121. Thyroid and Parathyroid Glands question Flashcards
(192 cards)
1
Q
Which artery primarily supplies the cranial portion of the thyroid gland in dogs?
A
b) Cranial thyroid artery
2
Q
The external parathyroid gland is usually located at which anatomical site relative to the thyroid gland?
A
b) Dorsolateral margin
3
Q
What percentage of cats with hyperthyroidism have bilateral thyroid gland involvement?
A
c) 70-90%
4
Q
Which of the following is the most common cause of hyperthyroidism in cats?
A
b) Multinodular adenomatous hyperplasia
5
Q
What is the first-line medical treatment for hyperthyroidism in cats?
A
b) Methimazole
6
Q
In which breed is primary hyperparathyroidism most commonly seen?
A
c) Keeshond
7
Q
What is the preferred treatment for canine thyroid carcinoma if the mass is freely movable?
A
b) Surgery
8
Q
What is the most serious complication associated with bilateral thyroidectomy in cats?
A
b) Hypocalcemia
9
Q
The primary effect of parathyroid hormone (PTH) is to:
A
b) Increase calcium levels
10
Q
Which imaging modality is commonly used to confirm the diagnosis of hyperthyroidism in cats?
A
c) Scintigraphy with technetium-99m
11
Q
True or False: The majority of thyroid tumors in dogs are benign adenomas.
A
FALSE
12
Q
True or False: In cats, the caudal thyroid artery is often absent.
A
TRUE
13
Q
True or False: The cranial thyroid artery is the first major branch of the common carotid artery in dogs.
A
TRUE
14
Q
True or False: Calcitonin primarily functions to increase blood calcium levels.
A
FALSE
15
Q
True or False: Thyroid hormone (T4) has a longer half-life than triiodothyronine (T3).
A
TRUE
16
Q
True or False: Ectopic thyroid tissue is more commonly found in dogs than in cats.
A
FALSE
17
Q
True or False: Parathyroid autotransplantation may be necessary if the external parathyroid gland is inadvertently removed during surgery.
A
TRUE
18
Q
True or False: Hyperthyroid cats frequently present with hypertension.
A
FALSE
19
Q
True or False: Scintigraphy is not effective in distinguishing between benign and malignant thyroid masses in cats.
A
TRUE
20
Q
True or False: Hypothyroidism is commonly seen after thyroidectomy in dogs.
A
FALSE
21
Q
Describe the anatomical location of the thyroid glands in cats.
A
The thyroid glands in cats are located along the trachea, typically spanning the third to eighth tracheal rings, with a tan, flat appearance.
22
Q
What is the function of calcitonin, and where is it produced?
A
Calcitonin is produced by parafollicular (C-cells) of the thyroid gland and functions to decrease blood calcium levels by inhibiting bone resorption.
23
Q
What is the primary cause of hyperthyroidism in cats?
A
The primary cause is benign multinodular adenomatous hyperplasia or adenoma of the thyroid gland.
24
Q
List two potential complications of thyroidectomy in cats.
A
Hypocalcemia and laryngeal paralysis.
25
Explain why methimazole is used in the preoperative management of hyperthyroid cats.
Methimazole is used to achieve a euthyroid state, reducing metabolic stress on the body and minimizing surgical risks.
26
How does parathyroid hormone (PTH) affect the kidneys?
PTH increases renal calcium reabsorption and decreases phosphate reabsorption.
27
Why is thyroid scintigraphy performed before thyroid surgery?
To confirm the diagnosis of hyperthyroidism and to localize hyperactive thyroid tissue.
28
What is the main risk of performing bilateral carotid artery ligation during thyroid tumor removal in dogs?
It can lead to severe hypertension and tachycardia due to loss of baroreceptor function.
29
What dietary management option is available for cats with hyperthyroidism?
Feeding a low-iodine diet (e.g., Hill’s y/d) to reduce thyroid hormone production.
30
What are the indications for radioactive iodine therapy in cats with hyperthyroidism?
Radioactive iodine therapy is used to treat hyperthyroidism, particularly in cases with ectopic tissue or when surgery is contraindicated.
31
Explain the surgical approach to accessing the thyroid glands in dogs.
A ventral midline cervical approach is made from the larynx to the manubrium, separating the sternohyoideus muscles.
