Endocrinology, GI Med, Repro and Dermatology

What is the endocrine system?

Autocrine = hormone signalling produced by a cell which binds back to itself

Paracrine = hormone signally between neighbouring cells

Endocrine = hormone signalling of one to far away cells

• regulated by via negative feedback loops

• hormones and cytokines act on gland directly to inhibit own production / downregulate → indirectly affecting hormone production

• disease = when endocrine hormones are unbalanced and metabolic derangements occur

  • hypo = under functioning

  • hyper = over functioning

Pituitary Disease = Diabetes Insipidus and Acromegaly

Pituitary Gland

• pedunculated gland (on a stalk) below midbrain

• glandular and neurological tissue → produce many hormones

• controls thyroid gland and adrenal glands directly

Diabetes Insipidus

• decreased vasopressin = antidiuretic hormone, ADH

  • ADH normally maintains BP by constricting vessels (central pituitary gland) + resorption of water in distal tubules (nephrogenic)

• caused = head trauma, neoplasia, cysts

Symptoms + Diagnostics

• increased water intake + long term polyuria ad polydipsia (PU/PD)

• urinalysis = USG

• bloods = high urea/BUN, PCV, TP

• water deprivation test (5% each day) to restore USG + normal hydration and body weight

• Desmopressin = synthetic ADH to reduce water intake and ± USG

• MRI to see if head trauma or cyst impeding pituitary gland

• good prognosis with or without treatment, and can be asymptomatic

Acromegaly

• increased excretion of growth hormone

• also known as hypersomatotropism or “big face'“

• common in cats - usually due to grown hormone pituitary tumours → insulin resistance + diabetes mellitus

• rare in dogs = due to excessive progesterone (German shepards)

• hard to treat → brain surgery to remove tumour

What is the endocrine system?

Autocrine = hormone signalling produced by a cell which binds back to itself

Paracrine = hormone signally between neighbouring cells

Endocrine = hormone signalling of one to far away cells

• regulated by via negative feedback loops

• hormones and cytokines act on gland directly to inhibit own production / downregulate → indirectly affecting hormone production

• disease = when endocrine hormones are unbalanced and metabolic derangements occur

  • hypo = under functioning

  • hyper = over functioning

Pituitary Disease = Diabetes Insipidus and Acromegaly

Pituitary Gland

• pedunculated gland (on a stalk) below midbrain

• glandular and neurological tissue → produce many hormones

• controls thyroid gland and adrenal glands directly

Diabetes Insipidus

• decreased vasopressin = antidiuretic hormone, ADH

  • ADH normally maintains BP by constricting vessels (central pituitary gland) + resorption of water in distal tubules (nephrogenic)

• caused = head trauma, neoplasia, cysts

Symptoms + Diagnostics

• increased water intake + long term polyuria ad polydipsia (PU/PD)

• urinalysis = USG

• bloods = high urea/BUN, PCV, TP

• water deprivation test (5% each day) to restore USG + normal hydration and body weight

• Desmopressin = synthetic ADH to reduce water intake and ± USG

• MRI to see if head trauma or cyst impeding pituitary gland

• good prognosis with or without treatment, and can be asymptomatic

Acromegaly

• increased excretion of growth hormone

• also known as hypersomatotropism or “big face'“

• common in cats - usually due to grown hormone pituitary tumours → insulin resistance + diabetes mellitus

• rare in dogs = due to excessive progesterone (German shepards)

• hard to treat → brain surgery to remove tumour

Parathyroid Disease = Hyperparathyroidism

Parathyroid Glands

• x4 small glands embedded within the thyroid gland on ventral neck

• regulates Ca and P via parathyroid hormone (increase Ca, decrease P)

• parathyroid hormone is down-regulated by negative feedback from calcitriol in the renal tubules

Hyperparathyroidism

• excessive production of parathyroid hormone

  • primary = functional tumour or adenoma

  • renal secondary = secondary to chronic kidney disease

  • nutritional secondary = secondary to diet (low Ca or high P)

