Exam 2 Flashcards

1
Q

Infectious and Non-infectious diseases and disorders of the skin

A
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2
Q

Explain the cause of equine Sarcoids, describe the various types, diagnostic and treatment options

What is the most common skin tumor in the horse?
Is it malignant/benign?
What are the most common locations where it develops?
What age group is most affected?
Are multiple sessions common?
Which breeds have a genetic component?

A

Etiology

-The most common equine skin tumor fibroblastic
-Non-metastatic
-Bovine papilloma virus (BPV)
-Viral E5 protein = malignancy
-Vector vorne?
-Genetics: QH&raquo_space; TB

Young adults 2-9 yo
Head & ears, ventral abdomen
-Previous trauma areas predisposed
-Multiple lesions common

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3
Q

Types of Sarcoids

  1. Earliest form, circular, hairless area, thickened skin, may be stable for years
  2. Grey, scaly, warty appearance. Possible ulceration, small nodules, “occult halo”
A
  1. Occult
  2. Verrucous
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4
Q

Types of sarcoids

  1. Firm, discrete, nodule under skin. Eyelid, axilla, inner thigh, groin. Can ulcerate and bleed. Skin may or may not be firmly attached
  2. Do not heal like granular tissue, though looks like it. Fleshly, aggressive, can have a narrow pedicle attaching it to the body. Attractive to flies
A
  1. Nodular
  2. Fibroblastic
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5
Q

Types of Sarcoids

  1. Mixed
  2. Malignant
A
  1. Common to have more than one type. Seen in areas of repeated trauma or inappropriate treatment. May or may not be able to tell the primary type
  2. Malignant: rare. Extensive through skin and underlying tissues. Aggressively invades locally but not into organs
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6
Q

How do sarcoids behave?
Should you always biopsy a sarcoid?
What is the best treatment?
Which treatment requires 4-8 sessions and general anesthesia?
What type of sarcoids respond best to BCG and Aldera treatments?
Which treatment has the highest success rate? is it commonly used or not?

A

-They can regress spontaneously occult» verrucous» fibroblastic
-Biopsy makes them angry!

Treatment

-Depends!!
-They do not always work

  1. Surgery
    -Sharp incision, Laser, Cryosurgery
    -Need > 1.6 cm margins
    -Common recurrence
    -Best combined with other therapy
    -Laser&raquo_space; success than scalpel, but higher wound dehiscence (thermal damage)
    -Cryotherapy: necrosis of tumor, good only for small tumors (-20 C temp)
  2. Chemotherapy
    -Very expensive for large animals to do systemic chemo
    -Topical: Acyclovir, 5-FU
    -Intralesional: Cisplatin beads, 5-FU
    -Electrochemotherapy: high voltage pulses and chemo combo Very effective requires 4-8 treatments and general anesthesia
  3. Immunotherapy
    -Spontaneous resolution
    -BCG: Cell wall of Mycobacterium bovis = immunostimulant B & T cells
    First debulk
    -Multiple injections required
    -Best for small, periorbital or fibroblastic tumors.
    -Aldera: immune modulator, 3x per week, expensive.
  4. Gene therapy
    -Remove tumor and section of 3mm pieces frozen in liquid nitrogen for 10 min
    Implant into the neck
    -Autologous vaccination
  5. Radiotherapy
    -Iridium-192, Gold-198, Cobalt-60, Radon-22, Radium-226
    -86.6-100% success rate
    -General anesthesia, expensive
  6. Photodynamic and phototherapy
  7. Others

XXterra
-Blood root/zin chloride mixtures
-some success, but not as good as advertised
-clients can get it online

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7
Q

Should you remove an occult, verrucous, or nodular sarcoid that is not interfering?

A

Should you remove an occult, verrucous, or nodular sarcoid that is interfering? what if it is <10 cm, or 10-20 cm, or >20 cm? What is the best treatment?

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8
Q

Should you remove a fibroblastic sarcoid that is non-interfering or interfering? what if it is <10 cm, or 10-20 cm, or >20 cm? What is the best treatment?

A

Should you remove a malevolent sarcoid that is interfering or not interfering? what if it is <10 cm, or 10-20 cm, or >20 cm? What is the best treatment?

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9
Q

Describe guidelines for mass removal in horses

A

Rules

> 5mm margins (usually 1cm)
-Limb: use tourniquet, graft, immobilize
-Near orifice/anus: may need reconstruction, partial closure, +/- gift, scarring may interfere with function
-Body: +/- graft, usually do not need closure
Bleed a lot, prepare for hemostasis

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10
Q

Describe how to perform skin grafting: pinch, punch, tunnel, sheet/mesh.

