The mention of the words tumor or cancer cause most people to think of the death of their pet. Despite tremendous progress in the treatment of tumors, most people unfortunately still find their minds drawn into the worst thoughts possible. It is important to know that most tumors in domestic dogs can be cured with the pet living normally for years after treatment.

It is first important to understand the language of this branch of medicine as many terms are used to describe abnormal growths in the body. The words neoplasia or neoplasm are the proper terms used to describe any new and abnormal growth in the body. These words do not describe how "dangerous" a growth may be, only that an abnormal growth does exist. The word tumor is sometimes used instead of the word neoplasm. More correctly, the word tumor describes a swelling of or in a tissue. Oncology is the study of neoplasia or tumors.

The word benign means not malignant, and that the chances for recovery are favorable. It may also be used to describe a neoplasm that is not likely to spread to other parts of the body. The word everyone dreads most is malignant. A malignant tumor is one likely to become worse with time, likely to spread locally or to distant parts of the body and likely to ultimately lead to death of the dog. These would be the most dangerous types of neoplasms. Cancer is the common term for a malignant neoplasm so this word is commonly used to indicate a severe type of tumor.

Some tumors are classified as pre-malignant meaning that the tumor may be benign now but is likely to become malignant if more time goes by. These tumors may be removed before they turn into a cancerous growth. Another term commonly used is that of metastasis. This means that a neoplasm has spread from the area or organ where it originated to grow (also) in another organ or area. Once a neoplasm has metastasized it becomes very difficult to treat and will cause more damage to the dog.

Although our ability to diagnose and treat all types of tumors has come a long way in the last decades, we are still far from understanding what actually causes a particular tumor to form. Owners commonly ask, "what caused it?" when the diagnosis of neoplasia is discussed with the veterinarian. Unfortunately, most doctors are left to say that any such growth arose spontaneously, and that we just don't know, nor can we ever (yet) be exactly certain why.

It has been determined that radiation, poisons and toxins, viruses, hormones in the male or female, chronic irritations, internal and external parasites, and certain drugs can cause neoplasia. Most importantly, it seems that genetic factors are probably the single most important reason any individual will get a certain tumor. In other words, our dogs all have certain inherited genes, which either help to protect against the development of neoplasia or to some degree increase the chances that certain tumors will form. At best with good preventative care and by avoiding all the things mentioned above which are known to contribute to cancers and tumors, the odds of developing neoplasia can be kept as low as possible.

While tumors can occur at any age, they are most common in dogs older than 5 years of age. Some tumors are more common in certain breeds (genetics again) and in dogs with certain coat colors. Overall the chances any given dog will get any type of tumor are only about 4 dogs out of every 1000! Of this rate, only about 35% of these dogs will have malignant tumors, again supporting the fact that most tumors in dogs are curable. Boxers and Cocker Spaniels seem to have a slightly higher rate of tumors; the Beagle and mixed-breed dogs seem to have a lower rate. Skin tumors are the most common type of neoplasia in the dog.

In all other sections within this program, diseases are indicated based on clinical signs or symptoms that will usually appear. As neoplastic growths can occur in any tissue or organ, in any part thereof, and even spread to multiple areas, it is impossible to say that any one or general set of clinical signs points to some type of tumor. An important point to remember at all times when discussing neoplasia; tumors do not follow exact or specific patterns, they have tendencies, but we can only predict in general terms what a tumor will do once it begins to grow inside the dog.

External tumors will be the most obvious, appearing as a swelling, sore or evidently irregular growth. Some external growths may ulcerate, discharge or even begin to decay. Signs of internal tumors are often vague and can include pain, gain or loss of appetite, gain or loss of weight, swelling to the abdomen or feet, unusual bleeding, weakness, trouble breathing, constipation or diarrhea, vomiting, changes in gum color, seizures, paralysis, changes in thirst or urinary habits, fever, and a few other symptoms we have probably overlooked. With this said, one can see that the diagnosis is often less than obvious.

A veterinarian will use most any of the commonly used tests to help determine if a tumor is present. These include blood analysis, urinalysis, X-rays, ultrasound, cytology and biopsy. Where possible, cytology is an excellent preliminary test for neoplasia. Part of suspected tumors can often be aspirated into a syringe, washed off of an internal surface or scraped free from an area and placed on a slide to be stained and examined by the veterinarian under the microscope. While this may not constitute an exact diagnosis, it is easy and inexpensive and will quickly help the veterinarian determine what should be done to best help the dog.

A biopsy, however, is the only sure and accurate way to determine exactly what type of tumor is present and if it is benign or malignant. A biopsy is performed by taking a small section from a suspected tumor and having a veterinary pathologist examine it for an exact determination. A biopsy may be taken before surgery to help the doctor know what he/she is dealing with and how to best attempt a cure, or after all of a mass is removed to find out what is being treated and if more surgery or other therapy will be necessary.

Just as it is nearly impossible to list exact symptoms for the all the various types of tumors that can exist, is difficult to say precisely what treatment(s) or therapy will work best. The most common and most effective type of tumor therapy used on dogs is surgery. Up to 80% of all canine tumors can be completely removed and cured with surgery.

Chemotherapy is also available and many cities now have specialists who have the drugs and expertise to provide dogs with the most up-to-date therapy available. Chemotherapy is often the only reasonable coarse for dogs with widespread tumors and cancers of the blood or lymphatic systems.

Other types of therapy include cryotherapy or the freezing of tumors, radiation therapy which is available only in limited areas, immunotherapy which employs the use of antibodies and other immune system components to fight tumors, radiosurgery which employs electricity to cut and destroy tumor tissues, and various combinations of all the aforementioned methods. The best treatment will depend on the techniques available, the general health of the patient, the cost involved, the type of neoplasia present and if and where it may have spread, and the skills of the doctors treating the patient.

Adenoma: benign tumor from glandular surface lining tissues.

Adenocarcinoma: malignant growth from glandular tissues.

Carcinoma: malignant tumor from surface lining tissues.

Cyst: benign growth, non-neoplastic and filled with fluid or semi-solid material. 

Mass: general term for any lump or growth, may not imply neoplasia.

Polyp: any abnormal protrusion from a mucus membrane. (gums, rectum, etc.) 

