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Dermatology > Equine > Flashcards

Equine Flashcards

1
Q

Old horse with derm isssues think…

A

PPID

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2
Q

Quarter horse with derm issues think…

A

HERDA

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3
Q

Three systemic diseases that can cause derm issues

A

PPID
Pemphigus foliaceus
Liver disease (photosensitization)

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4
Q

Dermatophilosis (aka)

A

Common
Rain scald or rain rot

Cytology: railroad tracks!

Exfolication and crusts

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5
Q

Dermatophytosis (aka)
Species
Diagnosis

A

Ringworm
Fungal
Common

Trichophyton equinum
Microsporum gypseum or canis

Do a fungal culture (will take about 2 weeks)

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6
Q

Bacterial infectious agents

A

Not common

Staphylococcus
Corynebacterium
Streptococcus

Usually secondary infections not a primary issue

See exfoliation and crusts

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7
Q

Pemphigus foliaceus

Diagnosis

A

Immunologic problem

Biopsy needed for definitive diagnosis

Equine exfoliative eosinophilic dermatitis and stomatitis

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8
Q

Nutritional

A

Rare

Zinc, Iodine, Protein

Exfoliation and crusts

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9
Q

Dermatophilosis
Lesions
Clinical Signs

A

Exfoliations and crusts
Exudative, yellow

Can be very painful

Severe cases:
Fever, lethargy, anorexia

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10
Q

Dermatophilosis

Treatment

A

Soak and remove as many crusts as you can (this is very painful)
Chlorhexidine scrub (2%); SMALL amount 15 minute soak once/day for 1 week -takes about 2 weeks to resolve-
MUST rinse out all of the scrub or will make things worse

NSAIDs

Severe cases (not common): systemic antibiotics

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11
Q

Dermatophilosis

Treatment Setback

A

If in the winter will have to wait until summer to treat because have to give baths

If there is a facility where owner could give baths and have the horse dry off than can treat in winter; could come to your clinic but that is pricey

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12
Q

What is urticaria?

A

“Hives”

Wheals and edema

Antigen is hard to determine (need to see what has changed recently to know what could be the cause)

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13
Q

Uticaria
Clinical Signs
Treatment

A

Wheals and edema
+/- pruritus

Remove cause (will take several days for wheals to resolve)
Will resolve on own but:
Corticosteroids if pruritic
Antihistamines (not very effective)

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14
Q

What does HERDA stand for?

A

Hereditary equine regional dermal asthenia

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15
Q

HERDA

Background

A

Often in quarter horses; there is a genetic test for it (must submit hair samples WITH roots)

Autosomal recessive: both parents must have it

Effects:
Collagen

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16
Q

HERDA

Clinical Signs

A

Effects collagen therefore skin becomes hyperextensible/elastic
Skin comes undone from dermis and get a hematoma (PAINFUL)

Found mostly on dorsum

Most commonly see lesions where the saddle sits
Skin breaks and then heals via scaring

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17
Q

HERDA

Diagnosis

A

Clinical Signs
Breed
Biopsy
Genetic test

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18
Q

HERDA

Treatment

A

None
Usually have to euthanize

Even as a pasture pet if they hit themselves or itch on a post will rip skin

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19
Q

4 things that cause Pruritic dermatoses

A

Parasites
Allergies
Bacterial folliculitis
Fungal infections

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20
Q

Common parasites

A 
Lice
Mites
Ticks (but not many)
Onchocerca
Habronema
Pinworms (especially when pregnant)
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21
Q

Common allergen

A

Inset bite hypersenstivity

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22
Q

Allergy

Clinical Signs

A 
Pruritus (severe) - continually
Alopecia
Scaling
Ulcers
Hyperkeratosis
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23
Q

Insect-bite hypersensitivity

Background

A

Type I and IV hypersensitivity (eosinophils/IL-5)

