Skin Terminology/Diseases Flashcards
Papule
- a small pimple or swelling on the skin, often forming part of a rash
- can be a primary lesion resulting from a flea bite - developing as a direct consequence of disease process
- solid palpable skin elevation less than 1cm in diameter
EX: Canine FAD (crusted papules)
secondary lesion
- evolve from a primary lesion ot are caused by the patient (aka self trauma)
- selt trauma in veterinary patients may obscure the primary lesions
- secondary bacterial infection may present with primary lesions
Panniculus Adiposus
- vascular and nerve supply under the layer of the dermis
(generally find sweat glands in this area as well)
- The panniculus adiposus is the fatty layer of the subcutaneous tissues, superficial to a deeper vestigial layer of muscle, the panniculus carnosus. It includes structures that are considered fascia by some sources but not by others
the Epidermal Layer
(5 layers)
stratified squamous keratinizing epithelium with proliferation, differentiation, desquamation
happens in hair follicle as well - down to the insertion of the sebaceous gland duct - can get notable disruptions
shows there may be a foliclur keratinization or cornification (final stage of keratinization) defect going on
Cutaneous Basophil Hypersensitivity
- Cutaneous basophil hypersensitivity is a distinct form of hypersensitivity reaction with a delayed-time course that is different from both the classic delayed-type hypersensitivity reaction and immediate hypersensitivity reaction.
- It occurs in humans, guinea pigs, and other animals.
- It may be induced by sensitization with a variety of antigens (viruses, allografts, parasites, fungal antigens, etc.) in incomplete Freund’s adjuvant and elicited by skin testing 7 days later with the specific antigens.
- The cutaneous reaction in basophil hypersensitivity is characterized clinically by less indurated (hardened) erythema than in classic delayed hypersensitivity, and microscopically by numerous basophils in the papillary dermis.
- The reaction is mediated by both T- and B-lymphocytes.
Basophils
- Basophils appear in many specific kinds of inflammatory reactions, particularly those that cause allergic symptoms.
- Basophils contain anticoagulant heparin, which prevents blood from clotting too quickly.
- They also contain the vasodilator histamine, which promotes blood flow to tissues.
Primary lesion
If Foot and Mouth replicates in horse epidermis–> may lead to primary lesion in pigs and ruminants
- staphylococcal infection creating pustular lesion in the hair follicle
- a secondary lesion can have its own primary infections - staphylococcus taking advantage of allergy
Wheals
- you know as they “pit” upon the application of pressure- may get some with traumatic pericarditis
- so it is different to firm nodules or plaques
- YOU GET WHEALS FROM PENICILLIN = hives (urticaria)
- Urticaria (hives) is a vascular reaction of the skin marked by the transient appearance of smooth, slightly elevated papules or plaques (wheals) that are erythematous and that are often attended by severe pruritus. Individual lesions resolve without scarring in several hours
- Horses–> present with wheals more commonly as a species (dogs as well) –> horses are not generally pruritic!
- A skin wheal is a patch on the skin that is elevated, discolored, changes shape, and often itches (+/-). It can be due to an insect bite, an adverse reaction to something that touched your skin, eczema, or another small puncture wound you experienced. You may have also heard a skin wheal referred to as a ‘welt’ or a ‘hive.
- In some animals, serum oozes from the wheals matting the hair coat
Angioedema
- extensive type wheal
- angioedema is a localized or generalized area of extensive deep dermal and subcutaneous oedema
- affecting the whole body region –> vaccine reactions or maybe (may get dogs swelling up around the head after routine vaccine)
- in comparison, the oedema involves the deep dermis and subcutis where in urticaria it involves only the superficial dermis
- both involve type I and type III hypersensitivities
- pruritis is not always present, especially in the horse
Urticaria
- Urticaria, also known as hives, is an outbreak of swollen, pale red bumps or plaques (wheals) on the skin that appear suddenly (involving the superficial dermis) – either as a result of the body’s reaction to certain allergens, or for unknown reasons.
