Post-Chemotherapy Reactions/Instructions
Gastrointestinal Side Effects
Nausea (and refusal to eat) can occur in veterinary patients and seems to occur more frequently in cats than in dogs. If this happens 1-3 days post-treatment, it is usually transient and requires no specific treatment. Tempting the pet with favorite foods, and warming the foods slightly will often increase palatability. For dogs, adding cooked eggs, pasta, lean chicken, or hamburger can be helpful. If this condition persists, medication to reduce nausea and promote appetite can be used.
Vomiting can also occur at any time during treatment. When it occurs 1-2 days post-treatment, and the pet is otherwise bright, active, and alert you can use Pepto Bismol¬ using the label “adult dose” for dogs over 40 lbs.; “childrenÕs dose” for dogs under 40 lbs., and 1/4 tsp. for cats (dosed up to twice daily). Remove food for 12-24 hours, and replace it with a pile of ice in a dish. This will help to maintain hydration without stimulating further vomiting. If the vomiting is repetitive (greater than 4X), contains blood, or the pet seems weak and depressed, assume your pet requires immediate veterinary attention.
Diarrhea may occur but is often mild and transient. Several over-the-counter treatments may be given safely to pets and may reduce intestinal discomfort. Imodium A-D ¬ or “Kaopectate” is dosed at “adult dose” for dogs 40 lbs. and over; “children’s dose” for dogs less than 40 lbs.; and 1/4 tsp. for cats up to 2-3X daily. If the diarrhea is severe, persistent, contains blood, or the animal seems weak or depressed, veterinary attention is required.
Fever/Sepsis As previously mentioned, virtually all chemotherapeutic drugs have the ability to at least temporarily suppress the body’s own immune system. The normal range of white blood cell counts in animals is about 6,000-17,000/cmm. If the white blood cell count (neutrophils or “wbcs”) is below about 2,000, then the pet runs the risk of systemic infection. The pet will usually manifest fever (but not always). If the bacteria travel through the bloodstream, it is known as “sepsis.” In rare cases, shock can occur (septic shock), and without rapid treatment, the risk of death is high. Though this period of susceptibility is brief and occurs at a fairly predictable time, its consequences can be life-threatening. Below is a list of the most commonly used drugs and the expected low point in cell counts (the “nadir”), given in days post-treatment:
| Drug | High-Risk Period |
| Doxorubicin (Adriamycin®) | 7-10 days |
| Vinblastine | 5 – 7 days |
| Cyclophosphamide ( Cytoxan®) | 7 – 10 days |
| Lomustine (CeeNu®) | 7 days, then again at 21 days |
| Mitoxantrone | 7 – 10 days |
| Cisplatin | 10 – 14 days |
| Carboplatin | 10 -13 days |
| Vincristine | 7 – 10 days |
Signs of fever or sepsis
- Fever > 103F (temperature taken by rectal thermometer should be between 100 and 102.8 F.
- Extreme lethargy (refusal to get up off of dog bed, etc.)
- Complete disinterest in food
- Extreme weakness
- Pale and somewhat “sticky” gums
- Severe vomiting/diarrhea
What do you do if you suspect infection
- Immediate action is necessary
- Start the antibiotics you have been given; double the first dose, then continue as the label directs
- Track the temperature at hourly intervals
- If your pet is not significantly better in 1-2 hours, call your local veterinarian or a local emergency clinic. DO NOT WAIT OVERNIGHT! This situation can be treated rapidly and almost always successfully. However, an extended delay before initiation of treatment may result in health complications or even death. Your local veterinarian has been given treatment protocols for this situation and in most cases, this will be more convenient for you.