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Battling cancer Effectively!

A diagnosis of cancer in pets often brings with it some overwhelming emotions among pet parents, including a sense of loss of control and hopelessness. It is the number one natural cause of death in geriatric dogs and cats and it accounts for nearly 50 percent of deaths each year. Although cancer is the leading cause of death in geriatric patients, it’s also the most treatable disease when compared with congestive heart failure and renal failure. Let’s see how.

 

Dr PR Chaudhari

Dr PR Chaudhari

Cancer is the unrestrained growth of cells that destroy normal tissues and body parts. Majority of pet parents have common under standing that detection of cancer is the beginning of the end of a pet. When treating an animal patient with cancer, overcoming the pet parents’ fear is the first job for every veterinary team.
To understand cancer as a process, let’s look at the development of a tumour. Most cancers are believed to arise through a process called multistep carcinogenesis. This theory is based on the fact that in the majority of cancers, at least two genetic changes have occurred prior to the induction of malignancy. There are three basic steps in multistep carcinogenesis. These steps ultimately lead to the evolution of a cancer cell from a normal cell.
Initiation: Initiating agents induce a permanent and irreversible change in the DNA of the affected cell. In and of itself, the initiating event is not significant enough to induce neoplastic transformation. Initiated cells cannot be distinguished under the microscope from other cells in the surrounding environment.
Promotion: Promoting agents cause reversible tissue and cellular changes. Promoting agents can induce changes in the shape of a cell, its growth rate, and degree of terminal differentiation. Promotion serves to expand the initiated cell population and alter it in such a way as to increase the likelihood of occurrence of irreversible change.
Progression: Progressing agents are able to convert an initiated cell, or a cell undergoing promotion, into a cell exhibiting malignancy, capable of developing into a mature cancer. The process of progression is irreversible.
In order for a tumour to result, the affected cell must be irreversibly altered at least twice. The cell is altered once in the initiation phase and once in the progression phase.
Treating cancer…
Cancer can be treated with radiation therapy, which can be categorised broadly in two:
1. Systemic Radioisotope Therapy
The radionuclides with appropriate beta energy are administered orally, intravenously or locally in the lesion. This therapy is not very popular because of the requirement of dedicated facilities for housing animals administered with therapeutic radiopharmaceuticals. The most common therapies for animal cancers are Radioiodine Therapy and Bone Pain Palliation Therapy.
Radioactive Iodine Therapy: Radioactive iodine has become the treatment of choice for treating feline hyperthyroidism because of the single dose regimen and lack of side effects. This treatment is based on the fact that the thyroid gland is the only tissue in the body that actively accumulates iodine, which it uses to produce thyroid hormones. Radioactive iodine is rapidly absorbed by the hyperfunctioning thyroid tissue. The radioiodine emits a beta particle which selectively destroys the tumour while leaving normal tissue undamaged. Thyroid function typically returns to normal in 1-3 months. Before treatment with radioiodine, a thyroid scan is performed using a low energy radioisotope (technetium pertechnetate). The scan will confirm the diagnosis, identify the number of abnormal thyroid lobes, and aid in determining the radioactive dose required for effective treatment. The majority of cats (90 percent) need to be treated only once. Most cats are hospitalised from 5-7 days, depending on the dose of radioiodine administered and the excretion rate of the iodine. Once admitted, your cat cannot be discharged until her
radiation exposure rate is below permissible limits.
Therapy for Bone Primary and Secondary Lesions: Osteosarcoma and osteoblastic bone lesions due to secondary spread of cancers such as bone mammary gland cancer and prostate cancer are managed with systemic radionuclide therapy using 32P, 89Sr and 177Lu. Selectively these radiopharmaceuticals localise in osteoblastic lesions and the beta energy of the radionuclide kills the cells and controls the growth of the cancer. This therapy is used for treatment of skeletal micrometastasis. The haematological toxicity is one of the major concerns but this has been reduced to greater extent with new agents such as 153Sm and 177Lu labeled radiopharmaceuticals.
2. External Radiation Therapy
Radiation therapy is effective for control of certain types of cancer. It may be used alone or in combination with other forms of treatment. Radiation therapy is indicated for the treatment of tumours that would have unacceptable functional and/or cosmetic side effects if they were surgically removed. It can also be used to eliminate residual disease left behind when surgery could not remove the entire tumour without creating serious side effects. All of the side effects associated with radiation therapy will be limited only to the area where the radiation is applied. ‘Radiation sickness’, manifested by nausea, vomiting, and diarrhoea, is not seen in veterinary patients.
