Feline Lymphoma

Lymphosarcoma, commonly called lymphoma, is one of the most common cancers diagnosed in cats. It is a cancer of the lymphocytes (a type of white blood cell) and lymphoid tissues. Lymphoid tissue is normally present in many places in the body including lymph nodes, spleen, liver, gastrointestinal tract and bone marrow.

Unlike lymphoma in dogs, viral causes of feline lymphoma are well defined. Infection with the feline leukemia virus (FeLV) has been shown to cause a significant (~60 fold) increase in risk for development of lymphoma in cats. Cats with the feline immunodeficiency virus (FIV) are also at increased risk of developing lymphoma (7 fold) and infection with both viruses confers a 77 fold increase in risk. Cats of any age, breed and of either sex can be affected. We typically see lymphoma in younger cats that are infected with the feline leukemia virus, and in older cats that are not infected with the virus. Other possible risk factors include exposure to second hand tobacco smoke, chronic immunosuppressive therapy, as well as chronic inflammatory diseases.

Types of Lymphoma
Lymphoma can be subdivided into several different forms, depending on the primary or predominant site of the tumor. Some cats have multiple sites of involvement and do not fit well into just one category. These are usually animals with very advanced disease.

1. Gastrointestinal Tract: The most common form is involvement of the gastrointestinal (GI) tract. This includes the stomach, intestines and liver; as well as some of the lymph nodes surrounding the intestines. Cats with this type of lymphoma often have clinical signs consisting of vomiting, diarrhea, weight loss or a decreased appetite.

2. Mediastinal: The mediastinum is a term used for a special aggregation of lymphoid tissue in the chest. Cats with this type of lymphoma often are seen because of difficulty breathing due to a large mass in the chest or an accumulation of fluid around the lungs.

3. Renal: The kidneys may be the primary sites of involvement. Cats that have this type are often seen because of signs related to kidney failure (increased thirst, increased urination, loss of appetite, vomiting).

4. Bone Marrow: If the cancer were confined to the bone marrow, it is considered leukemia. The signs that we see in cats are usually related to the decreased numbers of normal cells such as red blood cells that carry oxygen, white blood cells that fight infection and platelets that help with clotting - all of which are made in the bone marrow. Anemia (low red blood cell counts), infections and bleeding are common problems.

5. External Lymph Nodes: In a few cats, the only site of involvement is the external lymph nodes. These cats may be seen because of problems such as vomiting and loss of appetite or because the owner found “lumps” (enlarged lymph nodes) on their cat.

6. Other Sites: We will occasionally see other sites such as the skin, nose, brain and spinal cord as the primary site of involvement

Diagnosis and Initial Evaluation
A biopsy (tissue) or cytology sample is required in order to make a diagnosis of lymphoma. In some cases, we can obtain a diagnosis by a fine needle aspirate but sometimes a biopsy to obtain a larger piece of tissue is necessary to confirm the diagnosis. The ease with which a diagnosis can be obtained depends upon where the tumor is located.

A complete evaluation of a cat suspected of having lymphoma includes determining the extent of the cancer (i.e. looking for spread of the cancer to other sites) which is known as staging. A complete blood count (CBC), serum chemistry profile (which looks at things such as liver and kidney function, protein levels, blood sugar and electrolytes), urinalysis and FeLV/FIV testing are always recommended and provide important information regarding the effects of the cancer on body functions as well as the ability of the patient to handle chemotherapy or other treatments. Additional tests may include radiographs, abdominal ultrasound, bone marrow aspirate and CT/MRI. Chest radiographs (x-rays) allow us to look for internal lymph nodes, lung involvement, an enlarged mediastinum or fluid around the lungs. An abdominal ultrasound allows us to evaluate the liver, spleen, internal lymph nodes and intestinal tract for possible tumor involvement. A bone marrow aspirate allows us to look for tumor cells in the bone marrow as well as to evaluate the marrow’s ability to produce normal blood cells. Once we know the extent of disease, we can then decide on the best treatment for each individual patient.

Treatment and Prognosis
Chemotherapy is the mainstay of treatment for lymphoma; however, there may be situations when surgery and/or radiation are also indicated. Radiation therapy may be recommended if the cancer is localized to one site such as the nasal cavity. Often surgery or radiation therapy is used in addition to chemotherapy. Specific recommendations will be discussed based on your pet’s particular situation.