Sarcoma: tumors from supportive tissues such as blood, bone and muscle.

LEUKEMIA: Leukemia defines increased numbers of white blood cells in the circulation with the cells often being types not normally seen. Most all cases of leukemia will involve the blood and the bone marrow where blood is produced. Dogs with leukemia will often be weak, have a poor appetite, pale gums, altered consciousness and some type of bleeding problem. Diagnosis is based on blood counts and bone marrow biopsy where abnormal types and numbers of cells will be found.

There are several different types of white blood cells in the dog's body. Each of these cells develops from an embryonic precursor in the bone marrow. What this amounts to is that there are many various types of leukemia that can occur, depending on which blood cell and/or juvenile precursor cells become cancerous. All types of leukemia are considered malignant. While an individual discussion of each and every type of leukemia would be impractical, in the next paragraph we will list the names of some types of leukemia your veterinarian may diagnose. These include:

Acute Myelogenous Leukemia, Eosinophilic Leukemia, Basophilic Leukemia, Monocytic Leukemia, Acute Undifferentiated Leukemia, Acute or Chronic Myelogenous Leukemia, Mast Cell Leukemia, and Acute or Chronic Lymphocytic Leukemia. Lymphosarcoma may be considered a type of leukemia but is discussed elsewhere.

All types of leukemia are treatable with various types of chemotherapy and a cure is possible or good long-term survival available for these patients. The most established types of chemotherapy exist for treatment of these diseases. The only negative would be the costs and time needed for this type of therapy.

ERYTHEMIC MYELOSIS aka ERYTHROLEUKEMIA: would define an increased growth of abnormal red blood cells or their juvenile precursors. Almost unheard of in the dog.

MEGAKARYOCYTIC LEUKEMIA: occurs when abnormal platelets or their juvenile precursors are in increased numbers in the blood. May be concurrent with other types of leukemia. Usually will not cause much illness by itself and there is no treatment for most cases.

SPLENIC NEOPLASIA: most every cancer of the spleen has it's origin in some other system. This is not to say that cancer cannot be found to arise in the spleen only, but rather, that most spleenic tumors are in no way unique to the spleen. Most any tumor that can metastasize can end up in the spleen. These include hemangiosarcoma, mast cell tumors, lymphosarcoma and other various carcinomas. Usually dogs will have abdominal enlargement and discomfort. If confined to the spleen, splenectomy can be curative. More widespread neoplasms will require chemotherapy or radiation. 

OSTEOSARCOMA: most common bone tumor, highly malignant often having spread before diagnosis can be made. Most often seen in limbs of older, large breed dogs. Commonly seen at ends of the bone. Life may be spared or at least extended with early amputation of limb; chemotherapy or radiation may be helpful. Can be very painful if amputation is not performed. May sometimes cause bones to break spontaneously. A rare form of osteosarcoma can occur in soft tissues such as the esophagus, liver, spleen and skin. ((Osteosarcoma))

OSTEOMA: uncommon benign relative of osteosarcoma, will rarely spread but may damage bone in the area of the tumor. Will generally grow from surface of the bone. Surgery or amputation may be curative if complete removal is performed.

CHONDROSARCOMA: uncommon tumor of cartilage, malignant but may be removable with surgery and/or radiation therapy. More common in older dogs and on the skull and ribs. Not usually painful and tends to be slow growing. Amputation may still be required.

CHONDROMA: benign tumor of cartilage, quite rare, may still create defects within the bone or joint. More commonly grows on skull or ribs.

HEMANGIOSARCOMA: not as common in bone as in the spleen or liver tissue but can occur in bone tissues. Highly malignant and is rarely treatable by the time it is diagnosed. More information on this tumor available in another section.

FIBROSARCOMA: tumor of connective tissue that can occur in bone, may invade and destroy bony tissue. Often mimics osteosarcoma, often not removable by surgery, (often grows back) but amputation can prove curative.

MULTIPLE MYELOMA: very malignant tumor of bone marrow tissue, usually of antibody producing cells. Will invade the bones, often of the spine, skull, pelvis and ribs, but long bones can become involved. Causes severe pain, lameness and high blood protein levels, as well as disease in other organs; may be treatable with chemotherapy. see multiple myeloma.

GIANT CELL TUMOR: a very rare tumor, most likely found at the ends of long bones. Can be benign or malignant. Amputation will probably be needed. Little information is available as to the effectiveness of other therapies. Malignant forms will spread wildly.

SYNOVIOSARCOMA: rare, malignant tumor of joint capsule tissues, will often spread into the bone. Most dogs are over 7 years old at diagnosis. Tends to metastasize quickly. Surgery and chemotherapy can be useful.

SYNOVIOMA: rare, benign tumor of joint capsule. May damage or destroy joint function. Possible to remove directly with surgery or via amputation.

BONE CYST: not a neoplasm and very rare. Seen as a solitary, well-defined lesion on an X-ray. May be seen associated with other types of bone tumors.

ORAL PAPILLOMATOSIS: proliferative and warty tumors of the oral cavity only, caused by a virus. Most common in young dogs, will produce foul oral odors, trouble swallowing and oral bleeding. In severe cases surgery can be performed to prevent oral trauma or swallowing difficulties. Will naturally regress in a few months.

EPULIS: a hard, fibrous tumor that arises from periodontal tissues, may be single or multiple and occur along the gums. Some consider this non-neoplastic. A few of these tumors may become calcified and feel like a bone. May be confused with more serious oral tumors and should be removed and biopsied. With surgery and hyperthermia most are cured. ((Epulis))

ODONTOMA or ADAMANTINOMA: oral/gingival tumor that originates from dental tissues. Benign but often recurs after surgical removal and can spread along the gums and jaw. Surgical removal, cryotherapy or hyperthermia are all advised.

