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Osteosarcoma in Dogs

What is osteosarcoma?

Osteosarcoma is the most common bone tumor in dogs, usually affecting the bones of the extremities of large breeds of dogs. Osteosarcoma is registered in dogs of middle and older age, but it also occurs in young dogs, especially large breeds.

  • Osteosarcoma can develop on any bone of the skeleton, but bones of the extremities are more often affected.

The growth of the sarcoma begins from within the bone, the pain syndrome increases with the development of the tumor and the destruction of the bone in the direction from the center to the periphery. Lameness from periodic to constant in 1-3 months. The apparent increase in bone size becomes apparent with the growth of the tumor and the replacement of healthy bone tissue by the patient.

The affected bone is inferior in strength to healthy bone and there is a tendency to fracture from minor injuries. Such fractures are called pathological and are a diagnostic sign of a bone tumor. Pathological fractures are not treated, overlapping of the fixation bandage or surgical stabilization is not required.

How do I know if my dog is sick with osteosarcoma?

X-ray examination: one of the first examinations performed with permanent lameness is radiography. Tumors of the bone are painful on palpation, so it is easy to determine which part of the limb should be examined.

Characteristic signs of osteosarcoma are:

  • Lysis: the bone region is dissolved.
  • “Flash in the sun”: with the growth of the tumor, radial ejection of normal bone tissue occurs.
  • The presence of a pathological fracture.
  • Osteosarcoma does not directly cross the joint space, it does not affect other bones that form the joint.

In most cases, an x-ray examination is sufficient to determine the diagnosis, but not always.

Biopsy : taking a sample of bone tissue for morphological examination. It is considered the most reliable method of investigation. The procedure is quite painful, and some veterinarians refuse to perform a biopsy with obvious signs of a bone tumor obtained by radiography. With a controversial interpretation of the results of the examination, a biopsy allows you to make a final diagnosis.

Sometimes, around the tumor develops a significant inflammatory process and requires several samples of pathological tissue. Taking samples is not dangerous and does not lead to the formation of a pathological fracture.

Also check out Osteosarcoma causes and symptoms on credihealth.

If this is not an osteosarcoma?

Localization and the results of X-ray examination in osteosarcoma are quite classical, but it is necessary to take into account some possible causes of bone tissue lysis: chondrosarcoma, squamous cell carcinoma or synovial-venous sarcoma.

Chondrosarcoma : chondrosarcoma is a tumor of bone cartilage, less malignant than osteosarcoma. Chondrosarcoma is usually localized on flat bones (ribs, skull bones) and rarely on the limbs. However, if the chondrosarcoma is located on the limb, it is recommended that you amputate and send the material to a biopsy in order to prescribe adequate chemotherapy.

Scaly-checkered carcinoma : a tumor of the superficial layer of the bone (periosteum). A tumor of local destructive effect with a tendency of slow spreading. The bone with a suspected malignant tumor is amputated, the material is sent to a biopsy, which results in further treatment. The tumor is usually localized on the bones of the jaws and fingers, which distinguishes it from osteosarcoma.

Synovial-cellular sarcoma : a tumor lining the joint capsule tissue. Osteosarcoma never spreads to adjacent bones.

Fungal bone infection : the causative agent of Coccidioides immitis is common in the US, the disease is called the San Joaquin Valley fever or California fever (more correctly called coccidiomycosis). In most cases, the disease is limited to the appearance of calcified lymph nodes in the chest and sometimes lung disease. In rare cases, the fungus spreads through the body and causes proliferative inflammation of the bone tissue. Coccidioidomycosis of bones is proliferative in nature, not lytic, characteristic of osteosarcoma. Thus, the tactic of treatment is to remove the malignant tumor of the bone and prescribe an additional treatment (depending on the type of tumor).

Treatment of osteosarcoma includes 2 aspects: the removal of pain and the fight against the spread of the tumor.

How to deal with pain?

As a rule, dogs are euthanized because of the severe soreness of the affected limb. Successful struggle with pain prolongs the patient’s life and improves its quality.

