches are on the face, especially the bridge of the muzzle or around the eyes. Color loss may wax and wane.
156
Leopard spotting complex + congenital stationary night blindness in horses (mostly Apaloosas) is caused by a defect in what gene?
TRPM1
157
What type of sweat glands do horses have?
Epithricial
158
Proposed mechanism for how sweating is controlled/sweat glands are stimulated in horses
cutaneous nerve supply
is predominantly to the blood vessels and that the principal
glandular agonist is blood-borne adrenaline
159
Anhidrosis likely occurs as a result of the failure of what process?
Secretory failure
*ductal blockage may also be a feature in chronic cases*
160
Likely mechanistic cause of anhidrosis in horses
failure at the glandular secretory cell as a consequence of prolonged agonist (mainly adrenaline) stimulation
*adrenergic receptors become saturated => down-regulation of cellular β2 adrenoceptors in anhidrosis*
*chronic agonist binding to β2 adrenoceptors may lead to reduced levels of β2 adrenoceptor mRNA and hence reduced receptor synthesis*
161
Factors that aggravate anhidrosis
factors that:
- raise the basal metabolism of affected horses (high protein feed, disease, exercise)
- exacerbate water loss (polyuria, purgation, etc.)
- influence heat loss and help to dislocate body heat control
162
Test used to diagnose/investigate anhidrosis
Evaluation of sweating response (or lack of) to local injection of β2 agonists
163
The most reliable treatment for anhidrosis
Removal of climatic stress
164
Sweating in horses is primarily controlled by what type of receptors?
beta-adrenergic receptors
165
What virus most commonly causes warts in horses?
EqPV1
(EqPV8 is more aggressive, causes widespread lesions, and may transform to SCC)
166
What virus has been reported to cause persistent, extensive warts over large areas of the the ventrum, inguinal, and axillary regions in horses?
EqPV8
167
What virus most commonly causes equine genital warts?
EqPV2
168
What is the most common location that PV plaques (not warts) are seen in horses?
Concave pinnae
169
EcPV induced aural plaques are thought to be contagious. What is their proposed vector?
Insects
170
What is the most common location of EcPV2 associated SCCs in horses?
the penis
171
Which papillomaviruses are associated with the development of equine sarcoids?
BPV-1, 2, and 13
172
Glanders in horses, mules, and donkeys is caused by Burkholderia mallei. What is described as the "characteristic lesion" of its cutaneous form?
Nodular cutaneous ulcers in a "crater-like" pattern appearing as chains with purulent exudate
173
Causative agent of Glanders
Burkholderia mallei (bacteria)
174
Infection which can cause "kunkers" (yellow-gray, hard concretions composed of necrotic debris with myriads of filamentous hyaline hyphae) in horses
Pythiosis
175
ACVD Exam
flashcards
Decks in class (24)
# Cards
-
Allergy and Hypersensitivity368
-
Otology167
-
Infectious Disease557
-
Staph and Resistance AWM REF 202543
-
Parasitology250
-
Structure and Function - Skin Barrier and Cornification143
-
Structure and Function - Basement Membrane Zone126
-
Structure and Function - Glands, Vessels, Sensory systems, and lymphatics63
-
Structure and Function - Cornification disorders68
-
Structure and Function - Collagen and Extracellular Matrix102
-
Structure and Function - Melanogenesis72
-
Structure and Function - Wound Healing92
-
Structure and Function - Hair Follicles120
-
Immune-Mediated Diseases248
-
Equine Derm175
-
Pharmacology315
-
Endocrine/Internal Med212
-
Histopathology (and a little Cytology)116
-
Oncology313
-
Nutritional/Environmental/Traumatic133
-
Large Animal (non-equine)92
-
Genodermatoses64
-
Psychoneurodermatology97
-
Exotics137
