Chapter 13/14 - Environmental/Hereditary Flashcards
What type of necrosis occurs in pressure sores?
Ischaemic necrosis
What is myospherulosis?
An extremely rare granulomatous reaction thought to be due to the interaction of ointments, antibiotics, or endogenous fat with erythrocytes
What are the clinical signs of myospherulosis?
Solitary subcutaneous or dermal nodules, which may or may not have draining tracts.
In myospherulosis, do parent bodies and spherules stain with PAS, GMS or acid-fast stains?
No
What is the pathological mechanism of gangrene?
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
Gas gangrene/subcutaneous emphysema is associated with which type of infecion?
Clostridial infections
What is a histopathological diagnostic feature of electrical burns?
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.”
What are the clinical signs of selenium poisoning?
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)
What are the clinical signs of chronic arsenic poisoning?
Gastroenteritis Emaciation Exfoliative dermatitis Dull, dry, rough, easily epilated coat Some horses develop a long hair coat, others alopecia
What are the clinical signs of chronic mercury poisoning?
Nephrosis Lameness Oral ulceration Emaciation Progressive generalised alopecia Depression Anorexia
What are the clinical signs of excessive iodine intake?
Seromucoid nasal discharge Lacrimation Cough Variable appetite Joint pain Severe scaling +/- alopecia - most common over dorsum, head, neck and shoulders
Claviceps purpura infected grain causes which diseae?
Ergotism
Which fungus causes painful, necrotic ulcers in the mouth, nasal region and lips in horses?
Stachybotrys atra (stachybotryotoxicosis)
Which UV spectrum (A, B or C) is associated with photosensitivity reactions?
UVA
Name three drugs that can act as primary photosensitisation agents?
Phenothiazine Thiazides (e.g. diurectics) Promazines Acriflavines Rose bengal Methylene blue Sulfonamides Tetracyclines Coal tar derivatives Furosemide
What are the histopathological features of acute and chronic photosensitisation in horses?
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
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
EBS - within the stratum basale of the epidermis
JEB - within the lamina lucida of the BMZ
DEB - within the sublamina densa of the BMZ
Name a breed of horse reportedly affected by epidermolysis bullosa?
Belgians
Trait Breton
Trait Comtois
All three share a common ancestor
Warmbloods
Appaloosas
American saddlebreds
What is the genetic defect found in Belgian horses with epidermolysis bullosa?
A mutation in LAMC2 gene on equine chromosome 5
(insertion) - AR
What is the genetic defect found in American saddlebred horses with junctional epidermolysis bullosa?
LAMA3 maps to equine chromosome 8
(deletion) - AR
Which histo special stain is used to show where the basement membrane is attached in vesicles of epidermolysis bullosa?
PAS
Mane and tail follicular dysplasia affects which breed of horse and at what age is it apparent?
Appaloosas
Horses with curly coats
At birth or a few weeks of age
What is a major differential for follicular dysplasia in horses?
Alopecia areata
Vitiligo affects which breed of horse?
Arabians
What breed of horse is reportedly affected by cutaneous aesthenia/HERDA?
American quarter horse and horses that share bloodlines (e.g. appaloosa)
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).
True
Name a breed of horse affected by chronic progressive lymphoedema
Belgian
Clysedale
Shire
Friesian
What are the early clinical signs of chronic progressive lymphoedema in horses?
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.
In chronic progressive lymphoedema in horses, special stains (e.g. acid-orecin and Giemsa) show distorted, fragmented, clumped and pale _____ fibres.
Elastin
In Friesian horses with chronic progressive lymphoedema, which limb measurements were significantly increased in affected horses?
Length of forearm and length of gaskin (tuber calcanei to distal end of patellar, length of tibia)
Can anti-elastin auto-antibodies be used to help diagnose chronic progressive lymphoedema?
No, values overlap in normal and affected horses
What are the clinical signs of immersion foot syndrome in horses?
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.
What are the clinical signs of HERDA (Hereditary Equine Regional Dermal Asthenia)?
- 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
In HERDA, which part of the dermis shows collagen abnormalities?
Deep dermis
Why do you see ocular abnormalities in horse with HERDA?
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
Is HERDA autosomal recessive or dominant?
Autosomal recessive
PPIB (SNP, missense)
Warmblood fragile foal syndrome type 1 (WFFS 1) is associated with a mutation in which gene?
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
Warmblood fragile foal syndrome type 1 (WFFS 1), associated with a mutation in PLOD1, has been reported in which other breed?
Thoroughbred
Carriers of the mutation have been found in Haflinger, American Sport Pony, Knabstrupper, Paint Horse and Quarter Horse although no cases are reported
Which type of gene mutation and what mode of inheritance are associated with PLOD1 mutations and fragile foal syndrome?
Missense
AR
Hoof wall separation syndrome associated with SERPINB11 insertion is seen in which breed of horse?
Connemara (AR)
Incontinentia pigmenti is associated with IKBKG (SNP nonsense) mutation in the Quarter horse and Warmblood; what is the mode of inheritance?
X semi-dominant