MALIGNANT MELANOMA: a cancer of pigment-producing cells almost always malignant (hence the name). More common in black-colored dogs, will grow on lips, gums and roof or floor of the mouth; often will decay and break apart. Will generally spread quickly to lymph nodes. Radical early surgical removal is advised. Removal of the jaw or part thereof has been used in extreme cases. ((Oral Melanoma))

SQUAMOUS CELL CARCINOMA: malignant cancer of oral surface tissues, more common to back of mouth. Can attack tongue, tonsils, gums and jawbone, quick to spread deeply in tissues and to lymph nodes. Surgery and radiation can be effective but few dogs live longer than 6-9 months after diagnosis. ((Oral SCC))

FIBROSARCOMA: malignant tumor of oral connective tissues. Most common along gums and jaw, invades deeply but slow to spread to distant sites. Can be partly removed with surgery but most always will regrow. Radiation also effective, and another therapy, injections of Acemannen, has been used with some success. Freezing of the tumor has also been used with some success. ((Oral Fibrosarcoma))

SALIVARY ADENOCARCINOMA: malignant tumor of any of the salivary glands, quite rare. Will produce localized swelling and may spread into the neck and mouth. Surgical removal before metastasis can produce a complete cure. Radiation could be used in advanced cases.

LEIOMYOMA: benign tumor of smooth muscle (the type of muscle in organs), may cause obstruction of the esophagus. Rare, possibly removable with surgery depending upon location of the tumor.

SQUAMOUS CELL CARCINOMA: malignant cancer of esophageal lining tissues, may be related to oral SCC. Surgery and radiation usually not effective.

FIBROSARCOMA: malignant tumor of connective tissues. Can produce a blockage of the esophagus. May be removable depending on size and location although there would be a limit to how much esophagus could be removed. Usually fatal.

BENIGN ADENOMATOUS POLYPS: pedunculated nodules along stomach lining. Cause no clinical disorder and no treatment is needed.

LEIOMYOMA: usually solitary tumors of the stomach muscle tissue. Can ulcerate but usually causes no dysfunction nor do they need any treatment in most all cases.

LEIOMYOSARCOMA: rare cancer of smooth muscle tissue, can involve large portions of the stomach. May be surgically removed if caught early although all or part of the stomach may also need to be removed.

ADENOCARCINOMA: malignant tumor, will often be associated with gastric ulcers; appears as a polyp or firm solid mass in stomach wall. Will spread to liver, adrenal glands, lungs and regional nodes. Possible to remove by surgically removing part or most of the stomach. Few other treatments are known to be effective.

LYMPHOSARCOMA see lymphosarcoma

LYMPHOSARCOMA see lymphosarcoma

INTESTINAL ADENOCARCINOMA: second most common intestinal tumor, very malignant, often leads to intestinal obstruction. May also produce polyploid masses in any location, especially near the rectum. In a few cases where metastasis has not occurred, it may be possible to remove part of the intestine and cure the dog. Most cases, however, have spread through the intestines, lymph nodes and other local tissues by the time a diagnosis is made. Chemotherapy after surgery has proven of some value. ((Adenocarcinoma in the Rectum)) ((Intestinal Adenocarcinoma))

LEIOMYOMA: usually solitary tumors of the intestinal muscle tissue. Can ulcerate but usually causes obstructions. Can be cured with surgery if obstruction occurs.

LEIOMYOSARCOMA: rare cancer of smooth muscle tissue, can involve multiple portions of the intestine. Can also result in obstructions. May be surgically removed if caught early although part of the intestines may also need to be removed. ((Leiomyosarcoma))

PERIANAL ADENOMA: is the major anal tumor in dogs and is quite common, mostly in non-neutered males. Can be prevented with neutering. Tumor forms from glandular tissue in the anus and will grow slowly and progressively. These can ulcerate and bleed. Many can be cured with neutering and tumor removal. Freezing, radiation and female hormones have also been used but the first treatment of castration is most always effective. ((Perianal Adenoma))

APOCRINE GLAND CARCINOMA: tumor of glandular tissue of anal sacs, uncommon and moderately malignant. May mimic anal sac abscess in appearance. Surgical removal or freezing the best hope of cure. Will spread to lymph nodes and other parts of the digestive system if not treated. ((Apocrine Gland Carcinoma))

Tumors or the ear do occur and are similar to any other type of Neoplasia Of The Skin. Diagnosis would be based on skin biopsy. Any nodule of the earflap should be considered neoplastic until proven otherwise. Surgery to remove the lump and/or part of the ear will be needed. Polyps inside the ear canal are sometimes found. ((Ear Polyp)) ((Ear Flap Tumor))

BETA CELL TUMOR aka INSULINOMA: tumor of insulin producing cells, most always malignant with early metastasis. Can produce excess insulin and cause blood sugar to drop to very low levels causing weakness, seizures and collapse. These symptoms may come and go but diagnosis can be made with blood tests including insulin levels. May be treatable with surgery and chemotherapy, but will often spread to the liver and lymph nodes. Chances for good long-term survival are poor. ((Beta Cell Tumor))

THYROID ADENOMA: benign growth, relatively rare, can grow quite large, often removable surgically. Usually will not secrete thyroid hormone.

THYROID ADENOCARCINOMA aka THYROID CARCINOMA: malignant tumor, quick to spread from one gland to the other, then to chest and other organs. Sometimes these tumors will secrete excess thyroid hormone and cause hyperthyroid condition but this is uncommon in the dog. Dogs with increased thyroid hormone production will be restless, have an increased appetite and thirst but will be loosing weight. Surgery can be very successful in curing the problem if caught early. Certain drugs can be used to suppress thyroid hormone production. Radioactive iodine therapy effective but requires specialty care facility.

ADRENAL GLAND CARCINOMA OR ADENOMA: adenoma is benign, adenocarcarcinoma likely to spread to liver, lymph nodes, kidneys and lungs. Some will secrete cortisol and produce signs of hyperadrenocorticism. Can be treated with medication that will destroy the adrenal gland or by surgical removal. Prognosis very poor if tumor has metastasized.

PHEOCHROMOCYTOMA: functional adrenal tumor which will produce epinephrine (adrenaline). Very rare, can cause panting, weakness, shock, heart failure, or less serious signs. Difficult to diagnose, often large and malignant. Surgery and chemotherapy may be useful if caught early.

Tumors of the eye are not common with the exception of benign eyelid tumors seen somewhat frequently. Many can be treated, at least by surgical means, with death from tumors of the eye being very rare. Internal eye tumors can require removal of the eye.

DERMOIDS: common tumor of all exposed eye tissues, usually has hairs growing from it which can be irritating. Benign, surgical removal is often curative. Dermoids do occur in other areas besides the eye.

