Toxicants Affecting Integumentary, Bones, & Teeth (16) Flashcards
What is photosensitivity?
a severe dermatitis that results from a heightened reactivity of skin cells and associated dermal tissues upon their exposure to sunlight, following ingestion or contact with plant pigments or secondary products that are UV or light reactive
When does photosensitization occur?
it can occur within minutes of exposure to the toxic substance by direct contact, within hours (via contact or ingestion) of deposition of the primary photosensitizing agent, or days after exposure due to activation of secondary photosensitizers (following liver damage and deposition of phytoporphyrin into skin)
T/F: Photosensitization is not equivalent to sunburn, though its appearance can be very similar
TRUE
What does not react with photosensitization?
pigmented skin
Where on an animal is photosensitization common?
areas of skin that remain hairless, such as the skin around the eyes, ears, face, muzzle, mammary gland, tail and the area directly adjacent to the hoof wall
Which layers of the skin offer limited or no protection from penetrating substances or light?
deeper layers of the skin, dermis and hypodermis
Look at this
Which amino acids are more susceptible to light-mediated oxidation?
tryptophan
tyrosine
histidine
What is type 2 photosensitization?
sensitizer itself causes the ROS to be created
What is type I photosensitization?
binds to substrate that then causes the oxidation
What is primary photosensitization?
occurs when phototoxic plant-produced compounds or their
metabolites become bioavailable within the animal after ingestion, or become localized in the cellular layers of the skin
What are type II - aberrant endogenous pigment synthesis photosensitization?
endogenous pigments (pigments produced in the body, from genes that hold their coding) that arise
from inherited or acquired defective functions of enzymes involved in heme synthesis
What does secondary hepatogenic photosensitization result from?
accumulation of the photodynamic compound phytoporphyrin
Secondary photosensitization may occur as a result of _____
either acute or chronic liver damage in the affected animal when porphyrin and derivatives are not cleared by the damaged liver
What is phytoporphyrin?
a microbially-produced metabolite of chlorophyll
What is the toxicant in giant hogweed?
furanocoumarins
What does giant hogweed cause - furanocoumarins?
Sap contains photosensitizers that cause contact phototoxic dermatitis
What is the toxicant in St. John’s Wort?
hypericin
What is the toxicant in buckwheat?
fagopyrin
Give examples of secondary photosensitization
sheep foraging in old turnips or rutabaga fields - primary
cows - secondary
What are the toxicants in lantana (vernbenaceae)?
triterpenes
What metals are skin toxicants?
arsenic, lead, cadmium, chromium, and nickel
What are clinical signs of selenium toxicity?
selenium may cause acute and chronic poisoning in all animals, especially cattle, sheep, horses, swine, chicken and dogs. A loss of hair/wool, deformation and sloughing of the hoof are seen in cattle, sheep and horses that were poisoned chronically with selenium
What is the difference between chronic selenium toxicity?
water-soluble: blind staggers, commonly naturally found in accumulator plants
insoluble: alkali disease, toxicity from eating plants or grain
What do flouroquinolones cause?
Increases the apoptosis of canine tendon cells and chondrocytes in a dose and time-dependent manner
What do tetracyclines do?
can bind Ca2+ during enamel formation, dental changeover
