This action inhibits the release of pro-nociceptive neurochemicals like glutamate, calcitonin gene-related peptide (CGRP), and substance P in the brain and spinal cord, resulting in pain relief. Therapeutic use
Due to the profound side effects or lack of efficacy when delivered through more common routes, such as orally or intravenously, ziconotide must be administered intrathecally (i.e. directly into the spinal fluid). As this is the most expensive and invasive method of drug delivery and involves additional risks of its own, ziconotide therapy is generally considered appropriate (as evidenced by the range of use approved by the FDA in the US) only for “management of severe chronic pain in patients for whom intrathecal (IT) therapy is warranted and who are intolerant of or refractory to other treatment, such as systemic analgesics, adjunctive therapies or IT morphine”. Research is ongoing to determine whether ziconotide can be formulated in a way that would allow it to be administered by less invasive means.However, this must be weighed against the high level of pain management, both in terms of degree and length, and the apparent lack of tolerance and other signs of dependence even after extended treatment along with the need for alternatives to other therapies that have not worked for the patient. Ziconotide is also contraindicated for patients with certain preexisting mental disorders (e.g. psychosis) due to evidence that they are more susceptible to certain severe side effects. Adverse reactions
The most common side effects are dizziness, nausea, confusion, nystagmus, and headache.
It is the third most common intestinal tumor in cats, after lymphoma and adenocarcinoma.Diagnosis and treatment are similar to that of the dog. Cases involving difficult to remove or multiple tumors have responded well to strontium-90 radiotherapy as an alternative to surgery. The prognosis for solitary skin tumors is good, but guarded for tumors in other organs. Histological grading of tumors has little bearing on prognosis. References
External links

Mast Cell Tumors from The Pet Health Library
Mast Cell Tumors in Dogs from Pet Cancer Center
Mast Cell Tumors in Cats from Pet Cancer Center