32
List three clinical signs commonly seen in dogs with thyroid carcinoma.
Coughing, dyspnea, and dysphagia.
33
What is the function of parathyroid hormone (PTH)?
b) Increase calcium levels
34
Which of the following is a major complication of parathyroidectomy in dogs?
a) Hypocalcemia
35
What is the most common clinical sign of primary hyperparathyroidism in dogs?
c) Urinary tract infections
36
Which imaging technique is most useful in detecting parathyroid adenomas?
b) Ultrasound
37
What is the preferred treatment for primary hyperparathyroidism in dogs?
c) Surgery
38
True or False: Bilateral thyroidectomy always results in permanent hypothyroidism in cats.
FALSE
39
What is the primary reason for using methimazole in cats prior to thyroid surgery?
c) Induce a euthyroid state
40
Which hormone is primarily responsible for increasing calcium absorption in the intestines?
b) Parathyroid hormone
41
List two clinical signs of hypocalcemia in cats following thyroidectomy.
Facial twitching and tetany.
42
What is the role of calcitriol in managing hypocalcemia?
Calcitriol increases calcium absorption in the intestines and decreases renal excretion of calcium.
43
What is the primary concern when treating hyperthyroid cats with methimazole long-term?
Potential side effects such as gastrointestinal upset, liver toxicity, and blood dyscrasias.
44
Which condition can be masked in cats by hyperthyroidism, making diagnosis difficult?
Chronic kidney disease.
45
What is the advantage of using radioactive iodine therapy in hyperthyroid cats?
It provides a permanent solution by selectively destroying hyperactive thyroid tissue.
46
Name one diagnostic test used to differentiate between hyperthyroidism and chronic renal disease in cats.
Serum total T4 concentration measurement.
47
Describe the impact of thyroid hormone excess on the cardiovascular system in cats.
Thyroid hormone excess leads to tachycardia, murmurs, and can cause hypertrophic cardiomyopathy.
48
Why might a beta-blocker be used in hyperthyroid cats preoperatively?
To control tachycardia and reduce cardiac workload.
49
How does thyroid hormone influence metabolism in the body?
It increases the basal metabolic rate and affects nearly every organ system.
50
Which diagnostic test is considered the gold standard for diagnosing hyperthyroidism in cats?
Serum total T4 concentration measurement.
51
What are the common metastatic sites for thyroid carcinoma in dogs?
Lungs and regional lymph nodes.
52
Explain the importance of the recurrent laryngeal nerve during thyroidectomy.
Damage to this nerve can result in laryngeal paralysis, affecting breathing and voice.
53
What is the role of the cranial thyroid artery in thyroid surgery?
It provides the main blood supply to the cranial portion of the thyroid gland.
54
Name one imaging modality used to detect ectopic thyroid tissue.
Scintigraphy.
55
What is the significance of finding ectopic parathyroid tissue in a cat during surgery?
It can affect calcium regulation and may require additional surgical management.
56
Describe the process of parathyroid autotransplantation.
The parathyroid gland is transplanted into nearby muscle tissue to restore function if blood supply is compromised.
57
What are the two main hormones secreted by the thyroid gland?
Thyroxine (T4) and triiodothyronine (T3).
58
Why is calcium gluconate used in managing acute hypocalcemia?
It quickly increases serum calcium levels to alleviate symptoms of hypocalcemia.
59
Which breed of dog is genetically predisposed to primary hyperparathyroidism?
Keeshond.
60
True or False: Hyperthyroidism in dogs is usually associated with benign thyroid tumors.
FALSE
61
How does dietary iodine restriction help manage hyperthyroidism in cats?
It limits iodine availability, reducing thyroid hormone synthesis.
62
What is a potential risk of thyroidectomy in dogs with large, invasive tumors?
Severe hemorrhage due to high vascularization of the tumor.
63
List two non-surgical management options for hyperthyroidism in cats.
Methimazole therapy and iodine-restricted diet.
