Lecture 13: Approach to Endocrine Disease Flashcards
1
Q
Why can diagnosing endocrine diseases be challenging (especially Cushing)
A
seasonal changes in hormones affect test interpretation
2
Q
where does PPID affect in body
A
pars intermedia
3
Q
PPID is the result of loss of __of the pars intermedia a
A
dopaminergic inhibition
4
Q
how does dopamingeric inhibition work in healthy horse pars intermedia
A
dopaminergic neurons inhibit the pars intermedia and therefore limit release of ACTH and related peptides
5
Q
Describe what happens when you lose dopaminergic inhibition in PPID and what causes it
A
pars intermedia hyperplasia/adenoma—> loss of dopaminergic inhibition -> increased release of aCTH and related peptides
6
Q
what products are released from pars intermedia
A
POMC—> ACTH and B-endorphin
ACTH—> a-MSH and CLIP
7
Q
what cleaves ACTH to a-MSH and CLIP in normal horses
A
prohormone convertase 2 (PC2)
8
Q
is PPID a condition of older or younger horses
A
older
9
Q
what are some clinical signs of PPID
A
- Hirsutism
- Muscle wasting/weight los
- PU/PD
- Hyperhydrosis
- Immunosupression
- Behavior changes
- Infertility
- Blindness
- Regional adiposity and insulin resistance
- Inappropriate lactation
10
Q
what early/subtle clinical findings is highly suggestive of PPID
A
regional hypertrichosis/delayed shedding
11
Q
what is an advanced sign strongly suggestive of PPID
A
generalized hyerptrichosis
12
Q
what is the protocol for testing for PPID with few, mild or early clinical signs in younger horse
A
- TRH stimulation test and assess insulin status
- Results in interpretative zone of PPID unlikely zone—> recheck 3-6 months
- Results supportive of PPID—> start pergolide
13
Q
What is protocol for testing for PPID when there are many, severe, more advanced clinical signs, older horse
A
- Baseline ACTH test and assess insulin status
- Results unlikely zone—> TRH stimulation test—> if supportive of PPID start pergolide or if unlikely zone recheck in 3-6 months
14
Q
what test is recommended for early PPID
A
TRH stimulation test with ACTH measured
15
Q
what test is recommended for advanced PPID
A
basal ACTH concentration
16
Q
a Dexamethasone suppression test can be used to dx PPID, but why is it risky
A
increase risk of laminitis
17
Q
what tests are not appropriate to dx PPID
A
- ACTH stim test
- Baseline cortisol
- Diurnal cortisol rhythm
- TRH stim with cortisol measured
18
Q
what is procedure for doing baseline ACTH test
A
- Collect in EDTA (purple top) tube
- Keep on ice
- Centrifuge
19
Q
what is procedure for TRH stimulation test
A
- Keep horses off grain
- Give TRH IV
- Collect in EDTA (purple top) tube at 0 minutes and 1-0 minutes
20
Q
currently there is no normal TRH stimulation result between what months, but a __ test is likely valid
A
july and December, negative
21
Q
what is MOA of pergolide/prascend
A
dopamine receptor agonist- restores inhibition of melanotropes
22
Q
do not exceed what dose of pergolide
A
0.01mg/kg
23
Q
t or f: pergolide cures PPID
A
false- manages disease
24
Q
what other drug can be added as adjunct to pergolide to tx PPID and what is MOA
A
cyproheptadine- serotonin antagonist, antihistamine activity, anticholinergic
25
what comorbidities do you want to test for in PPID patient
1. BCS
2. FEC
3. Baseline lateral films- laminitis
4. Baseline bloodwork
26
what lab findings besides increase ACTH are often found in PPID patients
lymphopenia/neutrophilia, hyperglycemia, hyperinsulinemia, hypertriglyceridemia, hypophosphatemia, high fecal egg count
27
what are the most characterizing clinical signs of equine metabolic syndrome
1. general or regional adiposity
2. Insulin resistance- hyperinsulinemia
3. Predisposed to laminitis
28
based on the appearance of this horse- what endocrine disease is more likely- PPID or EMS