A

Primary closures always best when possible

Grafting Indications

-Extensive tissue loss, not enough skin to close
-Excessive granulation impeding wound contraction
-Contraction/epithelialization will be sufficient to close

Requirements for success

  1. Good vascular supply
    -Won’t work over exposed bone, tendon, ligament, fat, etc.
  2. Free of infection
    -Pseudomonas sp. exudate interferes, other bacteria too - proteolytic enzymes
  3. Competent post-graft care
    -Proper bandaging
  4. NO motion
  5. Flat healthy bed of granulation tissue
    -Proud flesh should be removed before graft

Pinch Graft

-Small section of skin elevated with a needle and removed with scalpel
-Soaked in saline gauze before implantation
-Insert into granulation tissue bed
-Donor sites are left open or closed with a single suture
Areas of higher motion appropriate
-Wounds over joints or high motion areas

Punch Grafts

-Full thickness grafts
-Biopsy punch
-Usually mane on the neck or ventral abdomen or thorax donor site
-1-2 mm (smaller) prep punch site on receiving site prepared
-Want a tight fit
Pay attention to the direction of hair growth
-Close donor sites with monofilament
-Use in wound < 10 cm diameter, joints

Tunnel/Strip Grafts

-Partial or full thickness
-Partial - dermatome (hurts!!)
-Full - parallel incision 2mm apart
-Tunnel graft 6mm below surface of the granulation tissue, suture on the other side
-Place 2cm apart
-Granulation tissue over them sloughs or is removed in 7-10 days
-Use in large wounds with thick granulation tissue: good graft acceptance

Sheet Grafting

-Partial thickness obtained with a dermatome
-Very painful
-Need general anesthesia
-Removes partial thickness skin as a sheet: can be suture in place as a sheet or meshed
-Mesh: turns a large wound into lots of tiny ones, prevents fluid accumulation, improves acceptance
-Bandage as with other grafts

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11
Q

Describe types of skin grafting used for equine wounds and advantages/disadvantages of each

A

Skin Flaps
-Horses skin has less stretch than SA skin

Skin Grafts

  1. Split thickness
    2.Full thickness
  2. Autograft: most common
  3. Isograft: from identical twin or highly inbred animal
  4. Allograft: another animal same species
  5. Xenograft: another species
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12
Q

Describe how utilized methods pre and post grafting can increase graft acceptance

A

Bandaging

-Distal limbs best
-Areas of motion need cast
-Prevents examination of the wound
-Advantage: prevents motion
-Remove is there is heat, swelling above the cast, increased lameness, excessive discharge

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13
Q

Understand the causes of graft failure

A
  1. Poorly prepared recipient bed
  2. Poor perfusion
  3. Hemorrhage displacing pinch or punch grafts
  4. Motion
  5. fluid accumulation under graft
  6. Bacterial infection: Fibrin enzymatic destruction - usually holds graft into place

Prevention of failure

  1. Antibiotics
    -Broad spectrum
    -Timentin (ticarcillin with potassium clavulanate)
  2. Inflammation
    -Systemic NSAIDs
    -Phenylbutazone
    -Flunixin meglumine
  3. Movement
    -First bandage change at 4-5 days
    -Confine to stall
    -RBJ, cast, imobilize limb
  4. Fluid accumulation
    -Use meshed graft
    -Hemostasis for punch graft cotton swabs
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14
Q

Dentigerous Cysts & Nodular Necrobiosis

A

Dentigerous Cyst (ear tooth)

-Congenital defect
-Draining tract near the ear
-Cystic lining around a tooth in an abnormal location

Nodular Necrobiosis

-Eosinophilic granulomas
-Trauma, insect hypersensitivity
-0.5-1cm firm nodules
-Can be seen anywhere
-Cosmetic: if needed inject steroids (triamcinolone, methylprednisolone) into lumps
-Can reoccur

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15
Q

Equine Wound management

A
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16
Q

Describe the etiology, diagnosis, treatment, and prognosis for

  1. Fistuluos withers
  2. Cellulitis
A
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17
Q

Fistulous withers

A

Etiology

-Inflammation and infection of the bursa below the supraspinatus ligament along the dorsal spinous processes
-Head trauma history: horse flipping over backward
Brucella abortus - zoonotic & reportable
-Other bacteria
Poll evil = supra-atlantan bursa

Diagnosis

-C/S: draining tract over withers
-Pain on palpation
-Radiographs to assess spinal processes
-Culture

Treatment

-Establish drainage: can be difficult
-Debride wound, spinous processes, bursa
-Antimicrobials
-Lots of lavage

Prognosis

-Fair with early intervention
-$$ prolonged treatment

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18
Q

Cellulitis

A

Etiology

-Infection of the subcutaneous tissues
-Diffused edema in affected limbs
-Common bacteria: Staphylococcus or Streptococcus, negative anaerobes too
-C/S: Significant swelling, lameness 4 or 5/5, fever, small scab, wound, weep fluid from skin, sloughing in severe cases

Diagnosis

-Based on clinical signs

Treatment

-Broad spectrum antibiotics
-Gentamicin, ceftiofur/penicillin, enrofloxacin (resistance in refractory cases), SMZ/doxycycline in mild cases
-May be able to aspirate fluid and get culture/sensitivity
Sweat bandages
-Anti-inflammatories
Magna-poultice topical
Emergency within 12-24 hours

