Advances in the diagnosis and treatment of brain tumors in dogs. Part 3. Traditional methods of treatment

Brain tumors in dogs

Richard A. LeCouture, BVS, PhD, ACVIM Diplomate (Neurology), ECVN Diplomate University of California Davis CA 95616 USA
Meningiomas and gliomas are the most common types of cancer in dogs. Most primary brain tumors are single, but there are reports of multiple primary brain tumors. Secondary, or metastatic, tumors are less common and may result from the growth and spread of a local tumor (nasal adenocarcinoma) or metastasis of primary tumors elsewhere. Skull tumors can affect the brain when a local tumor spreads. Although brain tumors occur in dogs of all breeds, both sexes and at all ages, the incidence of tumors increases at age five and in certain breeds. Glial cell tumors and pituitary tumors are commonly found in brachycephals, while meningiomas are most common in dolichocephals.

Pathology.

Primary brain tumors arise from cells that are usually found inside the brain and meninges. Secondary tumors are metastases that develop from a primary tumor, are located outside the nervous system, or appear by local invasion of adjacent non-nervous tissues (for example, bone tissue). Pituitary neoplasms and tumors arising from cranial nerves are considered secondary brain tumors. Brain tumors cause cerebral dysfunction due to infiltration of healthy brain tissue, compression of adjacent structures, disruption of cerebral blood circulation and local necrosis. Secondary effects of brain tumors include hydrocephalus, increased intracranial pressure, cerebral edema, and brain herniation. Primary brain tumors usually grow slowly, and the brain adapts to the slow increase in intracranial pressure. During this compensation period, vague symptoms and slight changes in behavior may be observed. Even with slowly progressing tumors, clinical signs can develop rapidly when compensatory mechanisms are exhausted. With rapidly growing tumors, the same degree of compensation is not possible and severe neurological dysfunction may appear suddenly in the absence of prodromal signs.

Medical history and clinical signs.

The neurological signs resulting from a brain tumor mainly depend on the location, size and growth rate of the tumor mass. Many dogs and cats show vague signs such as not wanting to be held, trying to hide during the day, or decreasing purring frequency or activity level. Focal or generalized seizures are usually observed.

Focal neurological symptoms usually indicate a significantly advanced tumor. Neoplasms involving the brainstem can lead to cranial nerve dysfunction. Weakness and sensory disturbances are often observed with lesions in the brain's frontoparietal regions or their deep pathways. Visual impairment may accompany the development of tumors that affect the visual pathways from the occipital lobe of the brain to the optic nerve. Hearing loss occurs when the cerebellomedullary region, brain stem, or temporal lobes of the brain are affected. A decrease in the ability to smell can be observed with damage to the cribriform plate or olfactory bulbs, as well as other rhinocephalic connections. Balance or gait problems indicate damage to the cerebellum or vestibular system.

Secondary effects of brain tumors include increased intracranial pressure and cerebral edema. Clinical symptoms include changes in behavior (eg, lethargy, irritability), manipulative movements, head pressure, involuntary gait, changes in state of consciousness, or associated locomotor disturbances. Most dogs or cats with a brain tumor are seen by a veterinarian for problems related to side effects of the tumor.

Diagnostic methods.

Based on symptoms, medical history, and the results of a complete physical and neurological examination, it is possible to localize the disorder in the brain and, in some cases, determine its approximate location. Symptoms of the disease for a given location in the nervous system will be similar, regardless of the exact cause. In order to exclude other categories of disease, it is necessary to adhere to a consistent diagnostic plan. Minimum data from these patients should include: hemogram, serum chemistry panel, urinalysis, plain chest x-ray, and peritoneal ultrasound. Although plain skull x-rays are of limited value in diagnosing a primary brain tumor, their use may facilitate the detection of cranial or nasal neoplasms. Rarely, lysis or hyperstosis of the skull may accompany a primary brain tumor (eg, feline meningioma), or mineralization within the neoplasm may be visible on x-ray. General anesthesia is necessary for precise positioning of the skull for radiography.

