I just saw your second reply. I'm sorry, I was finding the abstracts for you and it took a few minuts.
I understand about the steroid risk and hesitation. I would be hesitant to repeat, also.
That's wonderful that your dog did so well!
With the A. montana, there are two forms. The herbal form and the homeopathic form. They are different. I believe you are likely referring to the homeopathic form as what you used with your dog if it was administered orally.
In general, I don't recommend A. montana in cats. It is toxic in herbal form, and in homeopathic form, it can still cause side effects depending on the potency and how long it is given.
From Int J Toxicol. 2001;20 Suppl 2:1-11.
Final report on the safety assessment of Arnica montana extract and Arnica montana.
"Ingestion of A. montana-containing products has induced severe gastroenteritis, nervousness, accelerated heart rate, muscular weakness, and death" This particular report focused on the safety of arnica topically in cosmetics and things, and noted the potential for hypersensitivity reactions, especially since this plant is a member of the daisy family, as is ragweed and lots of other common allergens.
And from Veterinary Herbal Medicine's monograph on Arnica:
"Type IV allergic contact dermatitis has been reported frequently in sensitive persons or with prolonged use. Internal use may lead to stomach pain, vomiting, diarrhea
, vomiting, kidney pain, dyspnea, tachycardia, cardiac arrest, and liver failure. One author (Kuhn, 2001) writes that a single gram dose can lead to heart damage and cardiac arrest in humans."
In addition, for your specific cat, I'm finding at least one reference that lists bradycardia
as a possible side effect of A.montana. It could be very dangerous for your cat depending on the cause of heart block.
I would recommend looking into acupuncture as an alternative to the A. montana, or working with a local homeopathic veterinarian to develop a safe treatment course for her.
Please let me know how else I can help with your cat, and if you have any other questions.