Surgically implanted vascular access ports in the jugular veins of patients requiring repeated intravenous therapy over weeks
to months are an attractive option to avoid pain from extravasation or unnecessary stress from multiple venipunctures and
catheter placement (Figure 5). Vascular access ports are standard-of-care for people receiving chemotherapy. Their use in veterinary oncology is becoming
more common, and now ports specifically designed for companion animals of various body sizes are available (Companion Port—Norfolk
Figure 5. A vascular access port (left) and the specifically designed right angle Huber infusion set.
Finally, radiation is a valuable therapeutic tool, but normal tissue toxicity may result in moderate to significant pain.
Mucositis is an early radiation side effect that commonly occurs with curative-intent protocols that involve daily treatments
over four weeks; it can be fairly painful.1,2,7,12,19,20 It typically develops toward the end of the treatment (in the third and fourth weeks) and may persist for a few weeks after
radiation is discontinued. The most common sites of painful radiation-induced mucositis are the mouth (stomatitis, glossitis)
when oral or sinonasal tumors are irradiated and the large intestine (colitis, proctitis) when pelvic irradiation is performed.7,20 Moist dermatitis is occasionally observed and can also be fairly painful (Figure 6).7,20 Computerized planning and precise analysis of dose distribution help prevent severe early radiation side effects to normal
tissues. Occasionally, pain may result from late side effects of radiation therapy, including osteoradionecrosis causing pathologic
fracture and peripheral neuropathies.20
Figure 6. This Boxer cross is recovering from radiation-induced acute moist dermatitis, two weeks after the end of a full
course of radiation therapy for an incompletely excised infiltrative lipoma. At this stage, the therapy-induced lesion is
no longer painful.
The authors thank Drs. Kurt A. Grimm and William J. Tranquilli for critically reviewing this manuscript.
Louis-Philippe de Lorimier, DVM
Timothy M. Fan, DVM, DACVIM (internal medicine, oncology)
Department of Veterinary Clinical Medicine
College of Veterinary Medicine
University of Illinois
Urbana, IL 61802
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