What is the prognosis for dogs diagnosed with untreated mast cell tumors?

Mast cell tumors in dogs are known for their potential to vary significantly in behavior, which is influenced by their grade and stage. When left untreated, the prognosis for dogs with these tumors is typically poor. High-grade mast cell tumors can be aggressive, leading to metastasis and significant morbidity. Even low-grade tumors can have a risk of recurrence and may progress if not adequately addressed.

Aggressive treatment is critical for improving the prognosis, particularly for higher-grade tumors. Options such as surgical excision and, in some cases, chemotherapy or radiation, are necessary to manage the disease effectively. Without treatment, the chances are high that the tumors will worsen, leading to severe health consequences.

The other choices suggest possibilities that do not align with the reality of mast cell tumors. For instance, aggressive treatment does not guarantee a favorable outcome, nor is it accurate to state that natural remission is common. Similarly, while monitoring is important, it cannot replace the need for proactive treatment given the serious implications of untreated mast cell tumors.