Lymphoma is very responsive to chemotherapy and 50-60% of treated cats will go into remission. The definition of remission is the complete disappearance of detectable cancer; however, microscopic amounts of tumor cells can remain hidden in the body. A remission is NOT a cure but it does allow your pet to experience a good quality of life without clinical signs associated with their disease. The length of the remission depends upon many factors including the primary site, how sick an animal is at the start of treatment and the extent of disease. In most situations, the average remission and survival times (with chemotherapy) are between six to twelve months; with about 30% of cats experiencing disease control for greater than one year and approximately 10-15% of cats living longer than two years.

Solitary lymphoma such as nasal is generally treated with radiation +/-chemotherapy. The radiation can be considered definitive with the intent for long term control or palliative for symptom relief in order to improve/maintain the patient’s quality with minimal negative impact. The prognosis for solitary lymphoma such as nasal lymphoma is generally better with many cats achieving local control for 1-1.5 years although there is still a concern that the cancer may spread within 3-6 months. If solitary lymphoma is treated with radiation and the cancer spreads later in life chemotherapy can be considered at that time.

The exact chemotherapeutic drugs and schedule will depend upon how aggressively the cancer is behaving, how sick an animal is at the start of treatment and any abnormalities in organ function, particularly kidneys and liver as well as the goals of treatment. Chemotherapy is more effective when we use a combination of drugs; therefore, most protocols generally consist of 4-6 different drugs. This is called a multi-drug protocol. Initially, treatments are given more frequently (i.e. once weekly) and then, depending upon the response and protocol used, are gradually spread out and/or discontinued. Other options for therapy may consist of using a single chemotherapy drug (single agent therapy) at 3- week intervals, or palliative care which is simply designed to keep your pet comfortable at home for as long as possible. While palliative care with drugs may provide comfort it generally only yields 1-2 month survival times. A disadvantage to single agent therapy is that remission rates and expected survival times are much more difficult to predict with these protocols. Bloodwork and/or radiographs and ultrasounds are generally repeated at regular specified intervals to monitor for side effects (such as a low white blood cell count) and to determine the pet’s response to treatment.

If a patient comes out of remission or relapses, we can try to put them back into remission using either new combinations of the same drugs or different drugs. Unfortunately, the chances of obtaining a second remission are lower; however, there are some cats that do respond and have additional time with a good quality of life.

Side effects
Most cats tolerate chemotherapy very well and experience minimal side effects. Serious side effects are only seen in 5-10% of the patients we treat. If side effects are serious or intolerable, we can consider either lowering the dose of the offending drug or substituting a different drug. Side effects include nausea, vomiting and loss of appetite, diarrhea, extreme tiredness or rarely infection. Certain chemotherapy agents can affect organ function over time. Cats do not lose their hair but may lose their whiskers and have a different texture to their fur secondary to chemotherapy.

Hyperthyroid Cats and the IDEXX SDMA Test for Kidney Function

Hyperthyroidism is a disease seen primarily in older cats, in which kidney disease is also common. The clinical challenge is that hyperthyroidism can mask the presence of kidney disease, and until now, there has not been a reliable routine diagnostic test that can assess kidney function in cats affected by hyperthyroidism.

Creatinine is a common test for kidney disease and is measured with a blood test. Creatinine, being a by-product of muscle, is under-produced in feline hyperthyroidism as a result of muscle loss, and thus becomes a poor indicator of kidney function in hyperthyroid cats. Creatinine is also lowered by the hyperfiltration associated with the increased metabolic state that is common in hyperthyroid cats.

IDEXX Laboratories has developed a test, the SDMA Test, which is NOT impacted by weight loss and muscle mass and appears to be only slightly blunted by hyperfiltration, making it a much more reliable marker of kidney function in hyperthyroid cats.

Heart Murmurs in Cats

Extra heart vibrations that are produced as a result of a disturbance in the blood flow—enough, in fact, to produce audible noise—are referred to as murmurs. Often, the murmurs are classified according to a variety of characteristics, including their timing. Systolic murmurs, for example, occur when the heart muscle contracts; diastolic murmurs occur when the heart muscle relaxes between beats; and continuous and to-and-fro murmurs occur throughout all or most of the cardiac cycle.