Prognosis

-Prone to recurrence: 44%
-Refractory treatment in some cases: chronically thick leg
-Decreased survival with development of laminitis

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19
Q

Pigeon Fever Lymphangitis

A

Etiology

Corynebacterium pseudotuberculosis
-Uncommon sequelae

Diagnosis

-Nodular lesions
-Abscesses

Treatment

-Broad spectrum antibiotics
-Bandaging
-Takes months to resolve

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20
Q

Determine which wounds are candidates for primary closure, delayed primary closure, and secondary healing, explain why a certain method was choses

A
  1. Initial evaluation
  2. Check synovial structures if applicable
  3. History, PE, Distance exam
  4. Initial evaluation
    -Clip the wound: sterile lube to keep hair from sticking
    -Clean the wound: DILUTE betadine or chlorhexidine
    -Wound lavage: 15 psi (19 g needle, 35 ml syringe)
    -Sedation: xylazine 0.2-1 mg/kg (150-250 mg average horse). Detomidine (3-5 mg), Butorphanol labeled dose or (5-10mg)
    -Local anesthesia: nerve blocks best
    -Radiographs: check for foreign body, fracture
  5. Synovial structures

-Aseptic prep away from wound for communication check
-Insert needle into synovial structure: sample fluid, Amikacin instilled broadspectrum.
-Lavage
-If it communicates refer. Initially not very lame, but 3-5 days later severe lameness bacteria sealed in wound

Treatment

-Antibiotics broad spectrum
-Systemic NSAIDs
-Local antibiotics: Regional limb perfusion, intraosseous perfusion.
-Lavage: arthroscopic, needle under anesthesia, standing.

Regional limb perfusion

-Get high concentration of antibiotic to the sire of infection
-Tourniquet above the site of infection: above and below if mid-limb
-25-27 g needle or catheter in a peripheral vessel
-1g Amikacin or Gentamicin qs to 30-60 ml
10-20 ml Carbocaine first
-Leave tourniquet in place for 30 minutes
-Aminoglycosides concentration dependent

Lavage

-Under general anesthesia

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21
Q

Lavage

A

Chronic Sepsis
-Hyperemia: bacteria hide
-Adhesion formation
-Cartilage thinning

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22
Q

Determine which wounds are candidates for primary closure, delayed primary closure, and secondary healing, explain why a certain method was chosen

A

Primary Closure

-Wound is closed immediately and completely
-Strict aseptic technique

When:
minimal tissue loss, minimal bacterial contamination, minimal tension

Mesh expansion/relief incisions
-Minimize tension
-Small incisions “gap” and heal by second intention
-Allows for drainage of fluid
Never cut skin off if it is still alive/bleeding

Delayed Primary Closure

-Initially debride
-Close within 3-5 days, before granulation tissue forms

When:
-Mild/moderate contamination present
-Minimal tissue loss
-Minimal tension
-Can place drain if needed to evacuate fluid after closing

Secondary Closure

-Less common
-After granulation tissue is covering wound bed
1-2 weeks after wound
-Tension sutures usually needed (button or rubber tubing)

Second intension healing

-Heal by contraction, granulation, epithelialization
-Complications: bone sequestration, exuberant granulation tissue

When
-Wounds can not be sutured
-Gross contamination
-Moderate to severe tissue loss

Exposed Bone

-Sequestrum
-C/S: draining tract from healed wound
-Prevention: cover bone with skin
-Tx: surgical removal

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23
Q
A
24
Q

Describe pathophysiology of the development of exuberant granulation tissue on distal limbs of horses

A

-Occurs on distal limbs only
-Related to: local hypoxia, bandaging, prolonged inflammation
-Delayed healing: epithelialization can not migrate across the wound

Treatment

-Sharp debridement: very vascular, no nerve endings, trim if >dime diameter. From bottom to top
-Topical corticosteroids
-Skin grafting
-Equine amnion dressing (depends on study)

25
Q

Develop a diagnostic and treatment plan for a wound on the limb of a horse, including those wounds involving joints

A
26
Q
A
27
Q

Infectious and Non-infectious diseases and disorders of the equine skin 1-2

A
28
Q

Equine Dermatology History Form

A

Ask questions & Systematic approach

29
Q

Lesions Localization

A

Face/head

-CHS (culicoides hypersensitivity)
-Insects
-Lice
-Sarcoptes
-Onchocerciasis
-Dermatophytosis
-Phythium

Generalized

-Food allergy
-Dermatophytosis
-CHS
-Lice
-Insects
Recurrent urticaria
-Drugs

Ventral Abdomen

-Diffuse
-Focal
-Horn fly
-Onchocerciasis
-Lice
-Dermatophytosis
-Phytium

Legs

-Phytium
-Habronemiasis
-Dermatophytosis
Chorioptes

Tail

-CHS
-Lice
Pinworms
Psoroptes
-Food allergy
-Vice
-Piedra

Mane

-CHS
-Lice
-Psoroptes

Ears

-Black flies

30
Q

Diagnostic Options

A

-Coat brushings
-Skin scraping
-Fungal culture
-Bacterial culture
-KOH preparation
-Dermatophilus preparation
-Acetate strips
-Cytology
-Biopsy
-Microfilarial preparation
-Allergy testing