- Hives usually cause itching, but may also burn or sting
- a unique form has been described in Jersey and Guernsey cattle bc of a type I hypersensitivity to casein (slow digesting protein) in their milk
- Urticarial lesions are wheals that typically arise suddenly and remain a few hours although chronic urticaria has been noted (lasting weeks to months)
macule
an area of skin discoloration
pustules
- A pustule is a bulging patch of skin that’s full of a yellowish fluid called pus
- discrete elevation of the epidermis containing PUS (within or just below epidermis)
- like a plaque with pus
- a mini abscess located near or in the epidermis
- Where as an ABSCESS: is a demarcated dermal/subcutaneous accumulation of pus
Vesicle/Bullae
Bullae: (Blisters)
Vesicles are circumscribed epidermal elevations in the skin containing clear fluid and less than ½ cm. in diameter. If the lesion has a diameter of greater than ½ cm, it is called a bulla. Vesicles and bullae arise from a cleavage at various levels of the skin
Sebaceous Adenitis
- Sebaceous adenitis in an uncommon skin disease found in some breeds of dog, and more rarely in cats, rabbits and horses. characterised by an inflammatory response against the dog’s sebaceous glands, which can lead to the destruction of the gland
- targets sebaceous glands and results in alopecia and epidermal and follicular hyperkeratosis
- useful to take a biopsy sample in suspected cases and then have disease confirmed by histopath
- In standard poodles, sebaceous adenitis is definitely a recessive genetic trait
Hyperkeratosis
abnormal thickening of the outer layer of the skin
- increase in the stratum corneum layer
- Hair follicles destroyed by fibrosis - where there should be a hair follicle is just collagen
- Could see cytotoxic lymphocytes are now seen attacking the hair follicles in this
- Can now think of drugs that would block lymphocytes mediated autoimmune disease - cyclosporine
- But some owner refuse due to the $$ and dog not suffering from itchy
- Hair follicles on normal histopathology
Examples of diseases that involve different areas of the skin:
- Dermis
- Panniculus (subcutis, hypodermis)
- Epidermis
- Hair Follicles
**note: panniculitis, not hepatitis
also in hair follicles: Demodecosis
Puppy Strangles
(juvenile cellulitis)
- DERMAL DISEASE
- Puppy strangles, or juvenile cellulitis, is a nodular and pustular skin disorder that affects puppies. It usually occurs between the ages of three weeks and four months, and is rarely seen in adult dogs.
- The face, pinnae (outer part of the ear), and salivary lymph nodes are the most common sites to be affected. The cause of this condition is unknown, but there are breeds that have been shown to be predisposed to it, including golden retrievers, dachshunds, and Gordon setters
Clinical Signs
- Acutely (sudden and severe) swollen face – especially the eyelids, lips, and muzzle
- Salivary gland lymphadenopathy: a disease process affecting a lymph node or multiple lymph nodes
- Marked pustular and oozing skin disease, which frequently fistulates (develops into a hollow passage); develops within 24–48 hours
- Pustular ear infection
- Lesions often become crusted
Sterile Nodular Palliculitis
- Panniculitis is a rare condition in which the layer of fat under the skin, which provides warmth, protection and energy to the body, becomes inflamed.
- While it may be caused by an infection with bacteria, fungi or other organisms, sterile nodular panniculitis is a descriptive term for an inflammation of the fat cells that does not involve infectious agents. In most cases, the exact cause is not known.
- The inflammation results in bumps on the skin surface that can be soft or firm, and are sometimes painful.
- The bumps can rupture, releasing an oily discharge that may be clear, yellow-brown or bloody.
- Most pets with sterile nodular panniculitis are treated with drugs designed to modify the immune system, such as steroids, but Vitamin E may also be helpful
Patterns of Inflammation in the Skin
(5)
Hyperepidermis
- increase in the stratum spinosum layer
- epidermal living layers thicken
- may be a protective response by the body to a noxious stimulant from outside
- also as an accidental consequence of a dermal disease triggering cytokines and inflammatory mediators trigerring the basal keratinocytes to increase the proliferative rate
- may see both hyperkeratosis and hyperepidermis in a chronically allergic animal
- hyperplasia more regular
- hyperkeratosis is quite marked
- CLINICAL EQUIVOLENT: SCALING
- scale = an accumulation of loose fragments in the stratum corneum
- Migration of lymphocytes into the epidermis (lymphocyte exocytosis) is common - as seen here
- can also see in this periodic acid–Schiff (PAS) stain that there is some fungal hyphae - Dermatophytosis (ringworm)
Scaling
- accumulation of loose cornified fragments from the stratum corneum
Follicular Cast
- when scaling then occurs in the hair follicle infundibulum
- accumulation of keratinous debris around hari shaft
- indicates issue with the keratinization process around the hair shaft –> ex: Demodecosis
- Most common cause of that would be demodicosis
And then next cause: sebaceous adenitis
- Must be doing skin scrapings and hair plucks
Comedo
- dilated hair follicles plugged with keratinous and sebaceous debris
- Black heads
- May indicate demodex, an endocrinopathy (hyperthyroidism, hyperadrenocorticism) or a primary kertinisation defect
- histology of comedo
- HF packed with keratinous, sebaceous and scaley material
- think DEMODECOSIS!
- but others are endocrinopathies (hyperthyroid, cushings - middle age/older) - cycle arrest –> all the hair is stuck in the telogen phase in arrest as well as the scaling process is distorted by the disease as well
- or primary keratinization defect - little young spaniel is producing shit loads of scales - get comedos, scaling and follicular casting in some cases (certain breeds at young age or immunosurpressed)
Perivascular Dermatitis
classic stereotypic dermatitis reaction
-hyperplastic superficial perivascular dermatitis
-vessels are dialted, cuff of inflammatory cells
CUFF: recruited leukocytes around BV’s
epidermis is thickened due to the cytokines and inflammatory mediators released
ex: malassezia
- make sure to know if it is just superficial or deep plexus and what cell types are present! -position of inflammatory cells depends on the pathogen (yeast–> more towards epidermis, food allergy –> lower as well as superficial)
- is the challenge from the outside or systemically??
