2-Pruritus and Alopecia Flashcards
Itch receptors are superficial, deep or both?
Superficial
An unpleasant sensation stimulating the desire to itch is known as what?
Pruritus/itch
Pruritoreceptors arise only from where?
Skin
Which axons mediate the sensation of pain or itch?
Unmyelinated axons (C fibers)
Where are 2 locations that cell bodies for itch are located?
- Dorsal root ganglia of spinal nerves
- Trigeminal (Gasserian) ganglion of CN V
Where are the spinothalamic-tract neurons that receive incoming action potentials and transmit them to the brain located?
Dorsal horn
Where is a possible location in the brain that may process itch?
Primary somatosensory cortex
What other type of neurons do itch neurons intersect or intercommunicate with?
Pain neurons
What often inhibits itch?
Pain
What type of drugs can cause pruritus?
Opioid pain-relievers
What is something that can modulate itch perception?
Noxious temperature changes, both cold and hot.
What is released by mast cells that can cause pruritus?
Histamine
What are 7 possible chemical causes of pruritus?
- Chemical mediators: cytokines-IL-2, TNF-alpha
- Tryptase (found in mast cells)
- Opioids
- Eicosanoids
- Growth factors
- Prostaglandins
- Heparin
What are 4 possible conditions pruritus can result from?
- Skin disease
- Systemic disease
- Neuropathic disease
- Psychogenic disease
What are 6 possible clinical signs of pruritus that owners can see?
- Biting
- Licking
- Chewing
- Scratching
- Gnawing
- Rubbing
What are 3 clinical signs vets can see?
- Alopecia (hair loss)
- Erythema (abnormal redness of skin)
- Excoriations (skin removal)
What can give clues to the etiology of pruritus?
Location of the body
What are 4 follow-up signs that can be seen with pruritus by the vet?
- More alopecia
- Lichenification (leathery hardening of skin)
- Hyperpigmentation
- Seborrhea (excessive/abnormal discharge from sebaceous glands)
What are 9 possible trigger factors for pruritus?
- Allergens
- Bacteria
- Yeast
- Food
- Irritant
- Psyche
- Temperature
- Humidity
- Hormones
What is the point under which patients can tolerate a certain load of sensation or pruritic stimuli without becoming itchy?
Threshold
What can be seen when multiple stimuli are present at the same time and exceed the threshold of pruritus?
Summation effect
T/F: Threshold varies among individuals.
True
What are 4 possible causes of allergy induced pruritus in the dog?
- Flea allergy
- Atopic dermatitis
- Cutaneous adverse food reaction
- Insect bite hypersensitivity/contact dermatitis
What are 5 possible ectoparasite causes of pruritus in the dog?
- Sarcoptes
- Demodex
- Cheyletiella
- Lice
- Chiggers
