Cat Health

Chlorambucil: Chemotherapy for your cat’s cancer

chlorambucil for cats

When it comes to our furry friends, we always want the best possible for them. This especially becomes true in regards to health care.

Diagnoses can be daunting to deal with, and it is important to proceed armed with all the best possible information.

Cancer, especially immune-mediated cancers, are formidable to hear about for human patients, and much-less discussed for animal ones.

Chlorambucil has been shown to be one such treatment option that has provided a happy ending for many feline friends.

Although initially broaching the topic can be overwhelming, we aim to provide a comprehensive list of reliable sources and information that help owners understand what exactly they’re giving their cat and how Chlorambucil works to defeat cancer.

What are signs my cat might have a lymphoma? 

According to PetMD, there are multiple different types of lymphoma and associated symptoms with each.

Mediastinal lymphoma (within the lungs) symptoms include open-mouth breathing, cough, weight loss, and appetite loss.

Alimentary lymphoma (gastrointestinal tract) includes symptoms such as lethargy, weight loss, vomiting, diarrhea, constipation, bloody stools, and tarry stools. Multicentric lymphoma (lymph nodes) symptoms include swollen lymph nodes, appetite loss, and depression. Renal lymphoma (kidneys) symptoms include anorexia, vomiting, and weakness.

What has caused my cat to come down with a lymphoma? 

PetMD believes that the frequency of lymphoma is believed to be associated with exposure to feline immunodeficiency virus and feline leukemia virus.

How would my cat be diagnosed with a lymphoma? 

If your cat is experiencing any of the above symptoms it is important to take your cat to a veterinarian as soon as possible, leaving symptoms could cause them to worsen and prompt diagnosis of a lymphoma ensures your cat’s survival.

PetMD explains that veterinarians can conduct routine lab testing including a blood count, biochemistry profile and urinalysis to give a proper diagnosis.

What exactly is Chlorambucil? 

Chlorambucil, commonly known as Leukeran, is a type of chemotherapy commonly prescribed for dogs and cats.

It is an immune-suppressing drug typically used to treat immune-mediated diseases; more specifically it is commonly used for cancers such as lymphoma and leukemia.

How does Chlorambucil help my cat’s cancer? 

Chlorambucil is what’s known as an immunosuppressant, meaning it prevents activation of the immune system.

Mar Vista Vet, explains that Chlorambucil is an alkylating agent of the nitrogen mustard group and functions by forming a strong bond with DNA strands so the helix can not unzip and therefore can not replicate.

This makes it impossible for cells to continue to divide and replicate, a problem with cancer cells which replicate out of control.

In this method, Chlorambucil also works to suppress antibody production, so the body does not continue to attack itself.

Why did my veterinarian choose Chlorambucil for my cat? 

The immunosuppressant properties of Chlorambucil make it ideal for treating tissue growth whether it be benign or malignant.

LifeLearn asserts that Chlorambucil can be used to treat conditions including arthritis, multiple myeloma, feline pemphigus foliaceus (skin disease), feline eosinophilic granuloma, and glomerulonephritis (kidney injury disease).

Dr. Barbara Forney asserts that Chlorambucil is one of the safest cytotoxic drugs as it is easily absorbed through oral administration and processed through the liver.

Why is my cat being treated with medication, what about other options? 

Typically cancer in both humans and animals can be treated with radiation therapy, surgery or medication.

Medication is especially helpful when the cancer is not necessarily localized to one area, as is the case with most immune-mediated cancers.

Mar Vista Vet explains that medication allows the treatment to be carried throughout the body, where Chlorambucil will target activity predominantly found in cancer cells. Toxicity is usually limited because chemotherapy drugs actively target cancer cells.

What side effects might my cat experience when taking Chlorambucil? 

The American Animal Hospital Association reported that neurotoxicity occurred in one case of treating a cat with Chlorambucil.

PetMD has reported the following side effects: GI tract damage, low white blood cell and platelet count, pulmonary disease, kidney disease, irreversible infertility in males, blood cell deficiency, and bone marrow suppression.

How can I tell if my cat may be experiencing one of these side effects? 

VCA Hospitals explains that if you notice bruising, bleeding, infection, depression, excessive lethargy, or difficulty breathing these could be symptoms of bone marrow suppression, resulting from Chlorambucil.

Since Chlorambucil is an immunosuppressant, it is advised to keep your cat away inside and away from other animals, especially strays, to minimize chances of infection.

Diamond Back Drugs advises taking your cat to the veterinarian if you see vomiting, diarrhea, hair loss, and loss of appetite. However, unlike with human chemotherapy, hair loss is relatively rare in cats.

Can my cat continue to take his/her regular prescriptions in addition to Chlorambucil? 

PetMD advises that the following drugs may have an adverse reaction when taken in addition to Chlorambucil: bone marrow suppressant, antineoplastic, corticosteroid, other immunosuppressant drugs, protein-bound drugs, amphotericin B.

Giano Panzarella of Diamond Back Drugs also concerns not to use Chlorambucil with males intended for breeding or on pregnant or lactating females as the drug has been known to cause birth defects.

How is Chlorambucil administered and how often should my cat take it? 

Typically the pill is given in the form of Leukeran 2 mg brown tablets. For dosage, consult a veterinarian as to what would be correct for your cat. Alternatively, high dose pulse therapy may be an option according to Dr. Kelly Mitchell.

How long does Chlorambucil take to work? 

Typically this will vary for every cat. A veterinarian will advise on how long the cat should continue the medication, typically depending on how the cat reacts and how long it takes until the cancer is considered to be in remission.

