Endocrinology Flashcards
what is aetiology for feline hyperthyroidism?
adenoma of thyroid tissues
adenocarcinoma
mostly bilateral
what are potential causes of feline hyperthyroidism?
high iodine in diet
pesticides in environment
genetics
circulation thyroid growth stimulating immunoglobulins
describe signalment for feline hyperthyroidism
middle aged or older
same for both sexes
list clinical signs of feline hyperthyroidism
enlarged thyroid glands weight loss PUPD tachycardia lethargy muscle weakness anorexia tachypnoea CHF pyrexia
what are signs of apathetic feline hyperthyroidism?
lethargy
inappetence
weight loss
obtundation
what is meant by apathetic feline hyperthyroidism?
reflects underling comorbidity, often severe cardiac abnormalities
describe how to nurse cats with hyperthyroidism
hand off approach
quiet dark room
oxygen
monitor RR
how is feline hyperthyroidism diagnosed?
clinical signs blood tests high liver enzymes urinalysis BP serum total thyroxine elevated
list treatment options for feline hyperthyroidism
anti-thyroid drugs
iodine restricted diet
thyroidectomy
radioactive iodine treatment
list examples of anti-thyroid drugs
methimazole BID
slow release carbimazole SID
what are advantages of anti-thyroid drugs?
readily available
rapid effect
inexpensive
practical
list disadvantages of anti-thyroid drugs
life long
can become resistant
side effects
state some side effects of anti-thyroid drugs
vomiting anorexia lethargy GI signs leukopenia anaemia thrombocytopenia dermatitis myasthenia gravis
what is the benefit of iodine restricted diets?
when fed exclusively can become euthyroid in 3 weeks
list presurgical considerations for feline hyperthyroidism
systemic effects of hyperthyroidism
cardiac disease
hypertension
other disease present
what are advantages of thyroidectomy to treat hyperthyroidism?
rapidly curative
quick recovery
list disadvantages of thyroidectomy to treat hyperthyroidism
need GA
cost
complications
need to preserve parathyroid
list complications following thyroidectomy
hypoparathyroidism if parathyroid tissue damaged
laryngeal paralysis
sympathetic trunk damage
recurrence if unilateral
how does radioiodine treat hyperthyroidism?
administered IV to concentrate in thyroid
beta causes local cell death of thyroid tissue
list advantages of radioiodine
curative
simple
high doses can treat adenocarcinoma
no GA
state disadvantages of radioiodine treatment
limited availability isolation needed irreversible longer to achieve euthyroid can cause hypothyroidism
how are feline hyperthyroid patients monitored?
6 monthly check ups when stable
monitor for recurrence, hypertension and CKD
what is prognosis for feline hyperthyroidism?
depends on severity of concurrent disease
good if curative treatment in uncomplicated patients
how are feline hyperthyroidism and CKD related?
hyperthyroidism can mask underlying CKD so treating can reveal it
how is risk of CKD managed in feline hyperthyroidism?
medical management before curative treatment to assess
what usually causes feline iatrogenic hypoparathyroidism?
bilateral thyroidectomy
list clinical signs of feline iatrogenic hypoparathyroidism
inappetence weakness tremors pawing face seizures coma death
how is feline iatrogenic hypoparathyroidism treated?
IV 10% calcium gluconate
monitoring for arrhythmia and bradycardia
oral therapy
what are common types of canine thyroid neoplasia?
carcinoma
adenoma
locally invasive with possible metastasis
list clinical signs of canine thyroid neoplasia
old
mass in ventral neck
cough
dyspnoea
how is canine thyroid neoplasia diagnosed?
FNA and histopathology of mass
how is canine thyroid neoplasia treated?
surgical removal
chemo
radiation
high dose radioactive iodine
what is prognosis for canine thyroid neoplasia?
poor if large invasive masses
good if surgical removal of small carcinoma
what do thyroid glands produce?
thyroxine/T4 and triiodothyronine/T3 from tyrosine AA by action of thyroid peroxidase oxidating iodine
describe the structure of thyroid glands
vascular bilobed structures lateral to proximal tracheal rings
what do thyroid hormones effect?
metabolic processes
enzymes
tissues
how is T4 found in the body?
protein bound in circulation
biologically active unbound in circulation is fT4
what is the function of T4?
negative feedback on TSH production
how is T3 formed?
