D64.81 isn't the same as D63.0, which applies to anemia caused by the cancer itself rather than by chemotherapy
There are in general three reasons for this ignorance of the prevalence of common diseases , the lack of specificity of particular drugs for particular diseases, and the lack of standardisation of therapy
I think I linked to this paper below

About VITAMIN B COMPLEX LIVER EXTRACT Brand- VETOMIL 50ml VETOMIL contains VITAMIN B COMPLEX LIVER EXTRACT is a dietary supplement which is prescribed for maintaining optimum health of livestock and provide resistance against adverse climates various bacterial infectionsThis solution is said to serve as support system for antibiotic treatment and has ability to prevent liver disorders It is also suitable to be prescribed for GI diseases nervous disorder and general weakness VITAMIN B COMPLEX LIVER EXTRACT is highly appreciated for assisting in enhancing appetite and supporting normal vision COMPOSITION Each ml Contains Thiamine Hydrochloride IP 10 mg Riboflavin Sodium Phosphate IP 3 mg Niacin amide IP 100 mg Vitamin B12 IP 10 mcg Phenol as preservative IP 05 vv Liver Injection Crude 066 ml derived from 8 gm of liver containing vitamin B12 activity eqv to 2 mcg Water for Injection IP qs INDICATION Anroxia Dyspepsia Dullness Debility Anaemia Hepatitis Jaundice Diarrhea Dermatitis Alopacia Laminitis hooves Sole disorders ROUTE OF ADMINISTRATION By IM route only DOSAGE As directed by the veterinarian PRESENTATION 30 50 100ml vial PACKAGING DETAILS Comprehensive Health Support VETOMIL Vitamin B Complex Liver Extract provides multifaceted support for animals suffering from various ailments such as anaemia, hepatitis, or general debility

Vitamin B12, also known as cobalamine, is an essential water-soluble vitamin
Choose an injection site on your abdomen (see image)