EMS- crust neck, fat pads
Normal hair coat so unlikely PPID
29
what horses have genetic predisposition to EMS
Pony breeds, andalusians, Morgans, minis, warm bloods
30
what is the algorithm to diagnose EMS
1. Test for insulin dysregulation and PPID
2. Negative- manage obesity or PPID
3. Positive and obese ID—> limit calories, low carb diet—> normalize insulin recheck 6 months, but if remains ID—> pharmacological intervention
4. Positive and non-obese ID—> maintain body condition- lower carb, high fat diet—> normalize ID check q6 months or remains ID—> pharmacological intervention
31
what tests can be done to dx EMS
1. Resting insulin concentrations
2. Dynamic insulin testing
3. Leptin
4. Triglycerides
32
when doing resting insulin concentrations for EMS horses can’t have grain within __hrs
4hrs
33
what resting insulin concentration is diagnostic
>50uU/L
34
how do you do dynamic insulin testing for EMS
oral sugar test with corn syrup, measure insulin and glucose, >45uU/L diagnostic
35
leptin is produced by __ cells
adipose cells
36
T or f: high leptin alone can indicate insulin resistance
false
37
PPID or EMS: normal leptin and insulin resistance
PPID
38
PPID or EMS: high leptin and insulin resistance
EMS
39
t or f: thyro-L is an appropriate tx for EMS
false- can be appropriate if unable to exercise b/c of laminitis
40
what is first line treatment for EMS
dietary modification and exercise
41
Case ex: 19yr Tennessee Walking Horse, mare. Walking on eggshells T=100.9, P=48, R-16, BCS: 4/9. What is gait indicative of
laminitis
42
what dietary modifications should be made in EMS or PPID to address insulin resistance
reduce starch, grass hay
43
what is anhydrosis
lose ability to sweat
44
what are some possible causes of anhidrosis
1. Down regulation of B2 adrenergic receptors
2. Decreased stimulation of receptors
3. Aquaporin-5 water channel dysregulation
45
what are the equine sweat glands and what are each important for
1. Humoral- B2 adrenergic secreted from adrenal medulla, more important in exercise
2. Nervous- autonomic adrenergic nerves, most consistently important
46
how can you test anhidrosis
terbutaline test
47
did a terbutaline test on 3 horses for anhidrosis- what horse is normal, partial sweater and and anhidrotic horse
1. Normal
2. Partial sweater
3. Anhidrotic horse
48
how do you manage anhidrosis
1. Move horse to drier climate
2. Diet/electrolytes (potassium)
3. A/C supplement (L-tyrosine, ascorbic acid, niacin, cobalt)
49
how does L-tyrosine work to manage anhidrosis
precursor of dopamine/catecholamines may help desensitize B-2 receptors
50
what triggers hyperlipidemia/hyperlipemia
negative energy balance—>fat stores mobilized
51
what is triglyceride range for hyperlipidemia
54-500mg/dl
52
what is triglyceride range for hyperlipemia
triglycerides >500mg/dl
53
what breeds are predisposed to hyperlipidemia/hyperlipemia
minis, pony breeds, donkeys
54
hyperlipidemia/hyperlipemia is a condition characterized by atypical __
VLDLs
55
horses with hyperlipidemia/ hyperlipemia have a apolipoprotein __ instead of __
apoB-48, apoB-100
56
what is a major consequence of hyperlipidemia/ hyperlipemia
hepatic lipidosis
57
how can you prevent hyperlipidemia/ hyperlipemia
monitor triglycerides in high risk patients, appropriate nutrition
58
what is tx for hyperlipidemia/ hyperlipemia
1. Enteral feeding with NG tube, small frequent feedings, IV dextrose
2. Parenteral nutrition- dextrose and amino acids
3. Monitor glucose frequently
59
do not use __ in parenteral nutrition formula
lipid fraction
60
pheochromocytoma is neoplasia of __
adrenal gland
61
how do horses with pheochromocytoma typically present
hemoabdomen
62
what are some signs of pheochromocytoma
1. Increased catecholamines
2. Tachycardia
3. Weight loss
63
how do you dx pheochromocytoma
Urinary catecholamines