31
Q
  1. Pruritus
A

A. Ectoparasites
-Lice
-Mange/mites
-Insects

B. Hypersensitivity Atopic Dermatitis
-Insects
-Other

C. Infections
-Staphylococcus pyoderma
-Dermatophytes

32
Q

Diseases Transmitted by flies

What is the agent, fly, and disease matching the c/s?

  1. Hypersensitivity reaction, chronic non-healing wound
  2. Eye glands, ducts, irritation, infection
  3. Microfilaria in skin (midline) adults in nuchal ligament
  4. Burrow into lip, tongue, Gasterophilus
  5. External or internal abscesses. Ulcerative lymphangitis
  6. Anemia, thrombocytopenia, chronic carriers
  7. Encephalomyelitis
  8. Hives, intense itching, abrasions, ulcerations, infections
A
  1. Summer sores
    -Face (Musca autumnal) Stable (Stomoxys)
    -Nematode larvae (Habronema)
  2. Eyeworms
    -Face
    -Nematode worm
    -Thelazia lacrymalis
  3. Onchocerciasis
    -Biting midges
    -Cullicoides
    -Onchocerca cervicalis
  4. Bot flies
  5. Pigeon fever
    -House, horn
    -Stable fly
    Corynebacterium pseudotuberculosis
  6. EIA
    -Horse, deer (Tabanid)
    -EIA virus
  7. EEE, WEE, VEE, WNV
    -Mosquitoes
  8. Hypersensitivity
    -Biting midges
    -Culicoides, others
33
Q

Insect biting hypersensitivity (IBH)

A

A.K.A: Sweet itch, summer itch, summer eczema

Etiology

-Type 1 hypersensitivity
-Culicoides (saliva)
-Breed: Icelandic or any breed
-Possible genetic factor

C/S

-Dorsal
-Ventral
-Combined pruritus
-Skin thickening, scaling, crusting, hives, hair loss
-Discomfort
-Rubbing
-Secondary infection

Dx
-Allergy panels
-History (season)
-Clinical signs
-Exclusion

Tx
-Management of manure, water, food and other
-Avoid wet bedding
-Avoid manure in stable
-Reduce exposure: netting, fans over stall, fly masks.
-Fly control
-Reduce itching: antihistamines, systemic corticosteroids, omega# and 6 FA.
-Control immune response: desensitization (30% effective), immune system shift

34
Q
  1. Nodules, tumors, swellings
A

Urticaria (Hives)

Causes
-Hypersensitivity
-Mast cell degranulation, histamine release
-Allegen, medication, vaccination, insect bit

Signs
-Rapid onset of wheals, pruritus
-Multifocal edema 0.5-3cm

Dx
-History, c/s, treatment response

Tx
-Avoid, remove cause, spontaneous resolution
-Corticosteroids
-Antihistamine
-Epinephrine if systemic

Eosinophilic Granuloma, Nodular Necrobiosis

Cause
-Unknown
-Silicone coated needles suspected

C/S
-Singular or multiple nodular lesions anywhere
+/- exudate, pruritus, mineralized

Dx
-History and c/s
-Aspirate biopsy

Tx
-May regress spontaneously
-Intralesional corticosteroids (triamcinolone or methylprednisolone)

35
Q
  1. Nodules, tumors, swellings
    Infectious
    Neoplastic
    Non-neoplastic
A

Pigeon Fever

Cause
-Corynebacterium pseudotuberculosis
-Ground feces, hay, shavings reservoir
-Insects transmission, direct, indirect
-Wound or small scrapes in skin = entry

C/S
-Abscess, ulcerative lymphangitis

Dx
-History, c/s, Ultrasound, synergistic hemolysin inhibition

Tx
-Drainage
-Abdomen if internal or ulcerative lymphangitis
-Prevention: biosecurity

Cutaneous Habronemisasis (Equine summer sore)

Causes
-Flies
-H. microstoma, H. musea, Draschia megastoma

Pathophysiology
-Adults in stomach, eggs hatch in GI or environment.
-Larvae deposited on horse flies
Hypersensitivity reaction
-Granulomatous reaction

C/S
-Stomach: mild gastritis
-Cutaneous or conjunctival lesions where larvae is deposited
-Ulcers, nodules granuloma (prod flesh) lesions

Dx
-Biopsy, PCR

Tx
1. Ivermectin
2. Topic/systemic steroids
3. Fly control
4. Topical wound care, debulking may be needed
5. Prevention: insect control, manure control

Phytosis

Cause
-Swamp cancer, Florida horse leeches
-Phytium insidosum fungus/mold
-Hot humid weather and break in skin

