Administration of aromatase inhibitor MPV-2213ad to blue fox vixens (Vulpes lagopus) as a model for contraception in female dogs

Lena Lindh, H. Lindeberg, A Banting, S. Banting, S. Sainmaa, S. Beasley, H. Korhonen, Olli Peltoniemi

Research output: Contribution to journalArticleScientificpeer-review


The interest in non-surgical approaches to contraception and fertility control in female dogs has
increased in recent years. In this study the effect of an aromatase inhibitor (finrozole) was evaluated in
fur production animals, farmed blue fox vixens, as a model for contraception in bitches. A total of 80
vixens were divided into 4 groups, receiving orally placebo (A) or finrozole 0.5 mg/kg (B), 3.5 mg/kg (C)
or 24.5 mg/kg (D) for 21 consecutive days beginning in the pre-ovulatory period of heat. Monitoring of
the vixens included clinical signs of heat, measurement of vaginal electrical resistance (VER) as well as
oestradiol and progesterone concentrations in plasma. The approximate relation of the start of treatment
to ovulation varied from 11 days before to one day after ovulation provided that the LH peak occurred 0.5
e2 days before the VER peak and ovulation was then estimated to occur 2 days after the LH peak. Seventy
vixens were artificially inseminated within 8 h after a 50 Udecline in vaginal electrical resistance was
detected. Ten vixens were not inseminated. Pregnancy was confirmed by transabdominal ultrasound
examination and birth of cubs was recorded. The pregnancy rates in the groups were 89.5% (A), 81.3% (B),
55.6% (C) and 52.9% (D). The average number of live born pups in the four groups was 9.4 (A), 7.0 (B), 5.8
(C), and 3.8 (D), respectively. No deleterious effects (for instance malformations) of finrozole on pups
could be verified. The administration of finrozole did not have a significant effect on oestradiol pa-
rameters and VER values in vixens. Progesterone values were significantly higher in treatment groups
compared with the placebo group. The results indicate that pregnancy could be avoided by finrozole
provided that doses of 3.5 mg/kg were used and the treatment was initiated at least four days before
the day of artificial insemination. This corresponds with two to six days before ovulation provided that
the LH peak occurred 0.5e2 days before the VER peak and that ovulation then occurred in average 2 days
after the LH peak.
Original languageEnglish
Pages (from-to)53-63
Number of pages11
Publication statusPublished - Aug 2020
MoE publication typeA1 Journal article-refereed

Fields of Science

  • Dog
  • Fertility control
  • Finrozole
  • Fur bearing animal
  • Oestrus inhibition
  • 413 Veterinary science

Cite this