Symptoms + Diagnostics

• polyuria and polydipsia (PU/PD)

• degenerative joint disease

• bloods = high calcium

• urinalysis = slightly low USG + crystals

• ultrasounds + xray = enlarged or a mass on parathyroid glands

• surgical removal of tumour

Thyroid Disease = Hyperthyroidism and Hypothyroidism

Thyroid Glands

• butterfly shaped gland wrapping either side of trachea, below larynx

• energy metabolism via production of thyroxine (T4)

  • hypothalamus produces thyrotropin-releasing hormone/TRH

  • pituitary gland produces thyroid stimulating hormone/ TSH

  • thyroid gland released thyroxine into blood

Hyperthyroidism = high thyroxine	Hypothyroidism = low thyroxine
weight loss despite increased appetite vomiting + diarrhoea increased stress and panting open mouth breathing	weight gain despite no change to diet constipation mental dullness and general lethargy truncal alopecia and thinning of hair
high HR and BP + gallop rhythm (lub-dub-dub) thyroid gland is palpable with thyroid slip	low-normal HR bilateral symmetrical alopecia generalised weakness
Bloods: high T4, and high PCV high metabolic rate (ALT, AST, ALP), high kidney function (high BUN/urea, creatinine, SDMA) treat with methimazole	Bloods: low T4 (but can change during the day and w meds) high TSH (thyroid stimulating hormone) slow liver function (high total bilirubin and high cholesterol)

Adrenal Disease = Hyperadrenocorticism and Hypoadrenocortism

Adrenal Glands

• x2 adrenal glands (x1 w each kidney)

• produce cortisol as a stress response

• maintains blood pressure, but maintaining Na and K balance

  • central medulla = catecholamine production

  • peripheral cortex = steroid hormone production

    • Glomerulosa = aldosterone → H20 balance

    • Fasciculata = cortisol → sugar metabolism

    • Reticularis = androgen → sex hormones

• adrenal glands controlled via hypothalamic pituitary adrenal axis

• hypothalamus responds by producing corticotrophin releasing hormone (CRH)

• Pituitary glands release adrenocorticotrophin (ACTH)

• adrenal cortex produces cortisol via negative feedback loop of corticosteroid

Hyperadrenocorticism Cushing’s Disease	Hypoadrenocorticism Addison’s Disease
Primary pituitary = over secreting ACTH from both adrenal glands Primary adrenal = single adrenal tumour → increased gland	destruction of adrenal cortex → low or no production of cortisol, aldosterone and androgens Females and breeds can be predisposed (poodles)
increased cortisol (and aldosterone, androgens) inhibited collagen synthesis (pot belly) immunosuppression dermatological change (thinning hair) polyuria increased RR / panting	symptoms come + go poor appetite vomit + diarrhoea ± blood PU/PD, dehydration (high Na excretion) hypovolaemia + shock bradycardia (K retention) collapse + death
Bloods increased liver function (high ALT, ALP) high cholesterol	Bloods little or no cortisol (stress would cause an increase) Na:K less than 27:1
chronic but not fatal Low Dose Dexamethason Suppression Test = cost effective, 90% sensitivity ACTH stimulation test = expensive, 50% sensitivity US or MRI / CT of adrenal and pituitary anatomy	ACTH stimulation = no response

Pancreatic Disease = Diabetes mellitus

Pancreas

• gland in abdomen near stomach and duodenum

• Exocrine unit = produced digestive enzymes

• Endocrine unit = produces insulin and glucagon

  • Insulin = made by beta cells to promote storage of energy/glucose

  • Glucagon = made by alpha cells to promote energy utilisation and ketone body formation, mobilise fat stores for energy

• Insulin and glucagon antagonist each other, and usual controlled by diet, insulin/glucagon activity and energy expenditure