VIRAL PAPILLOMA: warts caused by a virus, more common in young dogs, benign and can be removed with surgery or freezing.

CHALAZION: not a tumor but included here as it may be confused as such. Swelling occurs on eyelid due to plugging of glandular duct with possible secondary infection. Can be easily treated with surgery and medication. ((Chalazion))

MELANOMA: often found inside the eye, but may occur on other structures. Malignant per se, but usually will not spread outside the globe unless left untreated for some time. Removal of the eye is the usual treatment; local removal or freezing may work.

ADENOMA: most common on the eyelids, can irritate the cornea if it rubs against it. Removal by surgery or freezing advised early. For various types see the section on skin tumors. ((Eyelid Adenoma))

ADENOCARCINOMA: may be seen on conjunctiva or third eyelid; malignant and can spread to nearby structures. Surgery or freezing advised as soon as possible, third eyelid may need to be removed. For various types see section on skin tumors.

HEMANGIOMA: uncommon tumor most often of the conjunctiva, will bleed if irritated, can be removed completely with surgery.

HISTIOCYTOMA: uncommon, rapidly growing tumor of eyelids, cornea and conjunctiva. Can occur on lips and may invade other tissues. Surgical removal or freezing can be curative.

OVARIAN ADENOCARCINOMA: rare malignant tumor of the ovary. Can be prevented by spaying female dogs. Will widely and quickly spread; most dogs very old at time of diagnosis. Treatment includes ovariohysterectomy, injections of radioactive material or other chemotherapy.

OVARIAN CYSTADENOMA: uncommon cystic tumor, usually benign. May grow to a moderate size. Possible cure with ovariohysterectomy. Also preventable by spaying.

GRANULOSA CELL TUMOR: most common ovarian tumor and usually benign. May produce hormones in increased amounts leading to cystic endometrial hyperplasia or pyometra. Can cause the female to appear pregnant. Ovariohysterectomy and chemotherapy may be needed for treatment. Preventable by spaying. ((Granulosa Cell Tumor))

GERM CELL TUMOR: include dysgerminomas and teratomas; tumors from embryonic-type tissues in the ovaries. Uncommon, can be moderately malignant. Ovariohysterectomy, chemotherapy and radiation will be needed for a cure. Preventable by spaying.

TRANSMISSIBLE VENEREAL TUMOR: an uncommon and contagious tumor of either sex, transmitted during mating. Appears as a cauliflower-like growth on the genitals but may also be nodular, lobulated or hang from a stalk-like growth; some become quite large. Mass will be firm but can easily break and bleed; may also become ulcerated and raw; a discharge from the tumor is common. Weekly treatment with a chemotherapy drug is often very effective. Neutering and containment of dogs will be preventative.

UTERINE LEIOMYOMA: the most common uterine tumor, originates from smooth muscle within the uterus; usually benign. Often no outward symptoms will be seen. Ovariohysterectomy can be completely curative. Preventable with spaying except in very rare circumstances. ((Leiomyoma))

UTERINE LEIOMYOSARCOMA: malignant cousin to leiomyoma, will invade and spread inside the abdomen, often before diagnosis. Can cause notable abdominal enlargement among other symptoms. Ovariohysterectomy and chemotherapy poorly effective. Preventable with spaying except in very rare circumstances.

UTERINE FIBROSARCOMA: rare but very invasive malignant cancer, more common in other areas besides the uterus. Can be treated if caught early but often will have invaded other tissues before diagnosis. Ovariohysterectomy and chemotherapy are possible but mostly ineffective. Preventable with spaying except in very rare circumstances.

VAGINAL LEIOMYOMA: the most common vaginal tumor, originates from smooth muscle within the vagina, usually benign but can obstruct the vagina. Often no outward symptoms will be seen. Ovariohysterectomy and surgical removal can be completely curative.

VAGINAL LEIOMYOSARCOMA: malignant cousin to leiomyoma, will invade and spread locally and inside the abdomen, often before diagnosis. Can cause notable mass protruding from vagina, discharge, trouble urinating and/or defecating. Surgical removal, radiation and chemotherapy all useful but a cure is difficult.

MAMMARY GLAND NEOPLASIA: the most common type of tumor in female dogs comprising as many as 50% of all tumors the bitch may have. Can be almost completely prevented by spaying before the first heat as these tumors are highly hormone dependent. Dogs spayed after 2.5 years of age have a risk or incident rate 7 times higher than dogs spayed before the first cycle. Most tumors occur in dogs 9-11 years of age and are found primarily in the glands closer to the tail.

The mammary glands are highly complex and integrated organs. Breast tumors are not just some simple lump to be dealt with. Because of this complexity, there is no one common presentation for a breast tumor. The masses may be small or very large; round, smooth and encapsulated or irregular and spreading into adjacent tissues. Some are quite benign and harmless; others grow and metastasize rapidly. Some never grow and remain small; others grow so large as to ulcerate and decay as they develop. One breast or multiple glands may be affected, one side of the body or both may have tumors. Drainage may or may not be present.

As there is such great variability, there is also incredible uncertainty; in other words, you cannot tell by looking which tumors are benign and which are malignant. Understanding this, all dogs with any abnormal growth in/on the mammary glands should have the growth or the breast(s) involved surgically removed as soon as possible. This offers the very best chance for both cure and diagnosis.

This is not to say that a complete diagnostic work-up including blood tests, X-rays (to check for metastasis), and aspiration or other forms of biopsy should be neglected. Most dogs are older but many can be cured as long as thorough, aggressive care is not postponed. Only dogs with confirmed metastasis or severe debilitation should be excluded from surgery. Many malignant tumors can be stopped before they have spread by surgical treatment.

Several types of surgery are recommended. For small, solid, well-defined nodules a lumpectomy, or removal of the mass alone can be performed. This can be used as a biopsy technique also. For masses that affect only one breast, local mammectomy or removal of one gland alone can be performed. In more extreme cases with large and spreading tumors, several glands, one complete chain of glands (one side), or all glands on both sides can be removed. While some of these may seem to be extreme procedures, the goal is to remove the cancer before it can spread elsewhere in the body. On a few occasions certain lymph nodes should also be removed. 

