diseases 🦠 Flashcards
aetiology and pathophysiology for atopic dermatitis
Affected animals have a genetic predisposition to become sensitised to allergens and have abnormal skin barrier function
Allergens are proteins that, when inhaled or absorbed through the skin, respiratory tract, or GI tract, evoke allergen-specific IgE production
Ige molecules affix themselves to tissue mast cells or basophils.
When these primed cells come in contact with the specific allergen again, mast cell degranulation results in the release of proteolytic enzymes, histamine, bradykinins, and other vasoactive amines, leading to inflammation (erythema, oedema, and pruritus)
Golden Retriever
Labrador Retriever
Dalmatian
Boxer
Between 6 months and 3 years of age
CS for atopic dermatitis
Pruritis – VERY ITCHY +++
Inflammation
Lesions
Alopecia
Lichenification
Erythema
Papules
DOGS -
Can be seasonal or non seasonal or non seasonal with flare ups
The feet, face, ears, flexural surfaces of the front legs, axillae, and abdomenmost commonly affected areas
diagnosis for atopic dermatitis
History and clinical signs
Exclusion of other causes – treat any parasites / infections / rule out other skin dx
Examination
Microscopy – tape, skin scrape
Bacterial culture
Fungal culture
Biopsy
Exclusion diet
Intradermal skin testing
what is the aetiology of chronic renal failure
Idiopathic deterioration in geriatric cat – most common
Previous acute renal damage eg. Injury, toxin
Neoplasia
Polycystic kidney disease
Chronic infection/pyelonephritis/glomerulonephritis
Concurrent conditions eg. Diabetes mellitus, hypertension
what is the pathophysiology of chronic renal failure
The kidney is unable to filter nitrogenous waste from the blood leading to uraemia
Deterioration in renal function causes pH and electrolyte imbalance (potassium and phosphate)
Reduced production of erythropoietin leads to reduced erythrocyte formation in the bone marrow
Note; reserve capacity of kidneys means signs of renal failure only appear when 2/3-3/4 of functioning tissue is lost
what are the clinical signs of chronic renal failure
polyuria
polydipsia
vomiting
inappetance
dehydration
weight loss
depression
oral ulcers and halitosis
seizures
anaemia of chronic renal disease
end stage may be anuric
what is the diagnosis of chronic renal failure
Several options exist;
History and clinical signs
Physical examination
Urine testing, SG
Blood testing
Blood pressure
Radiography
Ultrasound
Determine cause and extent of azotaemia
aetiology for diabetes mellitus
type 1- beta cells have been destroyed and can no longer synthesise insulin adequately.
presumed immune mediated and some breed predisposed such as Keeshond and cairn terrier or besties and JRTs
causes a damage to the pancreas such as during an episode of pancreatitis may lead to inability to synthesise insulin.
known as insulin dependent
type 2- reduced ability to respond to insulin due to obesity, oestrus, Cushing disease, steroids, acromegaly
pathophysiology for diabetes mellitus
absolute or relative insulin deficiency.
reduced tissue utilisation of glucose
leads to hyperglycaemia in bloodstream
low glucose levels in cells
occurs secondary to acromegaly in cats
renal threshold for glucose exceeded- glycosuria
eventually fats are broken down as cells cant access glucose which leads to ketosis
CS for diabetes mellitus
polyphasic
polyruria
polydipsia
glycosuria
weight loss
ketosis - vomiting, depression, dehydration
on set blindness- cataracts 70% will go blind
diagnosis of diabetes mellitus
history and CS
blood tests - will have high glucose
urine tests- high glucose in urine
epilepsy
what is the aetiology for feline leukaemia virus
causal agent is retrovirus from the oncornavirus cancer-causing group. the incubation period is months-years.
what is the pathophysiology of feline leukaemia virus
the virus replicates in the lymphoid tissue and enters lymphocytes and monocytes. it transports all around the body and eventually enters the bone marrow. in some cats, persistent infection leads to immune suppression or anaemia. the outcome is variable
what is the CS fo feline leukaemia virus
immunosupression
recurrent infections
anaemia
tumour development
lethargy
diarrhoea
what is the diagnosis for feline leukaemia virus
elisa serum test
px side test
re-test after 12wks
PCR
viral isolation
what is the aetiology for hyperthyroidism
Functional thyroid tumour
Usually benign adenomatous hyperplasia (rarely cancerous) of the thyroid gland
May affect one or both lobes (also ectopic tissue)
Inciting cause theorised but unknown
what is the pathophysiology for hyperthyroidism
Affected gland overproduces thyroxine
This leads to a hypermetabolic state
As thyroxine affects a number of body tissues there are a wide range of clinical signs seen
Complications such as hypertension and hypertrophic cardiomyopathy may occur
what is the CS for hyperthyroidism
Polyphagia
Weight loss
Hyperactive/aggressive or restless
Tachycardia
Vomiting and diarrhoea
Poor coat/unkempt
Polydipsia
potential aortic thromboelism
what is the diagnosis for hyperthyroidism
Blood test – serum T4 levels, high levels confirm diagnosis, run in house with rapid results –
T4 is tested to show thyroid function and show increased levels.