- fleas or sarcoptic mange: may see more eosinophils near epidermis
- staphylococcal infection: neutrophils may be more dominant
- Histo is not pathognomonic
- This usually includes epidermal hyperplasia! stratum spinosum
Cutaneous Lymphoma
- The most common tumors in dogs are malignant lymphomas, which is a condition also defined as a lymphosarcoma. These types of malignancy generate within the lymphoid tissues of the dog, such as the spleen, bone marrow, or lymph nodes. They can occur in any of the bodily tissues (like skin)
- Cutaneous lymphoma is a type of skin cancer that occurs within abnormal T-cells of the dog
- may show as red, itchy skin–> in any case you may suspect for an animal, send off pathology
- where as in other situations this type of presentation may not be beneficial
- Cutaneous lymphoma, in the advanced stages, begins to affect the peripheral blood and the internal organs.
Plaques
- sometimes papules can coalesce to form plaques
- larger flat topped elevation cuased by the extension of papules (aural plaque)
- aural plaque - viral disease process (papilloma) –> transmitted by biting flies in most theories (BPV-1)
pustule within the epidermis
Intraepidermal Pustular Dermatitis
(eosinophilic vs. neutrophilic)
- 99.9% of neutrophilic will be Staphylococcus pyoderma
epidermal collarette
- evolution of a pustule into epidermal collarette (secondary lesion)
- expanding ring like erythematous lesions with peeling edges, they are the footprints of pustules (primary lesions)
- e.g. bacterial infection (Staph)
- THIS IS ONE OF THE MAIN CAHRACTERISTICS OF SUPERFICIAL PYODERMAS - collarettes in large numbers –> by Staphylococcal infection
Erosion
- break in the continuity of the epidermis but the underlying BM remains intact
- heals because you still have your basal keratinocytes intact
Ulceration
- unlike erosion, goes right through
- break in the continuity of the epidermis where the dermis is exposed
- pic: cutaneous lymphoma affecting the paws of a dog creating ulcers
Nikolsky sign
- The sign is present when slight rubbing of the skin results in exfoliation of the outermost layer
- where you can strip the epidermis off the underlying epidermis
- tells you that the disease is targeting the dermal/epidermal jxn
- may even be from an adverse drug reaction
Folliculitis
- Inflammation of the hair follicle
- perifolliclitis/luminal folliculitis/ (bulbitis/mural)
- Powerful pattern! : in dogs, usualy reflects pyoderma, demodecosis or dermatophytosis
Furunculosis
- inflammation and DESTRUCTION of hair follicle
- ex: deep pyoderma, anal furunculosis (GSD’s, also known as perianal fistula, part of GIT strand)
where as:
- Non-inflammatory alopecia: Alopecic disease with endocrinopathy –> Telogen hair follicles with scaling
But no inflammation! (different to furunculosis)
Crust
- accumulation of exudate (dead cells/dried serum) on skin surface
- site of previous active inflammation, epidermal degeneration, pustule, etc.
Panniculitis
- Panniculitis is a group of diseases whose hallmark is inflammation of subcutaneous adipose tissue (the fatty layer under the skin – panniculus adiposus). Symptoms include tender skin nodules, and systemic signs such as weight loss and fatigue.
- Inflammation of subcutaneous fat and connective tissue
- e.g. budding yeast organisms- Blastomyces (more imp in the US)
- Blastomyces dermatitidis is the causal agent of blastomycosis, an invasive and often serious fungal infection found occasionally in humans and other animals in regions where the fungus is endemic
Crusting
- pemphigus folleaceous
- need to be careful with scrubbing to get good samples
Pemphigus Foliaceous
- most common and milder form of pemphigus in domestic animals and has been reported in the horse, goat, dog and cat
- disease develops spontaneously in dogs and cats, as an adverse reaction to drug therapy
- autoantibodies recognize the desmosomal protein, desmoglein , which is predominantly expressed in the upper layers of the epidermis
- cause cutaenous rather than oral lesions (different to more severe, involving mucosal layers)
- immunological heterogenous
- gross lesions similar in all species: transient vesicles that rapidly become pustules which can be localized to areas of the skin (nose, pinnae, periocular skin, paw pads, claw beds, and coronary bands in horses)
- pustules quickly rupture as they are fragile –> leads to secondary crusts, scales, alopecia and superficial erosions
Top Causes of Pruritic Skin Disease in Dog
(parasitic, microbial, hypersensitivity)
- Parasitic: scabies, cheyletiella (surface mites), Burrowing mites (Sarcoptes), Trombicula (Harvest Mites - sometimes), maybe follicular mites (demodex) - but not as itchy
- Microbial: Staph Pyoderma, Malassezia
- Hypersensitivity: FAD, Atopic Dermaititis, Food Hypersensitivity
Top Causes of Pruritic Skin Disease in Cats
(Parasitic, Microbial, Hypersensitivity)
- Parasitic: Cheyletiella, other mites
- Microbial: Bacterial, Malassezia, Dermatophytosis
- Hypersensitivity: FAD, ‘Atopic Dermatitis’, Food Hypersensitivity, Eosinophilic Plaques
**Cats are a lot less likely to get bacterial or fungal secondary infection when they have allergic skin disease compared to dogs
Top Causes of pruritic skin disease: Horse
Parasitic: Chorioptes (Choriptes bovis) , other mites
Microbial: Staph infection, Dermatophilus (gram +, “mud fever”), Dermatophytosis
Hypersensitivity: Insect bite hypersensitivity (in horses–> cullicoides = biting midges), ‘atopic dermatitis’, food hypersensitivity?
