Dog and Cat 3 Flashcards
What is the pathogensis of canine atopic dermatitis
- Not inhaled by actually route via percutaneous
○ Primary defect in your skin barrier -> allows allergens to get access to yours skin -> large exposure to allergens result in allergic response
§ Allergens especially allergens and dust mites could also be food allergy
§ Increase colonisation of bacteria such as staphylococcus that break down skin further and produce antigens that result in production of danger signals
□ Microbiome changes on the skin -> don’t get dampening down of danger signal (IL33, IL25) -> result in TH2 -> IgE production
OVERREACTION OF THE IMMUNE RESPONSE
What are 5 factors that contribute to the atopic phenotype
- High IgE responder
- Low ceramide (lipid production in the skin)
- Low filaggrin expression (helps with sticking skin together)
- Claudin 1 mutation (retain water within the skin)
- TLR-2 mutation
What are the 5 components of atopy
different components based on individual genome
1. Allergy
2. Barrier dysfunction
3. Infections
4. Behaviour
○ Itching behaviour can become a habit more likely to itch
○ Highly anxious dogs are more likely to clinically present as itching
5. Itch
○ Pathogenesis within the skin
○ Midbrain response -> itch or not to itch??
§ Itch to create mild pain signal to inhibit the itch pathway
□ If won’t stop then -> anxious dog, habit or infection
®Anxious dogs have high serotonin levels which inhibit the pain inhibitory pathways therefore keep itching
◊ IN THIS CASE NEED BEHAVIOUR DRUGS
What increases the risk of developing atopy
- Urban life
- High human population density
- Increased average annual rainfall
- Adoption at the age of 8 to 12 weeks
- Regular bathing of young healthy dogs
○ Wash as infrequently as possible
○ Medicated shampoos should be used
Describe the clinical presentation of the 3 levels of severity for atopi dermatitis
- Mild -> Disease in armpits, groin, ears, feet (moist areas) -> more effective skin barrier, most of the skin normal
- Moderate -> allergen penetration where skin isn’t moist -> everywhere that touches the ground -> less effective skin barrier
- Severe -> generalised disease all over the skin
Can get very bad
Atopic dermatitis diagnosis what are the 3 main things involved
- Signalment
- Clinical signs
○ Generally present before 3 years old
○ Itchy and licking - face, leg and ventral abdomen - Exclusion of other DDx
○ Blood test for sensitisation DOESN’T WORK
Diagnostic check list for atopic dermatitis
a. Could this be infection? -> multiple infections?? -> generally have secondary infection due to allergy
b. Could this be demodex? -> primarily not itchy disease but would be if infected
c. Could this be scabies? -> ALWAYS ON THE DIFFERENTIAL LIST
d. Could this be fleas? -> possible
e. Could this be contact allergy?
f. Could this be food allergy? -> NEEDS TO BE CONSIDERED
§ First symptom for food allergy dogs -> Ear infections
g. If this is atopy can I manage this or should I refer?
Outline a diagnosic plan for atopic dermatitis
Step 1
- Resolve infection - DON’T MISS MRSP
○ If 2 weeks on antibiotics and not resolving -> CULTURE
- Bravecto/Nexgard/simpatico to rule out scabies/flea/Demodex
Step 2
- Still itchy when infection free and on isoxazolines - eliminated above
- Where itchy?
