Case 26
An 11-year-old spayed female Domestic Shorthair cat was presented to the clinic with a 2-month history of progressive weight loss despite a ravenous appetite (polyphagia). The owner also reports increased thirst and urination (polyuria/polydipsia) and occasional vomiting for the past few weeks. The cat has become more vocal and restless, especially at night. She is an indoor-only cat and is current on all preventative care.
Physical Exam:
T: 102.9°F
P: 230 bpm
R: 40 bpm
MM: pink/moist
CRT <2 sec
The cat is thin with a body condition score of 3/9 and has palpable muscle wasting over the spine and hips. The hair coat is unkempt and mildly greasy. Cardiac auscultation reveals a tachycardia with a Grade II/VI systolic heart murmur. Careful palpation of the ventral neck reveals a small, firm, movable nodule on the right side, consistent with a "thyroid slip".
CBC and Biochemistry:
CBC: Mild erythrocytosis (PCV 48% [Ref: 29-45%])
Biochemistry: Alanine Aminotransferase (ALT): 155 U/L [Ref: 12-130 U/L]. All other values are within reference range.
Urinalysis:
Color: Pale yellow
pH: 7.0
SG (refractometer): 1.020 [Ref: >1.035]
Protein (dipstick): Trace
Blood (Dipstick): Negative
Sediment exam: Unremarkable
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What will be your tentative and differential diagnosis? What further diagnostic test(s) you will perform to confirm your diagnosis? What will be your treatment plan(s)?