Cerebrospinal fluid analysis is recommended to help rule out inflammatory diseases and aid in the diagnosis of a brain tumor. Caution should be used when collecting cerebrospinal fluid because intracranial pressure often increases, and changes in pressure associated with drainage of cerebrospinal fluid can lead to brain herniation. Hyperventilation or administration of mannitol prior to CSF ​​collection will help lower intracranial pressure. Increased protein content in the cerebrospinal fluid and the content of white blood cells is normal or increased - these symptoms are considered a typical sign of brain neoplasm, although often the composition of the cerebrospinal fluid may not change. Neoplastic cells may be present in the cerebrospinal fluid, especially when sedimentation techniques are used for analysis. Computed tomography and magnetic resonance provide precise information about the presence, location and size of intracranial neoplasms. Magnetic resonance images provide a more accurate picture than CT scans when examining certain areas of the brain (such as the brain stem). Meningiomas are difficult to detect using magnetic resonance without the use of a contrast agent. Meningioma may have a “speckled” appearance and surface, and is often located between the tumor and surrounding brain tissue during tumor stages T1 and T2. A hypointense signal may indicate compression of the arachnoid plate as well as compression of the venous plexus. Hypointense areas within a meningioma may indicate intratumoral mineralization. The dural tail sign is not necessarily specific to meningioma, but is often caused by neoplastic infiltration of the meninges beyond the margins of the meningioma or hypervascularization of the dura. It is advisable to perform a biopsy of an intracranial lesion before starting therapy, but biopsy is not always used due to the high cost of its implementation, as well as the increased incidence of morbidity in animals. Lesions that are not neoplastic in nature and occupy a large space may mimic the appearance of neoplasm on computed tomography or magnetic resonance, and metastasis may resemble a primary brain tumor. Currently, biopsy is the only method used to definitively diagnose a brain tumor. Known biopsy techniques include ultrasound-guided biopsy as well as computed tomography. Stereotactic CT biopsy guidance systems provide relatively noninvasive, rapid, and highly accurate tumor biopsies with low complication rates.

Tumor in dogs | Where does | Symptoms | Treatment. (April 2020).

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Brain tumors in dogs are abnormal cell growths that affect the brain or the membranes surrounding it. They can be either primary or secondary. A primary brain tumor occurs in the dog's brain, and a secondary brain tumor can be a form of cancer that metastasizes and spreads to the brain from other places in the dog's body. These brain tumors are not brain cancer because the growing cells are not made up of brain tissue. Secondary brain tumors can also be tumors that are not directly located in the brain but have spread, for example, to brain tissue from another area, such as the nasal cavity or bone. The causes of brain tumors are not entirely understood, but various genetic, dietary and environmental factors can influence abnormal cell growth. Symptoms of brain tumors are often severe and debilitating, and they often lead to death. If you see signs of a brain tumor in your dog, contact your veterinarian right away for diagnosis and treatment. Here's what you need to know about the symptoms, causes and treatment of brain tumors in dogs.

Expected forecast

The prognosis is usually poor for pets treated for secondary symptoms without attempts to remove the tumor; One study reported a maximum and median survival time after CT diagnosis of a brain tumor of 81 days and 56 days, respectively (8 dogs were included in the study).

Some studies suggest that the prognosis for a dog or cat with a primary brain tumor can be improved by surgical removal of the tumor, radiation therapy, and chemotherapy (used alone or in combination).

Symptoms of brain tumors in dogs

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Symptoms of brain tumors in dogs depend on the size and location of the masses. These symptoms may come on gradually and increase steadily as the tumor grows, or they may occur suddenly and be very intense. The most common sign of a brain tumor is seizures, especially if these seizures appear for the first time after the dog's age of five. Here are some other possible symptoms of brain tumors in dogs.

• Blindness or visual impairment
• Abnormal eye movement
• Head tilt or rotation
• Whirling
• Unusual aggression or abnormal behavior
• Hypersensitivity to pain or touching the neck
• Loss of coordination
• Abnormal gait or posture
• Loss of appetite
• Weakness
• lethargy
• Urination in the house when dogs are usually house trained
• Nosebleeds
• sneezing
• Choking and making it difficult to breathe

Disease prognosis

The prognosis of the disease can be favorable only if the surgical operation to remove the tumor is successful. In the absence of metastases, such dogs usually have every chance of recovery and live quite a long time.

It is important for owners to follow all doctor’s recommendations. At home, you need to provide your pet with complete peace, protecting it from other dogs and children.

I really want to do everything so that after the operation the dog lives a full life. But we must remember that any brain surgery carries a certain risk. It is possible that important nerve trunks may be damaged. This is fraught with partial loss of organ functionality. Relapses of the underlying disease are also possible. Therefore, every 3-5 months the dog is brought to the veterinary clinic for a control examination.

Cerebral edema is a serious life-threatening condition that most often develops against the background of extensive damage to brain tissue, for example, due to head trauma.

Brain edema can also be caused by an acute lack of oxygen due to impaired blood supply to the brain, prolonged convulsive activity, brain tumors, exposure to toxins - both endogenous, produced in the body as a result of metabolism, and exogenous - received from the outside.

Head injuries are more common in young toy breeds.

The state of consciousness in animals with cerebral edema can vary from soporosis to deep coma.