Parasitic Diseases
Pruritis
- Surface mites (e.g. Cheyletiella)
- Burrowing Mites (e.g. Sarcoptes)
- Trombicula (harvest mites)
- Demodex - less itchy
Microbial Infection/Overgrowth
Pruritis
- Staphylococci (commensal)
- Malassezia (commensal)
- Dermatophytes - not typically as itchy
Hypersensitivity Disorders
Pruritis
- Flea Bite Hypersensitivity
- Atopic Dermatitis
- Food Hypersensitivity
- (contact dermatitis)
Less Common pruritic skin diseases
- Cornification/metabolic disorders
- Neoplasia - epitheliotropic lymphoma/mast cell tumor
- Drug Eruption
** note: you may have more than 1 disease at once!
Priority Dx’s to rule out with pruritic disease presentation
(4)
Is there anywhere else self trauma is occuring
Top: around muzzle, groin, tail, feet –> fits with certain types of allergic skin disease
Bottom: elbows, chewing hocks, licking around ventrum–> much more typical of scabies
Help prioritize likelihood!
Deep and Superficial Skin Scrapings
Cytology
(4 techniques)
- bacterial folliculitis!
- -cure to rid of itch and then work on keeping it away
Dermatophytosis Epidemiology
(who does it affect more commonly?)
Conidium
Conidium, a type of asexual reproductive spore of fungi(kingdom Fungi) usually produced at the tip or side of hyphae (filaments that make up the body of a typicalfungus) or on special spore-producing structures called conidiophores.
- The spores detach when mature
- ex: dermatophytosis pathogenesis–> conidia adhere to corneocytes from one infected squame of an individual to as susceptible squame of another
Dermatophytosis Pathogenesis
(5 steps)
trichophyton verrucosum
- Pretty well demarcated
- Green, thick scales of crust
- Housed cattle
- Contamination of face, head and neck
- Can be extensive
- important in cattle : may aso affect dogs, sheep, horses and people
Trichophyton equinum
- Similar to bovine lesions but these are a lot less crusty
- Stable situation allows for a lot of transverse spread
Expanding Ring like lesions in the dog…
- most likely staphylococcal folliculitis!
- If it looks like ringworm on a dog, probably is not
- need to get samples to know!
- CS’s: alopecia, circular lesions, crust, erythema, annular lesions with scaling, possible nodular lesions
- there is variability in presentation though!
- also may see them easier when clipped! like this cat (ring with inflmmation and hematogenous regions)
- T. erinacei dermatophytosis (hedgehog)
- Played with hedgehog
- Inflammatory lesions
Exudation
Symmetry –> coming from under the skin
Asymmetry–> lying on the skin
- could be staph though remember! - need to differentiate and match up Hx
dog presenting with folliculitis/furunculosis on the face
- may be “sylvatic” dermtophytosis
- or staph!
- sylvatic –> contracting from wild animals
Which one is which
- Was chasing rodents- JRT’s commonly get T. mentagrophytes (from rodents)
- Severe active leading edge of the disease
- Sometimes can get mixed up with pemphigus!! - they have totally different treatments
- in pemphigus foliaceous the nasal plate is affected
which one is which
- must do tests to know!
- pyoderma will also be responsible to AB’s, but don’t want to go ahead treating without ruling out ringworm
Dermatophytosis in cats
might just be an Alopecia patch
Not that big of an inflammatory reaction
May not be evoking a strong inflammatory response to “stay quiet” OR the animal cannot amount a response
Protect skin with lesions
- hunting cats may get it from rodents
Dermatophyte “ Pseudomycetoma”
- Rare: but Persian cats are more predisposed
- deep granulomatous nodular dermal and subcutaneous masses containing distorted fungal hyphae
- fungus drive into subcutanoeus and fat
- mycetoma–> nodular lesion with sinus tracts and tissue grains
- infectious granuloma
- Feline dermatophytic mycetomas (pseudomycetoma) are uncommon deep dermal and subcutaneous fungal infections caused by dermatophytes
- characteristic triad of nodular swelling, draining sinuses, and grains in tissue
- The grains are micro-aggregates of the causative organism. Causative agents in mycetomas may be bacterial or fungal. In true fungal mycetomas (eumycetomas)
- The disease as seen in cats is almost exclusively caused by Microsporum canis, a unique form of dermatophytosis, with the majority of cases described in Persian cats, suggesting a genetically programmed selective immunodeficiency
Dermatophytosis: Diagnosing
If you take a hair pluck:
May get hair pluck with microsporum dermatophytosis
Filamentous hyphae in the hair shaft
Has gotten into the hair shaft and has produced an arthrospore outside the hair shaft
-might see branching, not easy to find though!
