Determining the Prevalence of Hypersomatotropism in a North American Cohort of Diabetic Cats
Purpose of study
Diabetes mellitus is common in cats and its prevalence appears to be increasing in the United States. While the prognosis for cats with controlled diabetes is generally good, there is a population of diabetic cats that receive insulin and still have persistently high blood glucose levels. Cats that receive an insulin dosage greater than 1.5 units/kg/dose and still have high blood glucose are considered insulin resistant. One potential cause of this insulin resistance is a pituitary tumor (often benign). A mass on the pituitary can cause the gland to overproduce growth hormone, a condition called hypersomatotropism (HST). HST can lead to diabetes and acromegaly, a term used to describe physical characteristics such as broad facial features, a protruding lower jaw and enlarged paws or legs. A recent study showed that 25% of diabetic cats in the United Kingdom have HST and, of those cats, approximately 90% have a pituitary tumor. The goal of this study is to determine the prevalence of HST and pituitary tumors in insulin-dependent diabetic cats in the Pacific Northwest.
Enrolled cats will receive free fructosamine and IGF-1 blood tests. Cats with an elevated IGF-1 will receive a free CT scan +/- MR imaging. If their cat is found to have a pituitary tumor, owners will receive a free consultation with a boarded specialist to review treatment options.
Enrolled cats must be insulin-dependent diabetics that are healthy enough to undergo sedation and/or general anesthesia for diagnostic imaging. Cats that have received steroids within 6 months of blood tests will not be eligible for this study.
Once enrolled in this study, you will take your cat to your family veterinarian for a routine blood draw. This blood will be submitted for two blood tests: a serum fructosamine level, to help us determine how well your cat’s diabetes is controlled, and an insulin-like growth factor level (IGF-1), to help us determine how much growth hormone the pituitary is producing. If the IGF-1 indicates that your cat has an elevated level of growth hormone, we will make an appointment with you to bring your cat to the Washington State University Veterinary Teaching Hospital (WSU VTH) in Pullman, Washington for a CT scan to screen for a pituitary tumor. On the day of the CT scan, your cat will be sedated and an IV catheter will be placed so we can administer a contrast agent for the scan. Your cat will be monitored closely while the CT scan takes place. After the scan is finished, we will review the imaging. If your cat’s pituitary does not look enlarged on CT, then a magnetic resonance (MR) image will be done on the same day. If an MR image is needed, we will take your cat directly to the MRI where s/he will receive general anesthesia. Your cat will again be monitored very closely during the MR imaging process. The CT scan and MR imaging are both outpatient procedures, so once your cat is awake, s/he will be released to go home with you.
Owners are responsible for the costs associated with travel to WSU’s Veterinary Teaching Hospital in Pullman, Washington for diagnostic imaging IF testing shows that their cat has an elevated IGF-1. If imaging shows their cat has a pituitary tumor and they decide to treat, owners are responsible for the costs associated with treatment of that pituitary tumor.