In other cases, chemotherapy, radiation, anti-hormone drugs and immunotherapies have been used, but always to augment surgery. Unfortunately some tumors will regrow even after the best surgery. Many veterinarians will also advise ovariohysterectomy at the same time as tumor removal, and while there is some debate as to how this effects current or future tumors, this author agrees that there is some good therapeutic value for this procedure being performed.  ((Breast Tumor))

The types of breast tumors that may be encountered include:

MIXED MAMMARY TUMOR: benign.

SIMPLE MAMMARY ADENOMA: benign.

COMPLEX MAMMARY ADENOMA: benign.

FIBROADENOMA: from fibrous tissue, two types, benign.

SOLID MAMMARY CARCINOMA: malignant.

CARCINOSARCOMA: rare, very malignant.

TUBULAR ADENOCARCINOMA: two types, relatively common, malignant

PAPILLARY ADENOCARCINOMA: several types and variations, malignant.

ANAPLASTIC CARCINOMA: very malignant.

Other rare types are possible; some skin tumors can also occur in the mammary area

Tumors of the heart are quite rare although tumors of the blood vessels, which then spread to the heart, such as hemangiosarcoma, are seen frequently in practice. Clinical signs of these types of tumors include that of congestive heart failure, cardiac arrhythmia, weight loss, poor appetite, fever, general debilitation, weakness and fainting.

FIBROMA: benign solid mass of connective tissues, may interfere with heart function and often found inside the heart. The only treatment may be for arrhythmia or congestive heart failure. Otherwise open-heart surgery would be required.

MYOMA: benign tumor originating from muscle tissue, will cause mechanical interference and possibly conduction disturbances. (arrhythmia) The only treatment may be for arrhythmia or congestive heart failure. Otherwise open-heart surgery would be required.

RHABDOMYOMA: another benign tumor originating from muscle cells, will also cause mechanical or conduction disturbances and could be trouble to remove. The only treatment may be for arrhythmia or congestive heart failure. Otherwise open-heart surgery would be required.

HEMANGIOSARCOMA: most common tumor of heart and blood vessels. Often found on right ventricle of heart and in spleen and liver. Very malignant, this is an ill-defined tumor of vascular (blood vessels) tissue. Will often rupture and cause internal bleeding or sudden death. Dogs may often have a history of periodic weakness with spontaneous recovery. Pale gums and loss of weight can also be noted. It will often be too late to help most dogs by the time of diagnosis. Surgery to remove large tumors may give dogs some quality time. ((Hemangiosarcoma on the Heart))

Large masses are often seen on the spleen accompanied by some degree of intra-abdominal bleeding. Upon exploratory surgery many small tumors (metastasis) are often found. Will often also involve the liver, bones and kidneys. Chemotherapy has been tried besides surgery but overall the prognosis is grave for most dogs.

HEMANGIOMA: benign cousin of hemangiosarcoma. Most often seen on spleen and skin tissues. Can rupture and bleed but not as likely to spread as will a hemangiosarcoma. May be treated with surgery.

CHEMODECTOMA: very rare tumor of special blood sensor cells in the arteries in or near the neck. Difficult to treat and diagnose.

HEMANGIOPERICYTOMA: mildly malignant tumor of a cell type that resides near the blood vessels. (periocyte) Most often found in the skin on the legs. Can be surgically removed but often will regrow. Radiation therapy is very effective if available. ((Hemangiopericytoma))

MULTIPLE MYELOMA aka PLASMA CELL MYELOMA: a malignant cancer from plasma cells, a cell type which produces antibodies. May form solitary tumors but more often spreads and infiltrates in bone, the liver, spleen, nervous system and some other soft tissues. Can be extremely painful when in the bones. Will causes elevations in one type of blood protein. A rare disease, may be treatable with certain chemotherapies.

THYMOMA: cancer of the thymus, a tissue in the chest most active in young dogs; part of the immune system. May compress the heart and lungs leading to cardiac and respiratory dysfunction. May also put pressure on the large blood vessels of the chest. Will also be associated with myasthenia gravis and polymyositis. Quite rare, may be treatable with surgery, chemotherapy and/or radiation therapy. ((Thymoma))

THYMIC CYST AND THYMIC ENLARGEMENT: benign and non-neoplastic but may compress heart and lungs causing trouble breathing, fever and swelling of the hindlegs. Treatable with surgery.

Tumors can arise from any of the various liver tissues but more often cancers metastasize to the liver from other sites in the body. Clinical signs of liver tumors are similar to most other liver diseases and include poor appetite, weakness, weight loss, vomiting, diarrhea, increased thirst, fluid collecting in the abdomen, and jaundice. Diagnosis is made in a manner similar to other diseases of the liver.

HEPATOCELLULAR CARCINOMA: a malignant tumor, can be large, small, widespread or nodular. Will often quickly spread to lymph nodes near the liver then to organs nearby. Large solitary tumors or tumors in only one lobe (section) of the liver can be cured with early surgery. Chemotherapy may be helpful in more diffuse cases. ((Hepatic Carcinoma))

HEPATOCELLULAR ADENOCARCINOMA: see hepatocellular carcinoma.

HEPATOCELLULAR ADENOMA (HEPATOMA): benign tumor, tends to grow as large single or multiple masses. Liver will function normally otherwise. Can often be removed with surgery. ((Hepatoma))

BILE DUCT CARCINOMA: may occur inside or outside the liver or in the gall bladder. Forms from bile duct tissues. May occur as a large mass and be removable, but usually too diffuse for surgery. More malignant than hepatocellular carcinoma.

HEPATIC CARCINOIDS: very diffuse, very malignant tumor for which only supportive care may be available. A very rare tumor that arises from specialized tissues in the liver.

LYMPHOSARCOMA: a nodular or diffuse tumor considered malignant but might respond well to certain types of chemotherapy. see..lymphosarcoma

SECONDARY TUMORS which metastasize to the liver commonly include hemangiosacrcoma, mammary gland adenocarcinoma, and pancreatic carcinoma. ((Metastatic Liver Cancer))

LYMPHOSARCOMA aka LYMPHOMA: a relatively common and very significant malignant tumor of lymphocytes, a type of white blood cell and an important part of the immune system. Could be considered a type of leukemia, but considered here because of the distinct clinical syndromes it produces. Spontaneously occurring with no specific cause having been identified.