64
Inappropriate lactation is most often secondary to __
PPID
65
__ in forage can cause inappropriate lactation
phytoestrogens
66
how do you tx inappropriate lactation
1. Pergolide
2. Dietary modification- grass hay, no grain
67
what are some differentials for increase Ca2+ in horses
1. Chronic renal failure
2. Neoplasia- lymphoma—> increase PTHrP
3. Vitamin D toxicity
4. Primary hyperparathyroidism
68
how do you know if increase ca2+ is related to chronic renal failure
Issues with creatinine
69
if you have increase Ca2+ in horse and thickened colon wall on ultrasound what is presumptive dx
lymphoma
70
what are some differentials for decreased Ca2+
1. Blister beetle toxicosis
2. Exercise induced exhaustion
3. Sepsis
4. Lactation
5. Acute renal failure
6. Primary hypoparathyroidism
71
what other sign besides decreased Ca2+ in blister beetle toxicosis is supportive
urine positive for cantharidin
72
what other bloodwork sign besides decreased Ca2+ supports acute renal failure
Mg2+ low
73
if you have a horses with recent history of weight loss. What questions do you need to ask
1. Is horse eating and losing weight vs loss of appetite
2. Determine muscle wasting vs weight loss vs both
74
Case: 18yr old horse presents with recent hx of weight loss, bloodwork shows hypercalcemia- what is likely dx
neoplasia- increase PTHrp
75
case ex: 6yr Arabian competed in 50 mile endurance race in Oklahoma yesterday. Colicky signs early this morning. Bloodwork shows hypocalcemia- what is likely dx
canthardin- blister beetle toxicosis
76
if you have a male jack donkey breed with female mare what offspring do you get
mule
77
if you bred a stallion horse with Jenny donkey what do you get
hinny
78
what is normal TPR for donkeys
T= 98.8 (97.2-100.0)
P= 44 (36-68)
R 12-20; 13-31
79
t or f: donkeys are more prone to obesity than horses
true
80
t or f: crest fat may be insignificant
true
81
In Obese donkeys what do you need to be cautious about with IM vaccines/drugs
avoid IF injections
82
describe the hoof anatomy of donkeys/mules
“U” shaped foot, more upright wall, thicker sole and walls, P3 not aligned with dorsal wall
83
t or f: elevate heel in laminitis donkeys
false
84
what is a significant hematology finding in donkeys/mules vs horses
signifiant dehydration (12-15%) may occur before PCV increases
85
what is the serum color in donkeys/mules compared to horses
lighter than horses (horses more icteric)
86
t or f: creatinine, total bilirubin higher in donkeys/mules
false- lower
87
t or f: creatinine kinase, GGT, and alkaline phosphate higher in donkeys
true
88
T or f: insulin is lower in donkeys/mules and ACTH is higher
true
89
what dx should be on your differential list with any sick donkey
hyperlipemia
90
what can cause hyperlipemia
decrease feed intake for any reason, increase feed requirement
91
sick donkey presents- pull blood and this is what serum looks like- what is wrong
Hyperlipemia
92
what is triglyceride value for hyperlipemia in donkeys. What normal
>500mg/dl (normal <200mg/dl)
93
what is prognosis for hypothermia in donkeys
poor prognosis, 80% mortality
94
what Is potentially involved in hypothermia in donkeys
thyroid
95
what are common locations for colic in donkeys
pelvic flexure, cecum
96
parasitism in donkeys can result in ___
rectal prolapse
97
how does excretion of flunixin meglumine, phenylbutazone, and trimethoprim sulfamethoxazole differ in donkeys vs horses/mules
cleared much faster
98
donkeys and mules require __dose of alpha 2 agonists
higher
99
t or f: donkeys are more sensitive to guiafenesin
true
100
t or f: ketamine is cleared more slowly in donkeys
false
101
what is answer and what is likely cause of 2/6 heart murmur in this horse
C. Endogenous ACTH and FEC
2/6 HM- aortic regurgitation
102
what answer
C. Serum triglycerides