1. Contact areas affected = contact avoidance trail
2. Classical atopic areas = food elimination trial - BEEF most common food allergy in dogs,
In terms of contact avoidance trails what is involved in the 3 types of dermatitis
1) Allergic contact dermatitis
- When moving through areas that have these allergens and come into contact with
- AVOIDABLE ALLERGENS -> keep off grass
○ Test to see whether dogs better if off of the grass for 3-4 days
2) Pollen atopic dermatitis
- Exposure through the skin and the pollen comes to you through the air
- NON-AVOIDABLE ALLERGENS
3) Atopic dermatitis
- Pollen, mites, fungi, bacteria
- NON-AVOIDABLE ALLERGENS
In terms of a food elimination trail what should you feed - list 5 options
1) Hydrolysate diets -> Z/D royal canine etc -> inadequate
2) Restricted antigens diets -> extra things within, cross-contamination -> possible fail or food trial
3) Home-cooked diet -> novel protein +/- novel carbohydrate BUT WHAT IS NOVEL
® Cross-reactivity -> lots present within mammalian proteins, fish proteins -> if allergic to one thing may react to others
4) Anallergic diet -> royal canin - NO CROSS-CONTAMINATION
5) Crocodile meat -> LEAST cross-reactivity than other meats such as poultry and- NOT FULL PROOF
In terms of a food elimination trail how long should you do it for and what is needed long term
□ Treat infection and flea control before start
□ MINIMUM 8 weeks
□ Total compliance needed -> try not to give any medications during this time
□ Anti-pruritic (oclacitinib - apoquel) can give with food trial but not all prednisolone
□ Re-assess BEFORE rechallenge and IF flare reported or after 14 days if no flare
□ Sequential rechallenge
What are 6 important questions to ask with history with skin lumps and bumps
- When did you first notice it ○ Is this reliable - Has it changed - Painful or irritating - Any other masses (now, previously) - Other concerns - UV exposure risk
What are important things to look for with physical exam in approaching lumps and bumps
- Signalment
○ Breed predispositions, UV exposure risk - Size - measure, can use your fingers as in-built callipers
- Location - be specific (leg is not specific)
○ Cutaneous vs subcutaneous - As move skin does mass move within
○ UV associated tumors - Fixed or mobile
- Appearance, texture
○ Round/irregular, raised/flat, pigmented, ulcerated, oedematous, firm/soft - Any other masses on skin
- Lymph nodes
○ Which one is the draining lymph node - assess that
Diagnosis based on looks what skin lumps can you do with and what look like
1. Sebaceous adenoma/hyperplasia ○ Old dog warty appearance 2. Papilloma ○ Multiple in young dog 3. Fibropapilloma (skin tag) 4. Dermal Haemangiosarcoma - can be UV associated (sunbathing on ventral surface) 5. Squamous cell carcinoma ○ Appearance, breed disposition, location 6. Lipoma? - CANNOT Need to FNA it
What are the 2 main diagnostic tests for lumps and what information does it provide
1. FNA and cytology ○ Needle off versus needle on ○ Screen slides § +/- definitive diagnosis, if not then: § Is it diagnostic for a clinical pathologist -> are there enough cells to make a diagnosis 2. Histopathology ○ Diagnosis ○ Margins ○ Other prognostic factors if applicable
What are the 3 main options post diagnosis with lumps
- Surgery - in general for localised cancer is the best treatment
- Other
○ Radiation therapy - alone or adjuvant
○ Chemotherapy - alone or adjuvant - No treatment - still needs monitoring
○ Like sebaceous adenomas
Canine cutaneous MCT presentation - what age and growth
- Breeds: boxers, retrievers, pugs, boston and pit bull terriers
- Can occur in young dogs
- Often slow growing, can vary
○ Changes day to day suggestive of MCT, due to histamine
§ Swell one day then decrease the next - repeat
○ Rapid growth, ulceration, systemic signs, suggestive of aggressive disease
Canine cutaneous MCT what are the 2 main locations and diagnostic testings
Location
1. Muzzle/perioral
○ More likely to have LN metastasis at diagnostic than other sites
2. Subcutaneous
○ Unlikely to have aggressive behaviour
○ Some features may be predictive
Diagnosis
1. FNA usually diagnostic
○ Poorly granulated may be more challenging
○ May be suggestive of high vs low grade