Four distinct variations are observed:

MULTICENTRIC LYMPHSARCOMA: causes enlargement of all lymph nodes, liver and spleen as these organs fill with abnormal cells. Most common form of the disease.

ABDOMINAL LYMPHOSARCOMA: next most common form seen. Will attack all or parts of the intestines, sometimes causing masses to form; other times abnormal thickening of the bowel and a resulting malabsorption syndrome. Also will involve abdominal lymph nodes, spleen, liver and kidneys.

MEDIASTINAL LYMPHOSARCOMA: rare form which causes enlargement of the area in the chest between the heart and lungs. (mediastinum) Will cause compression of heart and lungs and enlargement of thoracic lymph nodes.

MISCELLANEOUS FORMS: several uncommon presentations of this disease do occur. Most common is a skin disease which can mimic many other types of skin disorders. Causes red, raised, itchy and sometimes ulcerated sores. Can also involve the eye and very rarely the nervous system leading to neurologic deficits of almost any form.

The clinical signs of lymphoma (LSA) will vary with the type and areas involved. Most dogs will have notable enlargement of the lymph nodes which is not painful. Clinical signs in general will otherwise include weakness and decreased activity, poor appetite and weight loss, difficulty swallowing, difficulty breathing, coughing, vomiting, diarrhea, abdominal enlargement and signs otherwise specific to areas involved. ((Lymph Node Enlargement in a dog with Lymphosarcoma))

A proper diagnosis is made with blood counts, serum chemical analysis, urinalysis, X-rays, lymph node aspirates and biopsy and bone marrow biopsy. Surgery is rarely useful as a treatment. For this condition, there are well-established chemotherapy protocols that have a moderate degree of effectiveness. These usually employ multiple drugs given on a specific schedule. A specialist is often needed to perform such treatment. Radiation, has also been employed in some cases. High quality nutritional support is highly recommended. Dogs not in remission in several weeks should try some other protocol. Maximum survival with therapy is about 1 year.

METASTATIC NEOPLASIA OF THE LYMPH NODES: because the lymph nodes reflect most any process within the body, inflammatory or neoplastic, their enlargement is often significant. While metastasis to other organs is generally briefly mentioned in this program, it is covered here because of the role of this organ system. Local carcinomas, mast cell tumors, melanoma and other cancers all may cause enlargement of and spread to the lymph nodes. Infections too can lead to enlargement so careful diagnosis is essential.

INTERSTITIAL CELL TUMOR: common tumor, usually benign being small and confined to the internal testicle. May produce male or female hormones but usually considered of little consequence. Neutering will be curative and preventative. ((Testicular Tumor))

SERTOLI CELL TUMOR: usually small and benign but can grow very large as part of a retained testicle. Can produce estrogen, which is the most severe effect of the tumor, causing liver and bone marrow damage. Often curable if caught early, otherwise chemotherapy may be needed. Surgery on dogs with high estrogen levels can be risky. Neutering is preventative. ((Sertoli Cell Tumor))

SEMINOMA: usually benign and confined to the testicle but some do metastasize. Can produce male or female hormones but most will not. Castration is curative and preventative.

TRANSMISSIBLE VENEREAL TUMOR: an uncommon and contagious tumor of either sex, transmitted during mating. Appears as a cauliflower-like growth on the genitals but may also be nodular, lobulated or hang from a stalk-like growth, some become quite large. Mass will be firm but can easily break and bleed; may also become ulcerated and raw; a discharge is also common. Weekly treatment with a chemotherapy agent is often very effective. Neutering and containment of dogs will be preventative.

PROSTATIC ADENOCARCINOMA: malignant tumor most often seen in dogs that have not been neutered. Will cause enlargement of the prostate gland; enlargement will often be quite irregular. Can cause urine and fecal retention, weakness, pain, bleeding from the penis, and weight loss. Spreads to areas inside the pelvis and sometimes other organs. No treatment effective towards a cure but neutering may slow growth of the mass for temporary relief. Almost never seen in castrated males, neutering considered preventative.

Cancers of the muscles are quite rare, but do occur. Cancers occurring in other locations can also spread to muscle tissue but these too are uncommon. Primary muscle tumors include:

RHABDOMYOMA: benign tumor, often localized, can be cured with aggressive surgery if tumor borders can be cleanly identified. Radiation or chemotherapy possible.

RHABDOMYOSARCOMA: very malignant tumor of muscle, can spread wildly through the affected muscle(s). If caught early and removed with very aggressive surgery a cure is possible although not likely. Once tumor spreads the prognosis is quite grave.

While cancers and tumors of the nervous system are uncommon, their composition is often complex, and as with any neurologic disease, the location of the mass and nerves or brain tissue affected will determine what symptoms are outwardly seen. Diagnosis of neurologic neoplasms is also difficult and may require a specialist in many cases.

Because of this complexity, only a regional classification is presented below.

INTRACRAINIAL TUMORS: or tumors of the brain. Pressure on brain tissue and other alterations caused by tumors can lead to seizures, altered levels of consciousness and responsiveness, and deficits of the nerves of the head and face. See..Brain Tumors

SPINAL CORD TUMORS: tumors in this area may occur inside the cord, on surrounding membranes, or put pressure on the spinal cord from surrounding tissues. Damage to this area will obstruct nerve conduction to areas between the tumor and the tail. (literally) Symptoms can include paralysis, weakness and staggering. See..Spinal Cord Tumors

TUMORS OF PERIPHERAL NERVES: neoplasia of the peripheral nerves is quite rare, and otherwise would most commonly occur near the spinal cord where the nerves emerge. Clinical signs include lameness, pain, loss of muscle mass (atrophy), paralysis and licking or chewing at the limb or area affected. See..Peripheral Nerve Tumors

TUMORS OF THE VERTEBRAE AND METASTATIC DISEASE: cancers which spread from the bones, such as osteosarcoma or fibrosarcoma, or cancers which spread to the nervous system from other areas, such as breast, prostate and bladder cancers, can damage the nervous system. Most will produce incurable disease.

