DM3 Pt8-2 Safe Chemotherapy

Question 1

What are the three biggest potential risks associated with chemotherapy in cats?

Answer 1

1. Bone marrow suppression 2. Gastrointestinal toxicity 3. Extravasation.

Question 2

What are some less common side effects of chemotherapy in cats?

Answer 2

Anaphylaxis, hepatotoxicity, and nephrotoxicity.

Question 3

What oncological emergency can result from a successful tumor kill in cats with lymphoproliferative disease?

Answer 3

Tumor lysis syndrome.

Question 4

What oncological emergency can result from chemotherapy in gastrointestinal lymphoma?

Answer 4

Gastrointestinal perforation and peritonitis.

Question 5

Which chemotherapeutic agents are commonly used in the treatment of lymphoma in cats?

Answer 5

Cyclophosphamide, chlorambucil, vincristine, and doxorubicin.

Question 6

What are some side effects associated with specific chemotherapeutic agents like L-asparaginase and hydroxyurea?

Answer 6

L-asparaginase can cause anaphylaxis, while hydroxyurea can cause gastrointestinal and bone marrow toxicity.

Question 7

What is the key to the successful use of chemotherapeutic agents in cats?

Answer 7

Prevention and early detection of potential complications to avoid oncological emergencies.

Question 8

How can the risk of oncological emergencies from chemotherapy be reduced in cats?

Answer 8

By predicting side effects, preventing them, and managing them early before serious clinical consequences arise.

Question 9

Why is bone marrow suppression a risk with chemotherapy in cats?

Answer 9

Chemotherapeutic agents affect rapidly dividing cells, including those in the bone marrow.

Question 10

Which chemotherapeutic agent is more myelosuppressive: cyclophosphamide or vincristine?

Answer 10

Cyclophosphamide is more myelosuppressive than vincristine.

Question 11

What is the most common consequence of bone marrow suppression in cats?

Answer 11

Neutropenia, due to the short half-life of neutrophils (7-8 days).

Question 12

What is the time frame for neutrophil nadir after chemotherapy in cats?

Answer 12

5-7 days after drug administration.

Question 13

What are the main concerns with severe myelosuppression if undetected?

Answer 13

Severe myelosuppression can lead to sepsis.

Question 14

How should a cat with neutrophils < 1.5x10⁹/l but clinically well be managed?

Answer 14

Give broad-spectrum oral antibiotics for 5-7 days and have the owner monitor the cat at home.

Question 15

What should be done if a cat is systemically ill or pyrexic due to myelosuppression?

Answer 15

The cat should receive aggressive treatment with intravenous antibiotics and supportive care. The dose of the next chemotherapeutic treatment should be reduced by 20%.

Question 16

What is a key preventive measure for managing bone marrow suppression in cats?

Answer 16

A complete blood count (CBC) should be performed before each chemotherapy dose to check neutrophil and platelet counts.

Question 17

How can dose accuracy be ensured for chemotherapeutic agents?

Answer 17

The cat should be weighed at each visit, and doses should be calculated based on body surface area.

Question 18

What should owners monitor for after their cat receives chemotherapy?

Answer 18

Any signs of illness, especially around the time of the neutrophil nadir (5-7 days after treatment). If illness occurs, a CBC should be performed.

Question 19

What are common gastrointestinal (GI) side effects of chemotherapy in cats?

Answer 19

Anorexia, nausea, vomiting, and diarrhoea.

Question 20

Which chemotherapeutic drug is most commonly associated with anorexia in cats?

Answer 20

Doxorubicin, likely due to nausea.

Question 21

What side effect is associated with vincristine in some cats?

Answer 21

Paralytic ileus, a rare side effect, which can occur after vincristine administration.

Question 22

What should be done if gastrointestinal signs occur with vincristine?

Answer 22

Care should be taken in using it again, as clinical signs may worsen with continued use.

Question 23

What are the potential causes of gastrointestinal signs in cats undergoing chemotherapy?

Answer 23

Chemotherapeutic drugs, concurrent disease, progression of neoplasia, or GI perforation (especially in GI lymphoma).

Question 24

What medications can be used to manage chemotherapy-induced nausea and vomiting in cats?

Answer 24

Antiemetics like maropitant and metoclopramide.

Question 25

What supportive treatments can be used for cats with chemotherapy-related GI toxicity?

