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Equine > equine oncology > Flashcards

equine oncology Flashcards

1
Q

What is the most common neoplasia of the horse

A

Sarcoids
Up to 2% prevalence

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2
Q

What is the cause of sarcoids and what cells are neoplastic

A

Bovine papillomavirus 1 and 2 are involved
= neoplastic proliferation of fibroblasts

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3
Q

What are the 6 types of sarcoids

A

Occult
Verrucose
Neodular
Fibroblastic
Mixes
Malevolent

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4
Q

What do occult sarcoids look like

A

Just a hairless raise area; = first early lesions and easy to miss

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5
Q

What do verrucose sarcoids look like

A

Warty, crusty dry lesions
Start discretely but can spread

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6
Q

What area are nodular sarcoids especially infiltrative

A

Periocular region

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7
Q

What do fibroblastic sarcoids look like

A

Ulcerated skin mass, often discrete and simple to treat

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8
Q

What are malevolent sarcoids

A

Rare form that spreads quickly along lymph vessels and are poorly defines

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9
Q

What are some predilection sites for sarcoids

A

Anywhere with less hair i.e periocular, axillary, inguinal, sheath
+ sites of previous wounds

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10
Q

what is the correlation between histopath of sarcoids and their clinical appearance; what about prognosis

A

No correlation
Makes biopsy harder to justify when there is a high sensitivity/specificity of presumptive visual diagnosis

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11
Q

What are the treatment options for sarcoids (in success order)

A

Radiotherapy is best
Laser surgical resection = good first line treatment for most lesions since more accessible

Electrochemotherapy
Intralesional treatments
Topical treatments; very variable success

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12
Q

What is plesiotherapy

A

= radiotherapy using strontium90 beta paricles; short penetration so good for small superficial lesions

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13
Q

What is brachytherapy

A

Radiotherapy using iridium gamma therapy
Has good penetration so can be used for any lesion
= gold standard for periocular lesions

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14
Q

What is teletherapy

A

Using linear accelerator to create beta or gamma beams
Needs GA so rarely done

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15
Q

What is the gold standard treatment for periocular sarcoids

A

Iridium brachytherapy

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16
Q

What are some complications that can occur with radiotherapy

A

White hair formation, alopecia
Can get scar tissue formation

May see transient uveitic with brachytheraphy near eye

Osteoradionecrosis, non-healing wounds, damage to tooth roots rare

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17
Q

How does laser surgical resection

A

Cut out region with laser and leave open wounds to granulte by second intention

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18
Q

What is the success of laser surgical resection

A

High; ~80% per lesion
So is a practical, effective and accessible first line treatment for many

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19
Q

Complications of laser surgical resection

A

Non-healing wound
Recurrence + aggressive transformation

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20
Q

What is electrochemotherapy

A

= where chemotherapeutic (e/g cisplatin) agents are injected into the lesion and then electrodes are used to enhance the penetration

Can be used in conjunction with other treatments

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21
Q

What are some considerations and complications of electrochemotherapy

A

Needs a GA for the horse
Health and safety concerns

Can lead to necrosis and wide slough, pain and oedema, non-healing wound

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22
Q

What must we remember when considering intralesional therapy for sarcoids

A

Need a lesion to inject into
Cannot do on verrucose or occult sarcoids since these are flat; will get very large slough and risk of leakage of drug

i.e for nodular and fibroblastic

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23
Q

What are some agents for intralesional therapy

A

Cisplatin
Mitomycin C (DNA damaging chemo)
Tigilanol tiglate
Immunocidin

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24
Q

How does Tigalanol tiglate (Stelfonta) work (intralesional therapy)

A

Causes haemorrhagic necrosis of the tumour

Risk = very large area of sloughing inc down to bone

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25
Q

How does immunocidin work (intralesional therapy for sarcoids)+ risks

A

Contains mycobacterium wall fraction
Immune modifying

Risks = swellin, pain, abscessation

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26
Q

How does 5-fluorouracil work and which lesions is it good for

A

DNA damaging chemo cream

Good for verrucose and occult lesions (flat)
2/3 success
Can get sore and cruty, skin scald may happen

27
Q

What is AW-5 liverpoor cream

A

Secret formula chemo agent

28
Q

What complications can occur with AW-5 cream

A

Wide local slough, severe pain, oedema

29
Q

What is imiquimod and which sarcoid lesions is it good for

A

Immune-modifying agent
Good for occult lesions i.e superficial

Treat 3 x per week until lesion goes away
Must clean lesion each time

30
Q

How does bleomycin work and which sarciods is it good for

A

DNA damaging chemo cream (but less risky than other chemos if gets into eye etc)
Only for occult lesions

31
Q

What is tazarotene and what use might it have in dealing with sarcoids

A

Retinoid cream
Can be used to reduce the crust on verrucose lesions before applying 5-FU crean