Chronic, recurrent

Seasonal, biting Culicoides

Secondary bacterial infection may occur

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24
Q

Insect-bite hypersensitivity

Diagnosis

A

Serology NOT useful

Intradermal testing (often get many false positives) – not recommended

Clinical signs and seasonality

Response to management

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25
Insect-bite hypersensitivity | Treatment
Insect management! Stable mid pm to mid am (when bugs are most active) Screens and fans (Culicoides so tiny fans blow them away) Fly sheets and fly masks (Zebra print helps a lot!) Topical: 2% permethrin Cypermethrin
26
Ways to decrease pruritus
Corticosteroids (usually not used alone, but done for relief until underlying cause under control) Shampoo Omega-3 FA Antihistamines are not very effective b/c Type IV reaction also happening (cell-mediated)
27
Insect-bite hypersensitivity | Prevention
Vaccine: Anit-IL-5 (not in US) Only helps 50% of the time
28
Skin tumors; are they likely to metastasize?
No! Example: oral melanomas are not a big deal like they are in dogs
29
What is the most common tumor type?
Sarcoid
30
What to keep in mind when approaching equine tumors
Not every tumor needs to be treated Wide margins may not be indicated in areas with limited skin; yay got tumor off so looks better but now can never close the skin... If small can remove than follow up with adjudicative therapies He will only take excisional biopsy; incisional is not very useful
31
Keys to successful tumor treatment
Be more aggressive than the tumor (some are very angry) Be more stubborn/persistent than the tumor Make sure owners are committed to the fight
32
What are 4 common tumor types?
Sarcoids Melanomas SCC Mast Cell Tumors
33
Where is the most common place to have neoplasia?
>50% of all equine neoplasias are on the skin
34
Sarcoid | Background
Usually on hairless spot Fibroblastic tissue type Locally invasive Non-metastatic (but can sometimes met) May have a genetic link
35
Sarcoid | What issues can they cause?
May disrupt normal eyelid function or indirectly damage eye May be in areas that inhibit normal use or function
36
Sarcoid Age Breed
3-6 years of age Quarter Horse, Appaloosas, Arabians
37
Sarcoid | DfDx
Papilloma especially in young horses
38
Sarcoid and Bovine Papillomavirus
No intact viral particles have been found in sarcoids BUT DNA and RNA proteins have been found Detected in both normal skin and tumors Detected in peripheral blood mononuclear cells Aggressive sarcoids have higher viral load BPV NOT a direct cause
39
Bovine Papillomavirus Transmission
Unknown Direct cattle to horse? Indirect? Both have been "appreciated" Horse-horse? Via insects; has been shown -- bite and virus gets into peripheral blood
40
Occult Sarcoid
Benign Found around mouth, eyes, neck Mild hyperkeratosis Slightly thickened skin +/- color change Slowly growing but can convert
41
Verrucose (Warty) Sarcoid
Most common Face, body, groin/sheth areas Rough hyperkeratotic appearance Scaling Flat or pedunculated Often slow growing and not very aggressive until it is injured Can change to fibroblastic sarcoid
42
Nodular Sarcoid
Groin, sheath, eyelid Firm, well-defined SQ, spherical nodules Nodules lie under apparently normal skin and may be freely movable Can have dermal and deep attachments
43
Nodular Sarcoid | Removal
Incise direction over sarcoid and remove it Do not take excess skin; just close the skin over the site
44
Fibroblastic Sarcoid
Groin, eyelid, lower limbs, wounds Fleshy appearance Pedunculated and extensive (looks like proud flesh; exuberant granulation tissue) If bumped will become angry Flies like them; causes irritation
45
Fibroblastic Sarcoid | Treatment
MUST treat these; may look ugly but try to remove and you might be shocked at good results!
46
Mixed Sarcoid
Verrucous, Nodular, and Fibroblastic Progressive/transient state between the occult/verrucous types and fibroblastic/nodular types
47
Mixed Sarcoid | Treatment
Expands over large areas => cannot remove Must use other modalities to treat (local or chemo)
48
Malevolent Sarcoid
ANGRY/AGGRESSIVE fibroblastic sarcoid (spreads rapidly) Jaw, face, elbow, and medial thigh area History of repeated trauma to other types of sarcoid
49
Malevolent Sarcoid | Pathophysiology
Infiltrate in lymphatic vessels resulting in multiple nodular or fibroblastic masses along these vessels Local lymph nodes might also be involved RARE
50
Sarcoid Management
Surgical excision (do not take more than necessary); removal early, when small, preferred Laser ablation (CO2 evaporation until you see normal tissue; may require multiple treatments) Cryotherapy Hyperthermia Chemotherapy (Cisplatin most common) Topical cytotoxic drugs Electrochemotherapy Immunologic methods
51
Squamous Cell Carcinoma
Second most common tumor Very invasive 18% metastasis (very slow process however) Eye, ocular adnexa, conjunctiva, and external genitalia (likes mucous membranes)
52
Squamous Cell Carcinoma | Age
11-19 years
53
Ocular tumor statistic
About 10% of horses evaluated for ocular tumors have a second mass at a different body site
54
Squamous Cell Carcinoma | External vs. Internal
External = better prognosis ``` Internal = no good treatment Stomach Esophagus Nasal Passages Pharynx Larynx Perianal Tissue Lungs ```
55
Squamous Cell Carcinoma | Predispositions
Sun damaged skin High altitude Light pigmented skin (grey, white, cremello) Breed (Draft, Appaloosa, Paint) Persistent phimosis, smegma, trauma to external genitalia Papilloma virus?
56
Squamous Cell Carcinoma Treatment Third eyelid
Remove entire third eyelid
57
Squamous Cell Carcinoma Treatment Genitalia
Topical 5-FU If lesions bad will have to resect penis
58
Crazy looking wounds
Biopsy Once you know what it is treat accordingly
59
Melanocytic Tumors
Tumor from melanocytes Grey horses (80% of older gray horses develop melanocytic tumors, 66% of those are not malignant)
60
Melanocytic Tumors Age Breed
Any age and of any color Arabians Percherons Thoroughbreds
61
Melanocytic Tumors | Location
``` Undersurface of tail near base Perineal or perianal regions Genitalia Mammary gland Base of pinna (ear margin) Commissures of lips Skin around eye Parotid salivary gland ```
62
Melanocytic nevus
Benign tumors that appear as a single, discrete, solitary mass Affects younger horses of all coat colors Location: umbilicus, forelimb, rump, shoulder, thigh, neck, cannon bone Sx removal is curative
63
Dermal melanomas
Most are benign Discrete, solitary masses (one or two) Older gray horses (13 years) Likes mucous membrane areas Sx is usually curative (and easy to remove)
64
Dermal melanomatosis
Internal metastasis is likely! -- invades deep 15 years or older Multiple tumors noted Likes mucous membrane areas
65
Dermal melanomatosis | Treatment
Surgical excision of these tumors often curative for the masses that are removed Remaining masses continue to grow New tumors will develop Often palliative treatment/care
66
Anaplastic malignant melanomas
Uncommon Older horses (>20 years) of any hair coat Metastasize quickly
67
Anaplastic malignant melanomas | Histology
Variable pigmentation Extremely pleomorphic epithelioid cells Single-cell invasion of epithelium Numerous mitotic figures
68
Mast Cell Tumors
Uncommon Five more times common in males than females Usually cutaneous nodule often located on head No age predilection
69
Mast Cell Tumors | Two Types
Hyperplastic (more common) Neoplastic Sx excision usually curative

Dermatology (13 decks)

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