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Veterinary Chemotherapy Side Effects

General Chemotherapy Information for Veterinary Patients

We do not typically anticipate major side effects from the majority of chemotherapeutics in veterinary patients. If side effects are noted, they are generally minimal or self-limiting. Side effects noted at home may consist of mild lethargy, decreased appetite, vomiting, nausea, and/or diarrhea. Side effects typically occur 2-5 days following treatment pending on the chemotherapeutic administered. We commonly prescribe anti-vomiting and anti-diarrhea medications that can be administered as needed if side effects are noted. If a patient is known to be more sensitive or has experienced previous side effects, then medications may be administered prophylactically as needed. If side effects persist more than 48 hours, then additional treatment may be warranted and we would reduce the next dose. Less than 5-10% of patients develop a fever and decreased white blood cells that require supportive care or 24-48 hours of hospitalization with intravenous fluids and antibiotics. If hospitalization is required and the white cells are reduced significantly, then we often never administer that particular chemotherapeutic again.

Gastrointestinal Side Effects, At-Home Management

• Nausea, vomiting, decreased appetite
  • Most common sign noticed by owners
• Acute (very rare)
  • May occur 1-8 hours post-infusion
• Delayed (more common)
  • 2-3 days post-chemotherapy
  • Small dogs can be worse
  • Diarrhea may be delayed and may occur 3-5 days post-chemotherapy
• Treatment:
  • May be self-limiting
  • NPO (nothing by mouth for 24 hours), then gradually introduce small amounts of bland diet and water
    Consider boiled chicken or hamburger (grease drained) and rice or sweet potato, scrambled eggs
  • Oral anti-nausea/anti-vomiting medications
    • Ondansetron (Zofran®)
    • Maropitant (Cerenia®)
    • Metoclopramide (Reglan®)
• Oral anti-diarrhea medications
  • Metronidazole (Flagyl®)
  • Tylosin (Tylan®) powder
• Appetite stimulants

Gastrointestinal Side Effects, In-Hospital Management

• In-Hospital supportive care
  • IV fluids-Correct electrolyte imbalances
  • Monitor for sepsis (bacterial translocation)-Start antibiotics
• Nausea, vomiting, decreased appetite
  • IV anti-emetics (anti-nausea/anti-vomiting medications)
    • Maropitant (Cerenia®) IV, SQ
    • Ondansetron (Zofran®) IV
    • Dolansetron (Anzemet®) IV, IM
    • Metoclopramide (Reglan®) CRI
• Diarrhea or colitis (hemorrhagic)
  • Severe-Dehydration, electrolyte imbalances
  • Treatment: Supportive care, injectable anti-diarrhea medications-Metronidazole (Flagyl®) IV
  • Most side effects are reversible
  • Prevention: Institute anti-emetics prophylactically, decrease dose of chemotherapy

Neutropenia/Sepsis (decreased white cells, bacterial translocation)

• Cancer patients may be predisposed
  • Myelosuppressive chemotherapy
  • Poor nutrition
  • Underlying disease, poor immune function
  • Tissue injury (surgery, radiation)
• Non-Emergency
  • Neutrophils (main type of immune white blood cell (Less than 1000)
  • No fever, Feeling okay
  • Treatment:
    • Delay further chemotherapy
    • Oral antibiotics
    • Monitor for fever or deterioration in clinical status
• Emergency
  • Acute decompensation
    • May occur 5-7 days post-chemotherapy
    • May or may not have gastrointestinal signs
  • Fever, anorexia, lethargy
  • Tachycardia (increased heart rate)
  • Collapse due to dehydration, shock, hemorrhage, decreased cardiac output