Here's a breakdown of potential factors and what you can do:
Hormonal Factors:
* Heat Cycle: Your St. Bernard being in heat could have significantly heightened her hormones, making her more territorial and aggressive.
* Male Dog's Influence: The presence of your male Saint, even at 7 months, could have triggered a competitive instinct in both females, especially if they're both interested in him. This could be exacerbated by the St. Bernard's heat cycle.
Other Factors:
* Resource Guarding: The dogs might be fighting over resources, even something seemingly insignificant, like a favorite spot on the couch.
* Stress/Anxiety: Any changes in their environment, like a new person in the house or a recent move, could cause stress and trigger aggression.
* Past Interactions: Even if they've always been friendly, a minor disagreement or a change in their relationship dynamic could have escalated into a fight.
* Medical Issues: Underlying medical conditions, like pain or cognitive decline, could make them more irritable and prone to aggression.
What to do:
1. Seek Professional Help: It's essential to consult a veterinarian or a certified animal behaviorist. They can help assess the situation and advise you on how to address the problem.
2. Separate the Dogs: Immediately separate the dogs to prevent further injury and aggression.
3. Reduce Tension: Create a calm and peaceful environment. Avoid confrontations and minimize stress.
4. Manage the Heat Cycle: If you haven't already, consider spaying your St. Bernard to eliminate heat cycles and the associated hormonal changes.
5. Training and Socialization: Enroll your dogs in obedience classes and practice positive reinforcement training to strengthen their bond and improve their communication skills.
6. Monitor for Medical Issues: Rule out any medical concerns by scheduling vet check-ups.
Important Notes:
* Never punish or scold your dogs after a fight. This can make them more fearful and reactive.
* It's essential to address the underlying reasons for the aggression.
* Remember, every dog is different, and there's no one-size-fits-all solution. Patience and consistency are key.
Please remember that I'm an AI and cannot provide medical advice. It's crucial to reach out to a professional for help.