Common tumors include:

Meningioma, Reticulosis, Oligodendroglioma, Astrocytoma And Ependymoma

Meningioma, Astrocytoma, Oligodendroglioma, Neuroepithelioma And Ependymoma

Schwannoma, Neurofibroma, Neurofibrosarcoma And Nerve Sheath Tumors

Tumors of the pancreas may cause symptoms similar to those of pancreatitis, but may include jaundice if the liver or bile ducts become involved. Sometimes a mass may be palpable in the abdomen or abdominal swelling is noted. Diagnosis is made in a manner similar to other pancreatic conditions.

NODULAR HYPERPLASIA: benign and insignificant. Not neoplastic.

PANCREATIC ADENOMA: benign and usually singular, isolated tumor, will rarely cause symptoms. Can be surgically removed but usually not needed.

DUCT CELL CARCINOMA: very malignant and usually will have spread to liver, lymph nodes and lungs before diagnosis is obtained. Can also spread into stomach and intestines. Poor prognosis although some chemotherapy may provide temporary relief.

ACINAR CELL ADENOCARCINOMA:very malignant and usually will have spread to liver, lymph nodes and lungs before diagnosis is obtained. Can also spread into stomach and intestines. Poor prognosis although some chemotherapy may provide temporary relief. ((Adenocarcinoma))

Neoplasia of the respiratory system is uncommon if not frankly rare. Metastatic disease, cancer that spreads to the lungs, is more common. This is why the chest is often X-rayed in cases of breast cancer, lymphosarcoma, mast cell tumors, osteosarcoma, and most any other type of carcinoma found in the body as all can and do find their way into the lungs. Otherwise tumors of respiratory origin are very rare indeed. ((Metastatic Lung Cancer))

PULMONARY ADENOCARCINOMA: malignant, solid and growing type mass. May be confined to one lobe of the lungs for some time. May cause coughing with blood or difficulty breathing. Surgical removal the best hope.

PULMONARY SQUAMOUS CELL CARCINOMA: cancer of lining tissues, very malignant spreading quickly to lymph nodes and other intrathoracic structures. May cause coughing with blood or difficulty breathing. Possible to remove all or part of a lung if caught early enough.

BRONCHOALVEOLAR CARCINOMA: variation of adenocarcinoma also malignant. Often found as solid mass but can be wide spread through lungs. May cause coughing with blood or difficulty breathing. Surgical removal possible if detected early.

NASAL SQUAMOUS CELL CARCINOMA: malignant cancer of nasal surface tissues, can also invade sinus cavities Can attack or be associated with oral lesions as well. Quick to spread deeply in tissues and to lymph nodes. Surgery and radiation can be effective but few dogs live longer than 6-9 months after diagnosis. To perform surgery one would need to open nasal cavity through bone. ((Squamous Cell Carcinoma))

FIBROSARCOMA: malignant tumor of nasal connective tissues. Most common having extended from roof or the mouth, invades deeply but slow to spread to distant sites. Can be partly removed with surgery but most always will regrow. Radiation also effective, and another therapy, injections of Acemannen, has been used with some success. Freezing of the tumor has also been used with some success but access to the cancer may cause difficulty. ((Fibrosarcoma))

CHONDROSARCOMA: uncommon tumor of cartilage, could occur in larynx or on tracheal rings. Malignant but may be removable with surgery and/or radiation therapy. More common in older dogs and on bone tissue. Not usually painful, the tumor is slow growing and can cause respiratory obstruction.

CHONDROMA: benign tumor of cartilage, quite rare, may still create defects within the larynx or trachea and on occasion within the lungs. More commonly grows on bone tissues.

The greatest variety and numbers of neoplasms occur on the skin. Fortunately, as the skin is exposed to view, the chances for early diagnosis and treatment are equally as opportune. All lumps, bumps, changes in texture or pigmentation of the skin should be investigated, biopsied and removed. Most cases of skin cancer are curable. Two major sub-classes of skin tumors exist; epithelial and adnexal tumors, and mesenchymal tumors.

Epithelial and adnexal tumors arise from the surface layers of skin and their associated structures such as sweat glands, oil glands and so forth. Mesenchymal tumors arise from connective tissues and fat in the deeper layers of the skin.

PAPILLOMA: small benign wart-like tumors in young dogs associated with a papilloma virus; in older dogs there is no viral association. May produce large cauliflower-like growths on the lips of young dogs. Very benign, may regress spontaneously or can be removed with surgery or freezing.

INTRACUTANEOUS CORNIFYING EPITHELIOMA aka KERATOACONTHOMA aka ICE TUMOR: benign solitary tumor, can occur on any dog but multiple masses are sometimes found on "arctic" breeds. Tumors contain a core of keratin, hair and other debris. Solitary tumors removable, multiples can be removed but surgery can be extensive; chemotherapy has been effective in many cases. ((ICE Tumor))

SQUAMOUS CELL CARCINOMA: common malignant tumor, also seen in other areas besides the skin. Most common on lighter areas of the skin, on feet, anus, legs, scrotum as well as on lips and in the oral cavity. Usually singular but may be proliferative and ulcerate. Very invasive and destructive, but slow to metastasize. Aggressive surgery, radiation and hyperthermia all useful. Cure depends on extent of tumor and location.

BASAL CELL TUMOR: usually benign singular masses of middle-age dogs. Often well defined, hairless and smooth with some dark in color. Surgical removal most always curative. Radiation, chemotherapy and freezing have also been used with success.

SEBACEOUS GLAND TUMORS: three types commonly found: Hyperplasia which is simply over-growth of these tissues. Benign, often found on eyelids, easy to remove. SEBACEOUS GLAND ADENOMA: usually small, darker, multilobulated and singular masses. Benign, slow growing and harmless, some breeds will grow large numbers of these tumors. Tends to become a nuisance in some cases if they break or become irritated. Surgical removal curative although many new ones can grow. SEBACEOUS GLAND CARCINOMA: rare malignant tumor, often will grow quickly then ulcerate. Locally very invasive and spreading, variable opinions about chances for metastasis. Very aggressive surgery and/or freezing important for a cure. Radiation also quite useful. ((Sebaceous Adenoma))

SWEAT GLAND TUMORS: quite rare, rarest of all skin tumors. Most involve what are called the apocrine sweat glands and occur in older dogs. Some benign, some malignant, most singular in nature, well circumscribed and firm. Aggressive surgery is curative in most cases although a few will spread to local lymph nodes.