Diabetes Mellitus

• unable to maintain glucose in a normal range → persistent hyperglycaemia and glucosuria

• Dogs = beta cells destructive, not reversible. Middle aged, breed specific

• Cats = beta cells functional, just lack insulin and sensitivity. Reversible if change obesity, diet and activity. Older male specific

• Diabetic ketoacidosis = acutely decompensate → emergency

Symptoms + Diagnostics

• normal HR

• plantigrade stance

• hair coat is dull and unkempt (inactive)

• low muscle condition

• bloods = high glucose and TP

• Fructosamide assay = glycated protein average to help monitor

Ptyalism vs Dysphagia (define, symptoms and diagnostics)

Ptyalism	Dysphagia
increased saliva / drooling may contain blood	difficult or painful swallowing
in oral cavity, salivary glands, oesophagus drug or toxin reaction concurrent GI signs tract urinary signs abdominal pain or urinary obstruction	obstruction in motility disorder of GI tract pain in mouth
good exam of oral cavity thoracic radiographs (foreign body, gas in oesophagus or pyothorax) CBC, Biochemistry + urinalysis (liver disease or sepsis)	normally oropharyngeal related, but could also be oesophageal or gastroesophageal

Regurgitations vs Vomiting (define, symptoms)

Regurgitation	Vomiting
passive movement no abdominal effort thick mucus = clear / food during or post eating disease of the oesophagus or pharynx	active movement severe abdominal stained w bile = yellow or green colour may have blood prayer posture + projectile disease of extra-GI or GI
no prodromal signs will extend head occur randomly	prodromal signs (will have nausea, lip smacking, anxious) stimulated by receptors in pharynx, heart, abdominal, vestibular, CNS

Diseases characterised by regurgitation

Obstructive = foreign body, stricture, vascular ring of oesophagus, neoplasia

Motility disorder

• Megasophagus - dilation of oesophagus due to low peristaltic activity

  • Congenital (breed)

  • Acquired (neuromuscular disease or toxicity)

• thoracic radiographs and endoscope → evaluate aspiration pneumonia, rule out foreign bodies or obstructions

• blood test → autoimmune or disease related

• treat underlying cause + nutritional support

  • gastrostomy tube

  • high caloric dense diet

  • small meals frequently to prevent regurgitation

  • hold dog upright or use Bailey chair whilst eating

  • no medications

Inflammatory = gastroesophageal reflux, oesophagitis , hernia

• Oesophagitis - inflam of oesophageal lining

• Due to: reflux, vomiting, foreign bodies, irritations, stricture formation

• Signs: regurg, discomfort swallowing, anorexia, salivation

• Diagnosis: history, radiographs or endoscopy

• Treatment: analgesia, antacids, meds to increase sphincter tone

Explain acute vs chronic vomiting - causes + diagnostics

• Organs = liver, pancreas, kidney, brain, chemoreceptor trigger zone

GI Causes

• dietary problems - change, foreign material, intolerance, allergy

• stomach, small intestine or large intestine disorders

  • obstruction, inflam, parasite, ulcer, neoplasia dilation

Acute Vomiting	Chronic Vomiting
dietary change viral or bacterial infection parasites	dietary intolerance inflammatory disease untreated parasites chronic pancreatitis, kidney or liver disease GI neoplasia
supportive care = fluids, antiemetic drugs, bland diet, get up to date with parasite treatment abdominal radiographs faecal flotation parvovirus antigen blood and urine tests abdominal ultrasound	rule out parasitic cause w faecal float diet trial rule out extra-GI cause with bloods, urine, and abdominal ultrasound exploratory laparotomy or biopsies

Small vs Large Intestine Diarrhoea

Small Intestinal	Large Intestinal
large volume (watery) normal frequency no mucous or blood ± weight loss may vomit also	small volume high frequency may have mucous or blood no weight loss vomiting rare