Forms
-Cutaneous, Subcutaneous, GI, respiratory, multi systemic

C/S
-Tumor like growths following the lesion

Dx
-Histopathology
-ELISA by Pan American Veterinary labs

Tx
-Difficult
-Debulking, chemotherapy, topical
-Vaccine

36
Q
  1. Nodules, swellings, tumors
    Non-neoplastic

Papillomatosis and aural plaques

A

Etiology

Papilloma
-Warts in young animals, variable size and number
-Spontaneous regression

Aural
-Form of papilloma inner pinna, genitalia, mammary gland

C/S
-Warts

Tx
-Crush, pinch, surgical removal, cryotherapy
-Autogenous vaccine
-Aural plaques: Imiquimod (Aldara 3M), NSAID local immune defense modifier 3x/week, 2-4months

37
Q
  1. Ulcerations and Erosions
    They are secondary lesions and often get infected
    Ulceration: complete loss of epidermis, often leaves scars
    Erosion: partial loss of epidermis, heal without a scar
A
38
Q
  1. Papules, pustules, vesicles
A

Dermatophilosis - Rain Rot

Etiology
-Dermatophilus congolensis
-Fomaties, flies, ticks
-Immune status
-Carrier animal + moisture + skin abrasion

C/S
-Fall & Winter
-Wet hair
-Lesion thick crusts moist underneath, peals off, “paintbrush”, pink moist underneath

Dx
-Impression smear: Rail road tract cocci
-Culture and histopathology
-Mostly clinical signs

Tx
-Move animal to dry environment
-Remove crusts and wash with Iodophores or lime sulfur
-Antimicrobial shampoos
-Penicillin, or TMS if severe

Folliculitis

Etiology
-Staphylococcus spp.

C/S
-Crusts (circular), epidermal collarettes, encrusted papules
-Saddle and lumbar regions, pastern, large areas

Tx
-2-6 weeks TMS, Doxycycline, Enrofloxacin
-Loacl Mucipirocin or silver sulfadiazine, stannour fluoride

Pastern Dermatitis Mud fever, Scratches

Etiology
-Infectious and non-infectious component
-Predisposing factors: pigmentation, photosinsetization
-Chorioptes, dermatophilosis, unpigmented skin, moisture.

C/S
-Erythema, scaling, exudate, crusts, alopecia, cracking
-Secondary infections, local inflammation, limbs swelling, lameness

Dx
-C/S
-Skin scrape, culture, biopsy

Tx
-Remove cause, clip hair, remove crusts
-Antiseptic shampoos
-Antibiotic ointments
-Corticosteroids
-Systemic antibiotics in severe cases
Prevention
-Remove underlying cause
-Keep legs clipped and dry
-Treat early

39
Q
  1. Scaling and crusting
A

Dermatophytosis - Ringworm

Etiology
-Trichophyton equinum
-Microsporum equinum
-T. mentagrophytes
-T. verrucosum
Zoonosis
-Direct contact, fomites, incubation for weeks
-Predisposing factors: age, crowding environment, damaged skin

C/S
-Circular lesions
-Face, axilla, girth, spread, areas that are rubbed.
-Superficial to deep lesions: crusts, scaling and alopecia
-Young horses
-Multiple horses affected

Dx
-Direct microscopic exam
-Fungal culture (!!Pemphigus)

Tx
-50% captan, lime sulfur
-Shampoos: miconazole, ketoconazole, chlorhexidine
Spores in chain

Pemphigus Foliaceus

-Autoimmune disease
-Desmoglein 1 and 3
-Destroy cell adhesion

C/S
-Depression
-Fever
-Urticaria
-Edema on ventral midline, limbs and head
Lesion: Pustules, erosion, epidermal collarette, scale, crust, erosion
+/- Pruritus, pain
Severe lesions around coronary band

Dx
-Challenging
-Biopsy with intact crust
-Histopathology: acantholysis
-Ddx stain for fungal (Trichophyton)

Tx
-Corticosteroids: prednisolone, dexamethasone
-Chrysotherapy (gold salts)
-Azathioprine - thrombocytopenia
-50% respond, life long medications

40
Q
  1. Abnormal coat length and density
A

Cutaneous Onchocerciasis

(Looks similar to dermatophytosis)
(Common in not regularly deworm horses)

Etiology
-Onchocerca cervicalis - Filarial dermatitis
-Adults (Nuchal ligament) Microfilariae (dermis)
-Transmission culicoides
-Decreased since ivermectin use

C/S
-Ventral midline, lower lid, lateral limbus eyes, face
-Base of mane, anteromedial proximal forelimbs, anterior pectoral
-Older horses: ocular and cutaneous lesions. Erythema, depigmentation, conjunctivitis, keratitis, uveitis, scaling, diffuse patchy alopecia.

