A familiar scenario – you’ve been carefully observing your favourite cow in the weeks since calving, patiently waiting for her first heat… But nothing. She sails past your deadline for heat observation which prompts you to put her in for a vet check. With the aid of an ultrasound scanner you’re given the diagnosis – “She’s cystic!”

Unfortunately, this is something we experience more often than we’d like. One in ten dairy cows are affected by cystic ovaries: ranging from 5% to 40% between farms. Most commonly, cysts occur at 30 to 40 days in milk (DIM) at the time when the first heat of the lactation is due. There’s also a tendency for cysts to appear at 190 to 220 DIM. Overall, the problem seems to be becoming more common!

Why is this problematic?

Cows with cystic ovaries have increased calving intervals and increased risk of culling. Financially, the 22-64 days extended calving interval adds up to a major cost, estimated at £5.89/day in the most recent Kingshay Dairy Costings Report. The losses easily exceed the 120 US dollars that was estimated per cyst in a 1986 study!

What are cystic ovaries?

Cysts are follicular structures which fail to ovulate, becoming larger than normal ovulatory follicles and persist for longer, preventing normal reproductive function. In dairy cows, they are defined as fluid-filled structures bigger than 2.5 cm in diameter which persist for 10 days or more, in the absence of a corpus luteum (CL).

When should I suspect my cow is cystic?

Most commonly cows simply do not come into oestrus (heat) – they are anoestrus and show no bulling behaviour. Other abnormal oestrus behaviour patterns can be seen, including persistent heat behaviour or frequent returns to oestrus at shortened intervals. Historically, increased bulling activity was a more common observation, however as ultrasound scanning of non-cycling cows has become more commonplace, we now see regularly detect cysts which prevent cows from coming into heat as expected.

How do I treat cysts?

Most issues with ovulation failure (including cysts) are linked to low progesterone levels in the cow in the period before the expected ovulation. Treatments therefore aim to either force ovulation of the follicle (cyst) or boost progesterone levels to allow normal cyclicity to resume. High doses of GnRH (e.g. Receptal), typically 5ml, can either induce ovulation of the cyst or other follicles present. These lutenize into a corpus luteum and produce progesterone. Other hormones such as Human Chorionic Gonadotropin (hCG) can be used in the same way.
Alternatively, progesterone can be directly supplemented in the form of a CIDR or PRID. These should be left in situ for 7 to 12 days and can be combined with GnRH and prostaglandin injections as part of a fixed time AI protocol, ensuring the cow gets served.
Manual rupture of cysts is also occasionally practiced, however this does not address the hormone imbalance and another cyst often forms!
“Luteal cysts” are cysts with thicker walls which may respond to prostaglandin treatment.

What about prevention?

Cows are at greater risk of developing cystic ovaries when they are experiencing negative energy balance (hence occurring mostly in early lactation), which can be exacerbated by high protein levels in the diet. The risk of becoming cystic is also 2.5 times higher in cows with excessively high body condition and those with a history of uterine disease such as retained fetal membranes, metritis or endometritis. The focus for prevention is on careful nutrition management, particularly during the transition period. Older cows and higher yielding cows are also more likely to develop cysts.
While prevention is always better than the cure, accurate and timely diagnosis of cysts is important to combat this time-consuming and costly condition.