Endocrine Organ Surgery Flashcards
Please sort these five endocrine surgeries in order from “Straightforward (if uncomplicated) and reasonable to do in general practice” at the top through to “referral surgery clinics only” at the bottom
A. Thyroidectomy in cats B. Parathyroidectomy in dogs C. Thyroidectomy in dogs D. Adrenalectomy in dogs E. Pancreatic biopsy
- Pancreatic biopsy
- Thyroidectomy in dogs
- Thyroidectomy in cats
- Parathyroidectomy in dogs
- Adrenalectomy in dogs
- Green LO* Where are the thyroid glands located?
- It’s a dark red, elongated structure attached to the outer surface of the proximal portion of the trachea.
- They are usually positioned laterally and slightly ventral to the fifth to eighth cartilage rings.
- In adult dogs they are approximately 5 cm long and 1.5 cm wide
- Green LO* Where are the PT glands located? How many are there?
- There are 4
- The external parathyroid glands are normally found on the cranial dorsolateral surface of the respective thyroid.
- The internal parathyroid glands are embedded within the thyroid parenchyma, usually at the caudomedial pole.
Green LO What is the most common cause of thyroid enlargement in dogs? What % are euthyroid/hypothyroid/hyperthyroid?
- Nonfunctional adenocarcinoma
- 60% euthyroid
- 30% hypothyroid
Green LO What is the most common cause of thyroid enlargement in cats? What % are euthyroid/hypothyroid/hyperthyroid?
- Functional adenoma or hyperplasia
- Tend to be hyperthyroid primarily
Behavior of thyroid adenocarcinomas in canines
- Nonfunctional and malignant
How to diagnose canine thyroid adenocarcinoma? What precautions must be taken?
- FNA is helpful and easy to do
- Highly hemorrhagic so plan biopsies well
In dogs, how frequently are thyroid neoplasias benign?
- ??? not sure
Prognosis for freely movable thyroid adenocarcinoma (i.e. you can feel the mass in the jugular groove)?
- 3 year median survival after surgery
Treatment for large, invasive thyroid tumors
- Radiation therapy
Green LO Answer yes or no for the following regarding thyroid masses in dogs:
- Hormone producing
- Malignant
- Bilateral
- Main surgery risks anesthesia related
- Main surgery risk hemorrhage
- No
- Yes
- Usually unilateral
- No
- Yes
Green LO Answer yes or no for the following regarding thyroid masses in cats:
- Hormone producing
- Malignant
- Bilateral
- Main surgery risks anesthesia related
- Main surgery risk hemorrhage
- Yes
- No
- Yes
- Yes
- Not as much
Green LO What complications should you always be prepared for during the surgery of thyroid neoplasia in dogs?
- Hemorrhage!
Green LO What surgical procedure is required for canine thyroid neoplasia?
- Extracapsular thyroidectomy
What do you do with the ipsilateral PTH glands in canine thyroid AC?
- Sacrifice
What happens if canine thyroid AC is bilateral?
- Dilemma
- May require calcitriol or calcium or soloxine
- This would definitely be a referral procedure
Green LO How frequently is the feline hyperthyroidism caused by bilateral disease?
- 80% bilateral
Green LO Is feline hyperthyroidism usually malignant or benign disease?
- Usually benign
- Most are adenomatous hyperplasia
Green LO Why may hypothyroidism lead to hemorrhage during surgery?
- Lots of vasculature nearby
- Carotid***
- Jugular vein
Green LO What % of cats with hyperthyroidism are affected by thyrotoxic heart disease, and how often are they in congestive heart failure?
- Thyrotoxicosis causes increased metabolic rate and sensitivity to catecholamines
- 80% of cats get cardiomyopathy
- Approximately 20% have congestive heart failure
Green LO What condition may have been masked during the hyperthyroid state and then consequently becomes a postoperative condition apparent after the cat becomes euthyroid?
- Renal disease
- GFR increase “masked” by thyrotoxocisos
Clinical signs of cats with hyperthyroidism
- Older cats
- Weight loss despite voracious appetite
- Aggression
- V/D, PU/PD
- Rough hair coat
- Palpable thyroid slip
Green LO Which are the three major approaches to treatment of feline hyperthyroidism?
- Palliative methimazole/carbimazole
- Definitive iodine 131
- Definitive surgery
Green LO How frequently is feline hyperthyroidism caused by ectopic thyroid masses?
- 5-10% of cats
Green LO Why are hyperthyroid cats considered high-risk anesthesia candidates?
- Thyrotoxicosis leads to increased metabolic rate and sensitivity to catecholamines
- 80% of cats have concurrent cardiomyopathy
- Anemia (may be occult)
- Hypovolemia
- Hypertension
- Tachydysrhythimas
- Ventricular ectopy
- Renal insufficiency that may be occult
- Increased metabolic rates
What are the palliative treatments for hyperthyroid?
- Methimazole or carbimazole