Chapter 13/14 - Environmental/Hereditary

Question 1

What type of necrosis occurs in pressure sores?

Answer 1

Ischaemic necrosis

Question 2

What is myospherulosis?

Answer 2

An extremely rare granulomatous reaction thought to be due to the interaction of ointments, antibiotics, or endogenous fat with erythrocytes

Question 3

What are the clinical signs of myospherulosis?

Answer 3

Solitary subcutaneous or dermal nodules, which may or may not have draining tracts.

Question 4

In myospherulosis, do parent bodies and spherules stain with PAS, GMS or acid-fast stains?

Answer 4

No

Question 5

What is the pathological mechanism of gangrene?

Answer 5

An occlusion of either arterial or venous blood supply.
Moist gangrene -impairment of lymphatic and venous drainage plus infection
Dry gangrene - arterial blood supply is occluded, but venous and lymphatic drainage remain intact and infection is absent

Question 6

Gas gangrene/subcutaneous emphysema is associated with which type of infecion?

Answer 6

Clostridial infections

Question 7

What is a histopathological diagnostic feature of electrical burns?

Answer 7

A fringe of elongated, degenerated cytoplasmic processes that protrude from the lower end of the detached basal epidermal cells into the space separating the epidermis and the dermis. The nuclei of the basal cells and often of the higher-lying keratinocytes appear stretched in the same direction as the fringe of cytoplasmic processes. This gives the image of keratinocytes that are “standing at attention.”

Question 8

What are the clinical signs of selenium poisoning?

Answer 8

Lameness (typically HL first)
Hoof changes (rings, corrugations, horizontal cracks)
Emaciation
Loss of the long hairs of the mane, tail, and fetlocks
Rough hair coat (breaks easily)

Question 9

What are the clinical signs of chronic arsenic poisoning?

Answer 9

Gastroenteritis
Emaciation
Exfoliative dermatitis
Dull, dry, rough, easily epilated coat 
Some horses develop a long hair coat, others alopecia

Question 10

What are the clinical signs of chronic mercury poisoning?

Answer 10

Nephrosis
Lameness
Oral ulceration
Emaciation
Progressive generalised alopecia
Depression
Anorexia

Question 11

What are the clinical signs of excessive iodine intake?

Answer 11

Seromucoid nasal discharge
Lacrimation
Cough
Variable appetite
Joint pain
Severe scaling +/- alopecia - most common over dorsum, head, neck and shoulders

Question 12

Claviceps purpura infected grain causes which diseae?

Answer 12

Ergotism

Question 13

Which fungus causes painful, necrotic ulcers in the mouth, nasal region and lips in horses?

Answer 13

Stachybotrys atra (stachybotryotoxicosis)

Question 14

Which UV spectrum (A, B or C) is associated with photosensitivity reactions?

Answer 14

UVA

Question 15

Name three drugs that can act as primary photosensitisation agents?

Answer 15

Phenothiazine
Thiazides (e.g. diurectics)
Promazines
Acriflavines
Rose bengal
Methylene blue
Sulfonamides
Tetracyclines
Coal tar derivatives
Furosemide

Question 16

What are the histopathological features of acute and chronic photosensitisation in horses?

Answer 16

Acute - epidermal and dermal oedema, vaculoated and apoptotic epidermal keratinocytes, intramural and perivascular deposition of eosinophilic amorphous material in superficial dermal blood vessels
Chronic - diffuse necrotising/fibrosing dermatitis and absence of adnexae

Question 17

Match the types of epidermolysis bullosa with the location of the blister:
EBS
JEB
DEB

within the sublamina densa of the BMZ
within the lamina lucida of the BMZ
within the stratum basale of the epidermis

Answer 17

EBS - within the stratum basale of the epidermis
JEB - within the lamina lucida of the BMZ
DEB - within the sublamina densa of the BMZ

Question 18

Name a breed of horse reportedly affected by epidermolysis bullosa?

Answer 18

Belgians
Trait Breton
Trait Comtois
All three share a common ancestor

Warmbloods
Appaloosas
American saddlebreds

Question 19

What is the genetic defect found in Belgian horses with epidermolysis bullosa?

Answer 19

A mutation in LAMC2 gene on equine chromosome 5

(insertion) - AR

Question 20

What is the genetic defect found in American saddlebred horses with junctional epidermolysis bullosa?

