Exam 3 MOD Flashcards
What is the brain’s itch processin center?
Primary somatosensory cortex
Where are the cell bodies for itch located?
- dorsal horn of spinal nerves (the spinothalamic tract (white matter) transmit it it from the dorsal horse to the thalamus)
- trigeminal (gasserian) ganglion of CN V
Give three examples to why we believe itch and pain are interconnected
- pain inhibits itch
- opioid pain-relievers can cause itch
- Noxious temp changes can modulate itch
There are itch specific neurons and neurons that also respond painful stimuli
T/F: Histamine is the only mediator released from mast cells that causes pruritus
False, other mediates modulate itch
Ex. IL-2, TNF-alpha, Tryptase, opioids, Eicosanoids, GF, prostaglandins, Heparin
Itch du to skin diseases, such as scabies and atopic dermatitis, are transmitted by ___ nerve fibers
C nerve fibers
What are the threshold and summation effects of itch?
Threshold: Different levels of itch stimulus will initiate itch sensation- highly variable
Summation: Multiple stimuli present at the same time are additive. The combination of stimuli may surpass the threshold.
What are th main causes of pruritis in dogs?
*** MEMORIZE***
-
Allergy
- Flea allergy (on caudal dorsum)
- Atopic dermatitis
- Food Allergy
- Less common: Insect bite hypersensitivity/ contact dermatitis
-
Ectoparasites
- Sarcoptes (on ears and elbows)
- Demodex
- D. canis- itch only due to SECONDARY pyoderma
- Cheyletiella
- Lice
- Chiggers
-
Infections
- Pyoderma
- Yeast
- Dermatophytes
What is the most likely cause of pruritis on the caudal dorsum?
flea allergy
What is the most likely cause of pruritus on the ears and elbows?
Sarcoptes mange
What is the most common cause of pruritus of that leads to the dog itchying and licking its feet?
Food allergy or Atopy
What are your top 3 DDx for severe (10/10) pruritus in a dogs (until proven otherwise)?
Scabies
Flea allergy
Food allergy
It what cases will the itch come before the lesions? and in what cases will the lesion come before the itch?
- Itch before lesion
- Allergies
- Scabies
- Lesion before itch
- Demodex
- Dermatophytes
- Pyoderma
What are the 3 forms of skin lesions in cats?
- Bilaterally symmetrical hair loss with normal skin (non-inflamm)
- Miliary dermatitis (pin-pricks or sores)
- Eosinophilic granuloma complex
T/F: excorations, lichinification and hyperpigmentation are commonly seen in pruritic cats
FALSE- they are rare to see
What are the causes of pruritus in a CAT?
- Allergy - flea, atopy, food
- Ectoparasites- notoedres, Demodex gatoi, chyletiella, ectopic ear mites, fur mites
- Infecton- yeast, dermatophytes, pyoderma (rare)