64
Which surgical technique is associated with the highest risk of hypocalcemia in cats after thyroidectomy?
b) Extracapsular
65
What is the major mechanism by which T3 affects cellular metabolism?
c) Enhancement of gene transcription
66
What percentage of dogs with thyroid carcinomas develop metastasis during the course of the disease?
d) 80%
67
In dogs, what is the most common clinical sign of a functional thyroid carcinoma?
b) Weight loss
68
What diagnostic test is used to differentiate between thyroid and non-thyroid cervical masses in dogs?
a) Fine needle aspirate cytology
69
Which hormone is responsible for the negative feedback regulation of thyroid-stimulating hormone (TSH) secretion?
b) Thyroxine
70
Which of the following is the least likely site for metastasis of canine thyroid carcinoma?
d) Spleen
71
In cats, what is a common side effect of long-term methimazole therapy?
b) Thrombocytopenia
72
What is the typical histopathological feature of feline hyperthyroid adenomas?
b) Adenomatous hyperplasia
73
Which procedure is recommended for cats with suspected ectopic thyroid tissue after unsuccessful thyroidectomy?
c) Radioactive iodine therapy
74
True or False: Laryngeal paralysis is a potential complication of thyroidectomy in dogs.
TRUE
75
True or False: Dogs with non-functional thyroid tumors often present with symptoms of hyperthyroidism.
FALSE
76
True or False: Thyroid carcinoma is more common in cats than in dogs.
FALSE
77
True or False: Thyroid scintigraphy can identify both ectopic thyroid tissue and thyroid carcinomas.
TRUE
78
True or False: Hyperparathyroidism can lead to fibrous osteodystrophy in dogs.
TRUE
79
What clinical condition is commonly associated with primary hyperparathyroidism in dogs?
c) Hypercalcemia
80
How is hypocalcemia managed in cats after bilateral thyroidectomy?
b) Intravenous calcium gluconate
81
What diagnostic test is most useful for confirming hyperparathyroidism?
b) Ionized calcium levels
82
What is the primary reason for performing a modified extracapsular thyroidectomy in cats?
c) To preserve parathyroid function
83
Which condition may develop in cats after treatment of hyperthyroidism if they have underlying renal disease?
b) Azotemia
84
What is the most common cause of hypothyroidism in dogs?
b) Lymphocytic thyroiditis
85
Which medication is used to reduce heart rate in hyperthyroid cats with tachyarrhythmias?
a) Atenolol
86
Describe the primary goal of parathyroid hormone therapy in hypoparathyroid animals.
To increase serum calcium levels and stabilize neuromuscular function.
87
What surgical technique is most commonly used to remove a parathyroid adenoma?
b) En bloc excision
88
How long after parathyroidectomy does parathyroid autotransplantation tissue typically regain function?
b) 7-21 days
89
What is the function of the isthmus glandularis in dogs?
a) Connects the thyroid glands
90
What is the role of iodide in thyroid hormone synthesis?
c) It is a precursor for thyroid hormone
91
What is the function of the isthmus glandularis in dogs?
Connects the thyroid glands
92
What is the role of iodide in thyroid hormone synthesis?
It is a precursor for thyroid hormone
93
In which dog breed are thyroid tumors more commonly reported?
Golden Retriever
94
Which thyroid hormone is primarily secreted by the thyroid gland?
Thyroxine (T4)
95
What is the most common side effect of radioactive iodine therapy in hyperthyroid cats?
Hypothyroidism
96
What is a common clinical sign of hypocalcemia in cats post-thyroidectomy?
Seizures
97
Which structure is most likely to be damaged during thyroidectomy, leading to vocal changes in dogs?
Recurrent laryngeal nerve
98
What is the first-line treatment for hypercalcemia in dogs with primary hyperparathyroidism?
Parathyroidectomy
99
True or False: Feline hyperthyroidism is often associated with weight gain.
FALSE
100
True or False: Thyroid carcinoma in dogs is frequently non-functional.
TRUE
101
What is the primary action of calcitriol in calcium homeostasis?
Increase intestinal absorption of calcium
102
What is the effect of parathyroid hormone (PTH) on phosphorus levels in blood?
Decreases phosphorus
103
What is the mechanism of action of methimazole in cats?
Inhibits thyroid peroxidase enzyme
104
Which imaging modality is best for localizing parathyroid adenomas in dogs?
Ultrasound
105
What is the most common complication associated with bilateral thyroidectomy in dogs?
Hypothyroidism
106
Why is scintigraphy preferred for evaluating thyroid function in cats?