Wood’s Lamp: Only good for M. canis!
Maximum result from microscopy: will only find hyphae or spores in about half the cases
-can do light microscopy if you have it to look for hyphae and spores
Note: the fungi tend to die in areas of inflammation in the center of lesions but are viable at the periphery
Pathogenic Genera of Dermatophytoses
(3)
- Epidermophyton - adapted to humans (anthropophilic) and rarely infects animals
- Microsporum
- Trichophyton
*all are adapted to digest keratinous debris
more contagious than other fungal infections!
dermtophytosis is the most important cutaneous superficial mycosis
- common to both human beings and animals, especially cats
- dermatophytes are able to colonize the cornified structures (hair, claws) and the stratum corneum and cause disease without ever entering the living tissue
- young animals and hot environments, or immunosuppression
zoophilic dermatophytes
- Microsporum canis and Trichophyton mentagrophytes
- primary animal pathogens but can infect human beings
- M.canis is well adapted to long hair breed cats
Breeds predisposed to M. Canis
- Perisan cats
- Himalayan cats
- Yorkshire Terriers
- source of an M.canis infection is usually an infected cat -ASYMPTOMATIC CARRIER
- most common cause of dermatophytosis in dogs and cats - also associated with equine infections
T. mentagrophytes
- acquired by contact with reservoir hosts (rodents!)
- find in JRT’s
- 2nd most common cause of dermatophytosis in the dog in the UK
- hunting dogs and cats most commonly affected
Microsporum gypseum
- Geophilic dermatophyte
- occur in the soil as saprophytes but under favorable conditions can infect humans and animals if the integrity of the skin is broken or host immune system is compromised
- dogs more often affected than cats
Arthrospores
- typical infective portion of the organism (dermatophytes)
- form by segmentation and fragmentation of fngal hyphae
- dhere strongly to keratin and germinate witin hours of contact- therefore the infection of the hair shaft does not progress below the zone where cornification occurs
- dermatophytes invade cornified tissues by producing proteolytic enzymes (keratinase, elastase, collegenase)
- The products elaborated by the dermatophytes cause dermal irritation and damage to the epidermis
- resulting epidermal hyperplasia (hyperkeratosis, parakeratosis, and acanthosis) and dermal inflammation
- Inflammaotry cells arrive via the superficial vessels (superficial perivascular dermatitis)
- get foliculitits and furunculosis as well - which bacterial infection increases the severity of
Onychomycosis
- Onychomycosis, also known as tinea unguium, is a fungal infection of the nail
- discolored, malformed, friable, broken or sloughed claws
microsporum periscolor
- zoophilic dermatophyte which results in scaling without hair loss
- which is unusual in Dermatophytosis as hair shaft invasion is part of the patho
- but M. periscolor only invades the surface of the skin and lacks enzyme properties for hair invasion
- Dermatocyte ‘pseudomycetoma’
- mainly Persian Cats/MC
- hair follicle rupture can –> infection deep dermis/subcutis by M.canis –> granulomatous dermatitis & panniculitis –> large nodular inflammatory lesion
Most sensitive test for dermatophytosis if done properly
- CULTURE
- sabourauds dextrose agar + cycloheximide + chloramphenicol, incubate for up to 4 weeks -con
- slow process and disease is rather contagious!!
- May see macroconidium (which is the spore stage that is never produced on the skin)
- There are also in house cultures for dermatophytes (SDA + phenol red indicator)
- skin biopsies may be helpful in some cases
Treatment for Dermatophytosis
- may resolve as a consequence of adaptive immunity!
- NO STEROID TREATMENT
- but it is a zoonotic disease so do not await resolution in SA
- clipping and topical therapy:
- Enilconazole (an imidazole) - dogs, cattle, horses
- Miconazole - chlorohexidine combo (malaseb shampoo) or lime-sulphur sol’n in cats
Systemic Therapy
- itraconzole (itrafungol) -licensed for cat
- Bovillis ringvac - cattle –> live attenuated T. verocosum vaccine
Dermatophyte Test Medium
which is the positive dermtophyte sample?