Symptoms and Types
The symptoms associated with murmurs depend on a variety of characteristics, including their grade, configuration, and location. If, however, the murmur is associated with structural heart disease, your cat may display signs of congestive heart failure such as coughing, weakness, or exercise intolerance.

Grading Scale for Murmurs

  •  Grade I – barely audible
  •  Grade II – soft, but easily heard with a stethoscope
  •  Grade III – intermediate loudness; most murmurs which are related to the mechanics of blood circulation are at least grade III
  • Grade IV – loud murmur that radiates widely, often including opposite side of chest
  •  Grade V – very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall
  • Grade VI – very loud, audible with stethoscope barely touching the chest; the vibration is also strong enough to be felt through the animal’s chest wall


  • Plateau murmurs have uniform loudness and are typical of blood regurgitation through an abnormal valvular orifice (regurgitant murmurs).
  • Crescendo-decrescendo murmurs get louder and then softer and are typical of ejection murmurs due to turbulent forward flow.
  • Decrescendo murmurs start loud and then get softer and are typical of diastolic murmurs.

Murmurs are caused by the following:

  • Disturbed blood flow associated with high flow through normal or abnormal valves or with structures vibrating in the blood flow.
  • Flow disturbances associated with outflow obstruction or forward flow through diseased valves or into a dilated great vessel.
  • Flow disturbances associated with regurgitant flow due to an incompetent valve, patent ductus arteriosus, or a defect in the septum (the wall that separates the heart’s right and left sides).

More specifically, the following are some conditions and diseases that may bring on murmurs:

  • Systolic Murmurs
  • Anemia
  • Hyperthyroidism
  • Heartworm disease
  • Mitral and tricuspid valve heart failure
  • Cardiomyopathy and aortic valve insufficiency
  • Mitral and tricuspid valve dysplasia
  • Systolic anterior mitral motion (SAM)
  • Dynamic right ventricular outflow obstruction
  • Dynamic subaortic stenosis
  • Aortic stenosis
  • Pulmonic stenosis
  • Atrial and ventricular septal defect
  • Tetralogy of Fallot
  • Mitral and tricuspid valve endocarditis (inflammation of the inner part of the heart)

Continuous or To-and Fro-Murmurs

  • Patent ductus arteriosus
  • Ventricular septal defect with aortic regurgitation
  • Aortic stenosis with aortic regurgitation
  • Diastolic Murmurs
  • Mitral and tricuspid valve stenosis
  • Aortic and pulmonic valve endocarditis (inflammation of the inner layer of the heart)

In order to determine exactly what is causing the symptoms, your veterinarian must differentiate a wide range of abnormal heart sounds—split sounds, ejection sounds, gallop rhythms, and clicks, for example. He or she must differentiate between abnormal lung and heart sounds, and listen to see if timing of abnormal sound is correlated with respiration or heartbeat.
The location and radiation of the murmur, as well as the timing during cardiac cycle, is another way to determine the underlying cause. This can be accomplished by conducting a variety of tests, including chest radiographs (x-rays), Doppler studies (blood pressure), and echocardiography. A complete blood count, meanwhile is one of the preferred methods for confirming anemic murmurs.

Unless heart failure is evident, your cat will be treated as an outpatient. The course of treatment will be determined based on the associated clinical signs. Kittens with low grade murmurs, for example, may require little or no treatment and the murmur may resolve itself within six months. Routine diagnostic imaging is recommended for cats with murmurs.
Source URL; http.//www.petmd.com/cat/conditions.cardiovascular/c_ct_heart_murmur

Hypertrophic Cardiomyopathy in Cats

The heart has four chambers: two chambers at the top, the right and left atria; and two chambers on the bottom, the right and left ventricles. The left ventricle is responsible of receiving oxygenated blood from the lungs and pumping the blood out into the aortic valve, the main artery of the body, which feeds the oxygenated blood to all parts of the body. Hypertrophic cardiomyopathy (HCM) affects the left ventricle and its functional ability to pump blood into the aorta. The normal, healthy left ventricle is already thicker than the right ventricle owing to its greater workload in pumping blood out into the body. In hypertrophic cardiomyopathy, the muscle of the left ventricle is abnormally enlarged or thickened. A cat may have other diseases of the heart, but they will be independent of HCM.