Dx
-“Nest” in skin - variable recovery
-Ddx hypersensitivity, dermatophytosis, mange
-Biopsy, minced, macerated, stained with methylene blue

Tx
-Ivermectin or Moxidectin
-No effective adulticide
-Re-treat in 4 months
-Pre-treat horses with recurrent uveitis

41
Q
  1. Nodules, tumors, swellings
    Infectious
    Neoplastic
    Non-neoplastic
A

Squamous cell carcinoma

Cause
-Tumor of squamous epithelial cells
2nd most common tumor in horse

Pathogenesis
-UV light + lack of pigmentation + genetics
-Older horses, unpigmented skin around mucocutaneous junction, Belgian WB & Draft, Halflinger, homozygous R/R

C/S
-Eyes, external genitalia
-Thickening, mild exfoliation, ulceration
-Erosive/productive lesion
-Raised, broad based, white-pink
-Cobbled/cauliflower-like surface
-Metastasis possible (2-18%)

Dx
-Clinical signs
-Biopsy

Tx
-Surgical excision
-Cryosurgery, radio frequency, radiation
-Chemotherapy: 5-fluorouracil, mitomycin C, cisplatin

Melanoma

Always do a full skin check on gray horses

-Exposure to sunlight
-Disturbance in melanin metabolism - graying
-Age 67% >15 yo
-Color 80% gray
-Breed: Arabian, Lippizaner, Percheron

C/S
-Black, gray
-Solitary, discrete, firm, spherical or flat
-Coalesce, cobblestone appearance
-Progress with age
-Metastasis

Classification
-Depth, age, location, metastasis
-Benign
-Dermal
-Malignant

Dx
-Clinical, aspirate, biopsy

Tx
-Surgical excision or cryo
-Chemotherapy
-Microwave energy
-Hyperthermia
-Electrochemotherapy
-Cimetidine 3 weeks past resolution
-Piroxicam
-Monoclonal Ab
-Canine melanoma vaccine

42
Q

Pediculosis

A

Winter, Multiple horses

Etiology

-Lice
-Sucking lice: Hematopinus asini (thick hair) Anoplura
-Biting lice: Damalina equi (thin hair) Mallophaga
Stressors are risk factor
-Poor feed quality, gestation, underlying health issue, winter coat, feathering

C/S
-Pruritus
+/- Self trauma
-Multiple animals affected, different ages
-Dry scaly skin, patchy alopecia, crusted ulcerations
-Anemia

Dx
-White exam coat: lice shows black
-Inspection, hand lens

Tx
Systemic
-Ivermectin q 2 weeks for sucking lice
-Moxidectin q 4 weeks

Topical
-Powders, baths
-Pyrethrins, synthetic pyrethroids q 7-10 days 2-5x
-Clean fomites

43
Q
  1. Pruritus
    Ectoparasites

Ascariasis (Mange mites)

A

Etiology

Sarcoptic
-Most severe, but rare
-S. Scabei var equi
-Body, think hair

Psoroptic
-P. ovis, P. cuniculi
-Mange, long hair
-Rare

Demodectic
-D. equi, D. caballi
-Body, eyelid, muzzle
-Rare

Chorionic
-C. bovis
-Most common
-Leg
-Draft horses
C/S:
-Stamp feet, rub
-Pastern dermatitis complex
-Pruritus, papules, erythema, scaling, crusting, ulceration, alopecia, thickened skin
Dx:
-Skin scrape
Tx:
-Lime sulfur 1x/week for 1 month
-OP spray
-Fipronil spray
-Ivermectin 14 d apart, moxidectin

Harvest mite
-Trombiculoid
-Forage mite
-Summer, fall, straw

44
Q
  1. Abnormal Pigmentation
A
  1. Overo Lethal Foal syndrome
  2. Leukoderma
    -Previous trauma or inflammation
    -Temporary or permanent
  3. Vitiligo of Arabian Horses
    -Arabian fading syndrome
    -Pink syndrome
    -Idiopathic acquired depigmentation
    -All breeds, Arabian most common
    -Pregnant, post partum mares
  4. Leukotrichia
    -Acquired loss of pigment in hairs (trauma, inflammation)
    -Reticulated inherited disorder QH, STB, TB
    -spotted leukotrichia
45
Q

Genetic Conditions

A

AQHA

HERDA - Hereditary equine dermal asthenia
-Autosomal recessive high % carriers
-Abnormal collagen
-Sunlight lesions

C/S
-Normal at birth and for 2 years
-Loose, hyperextensible skin
-Scars from minor trauma

Dx
-Biopsy and genetic test
-All stallions test!