Radiation therapy cannot be given in a single large dose sufficient to control tumours without causing severe complications. Giving small doses over a period of time gives the best chance of controlling the tumour with minimal damage to surrounding normal tissues. Radiation therapy is usually given in 12 or more small doses of radiation over a 3-4 week period. Each treatment requires 10-30 minutes. The patient must remain perfectly still during the treatment so that the radiation only goes where it is needed. A short-acting anaesthetic is given to immobilise the patients. There is a small but definite risk associated with repeated anaesthesia; therefore, patients are monitored closely.
Many factors affect the response of tumour to radiation therapy. Larger tumours require larger doses than smaller ones. The anatomical location may mandate that sensitive normal tissues, such as the eye, be included in the treatment field. The type of tumour is also important as well as the type of radiation therapy used. The effects of the radiation therapy are not instantaneous. Most tumours will not have any visible changes for several weeks. Some will not change in size, but stop growing. The most important thing to remember is that while the side effects will be manageable and transient, tumour control should be permanent.
Computerised treatment planning systems are used to improve the localisation and distribution of the therapeutic beam within the patient. This limits the dose to normal tissues and also increases the dose to the neoplastic tissue being treated, increasing cure or control rates and reducing the severity of normal tissue complications. These programmes are best used in conjunction with CT or MRI images, which determine the position and extent of the tumour within the body and its relative position to normal structures. Many hours of planning may be required to generate a treatment plan for a large, complex tumour.
Whenever possible, elimination of a tumour by surgery is preferred. However, in many instances, large neoplasms, or those in critical areas such as the brain, are not amenable to complete or even partial surgical removal. Even when a tumour is grossly removed, microscopic foci of neoplastic cells may extend beyond the limits of the surgical field. In all of these instances, radiation therapy, often in combination with chemotherapy, is useful in treating the remaining cancer. Radiation therapy is often the treatment of choice for brain tumours, nasal tumours and other neoplasms of the head and neck. Radiotherapy is also used to treat soft tissue tumours of the skin and subcutis either before or after surgery. It is seldom used in the treatment of lung neoplasia or in the treatment of neoplastic disease of the abdominal cavity, due to the mobility of tumours in these areas. As the sophistication of radiotherapy techniques increases, more and more types of neoplasia are being treated at least in part by radiation therapy.
In the course of radiation treatment of cancer, some surrounding normal tissues will be affected. The radiation-induced effects to normal tissues usually do not begin until the end of the therapy period and they continue for several weeks after the treatments have ended. These are called the acute side effects. They usually resolve within a few weeks to a month after radiation has been completed. Other adverse effects associated with radiation therapy may occur many months or years after radiation is complete. These are called delayed adverse effects. While the adverse effects of radiation therapy are difficult to predict, a few of the most common possible effects are listed below.
Skin: Radiation reactions that may appear toward the end of radiation therapy include loss of hair and a sunburn-like effect to the skin that may become itchy, dry or moist. Most pets develop a change in the colour of the skin and hair in the area being treated and, occasionally, hair will fall out and not re-grow in that area. Other changes to the skin that are much less common include formation of a non-healing wound and the formation of thickened scar tissue in the area being treated.
Mouth: If tumour in or around the mouth is being treated, injury to this area can result in a sunburn-like effect to the tongue and the tissues lining the mouth. This can result in loss of appetite, altered tongue function and tenderness to the lining of the mouth.
Large intestine and rectum: Occasionally, the colon and rectum are affected when tumours in that area of the body are being treated. Most pets have only mild, transient side effects that can include loose stool (bowel movement) that may contain blood, and perhaps some discomfort passing stool.
Eye: The eye is often unavoidable in the treatment field when tumours of the facial skin, sinuses or nasal cavity are treated. While most pets do not show any adverse effects associated with damage to the eye itself, side effects can include cataract formation months to years after therapy is finished, damage to the retina, decreased tear production, and irritation to the tissues around the eye. Occasionally, an ulcer of the cornea may be noted.
More than fifty percent of cancers are treated alone with radiation or in adjunct to other modalities. So, if your pooch is detected with cancer, do not lose hope!
(Dr PR Chaudhari, MVSc, DMRIT PhD, is stationed at Comparative Oncology & Experimental Nuclear Medicine, Advance Centre for Treatment, Research and Education in Cancer, Tata Memorial Centre, Navi Mumbai).

Fighting the dreadful cancer

Cancer is a common cause of death in canines as it is in humans. But a little observation and timely diagnosis and treatment can save the lives of our tailwaggers.