There is an apparent genetic predisposition for this condition. Some families have had a high number of cases, particularly Maine coon cats, where a mutation that is associated with the disease was identified in one large family. The role of genetics has not been definitively determined in other families or breeds, although some association has been documented in American Shorthairs and Persians.

HCM occurs more often in cats five to seven years of age, although the age range reported cases ranges from three months to 17 years, with most cases affecting males. Heart murmurs in older cats are generally caused by hyperthyroidism or hypertension rather than HCM.
Symptoms and Types

  •  Loss of appetite (anorexia)
  •  Lethargy
  •  Weak pulse
  •  Difficulty breathing
  •  Short, rough, snapping breathing sounds (crackles)
  •  Abnormal heart sounds (i.e., muffles, galloping rhythm, murmurs)
  •  Inability to tolerate exercise or exertion
  •  Sudden hind-limb paralysis with cold limbs due to clot in the terminal aorta
  •  Bluish discoloration of foot pads and nailbeds (indicates a lack of oxygen flow to the legs)
  •  Collapse
  •  Sudden heart failure

The cause for HCM may remain unknown in many cases. However, genetic mutations and predispositions are known to head to HCM in cats. And though not a direct cause of the condition, hypertension and/or hyperthyroidism can further complicate HCM in cats.
Your veterinarian will need a thorough history of your cat’s health leading up to the onset of symptoms, including any information you have about your cat’s genetic background.
An electrocardiogram (or EKG) recording can be used to examine the electrical currents in the heart muscles, and may reveal any abnormalities in cardiac electrical conduction (which underlies the heart’s ability to contract/beat), and can also help your veterinarian to determine the origin of the abnormal heart rhythms, if they are present. However, and EKG may not be adequate for a definitive diagnosis. Radiograph and echocardiograph (ultrasound) imaging will be more useful for visually examining the heart for enlargement or thickening of the walls, or for thickening of the mitral valve (which controls the flow of blood between the left ventricle and the left atrium). Other conditions will need to be either ruled
out or confirmed before your doctor settles on HCM. There are two conditions, which are especially likely to mimic HCM that your cat will be checked for. Blood pressure will be checked in order to rule out hypertension, and the blood will be tested for high levels of thyroid hormones. Hyperthyroidism will exhibit many of the same symptoms as HCM, such as lethargy, shortness of breath and irregular heart rhythm.
If there is a diagnosis of HCM, your cat will be hospitalized for appropriate care, especially if it is suffering from congestive heart failure, a common outcome of this disease. Your cat will be placed in a quiet environment to minimize stress, and if it is having trouble breathing it will be given oxygen therapy.

There are several possible medications that can be used to treat HCM:

  •  Diltiazim to slow the heart rate, treat irregular heartbeats, and possibly reduce the enlargement in the left ventricle
  •  Beta blockers to slow the heart rate, correct irregular heartbeats, and control blockage of the blood flow. These are not used if the cat has congestive heart failure.
  •  Ace inhibitors, in cases with congestive heart failure, to improve the flow through the ventricle
  •  Aspirin to decrease risk of blood clots
  •  Warfarin to prevent blood clots
  •  Furosemide (diuretic) to remove excess fluid from the body
  •  Spironolactone (a diuretic used sometimes in conjunction with furosemide) for cats with congestive heart failure
  •  Nitroglycerin ointment, to improve flow by dilating (opening) the ventricle and arteries

Living and Management
The cat should be put on a sodium-restricted diet, especially if there is congestive heart failure, to keep the pressure in the blood stable. Providing a quiet and safe space for your cat, away from other pets and active children, is important to its recovery. Environmental stress may activate the nervous system, placing excess stress on the already overstressed left ventricle, and possibly lead to heart failure.
You will need to monitor your cat closely during the recovery period, watching for difficulty breathing, lethargy, weakness, lack of appetite, and painful hind-limb weakness or paralysis. Periodic diagnostic testing (such as repeat echocardiogram) and bloodwork will be necessary (to monitor kidney function and electrolytes).
Source URL: http://www.petmd.com/cat/conditions/cardiovascular/c_ct_cardiomyopathy_hypertrophic

proBNP Testing in Cats

The cat’s heart increases production and secretion of BNP, B-type natriuretic peptide hormone, in response to excessive stretching of heart muscle cells, which is common in many forms of heart disease and heart failure. The magnitude of the increase in circulating BNP is correlated to the severity of the underlying heart disease. A diagnostic test is available, the feline NT-proBNP, which can measure this hormone.