Tx
-None
-Euthanasia

APH

LWO - Lethal overo white

Etiology
-Homozygous, lethal
-Frame overo pattern (spectrum)
-Endothelin B - pigment/nerve

C/S
-All white foals
-DD meconium impaction, white mimics
-Ileocolic aganglionosis

Dx
-Genetic test

Tx
-Eauthanasia

46
Q

Hemolymphatic system and diseases

A
47
Q

Red Blood Cells Diseases
Do not typically find Reticulocytes in equine blood

A

Equine Blood Types - Most antigenic

Aa, Ca, Qa
ACQ: encode for RBC surface antigen
a: encodes Ag factors

  1. Erythrocytosis
  2. Anemia
    -Blood loss: trauma, surgery, ectoparasites, GI parasites, Equine purpura hemorrhagica, Immune mediates
    -Hemolysis: neonatal isoerythrolysis, red maple leaf toxicosis, Equine infectious anemia.
    -Decreased erythrocyte production: anemia of inflammatory disease (chronic inflammation, neoplasia). Chronic abscess, lymphoma, chronic pneumonia or pleuritis
48
Q

Acute Blood Loss - Regenerative

A

Etiology
-Ex: guttural pouch mycosis (internal carotid)
-Internal or external
-Trauma, surgery
-Organ system: GI, respiratory, Guttural pouch

Anemia - TP low - Blood loss - External/internal

Dx
-C/S
-Lab parameters
-Additional: ultrasound, coagulation test, platelet count, rectal palpation, thoracocentesis, abdominocentesis

Estimated blood loss
Normal blood volume ~8% of BW (40 L for 500 kg horse)

Percentage loss & C/S

15% (<6L) Normal attitude, HR 30-40, RR 8-16, BP normal

15-30% (6-12 L) Anxiety, 40-60 HR, increased RR, increased CRT

30-40% Anxiety, depression, HR elevated, cool extremities, low BP

> 40% obtundation, palor, cool low BP

Tx
-Stop bleeding
-Treat hypovolemic shock: crystalloids (20ml/kg boluses). Hypertonic 7.2% NaCl
-Prepare for blood transfusion PCV <20% acute blood loss or <12% over 24 hrs
-Oxygen supplementation, naloxone, aminocaproic acid, yunnan baiyao

Blood donor selection

-No blood bank for equine blood, not useable after saved
-Blood typed and tested donor (Aa, Qa, Ca) and Ab negative
-Crossmatched: Major washed donor RBC + recipient serum
-Minor: donor serum + washed recipient RBC
Agglutination Hemolysis

Donor commonly:
STB or AQHA gelding, no history of exposure to blood products, UTD vaccines, Coggins test. Collect 8-10 L and use within 24 hours, replace with crystalloid, collect in 3 weeks again.

Recipient
-8-10 L
-Filtered, slowly for 15 minutes then fast
-Monitored TPR/2 min for 30 minutes, then every 15 minutes
-If reaction, stop transfusion, steroids and phenylephrine (epinephrine)

49
Q

acute Hemolytic Anemia - Regenerative

A

Intravascular

-In circulation
-Released hemoglobin
-Schistocytes

Extravascular

-Phagocytosis in spleen/liver
-Spherocytes

Toxic
-Red maple leaves
-Wild onions
-Phenothiazine
-L-Tryptophan-indole

Infectious
-EIA
-Piroplasmosis
-Leptospirosis
-Anaplasmosis

Immune mediated
-Primary idiopathic autoimmune
-Secondary autoimmune
-Neonatal isoerythrolysis

Other
-End stage liver failure
-Iatrogenic

50
Q

Toxic anemia

Oxidative stress

A

Ddx
Red Maple leaves Toxicosis
Wild onion, garlic, pistachia leaves
Phenotiazine drugs
Inflammation, neoplasia, metabolic disease
Envenomation snakes, bees

-Heinz bodies formation in RBC
-Hemolysis
-Methemoglobinemia

C/S
-Depression
-Increased TPR
-MM pale
-Urine dark red

Dx
-History and c/s
-Blood work
-Urine analysis
-Systemic inflammation

Tx
-Eliminate access to toxin source
-Activated charcoal
-Fluid therapy
-Blood transfusion
-Vitamin C
-Laxative (Mineral oit, magnesium sulfate)
-Vitamin E and Selenium IM
-Acetylcysteine
-Analgesics
-Intranasal oxygen at high rate

Prognosis: guarded

51
Q

Infectious Hemolytic anemia

A
  1. Equine infectious Anemia (Reportable)
    -Viral agent
    -Transmission flies, needles
    -C/S: acute fever, RR
    -Chronic: hemolytic, anemia, bleeding, edema,
    -Non-apparent
    -Dx: Coggins (AGID), ELISA
    -Tx: quarantine, euthanasia
  2. Piroplasmosis
    -Protozoal agent: Theileria equi, Babesia caballi
    -Not common in US
    -Transmission: ticks, needles
    -Acute: fever, depression, hemolytic anemia
    -subacute
    -chronic
    -Dx: cELISA, IFA
    -Tx: quarantine, euthanasia
  3. Anaplasmosis
    -Tick borne
    -Anaplasma phagocytophilum bacteria
    -WBC granulocytes affected
    -Equine granulocytic Anaplasmosis
    -Transmission ixodes ticks
    -Risk fall, spring, geographic area