-low temperatre may delay the speed of the color change
Dermatophyte Test Medium Pitfalls
- Skin biopsies can be useful
- Clear translucent fungal hyphae
- Dermatophytosis
- arthrospores around the hair follicle in pic below
- Malassezia Pachydermatitis
- spiraling unique to the genus
- Malassezia otitis
- erythamato-seruminous otitis externa
- red and waxy ears –> Malasezzia overgrowth
Scaling Disorders can favor Malassezia as well
ex: bulldog populations genetically prediposed
FOLDS IS ALSO A BIG COMPONENT: warm and moist
-will often have Malassezia, bacteria or both living in folds (even mammary folds and ear canals)
Thymoma-Associated Exfoliative Dermatitis
- scaling disorder as a paraneoplastic sign
- indicative of Malassezia overgrowth
- controlling the underlying trigger (thymoma) and the Malassezia populations wen back to normal
- these kinds of conditions are more seen in the cat than the dog
Predisposing Factors favoring the yeast
(7)
- about half these cases have underlying allergy! - so treating yeast may not solve the pruritis
- need to treat that to then possibly discover other possible diseases present
Clinical Signs in Dogs
Malassezia dermatitis
(7)
- Paronychia: crusting, discolored claw (infection of the nail)
- especially cats but also in dogs too
- Frenzied Facial Pruritis: cheilitis/muzzle erythema
- Malassezia paronychia
Malassezia dermatitis: frenzied muzzle pruritis
- Can sometime be confused for neurological disease
Trying to scratch the muzzle
It is malessezia!
- Malassezia on cytology
- tape strip and DifQuik
- can also do Quanititative culture plates in practice: stick right on lesions and grow from there
- CupScrub is the gold standard, but tape strip is most used
- green staining showing Malassezia
Systemic Therapy for dogs with Malassezia
Treatment for Deep Pyoderma
CS’s of Deep Pyoderma
- Furunculosis (painful)
- Interdigital Nodules (maybe lameness)
- Acral Lick Dermatitis - chronic self-trauma –> plaque formation & ulceration
- Chin Acne - Typically Young Dogs, Short-haired breeds, underlying causes varied
- Bacterial Granuloma - further tests needed to differentiate from sterile granuloma
Scale
- an accumulation of loose cornified fragments of the stratum corneum
- Seborrhoea is a type of scaling
Crust
- the presence of a dried exudate (serum/blood/pus) on the skin surface
“moving Escalator”
- constant turnover provides protection
- alcceleration of this can be protective in case of noxious stimulus on the skin surface
- Thickening also protects if trauma (e.g. itch)
Seborrhoeic Dermatitis
greasy, inflamed skin
- a lot of the time with this description they actually have Malassezia dermatitis
Lesion types you may see in scaling disorders
(3)
- surface scale may pack into the infundibulum and onto the hair from surface scale
Tachyphylaxis
- rapidly diminishing response to successive doses of a drug, rendering it less effective. The effect is common with drugs acting on the nervous system
- liver metabolizing a drug rapidly
- Depots of Dexamethasone can be good for non - pillable cats with allergic skin BUT, they may metabolize it in the liver rapidly making them less sensitive to the steroids
- more and more injections can lead to more side effects
- BUTTTT, overall cats are more resistant to the adverse side effects as they are more resistant - so we need to be a bit more brave with our GC doses while monitoring SE’s
- take care with Ciclosporin (2nd line Tx) in Toxoplasma naiive animals! -check toxoplasma Ab’s before treatment
- Basal Cell tumor/Trichoblastoma
- Epithelial tumors withoutepidermal or adnexal differentitation
- Epithelial Tumor - Follicular Tumor type
- #1 skin tumor in the cat! (20%) - With SCC being a close second (15%)
- presentation: pigmented, dome shaped, hairless, MOBILE, maybe ulcerated
- most common around head/neck and shoulders
- may have some melanin and inflammatory cells present
- There is a malignant form! - Basal Cell Carcinoma
- low rate of metastasis, take a wide excision –> may have to end up taking wider margins than an original excision or if the cytology looks malignant, take wider margins initially
Elkhound and Keeshonds predisposition
ICE/IKA
- Intracutaneous cornifying epithelioma/ keratocanthoma/infundibular keratinizing acanthoma
- Epithelial Tumor - Follicular Tumor Type
- MOSTLY YOUNG DOGS - rarely cats
- solitary or multicentric –> see in elkhounds and keeshonds
- Pore and toothpaste like material in the middle of it - keratin
- if you get rupture there may be inflammation
- If there are multiple lesions present - maybe try retinoids (can be teratogenic though!)
- otherwise, aim for excisional biopsy
Mesenchymal Tumors
(3 types with specific neoplasms)
- typically affect SQ tissues (connective/structural tissue origins) rather than the skin itself
- Benign Mesenchymal Tumors: lipoma, fibroma and haemangiosarcoma -Sx is often curative
- Malignant/soft tissue sarcomas - we tend to group the malignant tumors in this category (treat similarly) - EXCEPT: haemangiosarcoma and Feline Injection Site Sarcoma (ISS)
- Haemangiosarcoma of skin/SQ - UV related
note- LIPOMA: common, generally easy to excise and remove
PNS = peripheral nerve sheath tumor
Sebaceous Gland Tumors
- mostly benigg so excision should be curative!
- but there is a malignant form - sebaceous adenocarcinoma - low metastatic/recurrence rate
Perianal Adenomas
- QUITE COMMON! - intact males esp.
- ANDROGEN DEPENDENT
- breeds: cockers, English bulldog, samoyed
- Tx: castration, excise (delmadinone acetate). castration highly recommended so they dont develop more of them!
