Deterrent to Cribbing and Chewing in Horses
Posted on July 25th, 2016
Note: This text would have been used in a patent application, but the Patent and Trademark Office has let us down. Lobbyists and Congress weakened patent protections with the America Invents Act, and patent trolls from big business simply litigate with individual inventors until they get what they want.[1. Eden, Scott. “The Greatest American Invention”. Popular Mechanics, July/August 2016 p. 93-99]. At this writing, the PTO averages 16.1 months before it takes the first action on a patent application, and 25.7 months to process the average application. Over 500,000 patent applications are now awaiting examination[2. Patents Data at a Glance. USPTO.]
Field of the Invention
The invention is in the field of animal husbandry, and in particular the husbandry of horses and ponies.
Confined animals often develop anxiety, and sometimes fall into “repetition compulsion disorder” or “stereotypy”. Stereotypies are defined as repeated, relatively invariant sequences of movements with no obvious function.[1. Broom, D.M. and K.G. Johnson “Stress and Animal Welfare” Springer Science & Business Media, Kluwer Academic Publishers Nov 30, 1993. 211 pages.]
Stereotypy is commonly seen in caged zoo animals, who may pace back and forth in their cage, following the same route again and again. It may be seen in caged birds, such as parrots, dancing back and forth on a perch, or hopping from one perch to another and back. And it may be sometimes be seen in horses and other farm animals when they must be confined.
Stereotypies are abnormal behavior in that they occur very rarely in individuals living in a relatively complex environment which is appropriate to the biology of the species and where a wide range of their behavioral repertoire can be shown.[2. Broom and Kennedy, 1993]
The anxiety that captive animals sometimes develop can lead to self-injury and damage to structures. For instance, a nervous or bored horse confined to a stall may take to lignophagia – chewing on wooden parts of the stall. Such chewing inevitably damages the stall and wears their teeth. Wooden boards that are chewed may splinter, conceivably injuring the animal that swallows the splinter or steps on it. Painted boards or those treated with creosote may be toxic and carcinogenic if chewed.
“Cribbing” is a special case of these problems, in which the horse grabs a stall door or fence rail with its incisors, arches its neck, pulls against the object, and expels air, attempting to burp. (Many horse owners think the horse is inhaling, but the critical action seems to be exhaling.)
Causes of Cribbing and Chewing
Both cribbing and lignophagia in horses may sometimes stem from dietary deficiencies, feed that is hard to digest, or gastric inflammation, and may be exacerbated by boredom, stress, or anxiety. Horse breeds known for their generally high anxiety and activity levels, such as Throughbreds and Arabs, are more like to crib or chew than those known for their placidity, such as draft horses and ponies.[3. Kennedy, M.J. (1996). Common factors among horses performing stereotypies. Stocarstvo, 50 (6): 423 428. Available at https://www.dropbox.com/s/h3bqcrj3keq8r2g/Stocarsvo.pdf?dl=0] Apart from breed, there is evidence that horses are more likely to crib or chew when they can see fewer horses, when there are not given a chance to exercise, and when they are not given adequate access to hay.[4. Kennedy, 1996]
Horses that crib may show other symptoms of distress, including:
- History of intermittent colic.
- Evident wear of the labial surface of the upper incisors (nearest the horse’s lips).
- Difficulty in maintaining weight.
- Restlessness in the stable.
- Hypertrophy (enlargement) of the ventral neck muscles.
- Gastric ulceration.
- Lower than normal fecal pH.
- Greater activity at rest in the part of the nervous system associated with action and stress.[5. West, Christy Cribbing: Why I chose to not use a strap for my mare from AAEP Convention 2005: Weaving, Headshaking, Cribbing, and Other Stereotypies. February 2006 Article # 6491 Available at https://www.facebook.com/notes/caroline-larrouilh/cribbing-why-i-chose-to-not-use-a-strap-for-my-mare/10153587727710444/]
A stressed horse may develop stomach ulcers. Some horse owners have reported that giving their horses ulcer medicine stopped cribbing permanently in 3 weeks – presumably because it helped heal an ulcer that was the cause.[https://forum.horsetopia.com/health-nutrition/110951-cribbing-solutions.html]
The prevalence of cribbing or chewing has not been systematically studied, but there are reports of such stereotypies in 10.5%(6. West, 2006) to 18% (7. Kennedy 1996) of the population studied. According to West (2006), cribbing affects about 300,000 horses in the U.S.