in thyroid cell fT4 is deiodoinated to form T3
what controls production of thyroid hormones?
hypothalamus pituitary thyroid axis
TRH in hypothalamus stimulates TSH in pituitary which stimulates T4 and T3 production
T4 and T3 are inhibitory for TRH and TSH
state causes of primary hypothyroidism in dogs
lymphocytic thyroiditis
thyroid atrophy
what is lymphocytic thyroiditis?
destructive immune mediated process where lymphocytes, macrophages, plasma and fibrous tissue infiltrate
what is thyroid atrophy?
degeneration and progressive replacement by adipose and connective tissue
what are causes of secondary canine hypothyroidism?
pituitary hypoplasia
suppression of TSH secretion by glucocorticoids or hyperadrenocorticism
what is signalment for canine hypothyroidism?
middle aged
breed dispositions to lymphocytic thyroiditis including setter, retriever, ridgeback, cocker, boxer
list signs of canine hypothyroidism
decreased metabolic rate endocrine alopecia facial oedema persistent anoestrus bradycardia NMD myxoedema coma ocular issues SIBO low intestinal peristalsis
how is canine hypothyroidism diagnosed?
history clinical sign s mild anaemia hypercholesterolaemia hypertriglyceridemia low T4 high TSH anti-thyroglobulin antibodies
how is canine hypothyroidism treated?
synthetic T4
prohormone for T3
sodium levothyroxine
how are dogs with hypothyroidism monitored?
6-8 weeks after treatment 2-4 weeks after changing doses TT4 measured after 6 hours after admin monitor fT4 if chronic prednisolone admin monitor cTSH
list complications of canine hypothyroidism treatment
thyrotoxicosis
myxoedema coma
what are signs of thyrotoxicosis?
panting anxiety PUPD weight loss polyphagia
what is produced in each area of the adrenal glands?
zona glomerulosa- mineralocorticoids
zona fasciculata and reticularis- glucocorticoids and sex hormones
adrenal medulla- catecholamines
describe the physiology of aldosterone
mineralocorticoid
main site of action is late distal and collecting tubules
what is the action of aldesterone?
reabsorption of NaCl and water
secretion of K+ and H+
how is aldosterone production stimulated?
hyperkalaemia
increased angiotensin II
what causes primary hypoadrenocorticism?
lack of MC and GC
suspected immune mediated destruction of adrenal cortex
what are main causes of secondary hypoadrenocorticism?
neoplasia inflammation infection iatrogenic cause lack of GC only
list clinical features of canine hypoadrenocorticism
young female breeds including poodle and great dane history lack of cortisol and aldosterone weakness vomiting anorexia diarrhoea PUPD low Na addisonian crisis
what are signs of addisonian crisis?
collapse severe dehydration hypovolaemia pre-renal azotaemia cardiac arrhythmia hyperkalaemia bradycardia
how is canine hypoadrenocorticism diagnosed?
history clinical signs non-regenerative anaemia absent stress leukogram low neutrophils high lymphocytes and eosinophils hyperkalaemia and calcaemia pre-renal azotaemia hypoglycaemia and natraemia high liver enzymes low albumin and cholesterol
how is canine hypoadrenocorticism diagnosis ruled out?
basal cortisol over 55nmol/l
how is canine hypoadrenocorticism diagnosis confirmed?
ACTH stimulation test
if has disease pre and post ACTH cortisol concentrations are below 20nmol/l
cortisol is given and ACTH measured before and 1 hour after
how is Addisonian crisis treated?
IVFT
hydrocortisone or dexamethasone
slow correction of hyponatraemia
treat hypoglycaemia and hyperkalaemia
what is long term management for canine hypoadrenocorticism?