- perianal adenocarcinoma –> RARE luckily -also not hormonally driven. low metastatic rate - about 15%
Tumors of Glandular Origin
Perianal/hepatoid gland tumors
- Perianal adenocarcinoma - would possibly follow up excision with Rx therapy if the margins were incomplete
Apocrine vs. Eccrine glands
Tumors of Glandular Origin
Sweat Gland tumors
(apocrine and eccrine)
(2)
- apocrine cysts/adenomas: common in dogs, less in cats
- apocrine adenocarcinomas - more common in older pets and cats, less common in dogs. still a low metastatic rate (less than 6%) so hopefully most Sx is curative!
Apocrine Gland - Anal Sac Adenocarcinoma
- can even be the size of a pea in the anal sac!
- may get signs of PU/PD –> about a quarter of these lead to paraneoplastic hypercalcemia
- Paraneoplastic hypercalcemia or hypercalcemia of malignancy (HM) is aparaneoplastic syndrome as- sociated with an abnormal elevation of serumcalcium. It is normally associated with the secretion of parathyroid hormone-related protein (PTH-rP) by the neoplasm
- look at ionised calcium for the biologically active fraction
- Note: there ARE other malignancies that can cause hypercalcemia! - so rectal exam is crucial on these patients
- most are metastatic at Dx - you REALLY need to stage these before removal!! - by US, Rx or CT scans if possible
- can get distant metastasis but that likely would happen later on
Apocrine Gland - Anal Sac Adenocarcinoma
Treatment
- this dog has anal sac mass on CT and an enlarged medial LN
- think of local control first as these are generally slow to metastasise
- often these are incompletely resected due to the location
- usually think Sx and then RT in the local area and then down to the LN bed
- multimodal therapy tends to get the best results
Medical Therapy for Slow Growing Tumors
(4)
TKI = tyrosine kinase inhibitor
bottom ones –> other cytotoxic agents that some use
Tx of Mesenchymal Tumors
- issue is that they are locally invasive! - get recurrence
- may consider chemotherapy as well for the higher grade tumors - Doxorubicin based
Mesenchymal Tumors
Haemangiosarcoma of the Skin/SQ
-poorly pigmented dogs!
SQ ones have increased risk of metastasis! - Sx followed by chemo usually (doxorubicin based)
Epitheliotrophic Lymphoma Treatment
- most are partial responses to Lomustine
- they do tend to get secondary infections! - so it is good to use Malaseb or other shampoos to help with hydrating the skin and making them less itchy
Ideal Treatment of Anal Sac Carcinomas
- Sx and RT seem to have a greater effect over medical therapy
- but all of them together seem to lead to decent prognosis and survival times
Alternative Treatments to Anal Sac Carcinomas
(5)
Cutaneous Habronemiasis
- Cutaneous habronemiasis is a skin disease of Equidae caused in part by the larvae of the spirurid stomach worms (GIT parasites).
- disease that is transmitted to horses by flies!
- When the larvae emerge from flies feeding on preexisting wounds or on moisture of the genitalia or eyes, they migrate into and irritate the tissue, which causes a granulomatous reaction. The lesion becomes chronic, and healing is protracted. Diagnosis is based on finding nonhealing, reddish brown, greasy skin granulomas that contain yellow, calcified material the size of rice grains. Larvae, recognized by spiny knobs on their tails, can sometimes be demonstrated in scrapings of the lesions.
“Cushings” in the horse
PPID
pituitary pars intermedia dysfucntion (PPID)
- Hirsutism - shaggy long hair coat (60-100%)
- Predisposition to Laminitis (25-82%)
- hyperhydrosis: excessive sweating
- Tx: pergolide, Trilostane
Most common nodular disease in the horse…
(usually a bunch of firm nodules appearing in the saddle area)
- as well as neck/flanks in spring/summer
- not pruritic/painful, tend not to bother the horse
- mineralization in chronic lesions
- Collagenolytic Granuloma -sterile cause
- (eosinophilic granuloma)
- might be caused by hypersensitivity to insect bites
- NEED Histopathology and biopsy to confirm this!! - as there are loads of possible differential Dx’s - will seeeosinophils and changes to the collagen fibers
- can look extremely similar to Dermatophilosis
- Tx: Leave alone, sx excision, GC’s (usualyl intralesional, but systemic works)
Tx and Prognosis of Collagenolytic Granuloma
Equine Sarcoids
(differential Dx’s)
6 groups
Occult Sarcoids
Flat, circular thickened areas
May also appear as small nodules 2 – 5 mm in diameter
Usually found on the neck, mouth, eyes, and inside of the thighs and upper forelegs
- dermatophytosis
- burns
- trauma
Nodular Sarcoid
Firm, raised circular nodules
5 – 20 mm in diameter
Usually in the sheath/groin area and eyelids
- fibroma
- melanoma
- collagenolytic
- granuloma
- warble fly cysts
Verrucous Sarcoid
Wart-like appearance
Can occur anywhere along face, body, and groin area
- papillomatosis
- chronic sweet itch
- squamous cell carcinoma
Fibroblastic Sarcoid
Proliferative, fleshy, and ulcerative
Usually along the groin, lower legs, and eyelid
- Granulation tissue
- Botryomycosis
- Habronemiasis
- Neurofibroma
- SCC
Mixed Sarcoid
This type is more typical of a sarcoid that has been on the horse for a long time, or has experienced some sort of trauma.
