I am sorry to hear you are worried about your dog. How old is she? What breed of dog?
I am a veterinarian, and will do my best to help.
This may be an infection that is spreading, and she may need antibiotics.
It is also possible it is some kind of growth or tumor, but a infection is most likely from your description.
If I could, I would tap the swelling with a needle, and look at the cells under a microscope. If it does appear to be an infection, I would start her on antibiotics and anti inflammatory medication.
Can you take her temperature with a rectal thermometer?
Can she swallow? Eat and drink?
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If you check her gums, are they pink in color, or do they seem pale to you?
It must be sore and painful if she snapped. It is good she can eat, drink, and swallow.
It sounds like antibiotics and anti inflammatory medication would help; this is most likely an infection.
Yes, if her gums are pink, and she can eat and drink.
Do you have any kind of pain medication you could give her, such as tramadol? No ibuprofen or advil.
Warm compresses might help, if she will let you.
No, no ibuprofen. Sorry if I was not clear. No ibuprofen, advil or Aleve.
Tramadol, aspirin, paracematol, would be OK.
How much does she weigh?
paracematol given long term is not safe in dogs, but one or two doses should be OK. If she is 10 kg, she can take around 100 millgrams.
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Keep her quiet, try the compresses, and see if giving 75 mg paracetamol helps her to be more comfortable.
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I will be checking back to see how she is doing.
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