Some effect alone

32
Q

What is the best first line treatment for most sarcoids

A

laser surgical resection

33
Q

Where do we typically see skin squamous cell carcinomas

A

Non-pigmented skin; third eyelid, limbus, cornea
all related to solar exposure

34
Q

What does a typical SCC look like

A

Rapidly proliferating cauliflower lesions
But can look much less obvious

35
Q

What should we suspect a squamous cell carcinoma in a horse

A

Any unusual ocular or periocular presentation
Corneal and conjunctival infiltrates may be very artypical

Biopsy a good idea

36
Q

What is the most common squamous cell carcinoma in the horse

A

3rd eyelid

37
Q

Are genetics involved in SCCs

A

Yes one of the syndromes is genetic

38
Q

What is the cause of genital SCC

A

Virally-mediated; equine papilloma virus 2
Classic cauliflower lesiosn

39
Q

What are pale white lesions near a genital SCC

A

early SCC plaques i.e precancerous change

40
Q

Where do we see gastric SCCs and what is the prognosis

A

= rare type of SCC: typically seen at pylorus
OFten diagnosed late and already metastasised so poor prognosis

41
Q

What do sinus SCCs present like

A

Primary sinusitis so often just put on antibiotics and get to a late stage before proper diagnosis
Eventually erode through bone and cause facial deformation

42
Q

How do we treat squamous cell carcinomas

A

Wide surgical excisino = treatment of chocie
Radiotherapy can be a good adjunctive since SCCs are very sensitive

May do topical/intralesional treatments

43
Q

What is the prognosis for SCCs like after treatment

A

about 1/3 of eye lesions recur
10-30% of penile ones do

Can recur years later

44
Q

What radiotherapy would we use for squamous cell carcinomas

A

Strontium90 plesiotherapy

45
Q

What prophylactic drugs do we put a horse on before giving tigilanol tiglate

A

Place subpalpebral lavage and use prophylactic topical NSAIDs and atropine and systemic NSAIDs
Due to risk of uveitis

46
Q

How does 5-FU work

A

structural analogue of thymine so inhibits DNA formatino by blocking thymidylate synthetase
Taken up more by tumour cells

47
Q

Why might we use piroxicam in equine SCCs

A

BEcause COX-2 is overexpressed and this is an inhibitor
No clear evidence; could be a good adjunctive

48
Q

Why should we always stage SCCs

A

Because many have already metastasised at first presentation (~10%); so should tell owner care will be palliative

49
Q

Characteristics of melanoma in the horse and predilection sites

A

Usually benign
Predilection sites = perianal, tail, sheath, parotid salivary glands

50
Q

Which horses do we see melanomas in

A

Mostly grey horses; almost all have one in middle to old age

51
Q

How do melanomas change over horse lifetime

A

Grow and multiply
Can become necrotic, ulcerated and lead to seconday issues e.g maggots in sheath, rectal impaction

Benign but may eventually metastasise

52
Q

What are the treatment options for melanoma

A

Surgical excision is treatment of choice if possible
Laser resection also good

There is oncept melanoma vaccine

53
Q

How does oncept melanoma vaccine work

A

Xenogenic human DNA vaccine against tyrosinase
Can stabilise melanoma by preventing further growth or new lesions
But won’t cause regression

54
Q

How common is lymphoma in horses and what are the forms

A

Rare - but most common of the haematopoietic neoplasms

Forms = multicentric, alimentary, mediastinal, cutaneous, solitary

55
Q

How do we treat solitary lymphoma

A

Wide local excision usually curative

56
Q

Characteristics of cutaneous lymphoma and treatment

A

Can wax and wane for years
Prednisolone is a palliative treatment

Chemo has been described

57
Q

What types of haemangiosarcoma are possible and where do we see disseminated disease

A

Rare
Cutaneous, locally invasive or disseminated

Disseminated goes to lung, pleura, skeletal muscle, spleen

58
Q

What are some common clinical complaints with disseminated haemangiosarcoma

A

Dyspnnoea
Swelling
Epistaxis
Lameness

59
Q

Can we treat haemagiosarcomas

A

Cutaneous lesions can be surgically resectable
Locally invasive and disseminated forms mostly untreatable

60
Q

Characteristics of mast cell tumours in horses

A

Generally benign
Respond well to surgical excision/intralesional corticosteroids

61
Q

Where do we tend to find basal cell carcinoma in horses

A

Ditsal limb and tail
Otherwise look like sarcoids
Treat with wide local excision

62
Q

What are the different SCC syndromes in the horse

A

Skin lesions; non-pigmented skin
Genetic
Genitalisa
Gastric

+ others

63
Q

Which tumours are paraneoplastic syndromes esp common with

A

Lymphoma
(paraneoplastic fever, thrombocytopaenia, pruritis)

Equine (18 decks)

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