Cats with respiratory signs such as shortness of breath (dyspnea), rapid breathing (tachypnea), and cough may be associated with underlying heart disease such as cardiomyopathy and congestive heart failure, or a primary respiratory disease such as bronchitis/asthma, pneumonia, pleural effusion, and so on. At times it is unclear if the respiratory symptoms are related to cardiac (heart) or pulmonary (lung) disease, especially if the physical exam and chest x-rays are ambiguous. In such cases, a proBNP test may help guide further diagnostic testing and therapy. The proBNP is not a stand-alone test but can be valuable when included with other diagnostic testing such as chest x-rays and echocardiogram.

Treatment Explanation


Treatment for Hyperthyroidism in cats:

There are three options for treatment of hyperthyroidism. All three are identical treatment forms to those for human patients with hyperthyroidism.

Oral anti-thyroid medications

    This medication (methimazole) blocks the production of thyroid hormones by the thyroid gland. This oral medication does not cure hyperthyroidism, and is usually required twice daily (lifelong) to control the disease. Methimazole can be useful in the treatment of hyperthyroidism in cats but it is not an innocuous drug. Regularly scheduled blood tests are required to adjust dosages and to determine if potentially harmful side effects are present. Owners frequently find that oral administration of this drug to their cat is costly and difficult over time.


    Surgical removal of the thyroid tumor (s) is performed under general anesthesia. This procedure usually results in a return to normal thyroid function for the cat though the risk of anesthesia must be given careful consideration. If both lobes of the thyroid gland are not removed, approximately 70% of cats will eventually develop a functional benign tumor of the remaining tissue, requiring additional treatment or surgery.

    Alternatively, removing both thyroid lobes during the same surgery increases the risks of disturbing calcium metabolism, which is governed by the 4 small, adjacent parathyroid glands. Because affected patients are usually geriatric, and under-conditioned, they must be monitored for post-surgical side effects including low calcium levels (hypocalcemia), and kidney dysfunction. They are commonly hospitalized from 2-5 days. To lessen anesthetic and surgical risk to the patient, a cat may be required to undergo medical therapy with methimazole until physical condition improves. Occasionally, hyperthyroid cats are found to have functioning thyroid tumors in the chest cavity, where surgery is not feasible.

Radioiodine I-131

    Of the three treatment options, radioiodine is considered by many to be the treatment of choice for most hyperthyroid cats. Overall, radioiodine provides a simple, effective, and safe cure for cats with hyperthyroidism. This form of therapy has been used successfully for over 50 years in human medicine, and over 20 years in veterinary medicine. It requires no anesthesia and can be offered to medically stable patients, regardless of their age!

    How does it Work?

    Thyroid function requires the uptake of the element iodine in the body in order to produce normal thyroid hormones. If a radioactive form (I-131) of iodine is administered to hyperthyroid cats, it accumulates in thyroid tissue wherever it occurs in the body. Thyroid tumors accumulate the greatest amount of radioactive iodine. Once inside the tissue, the radioactive iodine emits radiation, which destroys the overactive thyroid cells.

    The radioactive iodine not trapped in the thyroid is excreted in the urine and to some degree in the feces. The amount of radioactivity emitted by the compound naturally decreases by half, every 8 days. Thus, the radioactivity remaining in the cat's thyroid tumor tissue will painlessly dissipate on its own. Normal thyroid tissue tends to be automatically protected from the effects of radioiodine since the uninvolved thyroid tissue is suppressed and receives only a small dose of radiation. As an added patient benefit, there is no injury risk to the adjacent parathyroid glands. The residual (normal) thyroid tissue resumes full function within 1-3 months after treatment. An average of 95-98% of I-131 treated cats are permanently and safely cured with a single injection!

    Is it Safe?

    "Radioactive" iodine, despite its somewhat scary title, is considered the "gold standard" for safety and efficacy in treating hyperthyroid cats. I-131 administration is a safe and effective treatment for feline hyperthyroidism. This therapy has been successful in large numbers of cats, and the only recognized deleterious side effect has been hypothyroidism (underactive thyroid gland). This occurs in an extremely small percentage of cats and almost never requires specific treatment. The greatest risks are to the doctors and staff who work in the thyroid unit on a long-term basis. However, with stringent safety regulations, protocols, and monitoring, this form of therapy can be safe for cats and the caregivers!

