Remember Burrowing Rodents in Farm Management Plans

Remember Burrowing Rodents in Farm Management Plans

Burrowing rodents can damage footing surfaces and cause injuries to horses. To reduce your horse's risk of injury, implement a management plan to eliminate burrowing rodents.

Photo: Thinkstock

Chances are you already have a management plan in place for your pastures, paddocks, and arenas, and you've likely got your fly control protocol down to a science. But do you have a management plan for other pests that can damage footing surfaces and cause horse injuries? What do you do about burrowing rodents?

Gophers, voles, squirrels, and other rodents can create major hazards for horses and riders by digging holes and tunnels just below the ground's surface. Frequently the horse and rider cannot see these and, when the horse places his weight on the thin layer of sod, the ground can give way, possibly causing serious injury or even death.

Fortunately, there are ways you can manage rodent problems and prevent these accidents from occurring. Some rodent control equipment is better than others for working around horses. Common methods that are safe for use in horse pastures include carbon monoxide fumigation, trapping, and igniting propane. Regardless of the extermination method you employ, be sure to remove the horses from the pasture during the pest control process and return them only when their fields are deemed safe.

Carbon Monoxide Fumigation

Carbon monoxide fumigation is the safest method of rodent control for horses and the most humane method of controlling burrowing rodents in horse pastures; it involves injecting engine exhaust into the rodent’s tunnel using a specialized probe. If you use the proper equipment, the rodents are not burned and they do not bleed to death. Rather, they fall unconscious and then die as their blood can no longer carry oxygen to the brain.

Additionally, carbon monoxide fumigation does not involve explosions that could spook horses, it doesn’t damage the ground further, and it leaves no residual poisons.

For carbon monoxide fumigation to work properly the carbon monoxide must be concentrated and pressurized through the use of a specialized machine such as a pressurized exhaust rodent control, or PERC, device. If the professional does not use pressure to inject the carbon monoxide, or if he or she opens the hole to insert the carbon monoxide, the rodents can react prior the gas taking effect: Voles and squirrels can escape the tunnel system, and gophers can wall themselves off with dirt until the threat is gone. Carbon monoxide fumigation, while very effective, does pose limitations during very cold periods when soil is frozen: The moisture in the engine exhaust can freeze inside the probe tips, effectively slowing or stopping the discharge of the carbon monoxide. This can be overcome by using specialized anti-freeze to keep the moist exhaust from freezing.

Regulations regarding PERC use varies from state to state. For example, in Idaho it's not necessary to hold an applicator’s license to use compressed carbon monoxide to control burrowing rodents. However, in California, applicators are required to receive certification prior to using PERC. Check with your state prior to purchasing equipment for this method of control.

Ignited Propane

Ignited propane is just what it sounds like: The pest removal professional injects propane into the rodent's tunnel and, once the tunnel is full and the oxygen/propane ratio is correct, ignites the gas, which causes a loud and destructive explosion. The concussion from the explosion is designed to kill the rodent and collapse the tunnel.

There are several drawbacks with igniting propane. This method can cause further ground damage or harm underground pipes and wiring. There is also the potential for igniting combustible materials (such as hay or grass in the area). The applicator must wear appropriate safety equipment and know how to properly use the equipment to avoid hearing damage, injury from projectiles and possible burns. The explosions can spook horses in stalls or neighboring fields—whether unattended or under saddle—possibly leading to injury.

Applicators using this method should notify local police, especially when working inside or near city limits, as it's common for neighbors to call the police when they hear the propane explosions.

Rodent holes can cause serious injury to horses that accidentally step in them.

Photo: Courtesy Keith Larson


The benefit of trapping is that it provides you with proof of elimination: When a gopher, vole, or squirrel is caught in a trap and removed from the area, there is no question of whether or not the animal has been eliminated.

While trapping is useful in many circumstances, it has its downsides. In order to trap a burrowing rodent you must open the tunnel system and place the trap inside. During this time horses should not be allowed in the pasture, as they could step into the hole and activate the trap and sustain major injury.

Additionally, trapping all of the rodents can take a significant amount of time. You must set and check the traps at least every 24 hours to see if a gopher or other rodent has been captured.

Further, with gophers in particular, traps can be rendered useless by intelligent rodents. Many times gophers will fill the traps with dirt, making them ineffective.

Despite these evasive techniques, gophers are the rodent most vulnerable to trapping because they isolate themselves in their tunnels and live one-per-tunnel except during breeding., trapping is less effective when attempting to eradicate voles, squirrels, prairie dogs, or other critters that share tunnels, as trapping might only eliminate a small portion of the population.

Poison Baits

Lastly, poison bait can be effective but isn’t without risks. The correct approach involves placing baits into the tunnel system via the opening, or dropping them further inside the tunnel system via a probe. When the rodent eats the bait, he's poisoned and dies.

The main concerns with baits include unintended residual or systemic poisoning. With residual poisoning, animals in the area, including horses, ingest some of the leftover poison and be harmed. With systemic poisoning, predatory animals such as cats and dogs eat the killed rodent and ingest the poison through the meat of the exterminated animal. For these reasons, it's advisable to avoid using poison baits until all other options that are safer for horses are exhausted.

Poison baits are the most effective when placed by a licensed applicator. Only licensed applicators are legally allowed to purchase and place the baits with the greatest efficacies at eliminating rodents. The U.S. Environmental Protection Agency has reduced the active ingredients in baits available for purchase to the general public. So, in some circumstances gophers or other rodents will “sample” the bait, feel ill but remain alive, and avoid the bait from that point forward. Conversely, baits with a higher dose of poison—such as those available to licensed applicators, are able to exterminate the rodent even if they only eat a small amount.

Take-Home Message

Controlling burrowing rodents in your pastures, paddocks, arenas, and around your farm can help supplement your current management and safety plans. Consult a pest control specialist to design the plan best suited to your and your farm's needs—doing so could save a horse from injury or even death.

About the Author

Matt Brechwald, MA

Matt Brechwald, a lifelong horse and livestock enthusiast, was born and raised in a rural area of Northern California. He received a bachelor of science in animal science from Montana State University, and later attended graduate school at Boise State University in social sciences. Brechwald and his family now farm in Kuna, Idaho. Brechwald opened Idaho Gopher Control in 2012 and focuses the business on four areas: horse properties, agricultural properties, small acreage, and residential properties. Since founding Idaho Gopher Control, Brechwald has continued to research equine injuries and death caused by burrowing rodents. Additional information is available at

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