Diagnosis is usually made based on clinical symptoms, neurological examination, and medical history. Studies such as tomography and electroencephalogram can reliably confirm cerebral edema, but for an animal in critical condition, the transportation of which is difficult, these studies are usually not available.

Treatment of cerebral edema

Successful treatment of cerebral edema in animals, as in humans, can only be carried out in a specialized intensive care unit and is always based on the treatment of the underlying disease. 24-hour monitoring and the availability of high-tech equipment are key to maximizing your chances of surviving cerebral edema.

A necessary condition is careful monitoring of neurological status every few hours, additional oxygenation (oxygen therapy), control and maintenance at physiological levels of indicators such as blood pressure, electrolyte balance, body temperature, nutrient intake, and an adequate level of analgesia (pain relief). In some cases, respiratory support (artificial ventilation) is necessary.

Causes of brain tumors in dogs

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The causes of brain tumors in dogs are not entirely understood, but genetic, dietary, environmental, chemical and immune factors are thought to influence abnormal cell growth. Trauma and infection may also play a role. Some dogs are more at risk of developing brain tumors. Older dogs, especially those aged five, are more likely to develop the condition. Brachycephalic dogs—dogs with short muzzles—are more prone to glial cell tumors and pituitary tumors, which are two types of brain tumors. Boston Terriers, Boxers, Doberman Pinschers, English Bulldogs, Golden Retrievers, Shepherds and Scottish Terriers also seem to develop brain tumors more than other breeds.

How does chemotherapy work for dogs?

The drugs used to treat dogs with chemotherapy will act primarily on cells that are dividing. Since cancer is defined by uncontrolled cell growth, chemotherapy is designed to attack and destroy tumor cells...

Part of the complication of chemotherapy treatment for dogs is that the attack is not selective. The drugs will act not only on tumor cells, but also on healthy cells. This is especially true for cells in the intestines and bone marrow, since these are the cells that suffer the most division. As we will see, it is the chemotherapy drugs that are responsible for any adverse reactions...

Treatment of brain tumors in dogs

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There are three main forms of treatment for brain tumors in dogs. These are surgery, chemotherapy and radiation therapy. The goal of these treatments is to eliminate or at least shrink the size of brain tumors, as well as control any fluid buildup that may be caused by the tumors. Surgery is used to remove all or part of brain tumors in dogs, while chemotherapy and radiation therapy are used to shrink tumors or control their growth. Most dogs that receive treatment will also be prescribed to treat symptoms such as seizures. The prognosis varies depending on what type of therapy is used, but in general the combination of surgery and radiation therapy provides the longest survival time, which usually ranges from six months to three years.

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Treatment method and prognosis

Treatment should be started as early as possible. It is important to understand that the count is not even in months, but in days. There is no effective drug therapy; no drug can promote tumor resorption. To date, the only way to slow down the development of a tumor is surgery followed by chemical and radiation therapy.

When it comes to cancer, chemotherapy methods give good results only at an early stage of the disease.

Radical surgery is carried out under the control of an ultrasound scanner and gives the most positive result. The procedure involves complete removal of the affected tissue (tumor), reducing intracranial pressure and eliminating perifocal edema.

Sometimes the location of the tumor is such that it is not possible to completely remove it. In such cases, palliative operations are performed - partial removal of the tumor. The main goal of the operation is to alleviate the dog’s condition and reduce the number of cancer cells.

After surgical partial or complete removal of the tumor, the dog undergoes chemotherapy or radiotherapy. These treatment methods are very effective, but cause serious side effects in the form of severe intoxication of the body.

In order to improve health and improve the quality of life, the dog is prescribed symptomatic treatment, which includes taking:

• diuretics (Mannitol), which relieve intracranial pressure;
• steroids that slow the growth of certain types of tumors;
• anticonvulsants (Phenobarbital, Bromide), eliminating seizures.

Infusion therapy is mandatory and a special diet is prescribed.

As for the prognosis, doctors give them extremely carefully. A favorable outcome depends on the age and individual characteristics of the dog, the size and location of the tumor, the quality and timeliness of treatment.

Dogs with benign tumors have a greater chance. However, it happens that in case of remission, an operated and treated dog can live to a ripe old age, and sometimes the dog dies without even living a year.

That is why it is so important to immediately show the animal to a specialist at the first alarming symptoms.

Brain Tumors in Dogs: Symptoms, Causes and Treatment

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Brain tumors in dogs are abnormal growths of cells that affect the brain or the membranes surrounding it. They can be primary or secondary. Primary brain tumors originate in the dog's brain, while a secondary brain tumor may be a form of cancer that has metastasized and spread to the brain from somewhere in the dog's body. These tumors are not brain cancer, as the cells do not grow from brain tissue. Secondary brain tumors can also be tumors that are not directly located in the brain, but spread into brain tissue from another area, like the nasal cavity or bone, for example. The causes of brain tumors are not well understood, but various genetic, nutritional and environmental factors likely influence excessive cell growth. Brain tumor symptoms are often severe and debilitating, and they often lead to death. If you see signs of a brain tumor in your dog, you should see a veterinarian immediately for diagnosis and treatment. Here's what you should know about the symptoms, causes and treatments of brain tumors in dogs.