TRICHOEPITHELIOMA: from hair follicle tissues. Most common on the back, benign, slow growing and well defined. Excellent cure rate with surgery.

PILOMATRIXOMA: very rare tumor from hair matrix. Often appear as hairless, ulcerated and well-defined lesions, may seem gritty. Usually benign and removable with surgery.

PERIANAL ADENOMA: is the major anal tumor in dogs and is quite common, mostly in non-neutered males. Can be prevented with neutering. Tumor forms from glandular tissue in the anus and will grow slowly and progressively, can ulcerate and bleed. Many can be cured with neutering and tumor removal. Freezing, radiation and female hormones have also been used but neutering is most always effective. ((Perianal Adenoma))

APOCRINE GLAND CARCINOMA: tumor of glandular tissue of anal sacs, uncommon and moderately malignant. May mimic anal sac abscess in appearance. Surgical removal or freezing the best hope of cure. Will spread to lymph nodes and other parts of the digestive system if not treated early. ((Apocrine Gland Carcinoma))

FIBROMA: benign tumor of connective tissue, well-defined, solid, solitary and firm. May be attached to epidermis. Easy to cure with surgery. ((Fibroma))

FIBROSARCOMA: malignant tumor of fibrous tissues in older dogs. All are highly variable in appearance which makes the old adage that "it doesn't look like anything to worry about" quite dangerous. Very locally invasive, many regrow after surgery. Only about 10%, however, will metastasize to the lungs. Very aggressive surgery is important if any hope of cure is desired. Radiation, chemotherapy and acemannen have all also been used with moderate success.

LIPOMA: very common fatty tumor. Benign, well defined and solitary although some dogs seem to get multiple tumors. Can grow very large if not removed; will then interfere with leg movement. Most grow slowly but progressively. Should be surgically removed as cannot differentiate these form their malignant cousins. Surgery is curative and the only realistic treatment. ((Lipoma)) ((Lipoma#2))

LIPOSARCOMA: malignant fatty tumor that tends to heavily invade local tissues. Does not arise from a simple lipoma but difficult to differentiate from a lipoma with surgery alone. Should be removed and many can be cured if removed before they invade surrounding tissues.

HEMANGIOPERICYTOMA: tumor from cells which surround blood vessels, outwardly may resemble the fibrosarcoma. Occurs on older dogs mostly near the feet on the leg. Usually solitary, firm and well attached although some feel like a lipoma. Are not malignant in over 90% of all cases but as they invade local tissues most regrow (although slowly) after surgery and will need to be removed again. Very few will metastasize. ((Hemangiopericytoma))

MELANOMA: tumor of pigment-producing cells can be benign or malignant although one could not tell by looking at the actual tumor. Occurs on about any part of the body including the lips and mouth where more or most will be malignant. Often appears as small, dark, hairless, raised masses with malignant versions larger (not much basis for comparison) than benign tumors. Some may be without pigment so further deception is possible. Very aggressive surgery is important and in some cases, amputation of the area affected should be considered. High cure rate for benign tumors, poor prognosis for malignancy. ((Melanoma, skin))

HISTIOCYTOMA: unique macrophage (a type of white cell) tumor of dogs that may make up to 10% of all canine skin tumors. Most common on the head but feet, legs and body areas can be involved. Usually appears as a dome-shaped round mass. May grow rapidly and appear malignant but most are quite benign and can be cured nicely with surgery. A few may regress on their own. 

MYXOMA: very rare benign tumor of embryonic connective tissues. Usually removable with surgery.

MYXOSARCOMA: very rare malignant tumor of embryonic connective tissues. Can invade and infiltrate locally but still may be removable surgically as they are slow to metastasize.

MAST CELL TUMOR: a relatively common benign or malignant tumor formed from mast cells which reside along vascular tissues. Benign forms may become malignant in time if not treated. Tumors are usually solitary, some can grow very large, and all are highly variable as to their outward appearance as to fool anyone who lightly approaches a diagnosis. The mast cells are (most always) very distinct so simple aspiration and cytology can warn the veterinarian of their presence and direct treatment. ((Mast Cell Tumor))

Mast cell tumors that become malignant spread to lymph nodes and most other organs. As the cells produce and can release vasoactive substances such as histamines, severe sudden reactions and death can occur. Many turn outwardly red, raw and ulcerated. Cytology is critical before surgery so that the tumor is not cut and that wide margins are taken around the mass to prevent recurrence. Adjunctive therapy includes intra-lesion and oral steroids, injection of the area of removal with pure water, other chemotherapeutic drugs and radiation. Aggressive therapy will allow many dogs to have good post-diagnosis survival times, nevertheless, this is a serious neoplasm and should be dealt with accordingly.

ADENOMA: benign local tumor, can be treated by removing all or part of the affected kidney.

FIBROMA: connective tissue tumor, can spread through the kidneys but will usually not through the body. Can be treated by removing the kidney.

TRANSITIONAL CELL CARCINOMA: tumor of the tubular lining cells of the bladder and related structures, can be rapidly growing but will be slow to spread inside the body. Can produce urinary bleeding, straining and ultimately, restriction of urine outflow. May be treatable by surgical removal of all or part of the bladder and urethra and some type of internal reconstruction. A specialist will usually be required and chemotherapy may also be useful. ((Transitional Cell Carcinoma))

SQUAMOUS CELL CARCINOMA: malignant tumor of lining tissues, may act and be treated similar to transitional cell tumors.

ADENOCARCINOMA: malignant tumor of lining tissues, may act and be treated similar to transitional cell tumors.

RENAL CELL CARCINOMA aka ADENOCARCINOMA: very malignant and most common tumor of the kidney. Often spreads through all organs of the body, and will generally be untreatable. Chemotherapy may help if caught early. If diagnosed very early removal of the kidney may be possible for a cure. May be caused by poisons and toxins.

EMBRYONAL NEPHROBLASTOMA: often occurs in young dogs, very malignant tumor composed of fetal-like tissue, and will quickly spread to lungs, liver, lymph nodes, muscles, bones and joints. In some studies a high survival rate has been achieved with removal of the kidney and ureter followed by chemotherapy.

SECONDARY TUMORS that commonly metastasize to the kidney include hemangiosarcoma, osteosarcoma, malignant melanoma, lymphosarcoma and mast cell tumors.

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