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152 Chemotherapy: Adverse Events

• Prevention of progressive ventricular systolic Recommended Monitoring Prevention
dysfunction (nonspecific cardioprotective • Monitor for arrhythmias by Holter recording • Limit exposure to the vector by upgrading
VetBooks.ir • Control of the organism (elimination of • Monitor for signs of systolic dysfunction by of raw reservoir hosts, and otherwise limiting
q 6-12 months.
therapies)
housing, using insecticides, limiting ingestion
contact between dogs and reservoir hosts.
infection is not considered possible)
echocardiography q 6-12 months.
Acute General Treatment PROGNOSIS & OUTCOME • Deltamethrin-treated collars may be effective
at repelling triatomine insects.
• See Heart Failure, Acute/Decompensated • Blood donors should be screened.
(p. 408) • High risk of sudden death if severe ventricular • Breeding bitches in endemic/high-risk
• See Atrioventricular Block (p. 101) arrhythmias during the acute phase areas should also be screened to prevent
• See Ventricular Arrhythmias (pp. 1033 and • Dogs that survive the acute phase may be transplacental and transmammary infection.
1457) free of clinical signs for months to years.
• Benznidazole 7 mg/kg PO q 12h for Some dogs never develop late complications Technician Tips
60 days or nifurtimox may be useful in of the disease. Blood specimens in veterinary practice often
the acute stage, but these drugs are not • Young dogs (<1 year of age), puppies typically are handled with less care than in human
approved by the U.S. Food and Drug are at higher risk for overt signs of CHF medical settings. In areas where Chagas’ disease
Administration (FDA) and are therefore and/or severe ventricular arrhythmias. is endemic, blood specimens and products from
extremely difficult to obtain. They may not • After clinical signs develop, appropriate pal- infected animals should be handled with caution
eliminate long-term effects of the disease liative therapy may prolong life. Dogs with by all staff (zoonosis).
and have clinically significant side effects. clinical signs of CHF or severe arrhythmias
• Glucocorticoids: antiinflammatory dose have a guarded long-term prognosis, but SUGGESTED READING
(prednisone 0.5-1 mg/kg PO q 12-24h) appropriate palliative therapy can prolong Barr SC: Canine Chagas’ disease (American trypano-
sometimes used their lives by months to a few years. somiasis) in North America. Vet Clin North Am
• Ketoconazole, albaconazole 1.5 mg/kg PO q Small Anim Pract 39:1055-1064, 2009.
24h for 60-90 days and allopurinol have been PEARLS & CONSIDERATIONS AUTHOR: Romain Pariaut, DVM, DACVIM, DECVIM
investigated, but proof of benefit is lacking. EDITOR: Joseph Taboada, DVM, DACVIM
Comments
Possible Complications Chagas disease is a regional cause of myocarditis,
Refractory CHF and/or cardiac arrhythmias which is likely underdiagnosed.
may occur during the acute phase in young
dogs and puppies and as late complications
months to years after infection.

Chemotherapy: Adverse Events Bonus Material Client Education
Sheet
Online

BASIC INFORMATION Cats (vs. dogs) have reduced risk of L-asparaginase • Extravasation injury (vinca alkaloids, doxo-
allergic reaction and lomustine hepatotoxicity rubicin, carboplatin [undiluted], dacarbazine,
Definition mechlorethamine, cisplatin, rabacfosadine,
Chemotherapy is well tolerated by most GENETICS, BREED PREDISPOSITION actinomycin D)
patients, but adverse effects (AEs) are possible MDR1/ABCB1-Δ mutations decrease per- • Acute vomiting: common (cisplatin,
due to actions of the drugs or idiosyncratic meability glycoprotein (P-glycoprotein) dacarbazine); less common (doxorubicin,
reactions. The Veterinary Cooperative Oncol- functionality and increase AEs with sub- cyclophosphamide, mechlorethamine,
ogy Group common terminology criteria for strates. A list of at-risk breeds is available procarbazine)
adverse events (VCOG-CTCAE, v1.1, https:// (p. 638). Delayed adverse reactions:
onlinelibrary.wiley.com/doi/full/10.1111/ • GI: common (doxorubicin, MOPP [mechlor-
vco.283#vco283-sec-0002-title) define AEs RISK FACTORS ethamine, vincristine, procarbazine, predni-
according to established standard criteria. • MDR1/ABCB1-Δ mutation sone], toceranib, cisplatin, dacarbazine); less
Most are mild to moderate and manageable • Small-breed dogs (<10 kg) common (vinca alkaloids, cyclophosphamide,
with supportive therapy. Alterations in treat- • Illness at time of treatment mitoxantrone, carboplatin, actinomycin D,
ment protocols/dosing may be required. • Pre-existing gastrointestinal (GI), renal, or rabacfosadine)
hepatic disease, especially if dysfunction • Myelosuppression: common (lomustine,
Epidemiology • Significant bone marrow infiltration: carboplatin); possible (doxorubicin, mito-
SPECIES, AGE, SEX myelosuppression xantrone, cyclophosphamide, vinca alkaloids,
AEs in cats but not dogs: • Breeds at risk for dilated cardiomyopathy: dacarbazine, toceranib, rabacfosadine)
• Doxorubicin: nephrotoxicity cardiotoxicity Unique adverse reactions:
• Temozolomide: pleural/pericardial effusion • Breeds at risk for pulmonary fibrosis, chronic • Paralytic ileus (vincristine)
Drugs not to be used in cats: pulmonary disease: pulmonary fibrosis • Hemorrhagic colitis (doxorubicin)
• Cisplatin: fatal pulmonary edema Clinical Presentation • Pancreatitis (toceranib)
• 5-Fluorouracil: fatal central nervous system • Cardiotoxicosis (doxorubicin)
necrosis and edema DISEASE FORMS/SUBTYPES • Hemorrhagic cystitis (cyclophosphamide,
AEs in dogs but not cats: Adverse reactions during administration: ifosfamide)
• Cyclophosphamide: hemorrhagic cystitis • Allergic reactions (L-asparaginase, doxoru- • Nephrotoxicosis (cisplatin; uncommon:
• Doxorubicin: cardiotoxicosis bicin, taxanes) doxorubicin [cats], toceranib)
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