GC usually prednisolone
MC desoxycortone privalate
fludrocortisone but cant manage MC and GC separately
what is prognosis for canine hypoadrenocorticism?
good if managed but long term medication needed
more GC needed in stress
how does canine hyperadrenocorticism happen?
excess production of cortisol
what are causes of canine hyperadrenocorticism?
pituitary tumour causing excess ACTH production and loss of negative feedback
adrenal tumour causing excess cortisol so suppression of ACTH production
iatrogenic
list clinical signs of canine hyperadrenocorticism
abdominal distension hepatomegaly lethargy panting alopecia polydipsia polyphagia
state complications of canine hyperadrenocorticism
DM from insulin resistance progression of major signs pulmonary thromboembolism neuro signs pancreatitis secondary infection hypertension
how is canine hyperadrenocorticism diagnosed?
mild erythrocytosis and thrombosis high neutrophils and monocytes low eosinophils and lymphocytes increased liver enzymes lipolysis hyperglycaemia increased bile acids USG lower than 1.015 urolithiasis ACTH stimulation test LDDST urine cortisol to creatinine ratio
define specificity
probability of negative result if not affected
define sensitivity
probability of positive result if affected
how is LDDST carried out?
collect serum for basal cortisol
inject dexamethasone IV
collect samples 4 and 8 hours later
what are negatives of treating canine hyperadrenocorticism?
expensive
may unmask other disease
can cause pituitary lesions to expand causing CNS signs
how is pituitary and adrenal dependent hyperadrenocorticism differentitated?
LDDST HDDST imaging PDH- symmetrical adrenal glands AT- asymmetrical adrenal glands
how is PD canine hyperadrenocorticism treated?
trilostane
hypophysectomy
bilateral adrenalectomy
radiation
how is AD canine hyperadrenocorticism treated?
adrenalectomy
trilostane
what is prognosis for canine hyperadrenocorticism?
depends on age and health
usually survive less than few years after diagnosis
list signs of feline hypoadrenocorticism
cachexia
fragile skin syndrome
alopecia
how is feline hypoadrenocorticism diagnosed?
HDDST
ACTH stimulation test
what is treatment for feline hypoadrenocorticism?
adrenalectomy
some success with hypophysectomy, trilostane
poor prognosis
what is aetiology for canine DM?
destruction of pancreatic beta cells due to genetics, immune mediated, pancreatitis, idiopathic
beta cell exhaustion due to obesity, diet, drugs
what type of diabetes is canine DM?
insulin dependent
state signalment for canine DM
middle aged to old
females
breeds such as schnauzer and bichon
what are signs of canine DM?
PUPD glucosuria polyphagia weight loss cataracts diabetic ketoacidosis
what are signs of ketacidosis?
vomiting
collapse
dehydration
how is canine DM diagnosed?
glycosuria
hyperglycaemia
fructosamine to show average glycaemia for previous 2-3 weeks
what are ways to manage canine DM?
insulin
spaying females
diet
what are commonly used insulin to treat canine DM?
lenate for immediate length action, caninsulin
PZI for long action
how should insulin be cared for?
store in fridge
replace bottle every 4 weeks
mix before use
why should intact females with canine DM be spayed?
progesterone causes insulin resistance
what should be components of diets to manage canine DM?
non simple sugar to limit hyperglycaemia post feeding
calories from complex carbs and protein
high fibre
consistent feeding in line with insulin
how are canine DM patients initially stabilised?
takes weeks to months
low dose insulin 2x daily
first day of inulin in practice monitoring BG to avoid hypoglycaemia
what are the ways of monitoring BG?
spot monitoring
continuous glucose monitoring
how does urinalysis help monitor canine DM patients?
usually mild glucosuria before insulin
no glucosuria for 24 hours may suggest insulin overdose
ketones may indicate poor control
what are short term complications of insulin therapy?
hypoglycaemia
somogyi overswing
short or prolonged duration of action
inadequate action
what BG is considered hypoglycaemic?
less than 3mmol/l
define somogyi overdose
rebound hyperglycaemia caused by physiologic response to hypoglycaemia
BG over 3.6mmol/l
what are long term complications of insulin therapy?
hypoglycaemia cateracts diabetic neuropathy hypertension diabetic ketoacidosis
what is prognosis for canine DM?
good when well managed
survival average 3-5 years after diagnosis
state aetiology for feline DM
old age obesity male indoors burmese maine coon
what type of diabetes is feline DM?
non-insulin dependent
what causes feline DM?
insulin resistance
reduced insulin secretion from beta cell damage, chronic high glucose and FAs
what are causes of insulin resistance?
obesity genetics pancreatitis UTIs CKD dental disease enteropathy hyperthyroidism hypercortisolism
what is meant by feline pre-DM?
BG consistently over 6.5mmol/l
what is sub-clinical feline DM?