Radiotherapy: What happens to my cat?

On or before the day of admission, you and your cat will meet with a veterinary medical specialist at PVESC. Your cat will be thoroughly examined and the medical records will be reviewed. The doctor will discuss any admission tests required (which can be done at your general veterinary hospital or on-site at PVESC prior to treatment) to ensure that radioiodine therapy is the best option for your cat. The results of any tests performed at PVESC will be discussed with you before proceeding with treatment. These tests can include:

    * A complete blood count

    * A thyroid hormone level (T4 or free T4) to an outside lab

    * Serum biochemistry analysis

    * Urinalysis

    * Blood pressure

    * Full body radiograph

    * Cardiac Pro BNP test

    * Ultrasonography (cardiac ultrasound to evaluate function if needed)

If your cat is judged to be medically stable, he or she will be admitted to the radiotherapy unit within 24-48 hours of your appointment. The unit is specially constructed for this use and houses only cats that are receiving radioactive iodine.

The quiet accommodations include "Southwest" decor and housing in roomy and cheery cat condos (by Snyder Manufacturing, Inc.). These condos have separate bathrooms and shelves for snoozing. The unit includes windows for natural lighting, music, and heated floors. The patients enjoy watching patrons of our bird and squirrel feeders.

Once the dose of radioactive iodine for your cat has been determined, it is injected painlessly under the skin (subcutaneous) exactly like a routine vaccination.

From that point on, your cat need do nothing else but sleep, eat and play while the radiation dissipates to safe levels (usually 3-7 days). We like to spoil all our patients as much as safely permissible. This brief separation is likely to be harder for the owners than the patients!

Your cat will be monitored daily while in our care. By daily monitoring of your cat's radiation level, we can determine when this level has declined to that allowable by law. At this time, your cat can be released to you. You will be contacted daily with updates during your cat's stay in the radiotherapy unit. If you have questions or concerns, do not hesitate to call us.


Pre-Treatment Diagnostic Testing

Pre-Treatment Diagnostics

These diagnostic tests are required before your cat can be admitted for radioactive iodine therapy.  We recommend that these tests be completed at your regular veterinarian’s office one to two weeks before your radioactive iodine consultation.  If these tests have not been completed, they can be completed at Portland Veterinary Specialists at the time of your radioactive iodine therapy consultation.  

Lab work
      - CBC, Chemistry
      - SDMA
      - Urinalysis
      - Thyroid level

Blood Pressure

Whole-body radiograph    
      - Radiograph(s) can be emailed to PVESC if digital, or brought with you to your appointment

Admission Information


   1. You or your referring veterinarian may request an admission appointment.

   2. Anti-thyroid drugs (Tapazole, Methimazole, etc.) Should be discontinued 1-2 weeks prior to admission. Most other medications are allowable but should be discussed prior to the admission process.

   3. Food containing fish products should be discontinued 2 weeks prior to admission. Fish products have been found to prohibit the uptake of radioactive iodine.

   4. You are welcomed and encouraged to bring your cat's favorite foods and/or treats. We provide an ample, tasty feline menu as well.

   5. Cat toys may be kept with your cat but they cannot be returned.

   6. Unfortunately, the State of Maine, in accordance with the strict regulatory guidelines of the Nuclear Regulatory Commission cannot permit client visitation while cats are in the radiotherapy unit.

   7. Once admitted and treated with I-131, your cat cannot be released to you until his or her radioactivity levels drop to a specific range. In the extremely unlikely event that a patient dies from another illness while being housed in the I-131 unit, the remains must be held by us until radioactivity diminishes (eighty days).


Radioiodine therapy is considered the optimal treatment for cats with hyperthyroidism. It has an extremely high success rate and safety record and we are pleased to offer this state-of-the-art treatment.