Treating the Underlying Causes
We believe that the horse community may be confusing cause and effect when they claim that cribbing and wind-sucking can lead to stomach problems or colic. It is more likely, in our view, that stomach problems may lead to cribbing and wind-sucking.
Cribbing and chewing likely have somewhat different etiologies, but both may benefit from the same treatment strategies:
- Examine and treat any underlying visceral pain, especially gastric ulcers.
- Reduce concentrate and sweet feed to a minimum or supplement with an antacid; if concentrates are essential, fat- or oil-based rations are preferable to carbohydrate-based ones.
- Remove grain from the diet, because grain may contribute to gastric discomfort such as stomach ulcers.
- Increase fiber and forage. Provide free choice hay at all times, to ensure that the horse has something meaningful to do with its mouth. In a stall, slow-feed hay feeders may give a horse some mental challenge and spread out his eating, so that he doesn’t have so many bored idle periods.
- Manage the horse on pasture as much as possible. 24/7 turnout frequently results in an end to cribbing and chewing.
It is our hope that horses in confinement who exhibit cribbing or chewing will be provided with opportunities for stress reduction: an enriched environment, a change of environment, a regular opportunity to run and roam in a pasture or paddock.
And it is our hope that the veterinarian will look for signs of stomach ulcers, gastric inflammation and dietary deficiencies. A horse that needs to burp should not be prevented from doing so. And if these stereotypies are the result of stress, dietary deficiency, or gastric inflammation, they should not be referred to as “stable vices”, even if they result in destruction to the stable.
Previous Attempts to Treat the Habit
Once established, cribbing or chewing become habits and may not cease even when the underlying conditions are corrected.
Several products exist to deal with cribbing and wind sucking.
- There are anti-wind-sucking collars, which may stop cribbing or wind-sucking when strapped very tight, but which do not stop chewing and must be very uncomfortable. Those that work by choking the horse are only effective when worn; cribbing returns as soon as they are removed. We strongly recommend against these inhumane devices.
- The Barclay’s Anti-Cribbing Collar contains a switch that is activated by the horse’s throat action just before windsucking, delivering a mild static charge to the horse’s throat. This may work, but only with wind-sucking. It is not likely to be triggered by a horse that is biting on a stall or fence. And there are reports that such collars can produce scars.
- Cribbing muzzles, made of vinyl or aluminum, prevent the horse from getting a grip on wood – or most anything else – with her teeth. We expect that such muzzles interfere with eating by preventing the horse from getting its lips to some food sources, such as short grass.
- Some horse owners have resorted to putting gum rings in between the horse’s teeth, which make biting painful. They “work” as long as they are in place, but fall out after a few weeks.
- Some have had veterinarians perform myotomy of the ventral neck muscles to prevent rertraction of the hyoid and larynx and depression of the tongue(Fossell, 1926); others have cut the ventral branch of the spinal accessory nerve (Firth, 1980), partial myectomies of various muscles (Hamm, 1977), and even buccostomy to prevent air swallowing(Karlander, 1965).
- surgically slice the muscles that control the flex of the horse’s neck, to prevent the horse from bending to the cribbing position. We consider both procedures unethical and inappropriate.
Several products try to deal with both cribbing and chewing.
- There are some products that are unpleasant tasting, and that may be applied to the boards where horses bite or chew. Bitter apple, Cribbox, Stockholm tar, and McNasty are three such products. Hot sauce, chili powder, liquid dish soap, and manure are sometimes also used. But such products need to be repeatedly applied, and there have been reports of horses developing coughs and other signs of nasal irritation with some of these chemicals. Most such products either have an unpleasant smell to humans or are somewhat toxic to horses. Creosote, which is sometimes used, is both toxic and carcinogenic. Also, if the applied product has a very strong odor, it may make a significant portion of the stall unusable by a horse until the odor dissipates. Nonetheless, some product ideas have received patent protection [8. John W. Dyer, Sr. “Anti-chewing and anti-cribbing composition” US5352454 A. Published Oct 4, 1994.]