On average, studies have shown this takes over a year. See below for more information on recovery times and remission period.

How do I give my cat Chlorambucil? 

Chlorambucil is administered in a tablet form. As many people are already aware, giving pill medications to cats presents its own set of difficulties.

Dechra Academy provides an instructive and informative video outlining tips on how to administer pills to your cats, especially if you are alone. Chlorambucil is best given to a cat with food.

Do I need to be careful when handling Chlorambucil? 

When handling Chlorambucil it is of the utmost importance that gloves are worn. VCA Hospitals also advises that owners should avoid contact with urine, feces, and saliva from the cat for 48 hours after administering and hands should be washed immediately.

If you have other cats, keep them away from the sick cat’s litter, so they do not accidentally consume the drug. If you yourself are immune-compromised you may need to take extra precaution when handling Chlorambucil.

How should I store Chlorambucil? 

Chlorambucil should be stored out of children’s reach in a tightly sealed container in a refrigerator between 2 and 8 degrees Celsius according to VCA hospitals.

I accidentally forgot to give my cat their dose of Chlorambucil, what should I do now? 

PetMD advises that for missed doses, give the dose as soon as possible. However, if it is already time for the next dose, then skip the missed dose and proceed as normal.

Can my cat overdose on Chlorambucil? 

Overdosing is possible and the dosage recommended by a veterinarian should be strictly followed. Symptoms of overdosing according to Dr. Barbara Forney may include seizures and pancytopenia.

If concerned a cat may have overdosed, stomach or gastric emptying is the best option depending on the neurologic status of the cat.

How expensive is Chlorambucil? 

Unfortunately, Chlorambucil is a fairly expensive treatment with each pill costing between $26-28 in the US according to IBD kitties.

Are there alternatives if my cat doesn’t tolerate Chlorambucil? 

There are alternatives if your car cannot tolerate Chlorambucil, these many include taking high doses of steroids. Other options are best discussed with a veterinarian.

What can I do to support my cat while he/she is taking Chlorambucil? 

Dr. Kelly Mitchell suggests that to best help your cat consider discussing with a veterinarian the possibility of adding on B12 supplements to aid in digestion and absorption of nutrients.

Additionally, the use of probiotics may be encouraged as well, especially if cats are having consistent diarrhea.

Should I change my cat’s diet while he/she is taking Chlorambucil? 

Since Chlorambucil in addition to the lymphoma is stressful to felines, it is likely cats diagnosed and undergoing treatment may already be malnourished.

It is important to keep continually monitoring a cat undergoing treatment to make sure weight-loss, anorexia, and consistent vomiting are not occurring.

Dr. Kelly Mitchell suggests that an internal feeding tube such as an esophagostomy may be necessary if the cat is consistently vomiting and unable to keep up weight.

How often should my cat be monitored by the veterinarian while taking Chlorambucil? 

It is necessary to do regular complete blood counts since Chlorambucil has been shown to cause bone marrow suppression which can lead to anemia.

Dr. Kelly Mitchell recommends that an initial complete blood count should be performed prior to starting the medication and then every 2-3 weeks following or prior to each Chlorambucil therapy treatment for high pulse sessions.

Bone marrow recovery should only take 1-2 weeks after stopping dosage of Chlorambucil.

Is Chlorambucil right for my cat? 

Only a veterinarian can truly prescribe and diagnosis if Chlorambucil is the best option. IVG hospitals have shown that cats with untreated lymphoma had an average lifespan of 4 weeks and cats treated with prednisone alone are only expected to live 60 – 90 days, thus cats that are treated with drugs including Chlorambucil have been found to have significantly higher life spans.

Other cats have made full recoveries on Chlorambucil! 

Stein et al found that the overall response rate to Chlorambucil was 96% in felines with a median remission time of 786 days.

Their follow-up studies found seven cats had relapsed but made a 100% recovery when treated with a second protocol.

Dr. Kelly Mitchell reported 76% of cats treated with Chlorambucil for a GI lymphoma reached full remission with a median time of 18.9 months.

She also states that cats who achieve full remission are more likely to have overall longer survival times, yet the direct effects of Chlorambucil on survival times have yet to be fully understood.

How long do other cats typically live after being fully treated by Chlorambucil? 

Pope et al found that median survival was 1078 days. They also found there was no significant difference in survival times for cats where lymphoma was in the GI tract as compared to lymphomas found in other areas.

IVG hospitals also state that survival can also depend on the initial site of cancer, the cat’s health at the beginning of the treatment, how quickly the cat is diagnosed and the extent of the disease.

Have other cat owners been through treatment with Chlorambucil? 

Yes! there exist many online support groups and multiple case studies to show that Chlorambucil has proved the effective treatment for many felines.

IBD kitties provide multiple case studies where owners have outlived their day to day experiences using Chlorambucil including everything from the diagnosis to the treatment process and after effects of recovery.

There exist multiple support groups of many people who have dealt with the process, you’re not alone!

Overall Chlorambucil has shown to be one of the most effective ways to treat feline lymphomas. Results from multiple studies have shown the highest survival with Chlorambucil with high median survival post-treatment as well.

While Chlorambucil may not be right for your cat, it is important to consult with a veterinarian to discuss all the proper treatment options and what your cat needs based on the results of laboratory tests and symptoms.

Lymphoma can be different for each cat, depending on their health, lifestyle and initial diagnosis, so veterinarian consultation is always of the utmost importance, as cases can vary from cat to cat.

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