Bad breath in dogs, also known as halitosis, can be a sign of various underlying health issues, particularly dental problems. You should consider taking your dog to the vet for bad breath if:

1. **Persistent Bad Breath**: If your dog's bad breath is persistent and does not improve with regular dental care, it’s time to consult your vet.

2. **Accompanied Symptoms**: Look for other symptoms such as difficulty eating, swollen gums, excessive drooling, or changes in behavior. These could indicate dental disease or other health issues.

3. **Age**: Older dogs are more prone to dental disease. If your senior dog develops bad breath, it’s best to have them checked out.

4. **Change in Breath Odor**: If the smell changes significantly (for example, a sweet or fruity smell), it could indicate a more serious health issue, such as diabetes.

5. **Dietary Changes**: If you've changed your dog’s diet and they develop bad breath, it may be worth discussing with your vet.

6. **Regular Check-ups**: Regular veterinary check-ups can help catch dental issues before they become serious. It's a good practice to have your dog's teeth checked at least once a year.

In summary, if your dog has bad breath that persists or is accompanied by other symptoms, don’t hesitate to make an appointment with your veterinarian. Regular dental care, including brushing your dog's teeth and providing dental chews, can also help prevent bad breath.

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Topics covered in this question:

Dog Health Dog Care Veterinary Care Dental Hygiene Bad Breath