I showed the image to the avian vet, and she said that it looks like lipoma. You can see similar images
here. It is a benign growth that happens often to parakeets due to an unbalanced diet. Or if the diet is balanced, it could happen due to some disturbance in lipid metabolism.
She said that it is hard to know for sure without an x-ray, and perhaps it has to do with liver after all, but the treatment is the same, so it doesn't really matter. Also, don't know if you read Russian, but there is a good
page about it, including explanation and treatment. The idea is that if you follow simple instructions and treatment, you can stop the progression of the growth and even lessen it to a large degree.
Here's a short version, including recommendations from the avian vet.
First the diet.
- You should try and exclude foods rich in protein, like eggs and nuts. Add more vegetables, fruits and fresh grass.
- It is also important to allow your birdie to fly free. Movement is good for him. He should have daily exercise and not to sit for long in one place.
- Provide him with mineral supplements.
Now for the treatment.
- Silymarin (it is an active ingredient in Milk Thistle) 7-7.5 mg twice a day. For 30-60 days
- Antibiotic Enrofloxacin 0.03 ml per os twice a day for 3 weeks.
- You can also give your birdie lipoic acid. 1/6 of a tablet. No less than 3 months.
You may not find silymarin in this exact name, but under all kind of trade names. It doesn't matter. As long as it contains only Milk Thistle, it is good. And even if it due to a large liver or not, it will still be good for your birdie, and will also help with lipid metabolism.
As for Enrofloxacin, pay attention to the dosage or concentration, They may vary.
Also, don't know if you have access to homeopathic remedies, but the site that I mentioned talks about Lipomin (Contains Natrium muriaticum C6, Graphit C6). It is intended for birds (and small animals) specifically for this kind of problems.
Now, it is possible that it isn't a lipoma but an abscess. After all, physical examination is always better. But then, just be careful not to stress the birdie too much when opening it, because unfortunately there are many cases of birds not being able to handle the stress. :(
Wish you and your bird a lot of good luck!