Bovine – Cystic Ovaries in Dairy Cattle

Cystic Ovaries in Dairy Cattle – Causes and Treatment Protocols

Cystic ovaries are a fairly common finding on fresh cow checks at herd healths, and can have a significant impact on the success of your breeding program if left undetected and untreated. Cows with cysts do not ovulate and cycle normally, and this can lead to delays in timely breeding. Cysts increase the time to first conception by an average of 13 days, and raises the calving to conception interval by an average of 33 days. Cystic cows require more services per conception, have reduced conception rates after treatment, and ultimately are more likely to be culled from the herd.

Follicular cysts are the most common type, and are by simplest definition, a follicle that has grown larger than normal and not ovulated, and persists for an abnormal amount of time in the absence of a corpus luteum (CL). Cysts are larger than 2.5 cm and can be diagnosed by ultrasound or manual palpation. The majority of cystic cows just show a lack of estrus behaviour, but rarely they can be seen as cows that are frequently in heat.

Failure of ovulation and development of a cyst can be due to a number of things that disrupt the normal pathway of hormone signals from brain to ovary. There are several risk factors that predispose cows to developing cysts:

Summer heat and heat stress: increases risk by 2.6
High milk production: increases metabolism of steroid hormones in the liver, leading to lower levels of hormones (particularly progesterone - the hormone in CIDRs and PRIDs) needed for normal cyclic activity.
Older cows
High body condition scores at freshening
Abnormal transition period: twins, retained placenta, metritis, ketosis and negative energy balance
Genetic predisposition: but difficult to select for in any economically efficient way.

Many of these factors are related to proper management of transition cows and heat abatement, which can be applicable to numerous other economically and reproductively important diseases on the farm. Reduction of cystic cows is just one of the many benefits to good management of transition cows.

So how do we treat cystic cows?

It can vary depending on your breeding program, underlying cause, and how many DIM the cyst is identified. Most of our herds do fresh checks at herd health starting at 27 DIM or so. If a cyst is identified at this earlier point, our priority is to get rid of the cyst and get the cow to resume cycling before it gets time to breed. Many herds will get another check before breeding, allowing for us to recheck the cow to make sure the cyst is gone. At this point, treatment usually includes a shot of GnRH (Fertiline) to try and ovulate the cyst, followed by prostaglandin (Lutalyse or Estrumate) 10 days later to lyse the corpus luteum (CL) formed after ovulation of the cyst, and resume normal cycling. When that cow is subsequently checked and the cyst is resolved, first breeding can occur following your normal protocol (natural heat, or by using hormonal manipulation).

However, if the cyst is identified closer to 50 DIM, we might want to start a protocol that allows for a timed AI on that cow in order to get timely resolution of the cyst and breeding. There are 2 main options for this:

Ovsynch/GLG protocol
Ovsynch/GLG protocol plus a progesterone implant (CIDR or PRID) inserted the day of the first needle (Fert) and removed at the time of the first prostaglandin (Lute or Estrumate) shot 7 days later.

Several studies have compared these 2 treatment protocols and their success rates. Recall that one of the causes of cystic cows is a low progesterone environment, such that inserting a vaginal progesterone slow release implant can increase the likelihood of resumption of normal cycling, even when the original cystic structure remains on the ovary. A recent study showed that the difference in conception rates between both treatments was not statistically significant, however the Ovsynch+CIDR protocol was higher than just Ovsynch (39% compared to 29.5%). As well, conception rates were affected negatively by various factors including: hot weather, increased parity, poor body condition score (3.0 or less), and the cow’s DIM being greater than 90 days at time of treatment. These variables amounted to statistically significant differences in conception rates, and should be taken into account when deciding how to treat an individual cow.

Lastly, a study out of the US also looked at the economic impact of both timed AI protocols for cyst treatment. Even with the higher conception rates with the Ovsynch+CIDR program, the Ovsynch-only protocol turned out to be more profitable ($73 compared to $56) per cow. These are American numbers, so take it with a bit of caution. Ovysnch+CIDR protocols can be a good option for persistently cystic cows, or for older, skinny cows that are longer in DIM or during hot weather.

References

Rosenberg, L. M. 2010. Cystic Ovaries in Dairy Cattle. Dairy Science Department, California Polytechnic State University.

Khalil, A. Y. 2019. Comparative Efficacy of Two Synchronization of Ovulation Regimens in the Treatment of Cystic Ovarian Disease in Dairy Cows. AJVS. Vol. 62(1): 61-71.

Brito, L. F. C., Palmer, C. W. 2004. Cystic Ovarian Disease in Dairy Cattle. Large Animal Veterinary Rounds, Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine. Vol. 4(10).