4 minute read
Bronson, J., DVM: Thumps
By Dr. Joanna Bronson | http://bronsonvetservices.com/
Horses can develop a form of the hiccups, which in equines is called Thumps. This sudden, involuntary contraction of the diaphragm muscle occurs at the same time as a contraction of the throat. The combination produces the hiccup sound, but it may also resemble a spastic cough.
The medical term for Thumps is Synchronous Diaphragmatic Flutter or SDF. The name Thumps was assigned since the repetitive sound that is produced during an episode that resembles a drum beat. The veterinarian who first labeled this condition first heard the sound coming from a horse’s abdominal cavity that had just finished a 13mile race in the mid-1800’s.
Equine Thumps is most often attributed to a low level of calcium in the horse’s bloodstream, which causes the nerve that controls the diaphragm to become excitable. As this jarred nerve passes alongside the heart on its way from the neck to the diaphragm, it can begin synchronizing and mimicking the horse’s heart beat instead of doing its usual job of passing along brain signals. The resulting flutter is beating in sync with the horse’s heartbeat which produces the thumping sound.
An occasional bout of Thumps will usually resolve on its own with rest, rehydration, and replenishment of electrolytes through fluids. However, Thumps is not a condition that should be ignored.
Upon examination, the severity of the deficiency will determine the clinical signs. Affected horses may display mild abdominal twitches, which can become whole body tremors, weakness, the onset of a fever, arrhythmias, and even seizures. If the horse is exhausted and dehydrated, this is a RED Alert situation and needs immediate veterinary intervention. The causes of Thumps are multiple and often combined. One of the most common causes is from prolonged strenuous activity especially in high heat and humidity. Horses involved in endurance racing and sport horse competitions are most often affected as heavy and excessive sweating can result in the formation of an electrolyte imbalance (especially of calcium levels) from dehydration, and acid-based or pH disturbances. While Thumps is considered a common condition in performance horses, it may also point to more serious underlying issues that may stem from certain endocrine and kidney conditions, digestive disorders, and even Blister Beetle toxicity. These suspicions need further testing to determine the source. The use of the diuretic Lasix (most often used in racing horses) can also increase the risk of dehydration and ultimately bring on a case of Thumps. Thumps is also related to poor nutritional intake in horses. Inadequate mineral or excessive mineral supplementation can upset the electrolyte balance of individual horses. Too much of an element can be as ineffective and dangerous as too little. Horses on high-calcium diets may also develop Thumps after endurance activities or extreme stress. Excessive amounts of calcium can inhibit the body’s ability to replace lost minerals. With dehydration, fluid loss, and imbalanced electrolyte levels, horses who sweat heavily suffer essential mineral losses of calcium, sodium, magnesium, and potassium. A horse ’ s sweat appears white and foamy since it is high in electrolytes/minerals. Hydration is the key for reversing dehydration. A fast-acting electrolyte paste can help correct imbalance problems associated with electrolyte loss of concentrated salts and minerals. The paste will also help stimulate a horse’s thirst mechanism helping him to rehydrate more quickly.
Horses who have experienced severe or chronic diarrhea can also become dehydrated and suffer from mineral depletion and may be candidates for a case of Thumps or other compromising conditions.
Fortunately, most mild cases of Thumps can be resolved after replenishing a horse’s electrolytes and allowing adequate rest. However, even if more serious intervention is required, the prognosis is typically good when the condition is recognized and treated soon after the appearance and recognition of Thumps.
Avoiding an occurrence of Thumps may be helped by providing a proper balanced diet, following a sensible conditioning program, paying attention to heat and humidity during work or competition, and providing electrolyte supplementation during exercise. Athletic horses involved in racing, high performance sports such as jumping and cross country, along with endurance riding, should be evaluated by a veterinarian and advised by an equine nutritionist who can recommend an appropriate diet for individual horses and their specific level of work.
An appropriate fitness program that includes a plan for electrolyte replacements should be employed. Salt should always be available to stimulate thirst.
Finally, any horse diagnosed with hypocalcemia should be evaluated by your veterinarian. Hypocalcemic tetany in horses is an uncommon condition associated with acute depletion of serum ionized calcium and sometimes with alterations in serum concentrations of magnesium and phosphate. It occurs after prolonged physical exertion or transport (transport tetany) and in lactating mares (lactation tetany).
Dr. Joanna Bronson graduated from MSU College of Veterinary Medicine in 2000 at the top of her class. After graduation, she worked as an intern at a large equine referral practice in Cleveland, OH, specializing in lameness, surgery, and racetrack medicine. In 2005, she opened Bronson Veterinary Services in Coldwater, MI, a full-service equine, small animal hospital and surgical center.
452 W. Central Rd., Coldwater, MI 49036