The basics…

‘Cancer’ is a malignant, cellular tumour. A ‘tumour’ is a swelling or tissue growth which has uncontrolled celldog health multiplication. It can be malignant or benign. If the tumour is malignant, it has a tendency to progressively worsen and may even lead to death. Usually a malignant tumour is accompanied by properties of metastasis i.e. transfer of disease from one part of the body to the other. This means cancer is basically uncontrolled and progressive transformation of normal cells into abnormal cells that worsen very fast. The main symptom of cancer in a canine is a mass or lump. Although each mass or lump may not be malignant (cancerous) but it is best to let veterinarian evaluate it. The vet would surgically take a sample and send it for biopsy.

Common signs of cancer in canines…

  • Lumps – any unusual lump or growth.
  • Non-healing wounds – if your pet’s wounds are not healing it can be a sign of skin infection, skin disease or even cancer.
  • Abnormal discharges – any sort of discharge (pus, blood or vomiting) should be examined by the veterinarian.
  • Weight loss and loss of appetite – sudden loss of appetite leading to unusual weight loss and lethargy.
  • Difficulty in breathing – this can be due to a heart disease, lung disease or even cancer.
  • Changes in bathroom habits– if your pet has blood in urine or stool, also check for increase in frequency.

Types of cancers in canines…

Bone cancer: It accounts to a total of five percent of canine cancer cases. It’s mostly common in legs, arms, skull, jaw, ribs and spine. During initial phases, it may just be considered a swelling in the bone, but as it progresses, it may lead to changes in pet’s behaviour due to severe pain in the affected area.

Liver cancer: It is of two types. First, primary (i.e. a malignant tumour in the liver) and second, metastatic (i.e. cancer spreading to the liver from other parts of the body). Blood in stool, vomiting, loss of appetite, unconditional weight loss, jaundice, frequent urination, increased thirst and lethargy may be some of the symptoms.

Prostate cancer: It results from the effects of testosterone hormone secreted by the prostate gland. Enlargement of prostate gland, abdominal swelling, frequent urination in less amounts, discharge or secretions from the genital area may be some of the symptoms.

Lung cancer: It is caused due to frequent and long exposure to environmental pollutants and passive smoking. Another cause can be spreading of malignant cells from other parts of the body to the lungs. It is believed that lung cancer is rare in dogs.

Stomach cancer: According to research, stomach cancer accounts for just one percent deaths of the total canine cancer deaths. This is a rather rare cancer and is mostly observed in senior (8-9 years and above) male dogs.

In half of the cases, the growth can be detected with physical examination. They are visible in the form of growths, sores, lumps, or can be seen beneath the skin. Testicular tumours, mammary gland tumours, lymph gland tumours and cancers in the mouth can be detected by inspection. Internal cancers are common in the spleen, liver and gastrointestinal tract.

Who is prone to cancer…

It is believed that older dogs are a greater risk as compared to the younger ones. Besides, some breeds are more prone to certain type of cancer. Talking to Dr Neelima Paranjpe from Mumbai, we found that there are some breeds who are at a greater risk of cancer due to the genetic makeup. Boxers, for instance, are more prone to cancer as compared to other breeds. She also added that Golden Retrievers are at a greater risk of skin cancer due to their genetic makeup. “It becomes difficult to explain pet parents that cancer in canines is based purely on genetics and not on their lifestyle,” added Dr Neelima.

According to Dr Aradhana Pandey, the following breeds are more prone to specific types of cancer: Golden Retrievers – Osteosarcoma (bone cancer); Rottweiler – Lymphosarcoma (cancer of the lymph nodes and system) and Hemangiosarcoma (cancer of blood vessels, common in the spleen); Boxer – Lymphos ar coma , Brai n cancers, Mast Cell tumours (a cancer involving specialised cells called mast cell, common in the skin and other body sites); Pugs – Mast cell tumour; Rottweilers and Great Danes – Osteosarcoma.

While, senior vet Dr GB Kaushik talks about how gender can have a connection to cancer in dogs. According to him, mammary cancer is common in unspayed females, whereas males are at a higher risk of testicular tumour.

Treatment…

As far as the treatment is concerned, it can star t immediately after the diagnosis. Some of the treatment options are surgically removing the tumour and in cases where the cancer is inoperable, other treatment options like Radiation and Chemotherapy can be opted for. Radiation means killing the malignant cancer cells by exposing them to high levels of radiations using calibrated X-rays. While, chemotherapy involves treatment with drugs, and is not very target specific. Chemotherapy drugs can have major side effects on your pet even when used in controlled amounts. Dr Aradhana says that side effects vary according to the drug use.