Answer 20

LAMA3 maps to equine chromosome 8

(deletion) - AR

Question 21

Which histo special stain is used to show where the basement membrane is attached in vesicles of epidermolysis bullosa?

Answer 21

PAS

Question 22

Mane and tail follicular dysplasia affects which breed of horse and at what age is it apparent?

Answer 22

Appaloosas
Horses with curly coats

At birth or a few weeks of age

Question 23

What is a major differential for follicular dysplasia in horses?

Answer 23

Alopecia areata

Question 24

Vitiligo affects which breed of horse?

Answer 24

Arabians

Question 25

What breed of horse is reportedly affected by cutaneous aesthenia/HERDA?

Answer 25

American quarter horse and horses that share bloodlines (e.g. appaloosa)

Question 26

True or false? The genetic defect in HERDA/equine cutaneous aesthenia has been localised to equine chromosome 1 and is a mutation in cyclophilin B (peptidyl-prolyl isomerase [PPI] B).

Answer 26

True

Question 27

Name a breed of horse affected by chronic progressive lymphoedema

Answer 27

Belgian Clysedale Shire Friesian

Question 28

What are the early clinical signs of chronic progressive lymphoedema in horses?

Answer 28

Mild swelling and scaling of the distal limbs, often visible only after the feathering has been clipped. One or two skin folds on the caudal pastern may be palpable.

Question 29

In chronic progressive lymphoedema in horses, special stains (e.g. acid-orecin and Giemsa) show distorted, fragmented, clumped and pale _____ fibres.

Answer 29

Elastin

Question 30

In Friesian horses with chronic progressive lymphoedema, which limb measurements were significantly increased in affected horses?

Answer 30

Length of forearm and length of gaskin (tuber calcanei to distal end of patellar, length of tibia)

Question 31

Can anti-elastin auto-antibodies be used to help diagnose chronic progressive lymphoedema?

Answer 31

No, values overlap in normal and affected horses

Question 32

What are the clinical signs of immersion foot syndrome in horses?

Answer 32

Dermal defects ventral to a sharply demarcated “water line” along the lateral trunk. The severity of the lesions progressed from ventral trunk to distal limbs and became more pronounced in the chronic cases. Moderate to severe perivascular dermatitis with vasculitis and coagulative necrosis consistent with ischemia.

Question 33

What are the clinical signs of HERDA (Hereditary Equine Regional Dermal Asthenia)?

Answer 33

- Age of onset ranges from birth to 4 years (see when breaking in) - Variably severe skin “swellings” that likely represent seromas or hematomas - Scars - Loose skin, fragile skin and deep tears that do not heal normally - Thinner skin than normal horses

Question 34

In HERDA, which part of the dermis shows collagen abnormalities?

Answer 34

Deep dermis

Question 35

Why do you see ocular abnormalities in horse with HERDA?

Answer 35

The cornea of horses with HERDA is thinner than that of normal horses, which is likely due to an abnormal arrangement of corneal collagen fibers

Question 36

Is HERDA autosomal recessive or dominant?

Answer 36

Autosomal recessive | PPIB (SNP, missense)

Question 37

Warmblood fragile foal syndrome type 1 (WFFS 1) is associated with a mutation in which gene?

Answer 37

PLOD1 Encodes the enzyme procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1 (previously known as lysine hydroxylase or lysyl hydroxylase I); responsible for the hydroxylation of lysine in collagen I alpha chains and the resulting formation of crosslinks between procollagen I heterotrimers

Question 38

Warmblood fragile foal syndrome type 1 (WFFS 1), associated with a mutation in PLOD1, has been reported in which other breed?

Answer 38

Thoroughbred Carriers of the mutation have been found in Haflinger, American Sport Pony, Knabstrupper, Paint Horse and Quarter Horse although no cases are reported

Question 39

Which type of gene mutation and what mode of inheritance are associated with PLOD1 mutations and fragile foal syndrome?

Answer 39

Missense | AR

Question 40

Hoof wall separation syndrome associated with SERPINB11 insertion is seen in which breed of horse?

Answer 40

Connemara (AR)

Question 41

Incontinentia pigmenti is associated with IKBKG (SNP nonsense) mutation in the Quarter horse and Warmblood; what is the mode of inheritance?

Answer 41

X semi-dominant