Lecture 18 4/7/25

Question 1

What are some general characteristics of cats and dermatology?

Answer 1

-limited ability to do topical therapy; cats more likely to reach meds
-owner’s ability to give meds is likely more difficult
-pyoderma and otitis are not as common as in dogs

Question 2

What are normal PE findings in cats regarding the skin?

Answer 2

-preauricular alopecia
-hair covering entire abdomen
-lentigo in orange cats

Question 3

Which cat breeds have abnormal dermatological findings that are considered normal for the breed?

Answer 3

-sphynx: alopecia
-devon and cornish rex: wavy coat
-kohana: no vibrissae/whiskers

Question 4

What are some indications on history that a cat is pruritic?

Answer 4

-increased hairballs/vomiting hairballs
-increased hiding behavior
-licking/biting/chewing/scratching
-rolling around
-rubbing on furniture

Question 5

What are the reaction patterns seen in pruritic cats?

Answer 5

-miliary dermatitis
-head/neck pruritus
-overgrooming
-eosinophilic granuloma complex

Question 6

What are the characteristics of miliary dermatitis?

Answer 6

-defined as erythematous crusted papular eruption
-often better felt than seen
-can be focal or generalized
-one of the most common reaction patterns
-often seen in preauricular region

Question 7

What are the characteristics of head and neck pruritus?

Answer 7

-allergic, infectious, auto-immune, and neoplastic dz are indistinguishable based on location alone
-diagnostic work up is imperative to determine etiology
-severe, primarily face-directed pruritus may warrant a diet trial, but does not ALWAYS indicate food allergies

Question 8

What are the characteristics of self-induced alopecia/overgrooming?

Answer 8

-aka “fur mowing”
-hair loss occurs over ventral abdomen, down limbs, on caudodorsum, and bilaterally on trunk

Question 9

What are the characteristics of eosinophilic granuloma complex?

Answer 9

-NOT a diagnosis
-antigen-driven eosinophilic infiltrate within the skin
-4 types of lesions:
*eosinophilic granuloma: oral or linear
*eosinophilic plaque
*indolent ulcer
*fat chin

Question 10

What is a linear granuloma?

Answer 10

cord-like linear plaque on the caudal thighs often covered by a yellowish crust

Question 11

What are the characteristics of eosinophilic plaque?

Answer 11

-thinner than a granuloma
-can be anywhere on the body
-most commonly found on ventral abdomen or medial thighs

Question 12

What is needed in order to resolve an indolent ulcer?

Answer 12

steroids

Question 13

What are the potential causes of pruritus?

Answer 13

*parasites
-fleas
-mites
*allergy
-flea
-food
-FASS
*infection/autoimmune
*neoplastic/neurogenic

Question 14

What are the steps to pruritus work up?

Answer 14

-rule out ectoparasites
-treat all infections
-allergy work up
-biopsy for neoplastic/immune-mediated differentials

Question 15

What are the characteristics of fleas?

Answer 15

-cats have type 1 and type 4 hypersensitivity to saliva
-diagnosis with flea combing and finding fleas and/or flea dirt
-can also diagnose via flea treatment trial and improvement
-should consider a fecal for tape worms

Question 16

What are the characteristics of flea prevention/treatment?

Answer 16

-all cats in the house must have consistent flea control
-majority of fleas are in environment; VERY important to clean
-good prevention/treatment products include Bravecto (Plus), Revolution Plus, Advantage Multi, Capstar, and NexGard
-important to warn clients of cat scratch fever risk; fleas carry the bacteria

Question 17

What are the characteristics of localized demodex cati?

Answer 17

-most common form, but clinically rare
-usually non-pruritic
-often a head/neck focus
-lesions around periocular skin and chin
-can cause erythematous ceruminous otitis
-commonly see alopecia, erythema, scaling, crusting, hyperpigmentation, and lichenification
-treatments weekly with lime sulfur dip

Question 18

What are the characteristics of generalized demodex cati?