2. Staging tests
○ Lymph node assessment recommended in every case
○ +/- ultrasound, liver, spleen FNA
If clinically aggressive features, cytology suggests high grade
Canine cutaneous MCT list the 4 main prognostics factors
1) histolgic grade
2) margins
3) other histopathology features
4) stage - prognostic
Describe the prognostic factor of canine cutaneous MCT histologic grade and margins
- Histologic grade
○ Two vs three-tiered systems
○ Low = better
§ 15-20% of low grade tumors may still have more aggressive behaviour
□ Therefore not necessary tells you the behaviour - Margins
○ Helps to predict risk of local regrowth but not 100% predictive - NOT METASTISE
§ Many low grade tumors never recur, some high grade tumours recur even through complete margins
Describe how other histopathology features and staging helps with prognosis fro canine cutaneous MCT
- Other histopathology features
○ Mitotic index/mitotic rate
§ Per TEN high power fields, should be reported for every MCT
□ 0 = very good, predict benign behaviour
□ 7 = definitive for aggressive behaviour - depending on the scheme used
○ Other additional tests - unclear how to apply them
§ If all come back bad most likely bad and vice versa - Stage - prognostic
○ Distant metastasis
§ Metastasis -> grave prognosis
○ Lymph node metastasis
§ Still local disease -> can get good outcome for aggressive treatment
What are the 3 main treatments for Canine Cutaneous MCT
- Local
○ Surgery
§ Wide vs planned marginal exicison
§ Only do if can excise ALL THE VISIBLE tumor
○ Radiation therapy - Systemic (chemotherapy)
○ Adjuvant for high-risk tumours
○ Known distant metastasis
○ Non-surgical primary tumour (+/- radiation therapy) - Supportive care medications
○ Anti-histamines - with every case
§ Don’t need to do before FNA
§ Should do before surgery -> needs time to take affect
○ Antacids - histamine can lead to stomach ulceration
§ If large and ugly then use this as well
○ Any bulky MCT
Feline MCT what are the 3 main sites and which are more likely
- Primary sites: skin > spleen (in dogs would be metastasis from skin) > GIT
1) Cutaneous
2) feline splenic MCT
3) Feline GI MCT
Cutaneous feline MCT general character, how many generally present and treatment
○ Most are benign, histopathology does not always correlate well with behaviour
§ Histiocytic subtype in young cats may regress
○ Multiple = associated with splenic MCT
§ Staging recommended
○ Treatment: surgery for all
Feline splenic MCT how common and treatment
○ MCT one of the most common cause of feline splenic disease
○ Clinical signs non-specific
○ Splenectomy recommended even if evidence of liver or peripheral blood involvement
§ +/- chemotherapy
Feline GI MCT clinical signs, character, treatment and prognosis
○ History of non-specific GI signs
○ Metastasis common
○ Typically treated with surgery and/or chemotherapy
○ Prognosis used to be thought to be very poor, more recent study suggests better than thought (even with corticosteroids alone)
Give some examples of canine soft tissue sarcoma and why are they grouped together, general presentation and the 2 main diagnostic techniques
- AKA spindle cell sarcomas, spindle cell tumours, soft tissue mesenchymal tumours
- Group of tumours with different cells of origin but similar behaviour
- Subcutaneous mass - firm, usually well-defined
Diagnosis
1. FNA may or may not be helpful
○ Aspiration techniques may be better
○ Rule out other causes
2. Biopsy histopathology
○ Small mass - consider excisional
○ Larger - incisional recommended
For canine soft tissue sarcoma what are 2 important tests in staging and list the 2 prognostic factors
Staging
1. Thoracic imaging - chest radiographs or CT
○ CT allows primary tumour imaging also
2. LN evaluation if enlarged, known high grade or clinically aggressive tumour
Prognostic factors
1. Histopathologic grade (1/2/3; low/int/high) - PROGNOSITC
2. margins - risk of regrowth
What are the two main prognostic factors for canine soft tissue sarcoma and how prognostic
- Histopathologic grade (1/2/3; low/int/high) - PROGNOSITC
○ Grade 1,2 = <15% chance of metastasis
○ Grade 3 = 3 40-50% chance of metastasis - after removal
○ Mitotic index alone is also prognostic (>9 = worse) - Margins