It measures iodine uptake
107
What is the most likely cause of increased serum ionized calcium levels in a dog?
Hyperparathyroidism
108
What is the main clinical concern when using radioactive iodine treatment in cats with hyperthyroidism?
Development of hypothyroidism
109
True or False: Ectopic thyroid tissue can be found along the aorta in cats.
TRUE
110
What is a common presenting sign in dogs with thyroid carcinoma?
Coughing
111
How is parathyroid hormone (PTH) secretion regulated?
By serum calcium levels
112
What is the function of the cranial thyroid artery?
Supplies blood to the cranial pole of the thyroid gland
113
What is the typical cause of hyperthyroidism in older cats?
Multinodular adenomatous hyperplasia
114
Which hormone regulates the secretion of thyroid-stimulating hormone (TSH)?
Thyroxine (T4)
115
True or False: Hyperthyroidism in dogs is commonly treated with dietary iodine restriction.
FALSE
116
What is the most common indication for performing a thyroidectomy in cats?
Hyperthyroidism
117
Which thyroid hormone is more biologically active?
Triiodothyronine (T3)
118
What is the primary action of thyroid-stimulating hormone (TSH)?
Stimulate thyroid hormone release
119
What is the role of the carotid sheath in thyroid surgery?
Contains the common carotid artery, jugular vein, and vagosympathetic trunk
120
Which of the following hormones is involved in calcium homeostasis?
Calcitonin
121
What is the most common type of thyroid neoplasm in dogs?
Adenocarcinoma
122
True or False: Cats with hyperthyroidism may present with increased appetite and weight loss.
TRUE
123
True or False: Parathyroid hormone decreases calcium reabsorption in the kidneys.
FALSE
124
What is the main purpose of using beta-blockers in hyperthyroid cats?
Reduce heart rate
125
Which imaging technique is most useful for detecting thyroid carcinoma metastasis in dogs?
CT scan
126
What is the significance of measuring free T4 levels in cats with suspected hyperthyroidism?
It helps confirm borderline cases
127
What is the effect of hyperthyroidism on blood pressure in cats?
Increases blood pressure
128
True or False: Thyroid carcinoma in dogs is usually non-functional.
TRUE
129
Which artery supplies the caudal portion of the thyroid gland in dogs?
Caudal thyroid artery
130
What is the primary cause of hypothyroidism in cats?
Thyroidectomy
131
Which of the following conditions can be masked by hyperthyroidism in cats?
Renal disease
132
What is the role of the cranial laryngeal nerve in thyroid surgery?
Controls the vocal cords
133
How does parathyroid hormone (PTH) affect bone?
Stimulates bone resorption
134
True or False: Methimazole therapy in cats can cause liver toxicity as a side effect.
TRUE
135
What is the first clinical sign of hypocalcemia in dogs post-parathyroidectomy?
Tremors
136
Which condition is associated with excessive production of parathyroid hormone?
Hyperparathyroidism
137
What is the purpose of using scintigraphy in hyperthyroid cats?
Localize active thyroid tissue
138
True or False: Dogs with thyroid adenomas usually require lifelong thyroid hormone supplementation.
FALSE
139
What is the effect of parathyroid hormone on renal phosphorus excretion?
Increases excretion
140
Which nerve is at risk of damage during thyroidectomy, potentially leading to Horner's syndrome?
Sympathetic trunk
141
What is the typical treatment for a canine thyroid tumor that is freely movable?
Surgical excision
142
Which enzyme is inhibited by methimazole in hyperthyroid cats?
Thyroid peroxidase
143
True or False: Hyperthyroidism in cats can lead to hypertrophic cardiomyopathy.
TRUE
144
Which hormone is primarily responsible for increasing blood calcium levels?
Parathyroid hormone
145
What is the preferred imaging modality to assess the extent of thyroid carcinoma in dogs?
CT scan
146
What is the most common clinical sign in cats with hyperthyroidism?
Weight loss
147
Which structure is at risk during thyroidectomy due to its proximity to the thyroid gland?
Carotid sheath
148
What condition is most commonly associated with increased levels of ionized calcium in dogs?
Hyperparathyroidism
149
Which hormone decreases in response to elevated calcium levels?
Parathyroid hormone
150
True or False: Ectopic thyroid tissue can be functional and cause hyperthyroidism.
