Dog - Medroxyprogesterone

Why has my veterinary surgeon prescribed this medicine?

Medroxyprogesterone is used to prevent and postpone oestrus (heat, season) in bitches. Continual hormonal control of pregnancy and seasons may cause side effects in your pet. If your bitch is not intended for breeding, think about having her spayed (neutered, sterilised).

Prevention or postponement of oestrus may be desired for various reasons and medroxyprogesterone is used in bitches in which breeding or whelping may involve a high degree of risk to the animal’s life, litters are not wanted or optional, or the animal is a high surgical risk.

It is often difficult to predict when your pet will come into oestrus (season) after medroxyprogesterone medication is stopped; the time between the last injection and the next oestrus varies between 6 months and rarely 3 years.

How does this medicine work?

Medroxyprogesterone is a progestogen. Progestogens exert a negative feedback on the hypothalamic-pituitary axis in the brain thereby suppressing the secretion of gonadotrophins and cyclical ovarian activity, which normally results in oestrus and ovulation.

How do I give this medication?

Your veterinary surgeon will administer this medication to your pet by injection under the skin on the inner surface of the thigh or fold of the flank. For continued prevention of oestrus, injections are given every six months.

The recommended time for administration is during anoestrus and three to five months after oestrus. Your veterinary surgeon may need to take a vaginal smear.

Potential side effects

• Tell your veterinary surgeon if your pet is intended for breeding or is diabetic.
• Medroxyprogesterone is not recommended for use in the pro-oestrus, oestrus or metoestrus stage of the oestrus cycle, bitches before their first oestrus, pregnant bitches, or in bitches with a previous history of genito-urinary disease, persistent or abnormal vaginal discharge, irregular oestrus cycles or nymphomania, or false pregnancy.
• Potential side effects with medroxyprogesterone include mammary changes, uterine infection (pyometra), increased appetite, increased thirst, increased urination, and changes in hair colour. If these effects are seen, contact your veterinary surgeon.
• Other side effects may occur. If your pet experiences anything unusual, contact your veterinary surgeon.

Possible drug interactions

• Make sure to tell your veterinary surgeon what other medication you are giving to your pet.
• Drugs may interact such that they can cause an increased or decreased effect or side effects. Although drug interactions may occur, it does not mean that there is necessarily a high risk of any of these occurring.
• Contact your veterinary surgeon if your pet experiences any unusual reactions when different medications are given together.