Acute vs Chronic Diarrhoea

Acute	Chronic- Small Intestine	Chronic- Large Intestine
dietary change viral or bacterial infections parasites	maldigestion (low enzymes or pancreas failure) malabsorption (intolerance or neoplasia)	inflam of colon and rectum disruption of mucosal integrity and motility = increase secretion of mucous, reduced absorptions of water and storing faeces → diarrhoea
fluid therapy antiemetics if vomiting as well treat for parasites bland diet	deworming blood + urine abdominal US diet trial antimicrobial trial endoscope, ex lap	deworming blood + urine abdominal US diet trial antimicrobial trial endoscope, ex lap
physical exam faecal float, smear and/or culture parvovirus antigen bloods abdominal US		physical exam = normal caused by parasites, trauma, allergic, inflammatory or immune novel protein diet fibre supplementation
Acute Gastritis Acute pancreatitis = middle ages, obese female dogs Feline Pancreatitis = liver, GI inflam or necrotic → anorexia		Colitis Proctitis

Constipation vs Obstipation

Constipation = infrequent, incomplete or difficult defaecation with passage of hard or dry faeces

Obstipation = intractable constipation cause by prolonged retention of hard, dry faeces (chronic)

Constipation signs, diagnostics + treatment

Symptoms

• more common in cats than dogs

• straining to defaecate with small volume produces

• hard and dry but infrequent

• mucoid stool or may have blood

• occasional vomiting, inappetence and/or depression

Causes

• dietary - excessive fibre

• environment - low exercise, dirty litter box

• drugs - opioids or diuretics

• painful - perineal hernia, anal sac disease,

• mechanical obstruction - prostatic enlargement, foreign body, stricture or narrow pelvic canal

• general muscle weakness or dehydration or hypothyroidism

• neuromuscular disease

Diagnostics

• History and exam or rectum + neurological

• Bloods - CBC, biochemistry, UQ

• abdominal radiography, ultrasound or colonoscopy

Treatment

• microlax enema or warm water with saline enema → monitor for defecation

• IV fluids

• deobstipation = manual removal of faeces under GA

  • endotracheal intubation = risk of aspiration

  • warm saline enema prior to assist with softening

  • manual breakdown by transabdominal massage

  • remove fragments via anus

  • radiograph to check progress

Dog vs Cat General Reproductive Cycle Time Periods

Dog	Cat
x1 oestrus per oestrous cycle seasonal - autumn + spring oestrous cycle = 6-7 months (x2 year) spontaneous ovulation puberty small breed = 6-10 months puberty large breed = 18-24 months no menopause → decreased fertility 8yrs+	seasonally polyoestrous = increased light polyoestruous = 4-30 day intervals induced ovulators = repeated mating or pheromones/ contact puberty = 2.3-2.5 kg, early spring. Females 6-9 months, males 9months cycle = anovulatory (release egg), pseudopregant (false pregnancy), pregnant

Explain the 4 Phases of the Canine Oestrus Cycle

Proestrus

• 9 days

• changes in behaviour

• swollen and turgid vulva

• serosanguineous (bloody) vulva discharge

• increased oestrogen

Oestrus

• 9 days

• most receptive to mating behaviour

• swollen but soft vulva

• clear coloured vulva discharge

• LH peak, increased progesterone, but decrease oestrogen

Dioestrus and Anoestrus

• dioestrus = 60 days → then anoestrus = 120 days

• normal behaviour

• small vulva

• no/sparse vulva discharge

• high (dioestrus) or low (anoestrus) progesterone levels

Explain the 5 Phases of the Feline Oestrus Cycle

Pro-oestrus

• 0-2 days

• changes in behaviour, head and neck rubbing

• rise in oestradoil concentration

• vaginal epithelium begins cornification

Oestrus

• 2-9 days

• receptive to mating and oestrus behaviour

• peak oestradoil concentration, and LH post mating

• vaginal epithelium, cornification

• induced ovulation 29-40 hrs after coitus

Post-oestrus

• 8-10 days

• follow one oestus and precedes the next when ovulation has not been induced

• no CL formation, low progesterone and oestradiol conc, no sex

Dioestrus

• 40-60 days

• ovulation induced (pregnant = 60days, pesudopregnant = 40 days)