- Rubber cribbing bars. Some horse owners have added rubber hose to the top of the stall or fence boards where horses crib, and some even cover this with molasses. This probably helps save the horse’s teeth and the barn, but it doesn’t stop cribbing or chewing.
- Some people have switched to electric fence, or have run a hot wire around the top of a wooden fence. But these approaches don’t work to protect a stall.
- Some have tried electric shock collars, but these need to be operated by a human observer, who can’t provide the consistency and immediacy required for aversive conditioning.
Inventors have conceived elaborate muzzles that prevent horses from cribbing and wind-sucking. It appears that the first such patent was issued in 1894. [9. Thomas Redmond. US526538 A. “Device for Preventing Horses from Cribbing and Wind-Sucking. Published September 25, 1894.] The device comprises “a rigid open, or longitudinally slotted, U-shaped frame, vertical side bars secured to said frame, and a bit-bar supported between said side bars and provided with a centrally disposed anti-windsucking ball.”
Several inventions hope to distract the bored horse and thus reduce chewing:
- William R. Visalli, Duane E. Saville, Terry Quashnick US 4825812 invented a horse pacifier, consisting of rubber wheels that could be mounted in the stall. They hoped that “The rotation of the rubber pieces plus the associated noise created by movement of the shaft in a supporting slot entertains or amuses the horse, serving as a pacifier to relieve horse boredom and reduce the penchant of horses to chew other objects.”
- Joseph Lavern Miebach invented an animal-operated grain dispenser, consisting of a drum with holes that the horse could spin, in an attempt to get grain to fall out.[Joseph Lavern Miebach, “Animal-Operated Grain Dispenser” US 20130139756 A1. Published Jun 6, 2013.] Fallen grain is supposed to land in a receptacle below the dispenser, where the horse can find and eat it.
- Ian Mercer applied for a patent [WO2003103381 A1] on a horse “Nuzzle Device”, being a toy that would be mounted near the area where the horse was chewing, and which would move when nuzzled, hopefully distracting the horse.
Of course, a bored horse can become bored with a pacifier, too. Anyone who has ever hung a toy in a bird’s cage, or a “Jolly Ball” in a horse stall knows that distractions don’t distract forever. Birds and horses may be smarter than inventors, and will bore quickly when caged.
Other inventions attempt to treat the cribbing horse with a combination of drugs. [10. Richard E. Chipkin. “Method of Treating Compulsive Self-Injurious Behaviors.” WO2012033874 A1 (Application). Published Mar 15, 2012.] Providing dopamine or other chemicals may suppress a behavior, but the behavior would be expected to return when the effects of the drugs have worn off. Further, if chewing or cribbing are the result of gastric distress, such drugs do not treat the cause of the problem.
Nevertheless, even if the underlying causes of cribbing and lignophagia are corrected or removed, these behaviors may continue as abnormal, compulsive stereotypy, under the control of habit. To break those habits, our invention uses aversive conditioning. Aversive conditioning is a form of training in which punishment is used to associate negative feelings with an undesirable behavior. Our invention will introduce a small shock to the nose of a horse when it touches the board where it intended to crib or chew.
Researchers have long established that punishment is most effective when it is certain and immediate. Just as horses quickly learn to not touch an electric fence, we expect that a horse will learn not to crib or chew any board that has been protected by our invention. And just as horses confined with electric fences never seem to touch them, we expect that a horse will refrain from contacting the boards that were previously protected by our invention.
Our invention is based on a short strand of electric poly tape, connected to a small electric fence energizer.
Tape schematic, showing DC current.
Our invention is based on a strand of electric poly tape, connected to a small electric fence energizer. This tape contains two lines that carry current – a positive charge on one side, and a negative charge on the others. When a horse touches the tape with its noise, if the current is on, the nose creates a temporary bridge between the positive and negative sides, causing a temporary short. The horse feels a shock when this happens, and pulls back.
The tape may be cut to the desired length with scissors or tin snips, and is attached to the top of the board to be protected. Attachment may be with non-conductive tape running cross-wise to the tape, or with staples, inserted into the middle of the tape, and running parallel to the edges of the tape so that they do not short out the wires on the outside edges of the tape, or with conventional electric fence tape insulators.