Amputation of the limb : removal of the affected limb in 100% of cases relieves the animal from pain. Unfortunately, many dog owners refuse surgery because of a misconception.

  • Deprivation of a limb for a person severely limits its possibilities, the loss of one limb from two is unequal to one of 4 (in the case of an animal).
    The amputation does not affect the motor function of the animal, the animal is also able to play and run (after the end of the recovery period).
  • Deprivation of the limb distorts the appearance of a person and entails social consequences.
    This does not happen in the dog, only the owner needs to get used to the changed kind of pet.
  • The average survival time for osteosarcoma without the use of chemotherapy is 4-5 months from the diagnosis, regardless of the amputation. Do you want your pet to live comfortably or suffer from pain for the last 4-5 months?

Operation with the preservation of the limb . The operation involves resection of the affected bone and its replacement with an allograft, or we build up the bone using a new technique of osteogenesis. The nearest joint is fixed in one position, i.e. can not bend and unbend.

  • The operation is not performed if more than 50% of the bone is affected and soft tissues are involved in the process.
  • Operation is not effective for tumors of the femur and humerus.
  • The operation is most effective in tumors of the distal radial part.
  • Complications of operations with preservation of the limb are bone infections, implant rejection, tumor recurrence, fractures.

Radiation therapy for pain control: it is carried out in a course of 3 doses with an interval of 1 week (between the 1st and 2nd) and 2 weeks (between the 2nd and 3rd). Improve limb function occurs within 3 weeks and lasts usually 4 months (from 0 to 19 months according to some doctors). With the return of pain, the course can be repeated depending on the stage of cancer at this time.

  • With a decrease in the painfulness of the affected limb, the motor activity of the animal increases, which leads to the formation of pathological fractures.
  • Radiation therapy is effective in approximately 2/3 of the patients. (If the extremity is amputated, the efficiency reaches 100% .If it is not possible to perform the operation, radiation therapy is helped by a 2-mind out of 3 patients to get rid of the pain).

Medicines : there are a large number of analgesics available for use by dogs. As a rule, a combination of drugs is prescribed for the most effective palliative action.
The use of analgesics is an extreme measure, unless amputation or radiation therapy is performed. For combination use several types of drugs.

Non-steroidal anti-inflammatory drugs : anti-inflammatory painkillers – kaprofen, etodolac, deracoxib, meloxicam, phyroxoxib and tepoxaline are developed for dogs . Usually the drug is prescribed 1-2 times per day orally. When appointing drugs of this type, the patient should have a healthy liver and kidneys.

Bisphosphonates : this class of drugs is widely used in medicine for bone tumors, veterinary use is not so widespread. Bisphosphonates slow down the destruction of bones, which allows you to control pain reactions and bone damage to the tumor. The most commonly used is pamidronate, which is administered intravenously drip for 2 hours every 3-4 weeks in the clinic. The person may experience side effects (fever, muscle pain, nausea for 1 or 2 days in 25%, sometimes kidney failure, lowering of the calcium level in the blood, destruction of the jaw bone cells); Such phenomena, however, are not a problem for cats and dogs. Due to the good tolerability of the drug by dogs and cats, its relatively cheap cost and effectiveness with many destructive bone tumors, it is expected that this class of drugs will be used more often.

Narcotic substances : these drugs do not have anti-inflammatory action, are well-known analgesics and have been used since ancient times in various forms. Drugs are effective for chronic pain, because they do not counteract other analgesics. Side effect is drowsiness. Tramadol is a fairly well-known drug, prescribed in combination with other drugs for bone cancer.

Other additional painkillers : two drugs were distributed as additional painkillers for chronic pain: gabapentin and amantadine . Gabapentin is effective for neurologic pain and quickly spreads in the treatment of arthritis, pain after surgery, etc. Amantadine is effective when it occurs when there is an increased sensitivity from stimuli that usually do not cause pain. The various drugs described above are used in combination to achieve a good analgesic effect in osteosarcoma in the event that amputation and radiation therapy are not performed.

