Q. What options exist to treat behavioral vices? In my case, a 5-year-old mare that I acquired off the track this spring is a cribber--something I was not aware of before I got her home. I never found a really good/descriptive/illustrated article on the "Forssell-Burba" or "modified Forssell" surgical technique and, in fact, found that most veterinarians I talked to were several years behind the times on the surgery's considerable rate of success. I looked at foul-tasting paints to discourage the behavior, electric fencing to limit the mare's access to cribbable surfaces, punitive collars as operant conditioning aids, and myriad less aggressive anti-cribbing collars.

Scot Gilies

Lexington, Ky.

A. Cribbing is very challenging to treat, and in fact, I've never known a case to be completely eliminated with true behavior modification techniques--for example, operant conditioning (when an animal learns that his or her initial action results in a reaction from you). That's because, as you have found with your horse, it's not just an ordinary behavior problem. There is likely an underlying physiologic condition driving the compulsion to crib that is very difficult to overcome with positive or negative diversion, reinforcement, or punishment techniques.

There is some pretty good evidence to suggest that the root cause might involve the changes in the gastrointestinal tract possibly related to general stress and to stressful diet and feeding schedules. So, in recent years one of the first recommendations has typically been to have a veterinarian perform a gastroscopic examination (stomach scope) to evaluate for gastric ulcers. If there are significant ulcers, whether they are a causal factor or a complication of the cribbing, treating to eliminate the ulcers is likely to reduce the time spent cribbing.

Another first recommendation is to explore the horse's diet. Diet and feeding schedule can significantly affect the incidence and severity of cribbing in horses and have been long known as risk factors for developing the problem in the first place. While a free-choice all-forage diet doesn't completely prevent or eliminate cribbing, we do know that most horses that have never been fed concentrated grain feeds in infrequent meals do not develop cribbing. It is also a common observation that if a grain meal-fed horse that is a cribber is transitioned back to a free-choice all-forage diet, then the rate of cribbing in that horse is almost always markedly reduced, although rarely completely eliminated.

Cribbing correction surgeries involve severing the nerves and muscles necessary for the grasping and grunting that comprise cribbing. Various modifications have been added to surgical methods over the years to try to improve efficacy and reduce side effects. There are reports that the various modified Forssell's surgeries have had more consistent results in stopping cribbing than many of the behavior modification techniques, such as foul-tasting paints and electrification of surfaces as you have tried for this horse.

You mentioned the Forssell-Burba surgery; Daniel Burba, DVM, Dipl. ACVS, a surgeon at Louisiana State University, has reported the highest success rates to date with a surgical approach to reducing cribbing (roughly 90%). His modification of the Forssell's operation adds laser technology to alter the throat structure that creates the grunting sound at the end of each cribbing event. Burba was interviewed for a 2008 article in The Horse ("Cribbing: Can You Stop It?"; see TheHorse.com/10705) by Heather Smith Thomas. In that article there is a pretty good explanation of the basic surgery and the Burba laser modification.

Over the last few years a horse behavior group in Budapest, Hungary, headed by PhD candidate Krysztina Nagy, has been studying the efficacy of modified Forssell's surgery, comparing it to other techniques meant to physically impair a horse's ability to crib. In a study of 20 horses that had undergone a modified Forssell's operation, 16 of the 20 owners reported that the cribbing had stopped (13) or improved (3) after the surgery. For the remaining four owners reported no improvement. Thirteen of these 20 horses were directly observed by behaviorists. Each horse was presented with a brief stall-side challenge test known to provoke a cribbing episode in most cribbers. The challenge involves placing a feed pan filled with grain on the floor just beyond the reach of the tethered horse and offering a few bites to the horse. Seven of the 13 horses tested cribbed during the 20-minute test. Interestingly, in a similar study looking at efficacy of a cribbing collar in a similar population of horses, efficacy of the collar and the surgery were about the same. The research included evaluation of stress indicators during the test. Stress levels in response to the challenge test were higher in the horses that did not crib (either with collar or after surgery) than in those that did crib.

In addition to the usual risks of potential complications of general surgery, the most common side effects of the Forssell's operation include laryngeal hemiplegia (also known as roaring, in which a horse's arytenoid cartilage obstructs a part of the windpipe) and changes in neck conformation known as swan neck. So, with the only published study finding no better results with this procedure than with a well-fitted cribbing collar, the ethical wisdom of such a surgical correction, as you can imagine, has been questioned. I certainly know veterinarians who are aware of the surgery, but who don't feel comfortable doing or recommending the procedure. Last time I asked around informally, these surgeries were not routinely recommended, performed, or even taught in many of the North American veterinary schools. This may be why you have found veterinarians who are not aware of some of the recent reported successes.

About the Author

Sue McDonnell, PhD, Certified AAB

Sue M. McDonnell, PhD, is a certified applied animal behaviorist and the founding head of the equine behavior program at the University of Pennsylvania's School of Veterinary Medicine. She is also the author of numerous books and articles about horse behavior and management.

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