Chemodectoma in Dogs
Key takeaways
Chemodectoma in dogs is a type of tumor that arises from chemoreceptor cells.
- Abnormal growth of these cells forms a tumor that is typically located just above the heart in the upper chest
- Chemodectoma is the second most common type of heart tumor but is rare overall
- The cause of chemodectoma is unknown and likely due to a mix of risk factors
- Often, chemodectomas are asymptomatic
- Clinical signs are mostly due to the resulting pericardial effusion and include weakness, lethargy, cough, and increased heart rate
- Diagnostics consist of a complete physical examination, including bloodwork, urinalysis, and diagnostic imaging
- Treatment usually consists of surgical removal of the tumor, or the sac around the heart (pericardium) but is not always possible due to the delicate location of this type of tumor
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A closer look: Chemodectoma in Dogs
The chemoreceptor cells in the body are receptive to chemical changes and are involved in regulation of the respiratory and heart rate. A chemodectoma is the result of overgrowth of these cells into a tumor.
Chemodectoma is a rare tumor that can cause a very serious, life-threatening condition. The prognosis is usually poor to guarded, especially considering that in some cases surgical removal is impossible due to the extremely delicate location of the tumor.
If left untreated, the tumor keeps growing, eventually impairing the function of the surrounding organs, and potentially causing heart failure and cardiac arrest. Clinical signs associated with chemodectomas warrant emergency veterinary care.
Risk factors
Age and breed-related factors might lead to a predisposition, as it appears more commonly in brachycephalic breeds such as Boxers and Boston terriers, especially those over the age of 10.
The severity of the symptoms varies depending on the location, size, and stage of the tumor.
Symptoms can present suddenly and dramatically without prior signs.
Collapse and sudden death are possible consequences of chemodectoma.
Possible causes
Chemodectomas are tumors that arise from specialized chemoreceptor cells in the aorta (most common type) or the carotid arteries.
As with most tumors, the specific cause of chemodectoma is mostly unknown. It seems to be the result of a mix of risk factors.
Main symptoms
Most dogs are asymptomatic until the tumor reaches a size that impairs normal heart and blood functions. When present, common clinical signs are mostly due to the resulting pericardial effusion (excessive fluid in the sac that shelters the heart).
Testing and diagnosis
As chemodectoma usually presents as asymptomatic, it is often discovered incidentally.
The diagnostic process involves:
- Complete physical examination
- Medical history
- Bloodwork
- Urinalysis
- Diagnostic imaging (chest x-rays, heart ultrasound)
- Electrocardiogram (ECG)
- Biopsy (when is possible to collect a tissue sample)
Steps to Recovery
Treatment can prove difficult as surgical removal is not always possible due to the extremely delicate location of this type of tumor. Other therapies, such as radiotherapy or chemotherapy can be used to slow the growth of the mass.
A pericardiectomy does not remove the mass but can provide symptomatic relief from signs of pericardial effusion and improve prognosis.
The prognosis is usually poor to guarded in cases of symptomatic chemodectoma, especially because surgical removal is not always possible.
In cases of symptomatic chemodectoma, euthanasia may be recommended if surgery is not possible or if it is unsuccessful.
In asymptomatic dogs with small, slow growing tumors, the mass may not affect survival time.
Prevention
As per most tumors, prevention often proves difficult as the cause is unknown. Regular veterinary exams can identify issues earlier, often leading to a better prognosis.
Chemodectoma is not contagious.
Is Chemodectoma in Dogs common?
Chemodectoma is a very rare condition.
Typical Treatment
- Surgical removal (when possible)
- Radiotherapy
- Chemotherapy
- Pericardiectomy