Treatment of osteosarcoma

Osteosarcoma is prone to rapid spread. By the time of detection of the tumor in the bone, as a rule, metastases already affect other organs of the body (the lungs most often). The prognosis is unfavorable, especially in the presence of metastases, detected by X-ray examination. Thus, before the start of chemotherapy, an X-ray examination should be performed.

  • Chemotherapy is the most effective way to influence the course of cancer.
  • Young dogs tend to have a faster (shorter survival period) and malignant osteosarcoma flow than older dogs.
  • Increasing the level of alkaline phosphatase, a blood enzyme, is a bad sign. The survival period is further reduced by 50% of the values given below.
  • A bad sign is also the presence of a tumor in the local lymph nodes of the affected limb being amputated.
    According to a study by Hiller published on April 15, 2005 in the Journal of the AVMA, the average survival rate for dogs was significantly longer (318 days versus 59), who had no malignancies in the local lymph nodes at the time of amputation.

Cisplatinum 

  • The average period of survival is 400 days.
  • Survival of the 1st year: 30-60%.
  • Survival of the 2nd year: 7-21%.
  • The appointment of less than 3 doses does not increase survival (for example, if the owner has the opportunity to spend 1 or 2 courses, it does not make sense to increase the cost of treatment).
  • Cisplatin may have a toxic effect on the kidneys, it should not be used in the presence of kidney disease.

Carboplatin

  • The same statistical indicators, but Carboplatin is not toxic to the kidneys, therefore, it can be used with existing kidney diseases.
  • Carboplatin is significantly more expensive than Cisplatin.

Doxorubicin

  • The average survival period with therapy is 365 days.
  • 10% live longer than 2 years.
  • Toxic effect on the heart.
    Before use, it is necessary to conduct an ultrasound examination, not applied to animals with reduced cardiac contractility.

Doxorubicin and Cisplatinum in combination

  • 48% survival in the first year
  • 30% survival in the 2nd year
  • 16% survival in the 3rd year.

What is the average survival period?

When the number is studied statistically, there are several ways to study the mean value of a group. Median value (median) is a number dividing the numeric set into 2 groups, equal in number (the values of 50% of the group are located above this number, and the other 50% are located below this number). The median number is slightly different from the average number, which is more understandable for most people. The first means that 50% of individuals will survive the average survival period, and the second 50% will not reach this time.

What happens to my dog during chemotherapy?

Most people develop ideas about the consequences of chemotherapy from the media: weakness, nausea and baldness. In animals, everything is not so dramatic. During the first 1-2 days there is drowsiness and nausea. These symptoms can be removed with antiemetic drugs.
Side effects are more pronounced when using a combination of drugs, as a rule, they disappear on the third day after treatment. In fact, 8 days of malaise pay off in 6-12 months of a comfortable life.
Animals do not suffer from hair loss during chemotherapy.

Axial osteosarcoma

Osteosarcoma of the extremities is a classic case, but it can develop on any other bone. The term ” axial ” refers to an osteosarcoma that does not localize on the bones of the extremities, most often the jawbone (upper or lower) is affected.
Such tumors are often recorded in dogs of small breeds, middle age and female (ratio 2: 1 females and males).
On the axial bones of the skeleton, tumors develop much more slowly, which often results in a flow form without obvious signs of manifestation. By the time of detection of osteosarcoma can take about 2 years (from the beginning of growth). An exception is the osteosarcoma of the rib, with a tendency to more aggressive flow compared to other axial osteosarcomas.
The treatment of axial osteosarcoma is similar to the treatment of an appendicular form: a surgical operation followed by chemotherapy. An exception is the osteosarcoma of the lower jaw. Since the axial tumor grows slowly and it is possible to remove part of the bone or its entirety without loss of function or cosmetic defect, there is evidence of a survival rate of more than 1 year in 71% of cases without chemotherapy.

Specialist-oncologist

Each patient with a tumor must undergo an individual reception, consultation, diagnosis and treatment with an oncologist. Do not view the Internet as a worthy substitute for an individual expert advice

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