Blood biochem – this is used to check for raised kidney enzymes or any other conditions
Scintigraphy – imaging using radioisotopes injected into the patient and imaged using a gamma camera. Used to locate thyroid tissue/plan surgery. Referral centre and ££
Evaluation of cardiac function and measurement of BP advisable – Why?
aetiology of hyperadrenocortism
Caused by either
Pituitary tumour – increased production of ACTH (most common)
Adrenal tumour – direct increase of cortisol
Both lead to increased serum cortisol
diagnosis of hyperadrenocorticism
History and clinical signs
ACTH stimulation test –blood at 0 and 1hrs, inj with ACTH after first blood sample – Why would we use this test?
Low dose dexamethasone suppression test – blood at 0,4 and 8hrs, inj of dexamethasone iv after first b/s – this test distinguishes the types of cushings, it can tell us if the pituitary gland is at fault or adrenal gland
urine cortisol:creatinine ratio (UCCR)
Endogenous ACTH
Often diagnosis requires combination of tests – see recommended resources
Imaging
pathophysiology for hyperadrenocorticism
Overactive tissue in pituitary or adrenal gland leads to increased production of cortisol (2 different aetiologies)
High levels of cortisol lead to hyperglycaemia and inhibit ADH – leading to PUPD
High cortisol also causes protein catabolism leading to muscle wasting and poor wound healing
Cortisol affects hair growth and distribution of fat
what are the CS of hyperadrenocorticism
Polyuria
Polydipsia
Weight loss
Alopecia (flanks)
Pot bellied- weakness of abdominal muscles due to excess cortisol and this causes fat redisposition
large liver due to the same above
Hepatomegaly
Muscle weakness
Panting
Thinning of the skin
aetiology for keratoconjunctivitis sicca
reduced or absence of ability to form tears
Immune mediated
Breed predisposition eg. Cocker spaniel, Shih Tzu, YT, Lhasa Apso, Bulldog breeds (particularly English bulldog)
Protruberant eye breeds
Secondary to some endocrine conditions/drug toxicity
pathophysiology for keratoconjunctivitis sicca
overproduction of mucus to keep cornea moist
immune mediated or caused by drug toxicity, trauma or surgery
variation in the degree of severity
Reduced activity in the lacrimal glands leads to inadequate formation of the aqueous tear film
As adequate tear film is essential for corneal health absence of, or reduced tear film leads to corneal drying and inflammation
CS for keratoconjunctivitis sicca
vascularization
ulceration
opacity of the cornea
recurrent conjunctivitis
mucoid or mucopurulent discharge on and around eye
Mucoid/mucopurulent conjunctivitis
Any dog with sticky discharge in the medial canthus should have a test for KCS
Neovascularisation of cornea
Clouding of cornea
dull/dry appearance
This condition is painful and left untreated can lead to blindness!
diagnosis for keratoconjunctivitis sicca
schirmer test to show tear production
History and clinical signs should lead to suspicion of this disease
Fluorescein to rule in/out ulceration of the cornea
After Schirmer tear test – fluorescein will alter results of schirmer
Schirmer tear test – definitive test, tear production should be more than 15mm per minute
mast cell tumour
what is the aetiology for mitral valve disease/ endocarditis
Degeneration of the AV valves – Cause is unknown.
Hereditary component.
Common in Cavalier King Charles Spaniels.
Rare in Cats
what is the pathophysiology for mitral valve disease/ endocarditis
Valvular tissue degenerates, becoming thickened and develops lesions.
Valves cannot close properly
Allows regurgitation of blood from the ventricles back to the atria.
Eventually leads to cardiac enlargement and output failure.
what are the CS for mitral valve disease/ endocarditis
Murmur
Exercise intolerance
Coughing – Normally morning or at night.
Ascites
Dyspnoea
Later – Weight loss/anorexia.
what is the diagnosis for mitral valve disease/ endocarditis
Blood tests: A complete blood count (CBC) and serum biochemistry can show abnormalities. Blood cultures can help identify the bacteria causing the infection.
Chest X-rays: Can show an enlarged heart or signs of heart failure.
Electrocardiogram (ECG): Records the heart’s electrical activity and can show an irregular heartbeat.
Echocardiogram: An ultrasound of the heart that can help identify the affected valve and the extent of damage.
Infectious disease testing: Can help identify the specific pathogen causing the infection.
aetiology for osteoarthritis
affects 1 in 5 dogs/cats.
most common cause of lamenes.
develops from an underlying deformity or trauma
hip dysplasia, elbow displasia, or Osteochondritis dissecans will lead to OA due to abnormal wear on joint surfaces
pathophysiology of oesto arthritis
characterised by degeneration of articular cartilage often associated with the formation of new bone at joint surface
may have a gradual onset, but may also occur acutely.
(Osteoarthritis can be a primary disease of joint cartilage, but is more often secondary to abnormal stresses on joints)
slowly progressive but can have a rapid onset
chronic and progressive
CS of osteo arthiritis
stiffness/ lameness (worse after rest) - less common in cats
reluctant to jump or climb
reduced range of movement of affected joint
+/- swelling
alteration to gait
muscle atrophy In affected limbs
may affect appetite and personality/ behaviour dependent on severity
diagnosis of oesto arthritis
history and examination findings (swelling and crepitus evident on exam)
radiography of joints and contralateral joint
arthroscopy to visualise cartilage and lesions and synovial fluid
CT/MRI
synovial fluid analysis
aetiology for otitis externa
Infection
Parasites
Trauma
Allergy
Neoplasia
pathophysiology for otitis externa
Irritation/self trauma leads to tissue hyperplasia, inflammation and excess production of wax
Any obstruction of the ear canal may lead to accumulation of cerumen, discharge and predispose to infection