The costs of therapy reflect costs associated with providing these services:

   1. Pre-admission consultation with a veterinary medical specialist

   2. Cost and administration of the radioactive iodine

   3. Hospitalization and patient care in the radiotherapy unit

   4. Litter, food, and patient monitoring with radiation monitoring equipment according to stringent state nuclear medicine regulatory guidelines

   5. Time and expertise of the staff

   6. Costs associated with nuclear regulatory licensing and adherence to strict safety guidelines for hospital personnel

   7. Radioactive waste-removal

The cost for treatment is $1500.00.  Pre-admission diagnostic tests are associated with separate fees.  These diagnostics may be completed at your primary care veterinary office or at PVESC and include such tests as radiographs, blood work (CBC Chemistry Electrolyte panel, T4, SDMA test), urinalysis and blood pressure.  Other tests, such as echocardiogram, may be recommended.  In the rare instance that your cat will require an increased dose of therapy, there will be an extra fee of $250.00 for cats that require more than 4 mCi of radioactive iodine for treatment due to the extra expense of the therapy and the extra hospitalization that is required. 


Admission Agreement


Owner: _________________________

Address: ________________________

Phone: (Day)____________________





Cat's Name: __________________

Age: _____ Breed: ______ Sex: ______

Color/Markings: ___________________



Referring Veterinarian: _______________________________________

Referring hospital/clinic: ______________________________________
Consent to Treat

I authorize Dr. Gail Mason to hospitalize and treat the above-described cat with radioactive iodine (1-131). I understand that my cat will remain at this facility (PVESC) after administration of radioiodine until the radiation levels have decreased sufficiently to permit release of my cat. Until this time, no visitation is permissible for human safety reasons. The radiation levels permitted are determined by the State of Maine radiation safety guidelines and regulations.

I understand that:

    * My cat will be medically evaluated (including blood/urine tests, radiographs, and ultrasonography) to assess overall health status and eligibility for treatment.
    * Though the radioiodine treatment is successful with one treatment 90-95% of the time, outcomes cannot be guaranteed. For any cats requiring re-treatment at PVESC, the cost will be one-half the original amount.
    * Rarely, a small percentage of cats (<5%) develop an under-active thyroid (hypothyroidism) within a few months after treatment. This situation would require daily thyroid supplementation.

In the event of an emergency, I authorize the veterinarians at PVESC to render such medical and/or surgical treatment as deemed necessary, and I accept financial responsibility for costs incurred.

I agree to follow discharge instructions that are provided to me and understand that pregnant women and children younger than eighteen should not have direct exposure to my treated cat for 2 weeks following hospital release.


Signature of Owner______________________________ Date_____________

Discharge Instructions

Discharge instructions for owners of radiotherapy-treated cats:

For the first two weeks please follow these detailed home instructions for handling your cat and litter waste.

Please note that if you cannot or will not follow these instructions, you must notify us, and we may need to keep your cat hospitalized for additional time before release (additional fees apply).

The thyroid hormone level continues to decline for 30 to 60 days after treatment. During this time, the symptoms of hyperthyroidism are expected to abate. Gradual weight gain and return to healthy body condition are expected. If your cat is showing signs of illness or depression, please contact PVESC.

Upon discharge from PVESC (after an average of 4 to 7 days after treatment), treated cats will still be excreting radioiodine in their urine, saliva and feces. This radioiodine is in a form that can be taken up by the human thyroid where it may cause damage. Even through the level of radioactivity is much lower than the level at which human patients are released from the hospital, you must exercise caution during this period. The remaining radioactivity will be gradually eliminated from the cat over the next 2 to 4 weeks.

1. Treated cats must remain indoors only for two weeks after discharge.

2. Pregnant women, children under eighteen and people with immune mediated diseases should not have any contact with the cat or litter pan for two weeks.

3. Prolonged close contact with your cat (under 3 to 6 feet) must be avoided during this time. Limit visits to 20 minutes per session. Visit and pet your cat briefly, but do not allow the cat to sleep on your bed with you. Avoid contact with urine and saliva and do not allow the cat to sleep on your bedding.

4. Foods containing fish products can be reinstituted post-treatment.

5. Use disposable litter pan liners and plastic gloves to minimize handling of litter/waste.

6. Wash your hands after handling your cat, its food dishes and litter pan.

7. There is no need to quarantine your cat from other pets in the household.

8. If your cat must be seen by a veterinarian before the end of the 2-week quarantine, please alert PVESC.

While the amount of radioactive material remaining in your cat’s body is low, it is prudent to follow the above instructions exactly. If this is not possible, please consider boarding your cat with PVESC during the quarantine period (additional fees apply).

