Page 130 - WSAVA2018
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C. Ward1
1University of Georgia College of Veterinary Medicine, Small Animal Medicine and Surgery, Athens, USA
Cynthia Ward, VMD, PhD, DACVIM
College of Veterinary Medicine, University of Georgia Athens, GA USA
Insulin is a small peptide hormone that has a highly conserved amino acid sequence throughout different mammalian species. This allows for the use of human- based insulins in veterinary species. Insulin is secreted in a stable hexomeric form stabilized by a zinc molecule in the middle. The hexomer needs to be broken down to a monomer before it can bind to the insulin receptor and activate cells. In considering insulin therapy, the practitioner should be aware of the source of the insulin (animal, human recombinant DNA, human sequence mutated), the type of the insulin or how it is made into
a repository form, and the concentration (U-40, U-100, U-300).
Regular insulin is available as a human recombinant insulin in 100 U/ml (U-100) form. It is the stabilized hexomeric form of insulin, and therefore, not precipitated or mutated. It may be used intravenously, intramuscularly, and subcutaneously. Regular insulin is used to treat unstable or dehydrated diabetics. Effective protocols for IM intermittent therapy or continuous rate IV infusion are available in any emergency medicine handbook.
Protamine Zinc Insulin (ProZincR) is human recombinant insulin. It is precipitated with protamine zinc and is stable in suspension. It should be rolled gently to mix. ProZincR is formulated at a concentration of 40 U/ml; therefore dosing can be easier in smaller animals like cats. The 0.3 ml syringes can be used so that half units can be easily measured. ProZincR is approved by the FDA for veterinary use; therefore, company support of the product is readily available for veterinarians. This is a great insulin in cats and also is effective in dogs.
VetsulinR is a purified porcine insulin that has an identical animo acid sequence to canine insulin. It is a mixture
of ultralente and semilente insulins and is precipitated with zinc to form a suspension. To keep the ratio of semilente to ultralente consistent, it must be shaken vigorously before use. VetPensR containing VetsulinR are available for convenient dosing by owners. These pens may be measured for accurate 1⁄2 unit dosing. VetsulinR
25-28 September, 2018 | Singapore
adrenal mass to evaluate for vascular invasion and screen for metastasis. Testing for functional status should include assessment for hyperadrenocorticism and evaluation of urine catecholamine/ metanephrines. Fine needle aspiration and cytology of adrenal masses in many cases can distinguish between the two main tumour types. There are potential risks with this procedure, however in the little published data available it overall seems safe.
The primary treatment for adrenal tumours is surgical excision. This can be acheived by open ventral midline laparaotomy approach or via a retroperitoneal approach. For smaller adrenal masses without caval invasion, laparoscopic adrenalectomy is possible. Tumour invasion into the phrenicoabdominal vein and caudal vena cava require venotomy to remove the tumour emboli. In
the case of phaeochromocytoma, pre-operative use
of phenoxybenzamine decreases the perioperative mortality rate. After the perioperative period, outcomes for both adrenal carcinomas and phaeochromocytomas can be very good in dogs. Vascular invasion, emergency surgery for haemorrhage, and large tumour size increases the perioperative risk but do not necessarily impact on long term outcome.
In non-resectable adrenal tumours, stereotactic radiation therapy has been recently reported with good outcomes (several year survival time). Adjuvant therapy following surgery has not been established in companion
animals. For adrenal dependent hyperadrenocorticism, if surgery is not a good option medical therapy can be attempted. MItotane can be used as a cytotoxic agent (higher doses than required for pituitary dependent hyperadrenocorticism are typically required, and approaches to ablate the adrenal tissue are described), or trilostane to control clinical signs can also be considered. Other chemotherapy agents have not been evaluated in companion animals with adrenal gland tumours.

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