mix of other groups
- easy to recognise
- granulation tissue
- habronemiasis
Malevolent Sarcoid
Appear as multiple nodules
Are locally invasive and occasionally infiltrate the local lymphaticsystem, appearing like cords under the skin
- Lymphangitis
- Glanders
- Lymphosarcoma
- Subcutaenous mycosis
E. rhusopathiae
Erysipelothrix rhusiopathiae is a Gram-positive, catalase-negative, rod-shaped, non-spore-forming, nonacid-fast, nonmotile bacterium. Distributed worldwide, E. rhusiopathiae is primarily considered an animal pathogen, causing the disease known as erysipelas that may affect a wide range of animals
Blowfly Strike
(Cutaneous Myasis)
- V. important disease in sheep! - causes much distress and a slow death
- survivors lose productivity and it is $$ to try and prevent
- Predilection sites: head (base of horns), Breech (ass), prepuce, body, wounds
- Will see these one nibble at their back end rather than scratching
- primary flies lay eggs in wool/inflamed skin
- larvae feed onsurface and cause extensive skin damage –> toxemia due to skin necrosis and absorption of bacterial toxins
- secondary and then tertiary flies may then invade
- Tx: clip, clean tissue, remove maggots, apply insecticide, and supportive therapy in extreme cases
- Prevention: tail docking of lambs assists in reducing “breech strike”
- -Cyromazine (Vetrazin)/Cypermethrin
dermatophilus in sheep
- “LUMPY WOOL” in sheep
- Actinomycete bacteria!! - filamentous
- see in sheep, camelids, goats, pigs and rarely cattle
- produces crusts of varying thickness on wooled and/or haired skin
- tends to follow WET WHEATHER
- Dx: history, CS’s, smears from scabs with DiffQuik –> look for rows of Gram positive cocci and railroad track formation (filaments)
- Tx: remove animals from wet weather, chlorohexidine scrubs (topical Tx) , give AB’s (Penicillin - 5days, Oxytetracycline - 1 dose)
Psoroptic mange (sheep scab)
The image shows the typical yellow crusts of sheep scab. It is present in several sheep producing countries, including the UK. It causes severe itching in affected sheep if left untreated. Scaly lesions develop on the woolly parts of the body and sheep often bite themselves and rub against objects to relieve the irritation causing loss of wool. Untreated sheep may lose weight.
Please note: Sheep scab is a notifiable disease only in Scotland
Example: Lucilia sericata, on the skin of a sheep – following a moist dermatitis such as fleece rot or dermatophilosis
Leishmania
Inflammatory Hair loss in the Dog!
- Leishmaniosis is a disease caused by protozoan parasites of the genus Leishmaniaand transmitted through the bites of female phlebotomine sand flies.
- Dogs are the main reservoir host for human visceral leishmaniosis caused by L infantum, and the disease is potentially fatal in dogs and people
Some Inflammatory causes of hair loss
(4 examples)
- dermatophytosis
- Leishmania (Secondary inflammation)
- Bacterial folliculitis
- Demodecosis
Non-inflammatory causes of hair loss
- hair follicle/function problems
Hair Loss
(Impaired anagen promotion/premature catagen)
catagen - atrophy/recede of anagen bulb
- Hyperoestrogenism/hypothyroidism
- Hair follicles can’t start growth phase well or a re prematurely shut down
Hair Loss
(if NOT self trauma…then inflammatory or non-inflammatory?)
Scaling skin
More subtle
Often scaling –> epidermis trying to repair fromm inflammation
Hyperpigmentation - where sun doesn’t show
Chronic inflammation likely
Inflammation
Case of ringworm treated with glucocorticoids
- patches of hair loss
- very faint erythema in those patches (would see close up in practice)
-demodecosis
INFLAMMATORY
Differentials in Acquired Non-Traumatic Alopecia
- telogenisation of the hair coat
- Hormonal mediated coat abnormalities
- Hairs in the telogen phase do not get initiated into the anogen phase as they should - should be about 80% telogen, 20% anagen, but becomes about 100% telogen
- As hormonal influence persists - there is a synchronization of the hair coat into the telogen phase
- If you clipped the dog in that phase, it wouldn’t really grow back well
- But remember you need to look at SYSTEMIC SIGNS AS A SIGN
Acquired Non-Traumatic Alopecia
(non-inflammatory)
4
Most common causes of an Alopecia work up:
In order (4)
- Inflammatory/parasitic causes are the most common and most easily fixable!
- but always suspect traumatic removal of hair first! - if so, work up as pruritic skin disease
- consider inflammatory (infectious causes first), then endocrine, then lastly micellaneous alopecias
- congenital reasons likely more apparent when young, but become more marked with age!
Diagnostic Approach to hair loss
(3 work ups)