TRUE
151
Which artery supplies blood to the external parathyroid glands in dogs?
Cranial thyroid artery
152
What is the function of thyroglobulin within the thyroid gland?
Precursor to thyroid hormones
153
What is the effect of parathyroid hormone on bone?
Stimulates bone resorption
154
Which condition is treated with methimazole in cats?
Hyperthyroidism
155
What is a common side effect of methimazole therapy in cats?
Vomiting
156
Which of the following is a clinical sign of hypocalcemia in dogs?
Seizures
157
What is the primary risk associated with bilateral thyroidectomy in cats?
Hypoparathyroidism
158
What is the function of the thyroid nerve in dogs?
Controls the thyroid hormone release
159
True or False: Thyroid scintigraphy is used to evaluate thyroid gland function in hyperthyroid cats.
TRUE
160
What is the role of calcium gluconate in the treatment of hypocalcemia?
Rapidly raises blood calcium levels
161
Which breed is most commonly associated with primary hyperparathyroidism?
Keeshond
162
What is the effect of calcitriol on calcium levels?
Increases calcium absorption
163
Which clinical sign is commonly associated with thyroid carcinoma in dogs?
Dyspnea
164
Which hormone is monitored after parathyroidectomy to prevent hypocalcemia?
Parathyroid hormone
165
True or False: Cats with hyperthyroidism often present with decreased appetite.
FALSE
166
What is the mechanism by which thyroid hormone influences metabolism?
Increase in cellular oxygen consumption
167
What is a common complication of untreated hyperthyroidism in cats?
Hypertrophic cardiomyopathy
168
What influences metabolism?
b) Increase in cellular oxygen consumption
169
What is a common complication of untreated hyperthyroidism in cats?
b) Hypertrophic cardiomyopathy
170
Which medication is commonly used to treat hypercalcemia in dogs with primary hyperparathyroidism?
d) Pamidronate
171
True or False: Parathyroid hormone decreases the reabsorption of calcium in the kidneys.
FALSE
172
Which structure runs medial to the thyroid gland and can be at risk during surgery?
b) Recurrent laryngeal nerve
173
What is the expected outcome of administering radioactive iodine (I-131) therapy in cats with hyperthyroidism?
b) Permanent destruction of hyperactive thyroid tissue
174
What is the most common side effect of radioactive iodine therapy in cats?
a) Hypothyroidism
175
Which hormone stimulates the absorption of calcium in the intestines?
c) Calcitriol
176
What is the role of the internal jugular vein in thyroid surgery?
b) Drains blood from the thyroid gland
177
Which condition is characterized by low blood calcium levels due to parathyroid dysfunction?
b) Hypocalcemia
178
What effect does thyroid hormone have on the cardiovascular system?
b) Increases cardiac output
179
True or False: Dogs with thyroid carcinoma often present with polyuria and polydipsia.
FALSE
180
What is the role of thyrotropin-releasing hormone (TRH) in the body?
a) Stimulate TSH secretion
181
What is a common clinical sign of hypocalcemia in cats?
b) Muscle tremors
182
What is the recommended approach for treating cats with bilateral thyroid disease?
b) Radioactive iodine therapy
183
Which condition is associated with increased levels of TSH despite normal thyroid hormone levels?
c) Euthyroid sick syndrome
184
What is the effect of hyperthyroidism on glucose metabolism in cats?
c) Hyperglycemia
185
Which hormone decreases blood calcium levels by inhibiting bone resorption?
a) Calcitonin
186
True or False: Hypothyroidism in dogs often results in weight gain and lethargy.
TRUE
187
Which medication is preferred for long-term management of hyperthyroidism in cats that cannot undergo surgery?
c) Methimazole
188
What is the function of the caudal deep cervical lymph nodes in relation to the thyroid gland?
c) Drain lymph
189
What is the role of iodine in thyroid hormone synthesis?
b) Serves as a precursor for thyroid hormones
190
What is a potential complication of staged bilateral thyroidectomy in cats?
a) Severe hypocalcemia
191
True or False: Cats treated with radioactive iodine are at risk of developing hypothyroidism over time.
TRUE
192
What is the main function of the thyroid nerve?
b) Stimulation of thyroid hormone release