Answer 18

-less common
-variable pruritus; occurs with secondary infections
-same lesions/symptoms as localized dz but with diffuse distribution
-occurs secondary to concurrent systemic dz/immune suppression
-inciting immunosuppression can be iatrogenic, viral, endocrine-related, neoplasia-related, toxoplasmosis-related, or autoimmune

Question 19

What are the characteristics of Demodex gatoi?

Answer 19

-superficial short, fat-bodied mite that burrows in stratum corneum
-predisposed in burmese, maine coons, bengals, and multi-cat households
-pruritus may be the only symptom
-must rule out psychogenic alopecia
-hypersensitivity causes the pruritus; asymptomatic carriers are not pruritic
-CONTAGIOUS
-not associated with immunosuppression/immune dysregulation

Question 20

How is Demodex gatoi diagnosed and treated?

Answer 20

dx:
-superficial skin scrape
-PCR
-fecal
tx:
-isoxazolines
-must treat ALL in-contact cats

Question 21

What are the characteristics of Otodectes cynotis/ear mites?

Answer 21

-lives along entire ear canal
-transmitted through direct contact among dogs, cats, and ferrets
-common cause of bilateral otitis externa amongst young, free-roaming dogs and cats
-clinical signs include head shaking, ear scratching, and drooping ears
-classic dark brown cerumen/”coffee grounds” seen on otoscopy

Question 22

How are ear mites diagnosed and treated?

Answer 22

dx:
-cytology
tx:
-systemic spot-on or otic products
-treatment of any secondary bacterial and/or Malassezia infections

Question 23

What are the characteristics of Notoedres cati/cat scabies?

Answer 23

-rare but contagious
-zoonotic
-causes severe pruritus
-causes very thick crusting on ears, head, and neck that generalizes with time
-easy to find to superficial skin scrape; burrows in stratum corneum
-treated with systemic spot-on and lime sulfur dips

Question 24

What are the characteristics of Cheyletiella blakei/walking dandruff?

Answer 24

-uncommon
-eggs loosely adhere to hair shafts
-nymphs hatch and feed on skin surface debris
-entire life cycle on host; poor off-host survival
-number of mites and hypersensitivity to bites determines level of pruritus and amount of scale
-typical lesion is excessive dorsally distributed scale that generalizes with severity/time

Question 25

How is Cheyletiella diagnosed and treated?

Answer 25

dx: -flea comb brushings -tape cytology -hair plucks -fecal -lesions on owners tx: -revolution/advantage multi/frontline/bravecto (plus) -treat all contact animals -improve husbandry/separate animals during treatment

Question 26

What are the characteristics of food allergies?

Answer 26

-head and neck pruritus is common location -must have non-seasonal clinical signs -can develop at any age -may have GI signs -pruritus can be intense -may be steroid responsive -can only be ruled out with STRICT diet trial

Question 27

What are the characteristics of feline atopic skin syndrome?

Answer 27

-diagnosis of exclusion -can be seasonal or non-seasonal -most animals are younger than 3 y/o -females more common than males -pruritus is steroid responsive -treated with antihistamines, steroids, and cyclosporine -toxoplasma titer should be measured before starting cyclosporine

Question 28

What are the characteristics of Staph. infections in cats?

Answer 28

-less common than in dogs -typically S. pseudintermedius when they do occur -treatment is the same as in dogs but cats are less amenable to topical treatment

Question 29

What are the characteristics of Malassezia infections in cats?

Answer 29

-less common than in dogs -seen in allergic skin dz, chin acne, paraneoplastic conditions, and greasy seborrhea -commonly seen on face, neck, chin, limbs, abdomen, and in otitis externa -treatment via itraconazole

Question 30

What are the characteristics of dermatophyte infections?