• CL formation and high levels of progesterone

Anoestrus

• 30-90 days

• seasonal absence of follicle activity in late fall and winter

• oestradoil and progesterone levels are base line

Clinical Signs of Oestrus in the Canine

3 Sexual Reflexes

• Upward tipping or winking of vulva in response to touching dorsal vulva (muscles preparing)

• Ipsilateral curvature of rear legs in response to touching skin beside vulva (leg spread for stability when mounted)

• Deviation or flagging of tail in response to touch skin beside vulva (tail up or to the side)

Other Key Signs

• Vulva = swollen and edema

• Discharge = serosanguineous

• Behaviour = attract + interested in males, flagging tail + accept mating

Clinical sings of mating and oestrous in the feline

Females

• crouching, w front legs on ground

• hyperextension of back / lordosis

• tail to side presenting vulva

• vocal and restless

• during coitus = steps with hind legs

• post intromission = screaming, strike at male, rolling, licking vulva

Male

• tom mounts the queen and bites her neck (5-50 seconds)

• step and hold her with front legs and mouth (1-10 mins)

• intromission and ejaculation (1-27 seconds)

• jump away to avoid queen striking him

• stay close to queen

• repeat 4-5 times in 30 mins

Natural Mating and Insemination of the Canine

Natural Mating = 80-100%

• dependant on heat period will change what day of cycle

  • 14 day heat = mate on day 11-13

  • 21 day heat = mate on day 18-20

  • 28 day heat = mate on day 25-27

• limited survival of oocytes (2 days) vs long survival of sperm in female (7-9 days)

• use oestrous behaviour w caution

• ideally vaginal cytology, speculum exam, changes in vaginal mucus, follicle growth (measure on US), serum hormone concentration (LH and progesterone)

Insemination = 55-75%

• Intra-vaginal insemination = fresh semen

• Intra-uterine insemination = frozen thawed semen

  • palpation (catheter), endoscope or laparoscopic (surgery)

Ovulation and Breeding of Felines

Induced Ovulation - Voitus

• LH released from pituitary within minutes

• ovulation induced 24-48 hours after coitus

• factors affecting LH surge

  • oestrogen espoure

  • multiple mating copulations

  • fertility - 2-3 first days of oestrus

  • pheromones and experience of sexual partner

Natural Breeding

• territorial = oesterous queen is brough to the tom

• photoperiod = more than 14 hours of light per day

• mating

  • active fertile male can service 15-20 at a time

  • sexual preferences

  • behavioural problems

Insemination

• AI with fresh or frozen semen - intravaginal or interuterine

• not common in felines as its hard to collect and induce

Pregnancy Diagnosis Methodology for Canine and Felines

Vaginal Cytology (ideal)

• increased oestrogen

• proliferation/ increase/ thickening of epithelium in vagina (dark purple on histology)

  • pre-oestrus = more para basal, small intermediate and RBC

  • oestrus = more large intermediate + anuclear keratinised cell

  • anoestrus = more neutrophils to help clean out vagina

• 10-15 cm into vagina, hold down + point up to avoid urethra

• roll swab over microscope slide 3-4 times, air dry → stain w Diff-quick or Wright-Giemsa → air dry

• easy and cheap but needs to be repeated to monitor level of oestrogen (not ovulation) different for each bitch

Serum Hormone Concentrations (ideal)

