Ask The Vet

Cysts Likely Cause Of Heifer Repro Woes

Image by Mark Parker

Q: We have a heifer that is cycling all the time. What could cause this, and what do I need to do?

A: Any reproductive issue during breeding season needs to be dealt with immediately. Time is critical. The most likely problem in this case is follicular cystic ovary disease. This occurs when there is a disruption of the normal hormonal pattern to the estrus cycle. These cattle develop one or more large cystic follicles on the ovary or ovaries. They display shortened heat cycles and excessive heat behavior because of low levels of the luteinizing hormone and persistently high estrogen.

Have your veterinarian check her. A rectal examination can confirm whether these cystic structures are the problem.

Treatment for the condition involves giving a GnRH (gonadotropin-releasing hormone) product to jump-start the heat cycle. That would be followed by a prostaglandin injection about 10 days later. Treatment is not always successful, and retreatment may be called for.

Follicular cysts are more common in mature cows than heifers. There can be a genetic component, especially if it’s a Holstein. But, the exact cause or factors involved in this condition are poorly understood.

Q: This year, we went into calving season with a lot of stockpiled grass. We want to use tubs or liquid feed along with the grass, but we keep a couple of donkeys in the same pasture to discourage dogs and coyotes from harassing the cattle. Is it safe for the donkeys to have access to those products?

A: Most lick tubs and liquid feeds contain some urea, which rumen microbes use to make protein. I do not know of any of these that are labeled for use with donkeys. Urea can be toxic to simple-stomached animals. I would not advise this unless you can figure out a system that prevents the donkeys from consuming these products.

Q: Our neighbor has had several barn cats die from a disease he believes they got from ticks. Do you know what this disease is and what we can do to protect our cats?

A: There are many diseases transmitted by fleas and ticks. In this case, I suspect Cytauxzoon felis. It is a serious tick-borne disease discovered in Missouri in the 1970s. It has spread through the Midwest and Southeast since then. It is caused by a protozoan parasite transmitted by the Lone Star Tick.

Affected cats will be depressed, painful, have a high fever and stop eating. Many will die even with aggressive treatment. Tick control is crucial for prevention of this disease and others.

In my practice we’ve found fleas to be a more common problem for cats than ticks. But, control of both parasites is important. Just be aware that safe options for tick control in cats are more limited than for dogs.

The old fipronil products (Frontline and the generics) were safe flea and tick products for cats. We no longer recommend them because of decreased effectiveness on fleas.

Seresto collars provide flea and tick protection, but many outdoor cats will not wear collars or will lose them. Bravecto is a topically applied flea and tick product that provides up to 12 weeks of protection for fleas and ticks; however, it’s not labeled to control the Lone Star Tick.

Talk to your veterinarian to help you choose the most effective product for your situation.

Please contact your veterinarian for questions pertaining to the health of your herd. Every operation is unique, and the information in this column does not pertain to all situations. This is not intended as medical advice, but is purely for informational purposes.

Write Dr. Ken McMillan at Ask The Vet, 2204 Lakeshore Dr., Suite 415, Birmingham, AL 35209, or email


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