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Veterinarian Technician February 2006 (Vol 27, No 2) Focus: Oncology

Benefits of using a venous access port

by Amy Sterling, LVT, BS

    Kaylee, a 7-year-old, spayed domestic shorthaired cat, presented with a 2-week history of decreased appetite and water consumption and weight loss. She had also been vomiting blood-tinged fluid intermittently for several weeks. During one episode, she vomited a piece of tissue. Cytology findings on this sample were inconclusive. Kaylee was referred to our internal medicine department for further evaluation.

    Click to view Use of Venous Access Port .

    Physical examination

    On physical examination, Kaylee was bright, alert, and responsive. She weighed 17 lb (7.7 kg), and her mucous membranes were pink and slightly tacky, indicating slight dehydration. Heart and lung auscultation was normal, and no abnormalities were noted on abdominal palpation. Her temperature and pulse rate were normal at 102.5°F (39.2°C) and 140 beats/min, respectively, and her respiratory rate was elevated at 72 breaths/min (normal: 20 to 30 breaths/min).

    Subsequent diagnostics

    Blood work showed only a mild neutrophilic leukocytosis, and thoracic radiographs were unremarkable. An ultrasonogram revealed a focal mass within the greater curvature of the stomach near the pylorus. There was also disruption of normal layers and regional thickening of the stomach wall. After discussion with the owner, Kaylee was admitted to the hospital for gastroscopy and biopsies. A catheter was placed in her cephalic vein, and she was started on lactated Ringer's solution. A premedication of butorphanol was given subcutaneously as an intraoperative analgesic. Anesthesia was induced with intravenous propofol and maintained with isoflurane and oxygen. Endoscopic examination revealed a mass at the greater curvature of the stomach near the pylorus. It was raised, firm, and pink, with superficial erosions. The lesion was extremely friable. Biopsy specimens were obtained and submitted for histo­pathology. Kaylee recovered uneventfully in our intensive care unit and was maintained on fluids overnight.

    Therapy

    Initial in-hospital cytology appeared consistent with lymphoma. The following afternoon, Kaylee was given 2,100 IU of l-asparaginase by subcutaneous injection for her initial chemotherapy. She displayed no adverse reaction to the therapy and was discharged with instructions to start oral prednisone at a dose of 10 mg once daily.

    Histopathology reports were conclusive for gastric lymphoma. A chemo­therapy protocol consisting of a 12-week induction using vincristine, cyclophosphamide, and prednisolone (COP II) with l-asparaginase predose was chosen. Another option was the addition of doxorubicin to the COP II protocol. Doxorubicin is an antitumor antibiotic commonly used in veterinary oncology. The owner elected against the use of doxorubicin because of its potential side effects, which include bone marrow suppression, alopecia, gastrointestinal toxicity, allergic reaction, anorexia, and renal failure.1 Weekly visits included a complete blood count, physical examination, and brief ultrasonography to assess tumor size before chemotherapy was administered. Because Kaylee was overweight, her chemotherapy was dosed on estimated lean body mass.

    After the first week of chemotherapy, the owner opted to have a venous access port placed. Venous access ports used in veterinary patients are similar to those placed in human oncology patients, but the manufacturer recommends that in pets, the port only be surgically placed into the external jugular vein and sutured under the skin.2 These ports can remain in place throughout the pet's lifetime even when treatment is no longer needed. Afterward, maintenance of the port only involves periodically clipping the overlying fur, performing a sterile preparation of the skin, and flushing the port with heparinized saline. In Kaylee's case, placement of the port allowed for less venipuncture and restraint of an overweight cat, which in turn made Kaylee's visits less stressful for both technician and patient.

    After induction, Kaylee remained in remission, and maintenance therapy was discussed. The owner elected a conservative treatment consisting mostly of oral chlorambucil and prednisolone, with one injection each of vincristine and cyclophosphamide. Chlorambucil was used at a dosage of 20 mg/m2 divided over a course of 14 days. This schedule included monthly visits for physical examinations, complete blood counts, and ultrasound rechecks while Kaylee received oral chlorambucil and prednisolone at home. She continued with this regimen for 5 months and remained in remission. The owner then chose to discontinue chemotherapy and to return monthly for rechecks and to have Kaylee's venous access port flushed.

    Conclusion

    Kaylee has now remained in remission for nearly 3 years. She has shown no signs of illness, and additional chemotherapy has not been necessary. Currently, she is enjoying a happy, healthy, cancer-free life. Every 3 months, Kaylee returns for a recheck and to maintain her venous access port, which has made it possible for her visits to be free of venipuncture, restraint, and, most importantly, stress.

    Without the benefits of ultrasonography, endoscopy, a venous access port, and chemotherapy, Kaylee could not have overcome the cancer that had invaded her body. This case is a wonderful example of how specialty medicine can extend the lives of animals and help them beat the odds.

    1. Ogilvie GK, Moore AS: Feline Oncology: A Comprehensive Guide to Compassionate Care. Yardley, PA, Veterinary Learning Systems, 2001.

    2. Norfolk Medical: Norfolk Medical Products. Accessed August 2003 at www.norfolkmedical.com.

    References »

    NEXT: Editorial: "Helping clients in distress"

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