C/S
<1 yo: fever
1-3 yo: fever, depression, adema, ataxia
Adult: fever, anorexia, depression, limb edema, petechia, icterus, reluctance to move
-Leukopenia
-Thrombocytopenia
-Anemia
-Mildly affected cells, cytoplasmic inclusion bodies in neutrophils

Dx
-C/S
-Lesions
-Blood work
-Cytoplasmic inclusion in PMN
-PCR, 4Dx, SNAP
PCR confirmatory + serology 4-fold antibodies increase

Tx
-Supportive care
-Oxytetracycline 8 days
-Oral doxycycline or minocycline
-Tick control

  1. Equine viral arteritis

-Worldwide
-Economic importance
Pathology
-Respiratory - panvasculitis - edema - congestion - hemorrhage
-Abortion 2-10 mts
-Persistent infection of stallions (testosterone dependent, ampulla)
Stallion carrier primary reservoir
-Alpha-arteri virus
-Transmission: respiratory, abortion, venereal, congenital, indirect
-Incubation: 2 days to 2 weeks

C/S
-Asymptomatic mostly
-Respiratory disease, abortions, anemia, others
-Young, old, debilitated: fever, depression, limb edema, anorexia, nasal discharge, genital edema, conjunctivitis, periorbital edema, rhinitis, urticaria, hives, abortion, stillborn, petechia, icterus, short term subfertility in stallions testicular temperature
Fetal respiratory or pneumoenteric syndrome rare

Dx
-PCR
-NP swab, EDTA blod
-Immunohistochemistry
-Virus isolation
-Serology
-Stallions: tite > 1:4 = positive. Detect sperm rich fraction of semen, test breed to sero-negative mare (seroconversion in 28 days)

Tx
-NSAIDs
-Diuretics
-Rest
-Nursing care

Prevention
-Vaccination MLV non pregnant mares, stallions
-Breeding management: select breeding, identify carriers

52
Q

Equine Infectious Anemia

A

EIAV
-Retroviridae, lentivirus
-1983 first

No vaccine, no treatment
-No cure
-Life-long carriers

C/S
-Weight loss
-Fever
-Icterus
-Anemia
-Swelling

Transmission
-Mechanical: bites from flies
-Iatrogenic: needles, syringes, IV set, dental instruments, surgical instruments
-Other: in utero, in milk, in semen, aerosolized
-Blood transfusions in bush track racing

53
Q

Infectious Pigeon Fever

A

Ddx: dryland distemper, false strangles

Etiology
-Corynebacterium pseudotuberculosis
-Gram (+) pleomorphic, intracellular, facultative anaerobe
-Worldwide - on the rise in US
Biotypes
1. Horses: nitrate positive
2. Small ruminants: nitrate negative

Reservoir: ground, feces, hay, shavings
Entry: small scrapes or wound in skin or mm abrasions
Transmission: direct, indirect, insects

C/S

External Abscess:
<1% fatality
Pectoral, abdomen, mammary gland, prepuce, limbs, head.

Internal Abscess:
Liver, lungs, kidney spleen

-Edema
-Fever
-Non-healing wounds
-Internal abscess: Decreased appetite, lethargy, fever, colic 30-40% fatality

Dx
-Bloodwork: anemia of chronic disease. Leukocytosis with neutrophilia, hyperfibrinogenemia, hyperproteinemia (globulins)
-Ultrasound
-Culture: blood agar 24-48 h
-SHI not helpful if external. synergistic hemolysin inhibition test. Measures IgG against toxin, helpful in internal abscess

Tx
-Drainage
-Asses with ultrasound
-Lavage but environmental contamination
-Antimicrobials: Rifampin & ceftiofur, doxycycline, enrofloxacin
-1-3 months treatment

Sequela

Ulcerative Lymphangitis
-Pen G or ceftiofur + rifampin
-Until lameness and swelling improve then oral
-NSAIDs, physical therapy

Prevention Pigeon fever

-Biosecurity
-Reduce environmental contamination
-Fly control
-Manure management sanitation
-PPE, barriers, cleaning, disinfection
-Wound care and protection

Abscess: consider culture and senstitivity, it could be strangles MRSA, re-asses.

54
Q

EIA & Equine Piroplasmosis

A

2022
-96 cases in 16 states
-84 iatrogenic transmission

EP
-Thaeleria equi (Babesia)
-Babesia caballi
Life long infections
-Ticks and blood products transmission
C/S
-Lethargy, fever, inappetence, anemia, icterus, colic, weight loss, exercise intolerance, sudden death or
-No signs at all

Endemic in Mexico, Middle East, etc.

Dx
-cELISA and CFT
-Exporting animals tested

Tx
-Euthanasia
-Export out of the country
-Life time quarantine
-Quarantine with enrollment in USDA-APHIS
-EP treatment program
Dually infected EIA & PE = euthanasia

Tx
-4 doses of 4mg/kg DIPROPRIONATE IM pre-treat with BUSCOPAN

55
Q
A