Diagnostics in a veterinary clinic

To be able to make an accurate diagnosis, the veterinarian needs, in addition to a visual examination of the animal, to carry out a number of diagnostic measures.

An important point is the differentiation of the tumor from other diseases with similar symptoms (Aujeszky's disease, canine plague, etc.), for which appropriate studies are carried out.

Physical, neurological, and laboratory diagnostic methods make it possible to determine the etiology, size and localization of the tumor. The most complete information is provided by ultrasound examination, stereotactic puncture biopsy, computed tomography, magnetic resonance imaging.

If the doctor suspects a secondary tumor, procedures are performed to determine the location of the cancer.

Symptoms of Brain Tumors in Dogs

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Symptoms of brain tumors in dogs depend on the size and location of the masses. These symptoms may appear gradually and steadily increase in severity as the tumor grows, or they may come suddenly and be very intense. The most common sign of a brain tumor is seizures, especially if these seizures occur for the first time after the dog's age of five. Here are a few other possible symptoms of brain tumors in dogs.

• Blindness or visual impairment
• Abnormal eye movements
• Head tilt or rotation
• Whirling
• Unusual aggression or abnormal behavior
• Increased sensitivity to pain or touch in the neck
• Loss of coordination
• Gait or posture disturbance
• Loss of appetite
• Weakness
• Lethargy
• Urinates in the house when dogs are normally trained
• Nosebleeds
• Sneezing
• Shortness of breath and difficulty breathing

Main symptoms

Determining that a dog has a brain tumor is quite difficult. Pathologies have a blurred clinical picture, symptoms often resemble other diseases of the central nervous system, in particular epilepsy.

OGM can be suspected based on the following signs:

• seizures;
• convulsions;
• glassy look;
• swinging gait (pendulum);
• uncontrollable vomiting;
• rotation in place;
• head tilt down;
• sagging lips and eyelids;
• blurred vision, nystagmus;
• hearing and smell impairment;
• increased thirst;
• frequent urination;
• cardiopalmus;
• labored breathing.

The dog's behavior also changes. He becomes aggressive or overly affectionate, he may refuse food or, conversely, absorb everything, even bags.

Unfortunately, most dogs go to the vet when the tumor reaches a significant size.

Causes of Brain Tumors in Dogs

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The causes of brain tumors in dogs are not well understood, but genetic, nutritional, environmental, chemical and immune system factors are thought to influence abnormal cell growth. Injury and infection may also play a role. Some dogs are more at risk for brain tumors. Older dogs, especially those over five years of age, are more likely to develop this disease. Brachycephalic dogs—dogs with short snouts—are more prone to glial cell tumors and pituitary tumors, which are two types of brain tumors. Boston Terriers, Boxers, Doberman Pinschers, English Bulldogs, Golden Retrievers, Old English Sheepdogs and Scottish Terriers appear to have brain tumors more than other breeds.

Prevention measures

It is impossible to prevent the appearance of brain tumors, since the mechanism of development of this pathological process is not fully understood. It is not always possible to cope even with known factors. However, some pathological conditions can be prevented.

Before buying a puppy, it is advisable for the future owner to familiarize himself with its pedigree. If neoplasms have been recorded in your ancestors and the reasons for their appearance have not been established, then perhaps you should refrain from purchasing. However, this recommendation does not work in most cases - you cannot use cold calculation when choosing a future family member.

A brain tumor is one of the most serious diseases of the nervous system in dogs with complex consequences. The mammalian nervous system is responsible for the coordinated functioning of all organs and systems. Therefore, any illness affects the functioning of the whole organism, and often ends tragically.

Treatment of Brain Tumors in Dogs

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There are three main forms of treatment for brain tumors in dogs. These are surgery, chemotherapy and radiation therapy. The goal of therapy is to eliminate or at least shrink the size of brain tumors, as well as control any side effects that may be caused by the tumors. Surgery is used to remove all or part of a dog's brain tumor, while chemotherapy and radiation therapy are used to shrink tumors or control their regrowth. Most dogs that undergo treatment will also be prescribed medications for symptoms such as seizures. The prognosis varies depending on the type of therapy used, but in general, the combination of surgery and radiation therapy provides long survival times, which usually range from six months to three years.

Source: dogsta.ru