We recommend that the tape color be selected to approximate the color of the board to be protected, since we want the horse to learn to keep her nose of the board, rather than learn to keep it off the tape. Electric poly tape comes in green, white, and brown; generally white or brown will blend best with the existing board color.
Electric poly tape comes in various widths, but for attachment to the top of a stall board or fence board, a width of 12 mm (½ inch) is probably fine. A narrow width is harder for a horse to see in an electric fence, and should also be harder to see on the top of the board that we about to eat.
The ideal setting for the electric current should be just strong enough for the horse to pull his head back when he completes the circuit. The objective is to cause adequate pain to stop the horse, but not to cause any injury, fear, or stress.
It has been reported that current at this level can be detected by a horse prior to contact. If the horse has had previous exposure to electric fencing, it may not make contact with the tape and board at all.
Powering the tape
In an electric fence, powering the tape is normally done with a fence energizer. Most fence energizer offer 5000, 7000, or more volts DC, and pulse at 1-2 second intervals. They plug in to 110/120 volt sources.
Pulsing uses less electricity, and allows an animal that has touched the tape to pull back. The best low impedance fencers have an on-time of less than 100 micro-seconds (100 millionths of a second) with a pulse rate of about 55 times a minute.
Electric fences for horses deliver such high voltage because horses will normally lean into a fence with their chest or side, and those parts of their body are well insulated electrically. High voltages are needed to produce long sparks that will jump the air gap of the animal’s insulating fur. A typical spark length is 1 mm (0.04 in.) for every 2000 volts. In comparison, a human hand will feel a shock from just 100 volts. The horse’s mouth, though, and especially his tongue with salty saliva, is a much better conductor of electricity than a human hand, and far less than 100 volts are enough to be a memorable and unpleasant experience for a horse’s tongue.
Because pulsing is needed to ensure that the horse will be able to pull away from the tape, it is appropriate to use a small fence energizer, one designed to safely keep dogs and chickens in, and rabbits and squirrels out. Such an energizer should be safe for contact with a horse’s nose or tongue, yet provide a memorable experience for the horse. An example of such a unit is the Patriot PE2 for 110/120 v hookup, or the Patriot PS5 Solar for gel cell or solar power. Such small energizers are available for about $26.
Broom, D.M. and K.G. Johnson “Stress and Animal Welfare” Springer Science & Business Media, Kluwer Academic Publishers Nov 30, 1993. 211 pages.
Broom, D.M. And M.J. Kennedy “Sterotypies in horses: their relevance to welfare and causation”. Equine Veterinary Education 1993 5 (3) 151-154.
Firth, E.C. (1980) Bilateral ventral accessory neurectomy in windsucking horses. Vet. Rec. 106, 30-32.
Fossell, G. (1926) The new surgical treatment against crib-biting. Vet. J. 82, 538-548.
Hamm, D. (1977) A new surgical procedure to control crib-biting. Proc. Am. Soc. Equine Practitioners. 23, 301-302.
Karlander, S., Mansson, J., and Tufvesson, G. (1965) Bucostomy as a method of treatment for aerophagia (windsucking) in the horse. Nord VetMed. 17, 455-458.
Kennedy, M.J. (1996). Common factors among horses performing stereotypies. Stocarstvo, 50 (6): 423 428. Available at https://www.dropbox.com/s/h3bqcrj3keq8r2g/Stocarsvo.pdf?dl=0
Kennedy, M. J., Schwabe, A. E. and Broom, D. M. (1993). Crib-biting and wind- sucking stereotypies in the horse. Equine Veterinary Education 5(3):151-154. Available at https://www.dropbox.com/s/3rjxflivde8fa12/Kennedy%20et%20al%201993.pdf?dl=0
West, Christy. Cribbing: Why I chose to not use a strap for my mare from AAEP Convention 2005: Weaving, Headshaking, Cribbing, and Other Stereotypies. February 2006 Article # 6491 Available at https://www.facebook.com/notes/caroline-larrouilh/cribbing-why-i-chose-to-not-use-a-strap-for-my-mare/10153587727710444/