Answer 25

GI protectants (H2 blockers, sucralfate), IV fluid therapy, appetite stimulants (mirtazapine, cyproheptadine), and enteral feeding (e.g., naso-oesophageal tube).

Question 26

What is a preventive strategy for GI toxicity from doxorubicin in cats?

Answer 26

Pre-treatment with antiemetics (maropitant or metoclopramide) or avoiding doxorubicin if necessary.

Question 27

What can be done if a specific chemotherapeutic agent causes significant GI toxicity in a cat?

Answer 27

The agent can be substituted (e.g., cyclophosphamide replaced with chlorambucil) or the dose can be lowered and administered more frequently.

Question 28

How should treatment be adjusted in cases of GI lymphoma to avoid complications like perforation?

Answer 28

Start with vincristine alone and monitor response with ultrasound. Adjust therapy according to gastrointestinal wall thickness and risk of perforation.

Question 29

What is extravasation, and why is it dangerous during chemotherapy?

Answer 29

Extravasation is the leakage of chemotherapeutic agents into surrounding tissue during IV administration, causing severe irritation and potentially requiring amputation if not managed properly.

Question 30

What should be done immediately if extravasation occurs during chemotherapy?

Answer 30

Aspirate as much fluid as possible through the catheter.

Question 31

How should vincristine extravasation be managed?

Answer 31

Infuse 3-5 ml of 0.9% sterile saline and apply warm compresses for 15 minutes, 3-4 times daily for 24 hours.

Question 32

How should doxorubicin extravasation be managed?

Answer 32

Apply ice packs for 10-15 minutes every 2 hours for 72 hours, then 3-4 times daily for 10-14 days. If extravasation is minimal, ice for the first 24-48 hours may be sufficient.

Question 33

What other treatments can help manage extravasation of chemotherapeutic agents?

Answer 33

Local instillation of hyaluronidase (300IU in 6ml saline) or applying topical DMSA.

Question 34

What preventive measures should be taken to avoid extravasation?

Answer 34

1. Use a clean, first-stick IV catheter, flushed with saline, not heparin. 2. Rotate limbs for consecutive treatments. 3. Use the smallest gauge catheters possible.

Question 35

What is the correct procedure for IV catheter removal to prevent extravasation?

Answer 35

Flush the catheter with saline before removing it and use a swab during removal to avoid dropping residual drug on the cat’s coat.

Question 36

What should be done if resistance, discomfort, or swelling is noticed during a chemotherapy infusion?

Answer 36

Stop the infusion immediately and investigate the cause.

Question 37

Which chemotherapeutic agent is most commonly associated with anaphylaxis in cats?

Answer 37

L-asparaginase, especially when given intravenously (should be administered intramuscularly).

Question 38

Which other chemotherapeutic agents have been associated with anaphylaxis in cats?

Answer 38

Doxorubicin and rarely cytosine arabinoside.

Question 39

What are the signs of anaphylaxis in cats during chemotherapy?

Answer 39

Hypotensive shock, acute bronchospasm, and gastrointestinal signs like vomiting and diarrhoea (which may be haemorrhagic).

Question 40

How should anaphylaxis during chemotherapy be managed?

Answer 40

IV fluids for circulatory support, adrenaline, antihistamines, bronchodilators, corticosteroids, gut protectants, and anti-emetics.

Question 41

What are the preventive measures for anaphylaxis when administering chemotherapy in cats?

Answer 41

1. Administer L-asparaginase intramuscularly. 2. Pre-medicate with chlorpheniramine before doxorubicin. 3. Avoid using the agent again if anaphylaxis has occurred.

Question 42

Which chemotherapeutic agent is potentially nephrotoxic?

Answer 42

Anthracyclines, such as doxorubicin.

Question 43

What should be considered when using drugs metabolized by the liver in cats?

Answer 43

Drugs like vincristine and doxorubicin should be used with caution in cases of liver dysfunction.

Question 44

What are the side effects of hydroxyurea in cats?

Answer 44

Stomatitis, nail sloughing, alopecia, dysuria, pulmonary fibrosis, gastrointestinal and bone marrow toxicity, and methemoglobinemia at high dosages (>500 mg).

Question 45

Why are cisplatin and carboplatin not recommended for use in cats?

Answer 45

They have severe toxicities in cats, which make their use inadvisable.