• LH peak duration <24 hrs

  • ovulation +2 → fertility max 0-5 days

  • measure 8-12 hours from proestrus until peak

• Progesterone increase duration preovulatory and ongoing

  • ovulation 4-10 ng/ml → dioestrus >10 ng/ml

  • measure every day/second day in oestrus

Vaginoscopy

• endoscopic observation - speculum, vaginoscope, optical endoscope

• examination of vagina - profile/colour of mucosal folds + discharge

  • think but pale = oestrus vs thin, pink, moist = dioestrus

Follicle Growth

• ultrasonography examination of right ovary - 5-7 mm

Explain the Copulation Tie in Canines

Intromission = 1-2 mins

• ejaculation of 1st semen

• engorgement of bulbus glandis and thrusting pelvic movement

• ejaculation of 2nd semen (sperm rich)

The Turn = 2-5 seconds

• the dog dismounts and turns (penis still inside)

Copulation Tie = 5-45 mins

• bent penis = locking by the engorged bulbus

• no drainage and high pressure

• ejaculation of 3rd semen

• flushes sperm rich into uterus (prevents falling out)

Gestation of Canine vs Feline

Canine Gestation

• from LH peak = 64-66 days

• from ovulation = 62-64 days

• from cytologic dioestrus = 56-58 days

• from mating to parturition = 57-72 days

• hormones, progesterone (CL function) and relaxin (placenta function)

Feline Pregnancy

• Pregnancy from mating = 63-65 days (53-74)

• Implantation = 12-13 days after ovulation

• Placenta will have brown boarders (not green from bile like canine)

Determining a Pregnant Bitch or Queen

Detecting Pregnancy

• Palpation + clinical signs

  • nipple enlarges + mammary develop

  • change body shape and weight

  • enlargement + palpate foetus

  • **from LH peak = 22-25 days

  • **from ovulation = 17-22 days

• Hormone measurements

  • Relaxin assay (in house serology)

  • **from LH peak = 20-29 days

  • **from ovulation = 18-24 days

• Ultrasonography

  • Embryonic vesicle D16, placenta D18 and embryo D22

  • **from LH peak = 19-22 days

  • **from ovulation = 18-19 days

• Radiography

  • foetal skeletal D45 - number of foetuses and dystocia

  • only do x1 per litter

  • **from LH peak = 44-46 days

  • **from ovulation = 41-43 days

Explain normal parturition

Week Before

• potential milk from mammary

• dilation of vulva and pelvis ligament s

• week inconsistent uterus contractions

Day Before

• nesting behaviour

• relaxing of cervix + loos cervix mucous

• decrease temp

• decreased progesterone

Stage 1 of Parturition

• 6-12 hours

• cervical relaxation and dilation

• restless, nervous, anorexia, shiver but panting

• temp and progesterone rise

Stage 2 of Parturition

• 6-24 hours

• birth of pups/kittens

• cervix fully open, strong contractions, licking vulva

• takes 1-2 mins per neonate, then 5-60 mins rest before next one

Stage 3 of Parturition

• 5-15 mins

• expulsion of placentas

• following each pup or every second (each uterine horn)

• allow her to clean pups/kittens

  • Thermoregulation - unable to maintain temp

  • Carbohydrate regulation - hard to maintain blood glucose, so ensure feeding from mum or give formula

Parturition Differences Canine vs Feline

Canine	Feline
Stage 2 = interval between puppies can be 30-60 mins max Bitch will should be completed within 1 day	Stage 2 = interval between kittens can be 5-60 mins + Queening is usually short (1hr) but can be up to 2-3 days can stop pregnancy if feels unsafe / stressed
placenta will be clear or with slight green colour due to bile bitch should not eat placenta	marginal haematomas of placenta is red-brown queen eats placenta

Abnormal births and went to interfere

• dependant on duration of birth

• health of bitch

• number of pups left in uterus

• appearance of discharge (normal is green from bile / placenta)

• maternal forces and contractions

• straining due to pain or abnormal positions

• no whelping

• pausing for more than 2-4 hours between pups or kittens

• symptoms of intoxication

What is the general approach to a skin case consult?