○ Risk of regrowth - varies with grade
§ 1,2 - many do not regrow even if narrow/incompletely excised
§ 3- 75% regrow with narrow margins, 30% if incomplete
□ If the case second surgery, OR radiation therapy OR THEN monitor
List the 4 main treatment options for canine soft tissue sarcomas and why choose
- Surgery - as long as hasn’t already metastasised
- Adjuvant radiation therapy if incomplete margins post-op and secondary surgery is not an option
- Chemotherapy - consider if high grade; known metastasis
- Non-resectable tumor - consider RT and chemo
Feline injection site sarcoma where more common what is the general presentation and what is concerning, how to remember this
More common USA - rabies vaccine maybe
- Rapidly growing mass at site of injection
- 3,2,1 - should be evaluated as concerning
○ Mass present 3 or more months post vaccine/injection
○ Mass is >2cm
○ Mass is growing more than 1 month post vaccine/injection
Feline injection site sarcoma what are the 2 main diagnostic techniques and staging
Diagnosis
1. FNA - rule out other causes, not always definitive Dx for ISS
2. Incisional biopsy not excisional!!!! - IMPORTANT
○ Aggressive (referral) first surgery = better outcomes
Staging
- Thoracic imaging - CT often ideal for imaging primary tumour also
○ Do metastasis to the lungs
Feline injection site sarcoma what are the 4 main treatment options and what is important
- Surgery: refer!! DON’T DO IN GENERAL PRACTICE
○ Time for recurrence after surgery in general practice is 2 months - Adjuvant radiation therapy post-op, or for palliation if non-resectable
- Chemotherapy - adjuvant can be considered, alone may help slow progression if non-resectable
- Other, non-injection associated STS in cats treat as for dogs
Canine mammary tumours (MGT) what are the 4 main factors
- Age > 7-8 years
- Hormone exposure - intact female, spayed later in life
○ Reduced risk if before 2nd oestrus cycle/ 4 year old - Breed - smaller dogs, springer spaniel, English setter
○ BRCA mutations in springers detected - Weight - increased risk of overweight at 1 year of age
Canine mammary tumours what is the general clinical presentation
- Mass - usually palpable on exam but may not be noticed by owner until quite large
○ Monitoring for at risk dog - when they come in for annual vaccines - Caudal > cranial glands, often multiple at diagnosis
- Inflammatory mammary carcinoma is a specific subset - present with diffuse involvement which can look like severe mastitis, systemically ill
○ Clinical diagnosis shouldn’t need histopathology
Canine mammary tumours what 2 diagnosis is important and 4 staging tests
Diagnosis
1. FNA - not always definitive for malignancy but should identify epithelial origin and rule out other causes
2. Histopathology - benign/malignant, subtype of carcinoma, grade, other features such as vascular or lymphatic invasion, margins
Staging
- Recommended prior to surgery in most cases
1. Lymph nodes - palpation/imaging AND sampling
○ Axillary or inguinal lymph node
○ Difficult to predict drainage pattern
2. Lungs - chest radiograph or CT (more sensitive)
3. +/- abdominal imaging
4. CT may be beneficial for full staging to evaluate all LN, chest, abdomen and other mammae
Canine mammary tumour what are the 2 treatment options and for which types
- Surgery - primary tumour and LN ideally
○ If distant metastasis then surgery may or may not be of benefit (palliation)
○ Wide enough to completely remove the tumour
○ Regional mastectomy if multiple tumours
○ NOT for inflammatory mammary carcinoma
○ +/- OHE - Chemotherapy
○ Adjuvant (following surgery) for high-risk tumours
○ Distant metastasisi (systemic disease)
○ Best agent
○ NSAIDS
What are the 3 main prognostic factors for canine mammary tumours
- Histologic grade, lymphatic invasion
- Size (<3cm best) -> DON’T WANT TO IGNORE, get them small
- LN involvement/other metastasis
Feline mammary tumours what is the general character and 3 risk factors
- 80-90% are malignant
Risk factors
1. Age: > 7-9 increased, mean 10-12 years
2. Hormone exposure:
○ if spayed <1 year old 90% risk reduction
○ May be no benefit if > 2 years olf
○ Exogenous progestins - DDx fibroepithelial hyperplasia
3. Breed: Siamese