Waste Disposal

Disposal of litter pan contents:

If your home is on a public sewer system:

  1. Use scoopable/flushable litter such a “World’s Best Cat Litter” or Swheat”

  2. Wear protective gloves (such as dishwashing gloves), scoop your litter pan twice per day and flush the waste down the toilet.

  3. At the end of the two-week quarantine, flush all remaining litter down the toilet. The litter pan and scoop can be washed with soapy water and flushed down the toilet; it’s not necessary to save these items for any extended period or to discard them.

  4. This is the approved method of the State of Nuclear Regulatory Commissions.

If your home has a private septic system or if you have a public sewer and choose not to flush it:

  1. Your cat’s litter box must be scooped twice per day.

  2. Wear protective gloves (such as dishwashing gloves) and place the waste in a Ziploc or tie bag, be sure to double-bag the litter and excretions, then place the bag in a plastic tote with a locking lid that has been lined with a large garbage bag. This tote should be stored outside and away from small children, other pets and wild animals.

  3. At the end of the two-week quarantine, add all of the remaining litter from the boxes to the trash bag in the outside tote, tie the bag and leave all waste until the 80-day mark on your calendar.

  4. The litter pan and scoop can be stored with the trash bag in the tote for 80 days. It can then either be thrown out or washed and reused.

  5. When it is time to discard the waste, simply remove the large garbage bag from the tote and dispose of it as you would your household trash. The tote itself may be disposed of separately or can be rinsed out and reused.

Follow Up

We would like to recheck your cat’s progress in 4 to 6 weeks. This includes a physical examination, thyroid level (T4), renal panel with SDMA, electrolytes and body weight. If you prefer to see your primary care veterinarian for this, please have the results forwarded to PVESC.

Waste Disposal

Disposal of Litter Pan Contents
If your home is on public sewer use flushable litter. To dispose of your cat's urine and feces during its first 2 weeks post-treatment, scoop the soiled litter daily and flush it down the toilet. This is the approved method of the State of Nuclear Regulatory Commissions. If you refuse to follow this method or, your home has a private septic system, you must take these steps:

   1. For the first 14 days after your cat returns home from receiving I-131 therapy, put on your gloves, use your litter scoop to drop all soiled litter into a Ziploc (or similar) bag. Zip it shut. Place this bag in the second Ziploc (or similar) bag and zip it shut.

   2. Place the double-bagged litter, feces and urine in a large Tupperware (or similar) type container, lined with a trash bag, and close it with a tightly locking lid.

   3. Follow this process for 14 days, placing all double-bagged litter, feces and urine in the Tupperware (or similar) container, and lock the lid after each addition to the container.

   4. Mark on your calendar 94 days after the date of discharge from our facility for the stored litter to be discarded.

   5. During the time you store the container, place it outside where it cannot be reached by small children, pets, wild animals, etc, or in a basement or garage. Do not place it in occupied areas.

   6. At the end of the second week, put on your gloves and, in one step, pick up the edges of the litter liner containing any remaining litter, tie them together and place it with the litter you have collected over the previous two weeks. Dispose of your gloves, and wash or dispose of your litter scoop in the outside trash. If you have been unable to successfully use a litter pan liner, dispose of your litter pan as well. You may now return to your normal litter disposal routine.

   7. 94 days after discharge from our facility, open the container, pick up the trash bag lining it, and place the bag in your outside trash. Do not bury the litter or use it in the garden. You may dispose of the container separately.

Patient Follow-up

What will Treatment be like for my cat?

The ideal goal of 1-131 therapy is to restore normal thyroid function with a single dose of radiation without permanently damaging normal thyroid tissue. Most hyperthyroid cats treated with 1-131 are cured by a single injection-No surgery! No anesthesia! No medication!

Successful treatment results in normal thyroid hormone levels within 2 weeks of treatment in 70-8O% of cats. Over 90% of treated cats reach normal hormone levels within 3 months post-treatment. Cats often feel better within days of treatment and most owners can expect gradual and steady health recovery within 2 months.


Medical Follow-up

Copies of all pertinent medical records and test results regarding your cat's treatment will be forwarded to your primary care veterinarian. We recommend a recheck examination, thyroid (T4) level and kidney (renal) profile with your veterinarian 2-3 months after I-131 treatment. Please have the results forwarded to PVESC.