1. History

   • signalment

   • main concern - when? change over time? seasonal?

   • what treatments have been tried so far? did they help?

   • any current medications or parasite prevention?

   • what is the diet + environment? has this changed?

2. Physical Exam

   • Distant = itching? coat quality? obvious lesions? bilaterally symmetrical or are they focal?

   • methodical search over skin = face, neck, limps, dorsum, ventrum, peri-anal, tail

   • any parasites? use a flea comb to see fleas or flea dirt

3. Describe lesion morphology

   • location and distribution

   • number of lesions

   • size and appearance - colour, texture, shape

   • lumps - subcutaneous or cutaneous?

4. Diagnostic testing

   • skin cytology - impression, fine needle aspirate or trichogram

   • skin scraping - superficial or deep

   • wood’s lamp test - uses ultraviolent light to see ringworm

   • fungal culture

   • laboratory culture - fungal or bacterial

   • skin biopsy - histopathology or culture

   • referral for intradermal skin testing

5. Treatment

   • if diagnosis = target aetiology

   • no diagnosis = symptomatic management

6. Re-assesment

   • have clients concerns resolved?

   • is it improvement based on your judgement?

   • adjust treatment as required

What are the types of skin lesions?

Pruritus = itching, biting, licking, scratching or rubbing (30-40%)

Alopecia = absence of hair, localised, mutli-focal, symmetrical or generalised. May be due to self trauma or abnormal hair follicles

Wheals/hives/urticaria = small oedematous, raised lesions, allergy

Pigmentary change = disruption of melanin pigment, eg post shave, hypopigmentation (reduced) or hyperpigmentation (increased)

Rashes = erythema (red) or papules (pimple), localised inflammation

Scaling = superficial accumulation of loose skin on epidermis surface

Crusting = scales + exudate like blood, serum or pus on surface

Erosion = partial loss of epidermis, intact basement membrane, superficial

Ulceration = loss of epidermis, exposure of dermis, deep lesion

Lichenification = thickening of skin with chronic inflammation

Hyperkeratosis = keratin deposits on nose, paw pads, thick + hard

Masses = inflammatory papules pustules or abscesses or neoplastic

“People always wonder, please rescue cute elephants under large hazy mountains”

What is an allergic skin disease?

• Type I Hypersensitivity reactions = foreign substance with IgE immunoglobulins

• Type IV Hypersensitive reactions = contact allergies

• History clues = breed, age (most star 1-3rs), duration/ seasonal, response to steroids

• Clinical clues = pruritus (most common), recurrent secondary infections, lesion distribution

Describe common the x4 patterns of common cat allergies

Head and neck pruritus = localised, pruritic with erosive lesions

Miliary dermatitis = multi-focal pinpoint papules (can be felt), pruritic rash that spreads and becomes scabby

Eosinophilic granuloma complex

• Plaque = well-defines, raised, red, on ventrum/thighs, itchy

• Granuloma = raised, circular, yellow-pink, on head/thighs

• Ulcer = well-defined, red skin ulcers, lip, not painful or itchy

Symmetrical / non-inflammatory alopecia = self trauma

Causes of common allergies

Flea Allergy Dermatitis

• most common in dogs at base of tail

• Diagnosis

  • wet paper towel or cotton wool → flea dirt will stain brown

  • intradermal testing - confirms reactivity to flea antigens

  • response to therapy

• Treatment - compliance!