Though the side effects are not as severe as that in humans but some of them can include:

  • Increased thirst – drinking large amount of water.
  • Increased need to urinate (from drinking so much water!).
  • Panting.
  • Some mild behaviour changes.
  • Loss of appetite.
  • Low white blood cell count (WBC).
  • Tissue damage at injection site.
  • Nausea or vomiting.
  • Diarrhoea (usually occurs 2-5 days after administration).

“The international circuit is concentrating on Targeted Cancer Therapies. By chemotherapy we are killing all actively dividing cells whereas in this targeted approach, techniques are being developed to target just the cancer growth,” said Dr Gautam Anand. Targeted cancer therapies are drugs or other substances that block the growth of cancer cells and prevent them from spreading by interfering with specific molecules involved in tumour growth and progression.

Since the research for canines is not at a very advanced stage, most vets take help from human radiologists. They help in surgical techniques depending on the organ affected, MRI (magnetic resonance imaging), CT scan, etc that help in targeting the cancer more effectively. “Also some of the new techniques that have been developed recently for canines are stinting, which means putting a stint through the tumour which would result in blocking the blood supply to it and intratumoral therapies. In intratumoral therapy we directly target the drug to the tumour for a targeted approach,” added Dr Gautam.

Talking about the efficiency of the treatment methods, Dr Aradhana tells us that it depends on a number of factors like: the type of cancer, the organ affected, the age of the dog, physical condition of the dog etc. She also said that if diagnosed at the proper time and early stages, cancer in canines can be cured completely.

“Usually when the patient is in the terminal stage or in cases of bone, brain, chest and abdominal cancer, we suggest that instead of chemotherapy or radiation, the pet be put to sleep. In these cases the physical suffering is immense and providing treatment would just mean prolonging their suffering,” added Dr Neelima.

Diet facts…

It is known that diet plays an important part during and after the treatment. Changes made in your pet’s diet may prove to be beneficial. The use of simple sugars should be limited whereas complex sugars (carbohydrates) and highly digestible proteins should be used in moderate amounts.

Dr Aradhana suggests, ‘‘Since tumour cells require glucose to grow, thus we should reduce the intake of direct glucose in pets as our aim is to minimise the energy available to the tumour to limit its growth. Simple carbohydrates like bread, pasta etc are direct source of energy so it needs to be reduced. Foods with low glucose carbohydrates like fruits (viz. apples, berries, etc), honey, brown rice, oatmeals, etc should be given.” “A large quantity of proteins coming from egg white, chicken, etc should be given because it helps in maintaining muscles. Vitamin D inhibits cell growth and also promotes cell death that plays an important role in the prevention of cancer. Vitamin D supplementation should be done guardedly and should not be more than 10,000 IU per kilogram of food,” Dr Aradhana added. Your vet would guide you best to make specific dietary changes in the diet of your beloved.

The silver lining…

One thing that helps canine fight cancer better than humans is that they are not psychologically affected by the disease. As long as the pet is with the pet parents and they are spending quality time with each other, it is really helpful for the pets. “They are usually in high spirits which certainly helps in the treatment,” added Dr Neelima. Citing an example of one of her patients, she said that one of her patients who is suffering from cancer is really naughty and playful. She has successfully taken the first round of chemotherapy and is ready for the second round. “By giving targeted treatment in the form of radiology and chemotherapy, we can increase the life expectancy of pets by 1- 2 years and most importantly their suffering is reduced to a great deal,” she added.

Preventing cancer in dogs…

Following some simple steps can help in preventing cancer in dogs:

  • Foods – Make sure that the pet food has the least amount of preservatives and added colours because these are believed to be directly linked with canine cancer. They should be given food that is rich in fatty acids and antioxidants.
  • Clean water – Make sure you provide your pet with adequate clean drinking water. It’s a known fact that drinking lots of water is a common way to prevent bladder cancer.
  • Exercise – Regular exercising should be an important part of your lil’ one’s daily routine. Walk, run, play, hop… make them do whatever they like. This would help in controlling their weight and in turn lead to a total weight management routine.
  • Spaying and neutering – Neutered males have a lower risk of testicular cancer as compared to the ones who are not neutered. Similarly female dogs who are spayed before coming to the season are at a lower risk of mammary gland cancer. A female spayed before sexual maturity (6-9 months of age) has one-seventh the risk of mammary cancer.
  • Avoid passive smoking – Passive smoking is as dangerous to pets as it is to infants. Make sure you kick that butt to make yours and your pet’s life healthier.

(With inputs from Dr Aradhana Pandey, Doggy World, New Delhi; Dr Neelima Paranjpe, Pluto Pet Clinic, Mumbai; and Dr Gautam Anand, Dr Anand’s Pets Clinic, New Delhi.)