BG between 10 and 16mmol/l
how can you manage sub-clinical feline DM to help prevent progression to overt DM?
low carb diet
weight loss
what is overt DM in cats?
BG over 16 mmol/l
high fructosamine
glycosuria
list clinical signs of feline DM
PUPD weight loss polyphagia DKA peripheral neuropathy cataracts
how is feline DM diagnosed?
hyperglycaemia
glycosuria
fructosamine
history and clinical signs
how is feline DM treated?
insulin
diet
exercise
consistency and commitment of owner
what insulin are used for treating feline DM?
prozinc
caninsulin
glargine insulin
how can oral hypoglycaemic drugs help treat feline DM?
increases insulin secretion
used alongside diet
how does diet help manage feline DM?
weight loss
reduce or prevent need for insulin dose
what are components of diets to manage feline DM?
wet
high protein
low carbs
what happens during DKA?
increased production of glucoregulatory hormones
lack of insulin allows unopposed glucogenic effects of stress hormones in liver, muscle and adipose
excess FFA breakdown
excess ketone formation
list clinical signs of DKA?
PUPD PP weight loss lethargy anorexia strong odour of acetone on breath dehydration hypovolaemia
how is DKA managed?
restore water and electrolytes insulin to turn off ketone production correct acidosis identify underlying disease analgesia feeding support monitoring
what is prognosis for DKA?
hard to treat
often have underlying disease
can become healthy diabetics or enter remission
25% dont survive
what are diseases associated with DKA?
heart failure
sepsis
pancreatitis
what is believed to cause PPID?
decrease in production of dopamine due to decreased inhibition, pituitary adenoma, overproduction of hormones
list clinical signs of PPID?
long curly coat laminitis PUPD weight loss neurological impairment altered fat distribution infertility skin disease periodontal disease
how is PPID diagnosed?
clinical signs
post mortem
ACTH test
TRH stimulation test
what is the response to positive tests for PPID?
treat but re test in 4-6 weeks for dose
retest annually as disease progresses
what should you do if negative test for PPID?
if clinically indicated start treatment and recheck
how is PPID managed?
farriery clipping parasite control dental care dopamine agonist
what are the effects of EMS?
obesity
insulin resistance or dysregulation
laminitis
what horses is PPID seen in?
older horses mainly over 15s
what is compensated insulin dysregulation?
high insulin
normal glucose
what is uncompensated insulin dysregulation?
high insulin and glucose
glucosuria
type 2 diabetes
how do genetics affect insulin dysregulation in horses?
hardy breeds genetically predisposed
poor diet so ID facilitating breakdown of glucose and fat and stimulating hepatic gluconeogenesis keeps glucose supply to vital tissue
how are obesity and insulin resistance related in wild horses?
plenty of food in summer so get fat and IR
loose weight over summer so restore insulin sensitivity by spring
why are horses not subject to the same insulin resistance phases as wild horses?
dont have seasonal weight loss
have chronic obesity so stay IR and get laminitis
list clinical signs of EMS
obesity regional adiposity laminitis lipoma hyperlipemia
how is EMS diagnosed?
resting insulin and glucose after overnight starving
IR seen by hyperinsulinemia and normoglycemia
how is EMS managed?
low carb diet no grass multivitamin and mineral supplement exercise considering laminitis weight loss feeding 1/3 less metformin to block SI carb absorption so decreases IR by weight loss
how does hyperlipemia in horses happen?
stress or negative energy balance triggers fatty acid metabolism
triggers catecholamine and GC release
lots of fat moves into circulation
list risk factors for equine hyperlipemia
obesity ponies pregnancy excess FA stores IR
what is the effect of hyperlipemia in horses?
hepatic lipidosis liver failure not enough hormones for fat fat embolism kidney failure pancreatitis
how is hyperlipemia in horses diagnosed?
identify if risk prevention better depression anorexia ataxia icterus
what are aims of treating hyperlipemia in horses?
improve energy intake and balance treat hepatic disease eliminate stress treat concurrent diseases inhibit fat metabolism from adipose increase triglyceride uptake by peripheral tissues
how is hyperlipemia in horses treated?
manage hepatic and underlying disease wean foal tempt to eat supportive nutrition glucose infusion
what is prognosis for hyperlipemia in horses?
60-100% mortality
how can equine hyperlipemia be prevented?
client education
identify risk
glucose infusion and insulin