  • Insect Growth Regulatory = Sentinel

  • Adulticides (kills adults) = Nexgard, Bravecto, Seresto collar

  • Repellent to stop flea landing = Seresto collar

  • treat all animals in house

  • clean environment, wash bedding, remove organic debris

Mosquito Bite Hypersensitivity

• most common in cats

• scaling, crusting, alopecia on nose and ears

• symptomatic treatment as for flea bite

Contact Allergy

• most common in dogs, rare in cats

• Type IV hypersensitivity response (cell mediated, not antibody mediated) due to direct contact w irritant, non-haired usually

• Usually caused by plants, or chemicals

• Diagnosis

  • contact elimination trial = eliminate for 10 days and observe for another 10 days

  • patch test = exposure in marked skin patches

• Treatment

  • prevent contact with known irritants or remove asap

  • medical intervention - steroidal anti-inflammatories

Atopic Dermatitis

• most common is pruritus and erythema on face, ears, perianal, paws, ventrum → saliva staining or secondary infections

• genetically predisposed allergic dermatitis with complex interactions with enviro, microbes, genetics and immunological factors

• Diagnosis

  • exclude parasites, infections, contact or food allergy

  • intradermal skin testing as blebs under skin → wheals

• Treatment

  • modify patient response by managing secondary infections

  • need to cytology to diagnose organism → use antimicrobial

  • desensitisation treatment = subcut inj weekly then monthly

  • promoting skin barrier w Omega 5+6, regular baths/shampoo, prevent self-trauma

  • life long management

Food Allergy

• immunological (true hypersensitivity) or non-immunological (food intolerance)

• signs = pruritus and or gastrointestinal abnormalities, no seasonal

• usually due to beef, chicken, wheat and lamb

• elimination diet trial = novel protein and carbohydrate for 6-12 weeks

• rechallenge trial = if symptoms improve, can reintroduce x1 protein at a time and monitor

• long term commitment, takes time to see improvements

Causes of infectious skin disease?

Bacterial pyoderma

• normal skin commensal bacteria in high numbers/overgrowth usually secondary to underlying allergy or disease

• scales, epidermal collaretttes, pustule lesions and/or discharge

• Diagnosis = cytology impression under microscope or swab to lab

• Treatment = shampoo, amoxycalv antibiotic, caphalexin tablet or neocort anti-inflam cream

Fungal pyoderma

• normal skin commensal fungal yeast in high numbers/overgrowth usually secondary to underlying disease

• scales, greasy skin exudate, if chronic can be lichenified + discharge

• Diagnosis = cytology impression under microscope

• Treatment = shampoo, PMP ear suspension, fluconazole tablet, or fungafite cream

Dermatophytosis (ringworm)

• fungal infection of the hair shaft creating round pruritic lesions

• zoonotic infection

• Diagnosis = trichogram (may show fungal spores), woods lamp (UV light) or fungal culture from hair plucked

Mites

• Demodex cani and Demodex cati = non-contagious overgrowth due to immunocompromise

• Sarcoptes scabei = infectious and zoonotic

• Diagnosis = skin scrape (demodex = deep, scabies = superficial)

• Treatment = parasite prevention and/or treat underlying immunocompromising disease

Otitis externa (bacterial or fungal)

• many predisposing factors = conformation/genetics, moisture, parasites, allergy, foreign bodies, yeast and bacteria

• Diagnose = cytology to see bacteria, vs yeast vs parasites OR otoscopic exam to see foreign material

• Treatment = ear cleaning to reduce debris and biofilm, antimicrobials, reduce bacteria and fungal numbers

How to treat unknown ‘lumps and bumps’ in dermatology?

• History

  • when first noticed? grown? appearance change?

  • every had a lump before? was it diagnosed?

  • is it bothering patient?

  • history of trauma like cuts or sun bath

• Examination

  • location - cutaneous or subcutaneous

  • texture - soft/firm/hard, regular/irregular, mobile/non-mobile

  • surface - ulcerated or pigmented

  • number - singular or multiple

  • inflammation - local or systemic

  • lymph nodes - palpate for enlargement

• Diagnosis

  • final needle aspirate to sample cells under microscope

  • biopsy = incisional (part of) or excisional (whole) mass → lab

    • inflammatory vs neoplastic

    • benign tumours = lipomas, sebaceous cyst, keratin cyst, histiocytoma

    • malignant tumours = mast cell, plasma cell or lymphoma