Answer 30

-most common infection in cats -Microsporum canis -alopecia w/ scaling starts on muzzle, face, and ears; moves to paws and tail -variable pruritus -increased number of spores and skin microtrauma are CRUCIAL for establishing infection -zoonotic but easily treated

Question 31

How are dermatophyte infections diagnosed and treated?

Answer 31

dx: -culture with dermatophyte test media -wood's lamp -trichogram -PCR tx: -topical and systemic antifungals; continued until 2 negative consecutive cultures taken 2+ weeks apart

Question 32

What are the characteristics of herpesvirus dermatitis?

Answer 32

-thought to be recrudescence of herpesvirus latent in trigeminal ganglia and cutaneous nerves -immune compromise likely triggers a flare -most common in cats around 5 years old -lesions occur exclusively on face -very pruritic -treat secondary infections -can use famciclovir or acyclovir

Question 33

What are the characteristics of Mycobacteria fortuitum?

Answer 33

-gram+ acid-fast intracellular rod -rapidly growing in specific medium -predilection for adipose tissue -ubiquitous in damp environments

Question 34

What is the pathogenesis of atypical mycobacteriosis?

Answer 34

trauma allows for direct inoculation of Mycobacteria into SQ fat, esp. if animal is in damp environment

Question 35

What are the clinical signs of atypical mycobacteriosis?

Answer 35

-multifocal to coalescing watery draining tracts along ventral abdomen/inguinal region -chronic non-healing SQ abscesses

Question 36

How is atypical mycobacteriosis diagnosed and treated?

Answer 36

dx: -deep tissue culture; must tell lab you're looking for it tx: -pradofloxacin -doxycycline -goal is to reach remission; can take months

Question 37

What are the characteristics of pemphigus foliaceus?

Answer 37

-most common autoimmune disorder -anti-keratinocyte IgG disrupts desmosomal adhesion -typically seen in middle-aged cats -no signalment predilections

Question 38

What are the clinical signs of pemphigus foliaceus?

Answer 38

-"pustulo-crustular" lesions on head, ears, dorsal neck, dorsal trunk, nipples, clawfolds, +/- paw pads -pruritic ONLY if secondarily infected -possible lethargy

Question 39

How is pemphigus foliaceus diagnosed and treated?

Answer 39

dx: -history -clinical appearance -cytology -biopsy tx: -steroids +/- cyclosporine

Question 40

What are the characteristics of cutaneous mast cell tumors?

Answer 40

-head/neck > trunk > limbs of older cats -typically solitary nodules -most are well-differentiated and benign, but may still have affected lymph nodes -pleomorphic MCTs are locally aggressive

Question 41

What are the characteristics of paraneoplastic alopecia?

Answer 41

-classic lesion is ventrally distributed "shiny alopecia" and peripheral easily epilated hairs -concurrent signs include lethargy, anorexia, weight loss, and V+/D+ -should consider CBC/chem/UA, rads, and ultrasound -associated with hepatobiliary carcinoma and colon carcinoma

Question 42

What are the characteristics of thymoma-associated dermatitis?

Answer 42

-rare paraneoplastic syndrome -characterized by diffuse erythroderma and exfoliation -often present for resp. distress/dyspnea and have non-compressible chest -radiographs show large mass in cranial mediastinum -suspected to be caused by T-cell mediated response -lesion resolves with surgery to remove tumor

Question 43

What are the characteristics of non-thymoma-associated dermatitis?

Answer 43

-same clinical skin lesions as thymoma-associated but with a different pathogenesis -no etiology currently identified -most respond to immunomodulation

Question 44

What are the characteristics of pruritus due to nerve pain?

Answer 44

-osteoarthritis is often overlooked in cats -use rads, ultrasound, CT, MRI to diagnose -can do pain trials with onsior, gabapentin, and/or solensia -should be suspicious if behavior/pruritus is directed at specific target and/or asymmetrical

Question 45

What is the typical antipruritic treatment?

Answer 45

physiologic doses of prednisone or other steroids *monitor for diabetes and PUPD