Anhidrosis is a word that sparks dread in the hearts of horse owners in the southeastern United States. In layman’s terms, it means the horse is a “non-sweater,” and in the Texas summers where the heat and high humidity can easily reach 110˚ F for extended periods, this can be a serious problem. Not only can horses’ show careers get put on hold, but their lives can easily be in danger from heat stroke. Horses lose 65-70% of their body heat through the evaporation of sweat, so when the body is no longer producing this, body temperatures can soar dangerously high, resulting in hyperthermia and death.
The cause of anhidrosis is not fully understood, but the condition is often listed with symptoms of PPID in horses and associated with a metabolic imbalance. This could possibly be because of overstimulation of the horse’s sweat glands by stress hormones. The disease’s onset can be acute or gradual, but in the case of this PPID-positive horse, signs showed up slowly and increased with age. Eatin on the Run, “Run,” was an 8-year-old Quarter Horse gelding competing in the cutting when his owner first noticed that he was not sweating after intense exercise. The owner tried various treatments, including several electrolyte supplements and the anecdotal can of dark beer once daily. Nothing proved to really cure the problem, although the horse faired better in the winter months and at air-conditioned indoor shows. If the shows were long enough and he was housed in an air-conditioned stall, he would start sweating near the end of his stay. This supports the theory that often moving the horse to a colder, less humid environment will eventually restore its ability to sweat.
Introduction of Acupuncture to Treat Anhidrosis
As the horse aged and retired, the pattern became a week or two of pronounced difficulty in thermoregulation (the ability to maintain a consistent body temperature) in early summer followed by the ability to remain comfortable given a pond and shady pasture. One year did require a three-day stay in an air-conditioned medical facility. At this point, the owner met a veterinarian trained in acupuncture who felt he might be able to help
By this time, Run was 19 and fully retired except for pasture riding. On June 8, 2019, upon presentation, Run was slightly depressed. His tongue was dry and tacky, dark red and with a thick yellow coating. He was tachypneic (42 breaths/min.) with rapid full pulses bilaterally (72 beats/min.). This was a June afternoon after standing in a pasture all day. His TCVM (Traditional Chinese Veterinary Medicine) diagnosis was summer heat with lung Qi deficiency. Dry needles were placed bilaterally at BL-13, the back-shu association point for lung; BL-22, the back-shu association point for triple heater (TH); LI-4; GV-14; and LI-11 to clear heat and open the sweat pores. Hemoacupuncture to clear summer heat was performed with 25 ga., 5/8” hypodermic needles at Tia-yang (GB-1) and TH-1, LU-11, SI-1 and HT-9 bilaterally, Wei-jian and Er-jian. Hemoacupuncture was also performed bilaterally at Xiong-tang using 22 ga., 1.5” hypodermic needles. All needles were left in place for approximately 20 minutes. One hour after treatment, the horse had begun to sweat in patchy areas. Watermelon rind (not the fruit) was also recommended to begin feeding whenever possible as this is a “cooling food.”
One week later, on June 16, Run was treated again. This time upon presentation, the tongue remained dark red but was moist. Pulses were still rapid and forceful bilaterally (68 beats/min.). Dry needles were placed at Bai-hui, LI-4, LI-11, HT-7, BL-13, BL-22, BL-40, GV-14, and Fei-shu. Hemoacupuncture was repeated at Er-jian, Wei-jian, Tai-yang, Xiong-tang, TH-1, LU-11, SI-1 and HT-9.
When examined on June 27, the tongue remained dark red and moist, but vitals had normalized to Temp: 99.4˚ F., Pulse: 44 beats/min, and Resp: 24 breaths/min. Run was much more comfortable and received similar treatment as on June 16, but with BL-10 substituted for Bai-hui for its sedative effects.
Upon examination on July 16, the tongue was dark pink and moist, and pulses were 48 beats/min. and no longer forceful. By this time of summer, flies were out in full force and Run’s fly allergy was active. Hemoacupuncture points treated on previous visits for anhidrosis were repeated as well as dry needles at LI-4, Fei-shu, HT-7, BL-13, BL-22, and KID-7. In addition, BL-10, BL-12, Fei-men (SI-14), and GB-20 were treated to help clear wind and stop itching.
By August 9th, after a long, hot summer, Run appeared comfortable, but his tongue was dark pink and tacky, and his pulses were again forceful. His sweat pattern was limited to his head and neck (Figure 1) Dry needles were placed at BL-10, BL-12, BL-13, BL-22, GB-20, LI-4 and SI-14. Hemoacupuncture was performed at Wie-jian, Er-jian, Tai-yang, TH-1, and Xiong-tang. He remained comfortable over the next year.
The following year, Run moved to an 80-acre pasture and was unable to be observed daily. As a preventative, Run was examined and treated for anhidrosis with acupuncture to prepare him for the summer months. He appeared comfortable with patchy sweating behind his ears and elbows like that of his pasture mate. His tongue was moist and pink, and his pulses and body temperature were normal. Dry needles were placed at BL-10, BL-13, BL-40 and LI-4, and hemoacupuncture was performed at Wei-jian and Er-jian. One week later, he was found to be in a full body sweat for the first time in more than a decade (Figure 2).
Results of Treating Anhidrosis With Acupuncture
This case report shows the effectiveness of acupuncture therapy for anhidrosis management. Run continues to be treated every spring/early summer, usually with two acupuncture sessions which keep him comfortable throughout the summer. His exercise is minimal, and any riding is done during the cooler parts of the day and always followed with a good water soaking to help him cool off. He can produce enough sweat to keep him cool and is fortunate to have breezes and large oak trees to keep him shaded.
Anhidrosis is not cured but can be managed, and acupuncture has enabled Run to live a much more comfortable life. Continual treatments are to be expected until this horse relocates to a cooler climate. If you have a horse with anhidrosis, prepare to change your performance expectations and make a treatment plan, which might include acupuncture, to help when the temperatures heat up!
About Karen Chapman, LVT
Karen grew up riding and loving horses from a very early age. She graduated from Texas A&M University with a degree in Education and taught school for several years before changing careers and becoming a licensed veterinary technician. As a technician, she worked in a busy private equine practice for nearly 10 years before she joined the staff at Texas A&M University Veterinary Medical Teaching Hospital. She worked in Community Practice and Ophthalmology and loved teaching vet students. Currently, she is working in research with the TAMU Comparative Medicine Program, but her heart will always be with the horses.
Brinsko, Steven P. Acupuncture Treatment of Anhidrosis in a Quarter Horse Gelding. TCVM Class: Fall 2016
Mallicote, Martha. Anhidrosis: Help – My Horse Doesn’t Sweat! University of Florida Large Animal Hospital. https://largeanimal.vethospitals.ufl.edu/equine-anhidrosis
Anhidrosis in Horses. Hagyard Equine Medical Institute. https://www.hagyard.com/anhidrosis-in-horses#