Aggression or Sudden Behavior Changes: Could It Be Medical?

Behavior changes in dogs or cats are often blamed on training issues—but sometimes, sudden aggression, irritability, or withdrawal can be a signal of an underlying medical problem.

Common Medical Causes of Behavior Changes

• Pain: Arthritis, dental disease, or internal injury can make pets irritable or defensive.
• Neurological conditions: Seizures, tumors, or cognitive dysfunction may affect mood and behavior.
• Endocrine disorders: Thyroid imbalances or diabetes can cause irritability or sudden changes in energy.
• Infections: Urinary tract infections, ear infections, or other illnesses can trigger unusual aggression or anxiety.
• Toxin exposure: Accidental ingestion of medications, plants, or chemicals may alter behavior.

Pets cannot always communicate pain or discomfort—they may instead act out, lash out, or hide.

Signs to Watch For

• Sudden growling, snapping, or biting
• Fearful or anxious behavior in familiar settings
• Changes in appetite or litter box habits
• Withdrawal from family or other pets
• Unexplained pacing, vocalizing, or restlessness
  

When to Seek Help

If your pet suddenly shows aggressive behavior or other unusual changes, it’s crucial to rule out medical causes first. A veterinarian will perform a physical exam, run bloodwork, and possibly order imaging to identify potential health issues.

Addressing the medical problem often resolves the behavior issue—or at least makes behavior modification much more effective.

Don’t wait for behavior to escalate—call us or book an appointment today for a medical evaluation if your pet shows sudden aggression or behavior changes.