Though comparatively uncommon, a brain tumor has always made a grim prognosis for adverse animal that is diagnosed with one. Traditionally they were many times assumed but seldom confirmed, but since MRI and CT scanning has become more mainstream they may be diagnosed correctly. Here we talk about the dissimilar types of brain tumor that affect dogs and cats, the clinical investigations that may be performed, the treatments available and the likely outcomes.
Brain tumors seem to be more mutual in dogs than cats, and sure breeds are over represented such as Boxers, Golden Retrievers, Dobermans, Scottish Terriers and Old English Sheepdogs.
Primary vs Secondary
Brain tumors may be crucial or secondary (metastasis from other sites). Primary brain tumors are normally solitary, the most mutual ones in the dog being gliomas and meningiomas. In cats, the most mutual type are meningiomas and these may take place at multiple locations.
Secondary tumors in dogs include extension of a nasal tumor, metastases from breast, lung or prostate cancer, hemangiosarcoma or extension of a pituitary gland tumor. Nerve sheath tumors and skull tumors have also been reported. Secondary tumors in cats include pituitary gland tumors, metastatic carcinomas, local extension of nasal tumors, skull tumors and middle ear cavity tumors.
What causes a brain tumor?
The cause of brain tumors is not known. Diet, environment, chemical, genetic, viral, immunologic and trauma have all been considered. In cats with meningiomas, because they often take place in very young animals, a genetic factor is suspected.
Benign vs Malignant
The terms benign and malignant ought to be employed with care when referring to brain tumors. Normally these terms implement to respective characteristics on a cellular level, but on a biological level, even benign brain tumors may kill the animal due to the secondary effects like increased intracranial pressure or cerebral edema. In short, any brain tumor may kill.
What are the symptoms?
There may be big assortment here. Many animals will present with vague signs, such as one or various of the following:
1. Loss of trained habits
2. Decreased levels of activity
3. Decreased frequency of purring in cats
4. Disorientation
5. Confusion More specific sensations or changes are dependent upon where incisively the tumor is located within the brain, the size of the tumor and how quickly it is growing. As a tumor enlarges, sensations or changes tend to become more severe. These may include:
6. Seizures (often indicate a tumor in the cerebral cortex)
7. Facial paralysis (may indicate a brainstem tumor)
8. Tremors (may indicate a tumor in the cerebellum)
9. Wobbliness (may indicate a tumor in the cerebellum)
10. Full or partial blindness (may indicate tumor in hypothalamus or optic nerve)
11. Loss of smell (may indicate tumor of olfactory system)
The physical presence of the tumor may cause knock on effects due to inflammation and edema of the surrounding area. This may cause sensations or changes such as:
12. Changes in behaviour or temperament (irritability, lethargy)
13. Compulsive walking
14. Circling
15. Pressing head versus a wall or hard surface
Animals may now and then carry brain tumors for various years before presenting to a veterinary clinic, if the tumor is slow growing. In these cases the sensations or changes fabricate gradually, and the owner have a tendancy to get employed to them so that by the time the animal is examined, the tumor has reached a significant size.
How is a brain tumor diagnosed?
History and Clinical Examination
The original step for a veterinarian is to take a indepth history of all of the clinical signs, and when they developed. This is followed by a full frequent clinical examination and a full neurological examination.
Bloods
After that, blood ought to be taken for procedure haematology and biochemistry profiles. This is to look for any impairment of normal physiological function outside the brain. Results will be normal for brain tumors, with the possible exception of a heap of pituitary gland tumors.
Radiography
Plain skull radiographs (xrays) under standard anesthetic have little value in detecting a brain tumor, but they may be utile if there is a tumor in the nasal cavities or the middle ear which could extend into the skull. On rare occasions, they may tell apart bony changes in the skull which may accompany a brain tumor, or mineralization within the tumor itself. Radiographs and ultrasound of the chest and abdomen are utile to look for a tumor elsewhere in the body, in cases where the brain tumor is a secondary metastasis.
MRI and CT Scans
Confirmation of a brain tumor may is normally only achieved using the progressed imaging techniques, CT scans or MRI. Both of these have masters and cons when equated to one another. CT is better for bony changes, while MRI is better for soft tissue definition, for the detection of a great deal of of the knock on effects of brain tumors such as edema, cysts and bleeding. MRI is the preferent option for diagnosing primary brain tumors.
Biopsy
This is the only way to definitively diagnose a brain tumor. The modern imaging proficiencies above offer much information, but they may at times confuse a tumor with a non cancerous mass or a cyst, and they also do not tell us the precise type of tumor present, and hence the suitable treatment and prognosis. The best type of biopsy is the CT guided stereotactic brain biopsy system, which is rapid, precise and rather safe. Since exploratory surgery is high risk, it is not normally attempted unless there is a reasonable probability of removing the whole tumor with minimal collateral damage. Many brain tumors in cats and dogs are not categorized on a cellular level until post mortem.
Cerebrospinal Fluid (CSF) Analysis
CSF analysis is utile for ruling out inflammatory causes of the symptoms, but tumor cells are seldom identified here. Increased levels of white blood cells and increased protein levels may be present in the CSF with a lot of brain tumors, though this is not diagnostic. This test may be high peril when intracranial pressure is increased, as brain herniation may occur.
Treatment
Treatment is purposed at being either curative or palliative. Curative treatment eradicates the tumor or reduces it is size, whilst palliative therapy reduces the surrounding cerebral edema and slows down the growth of the tumor. Palliative therapy likewise involves administering antiepileptic drugs, if seizures are occurring as a result of the tumor.
Surgery
Whether this is an option depends on the usual health of the animal, and the precise location, size, extent, invasiveness and nature of the tumor. Tumors such as meningiomas in cats may be got rid of with great success by surgery. However, surgery to remove tumors in sure emplacements such as the brainstem may be exceedingly dangerous, perchance resulting in death. Even partial remotion may gain the animal though, peculiarly if the tumor is slow growing.
Radiotherapy
This is in all likelihood the most widely employed form of treatment for brain tumors. Radiation therapy may be used alone or in combining with other treatments. It is also utile in the treatment of secondary brain tumors. The aim is to demolish the tumor without harming the normal tissue too much.
Chemotherapy
The main problem with chemotherapy for brain tumors is that some drugs do not cross the blood brain barrier. In addition, the tumor may only be sensible to high doses, doses which are toxic to normal brain tissue and accordingly unfitting for use. However, assorted drugs have been used for this aim that may cross the blood brain barrier with reported success, including cytosine arabinoside, lomustine and carmustine.
Probable Outcome
Studies of animals that receive palliative treatment (corticosteroids) for brain tumors show a survival range post diagnosis of 64 to 307 days. This demonstrates the disability to accurately predict life expectancy in these cases. What is sure is that the survival times significantly increase with surgery, radiotherapy or chemotherapy. Radiation therapy seems to offer the best results, alone or in combining with other treatments. Generally, the more severe the symptoms, the shorter the life expectancy.