Anhidrosis, the inability to sweat, happens in humans and horses as a result of heat-related illnesses. It typically involves dysfunction of the nervous system or sweat (eccrine) glands, whether due to medications, various autonomic nervous system disease, or other unidentified reasons. When patients cannot sweat, they lose the ability to properly regulate their body temperature, potentially leading to a life-threatening state; horses reduce body heat by an estimated 70% through the evaporation of sweat.
The three case reports that follow, all compiled by graduates of the CuraCore VET course called “Medical Acupuncture for Veterinarians” (MAV), document the improvement in horses diagnosed with anhidrosis. Because acupuncture works through normalizing influences on the central, peripheral, and autonomic nervous systems, it makes sense that this rational, scientifically supported type of treatment could help horses who are experiencing autonomic dysfunction.
Case #1. By Dr. Meghan Schuman
The synopsis of the first case, sent in by Dr. Meghan Schuman (now Dr. Meghan Richardson), appears below. It involved treatment of a seventeen-year-old thoroughbred mare who presented for decreased sweating and progressive right leg lameness. Dr. Schuman performed three weekly treatments with gentle, dry needling and cold laser therapy. The results included increased comfort with exercise and increased ability to sweat.
This horse “is a seventeen-year-old thoroughbred mare who was rescued a few years ago and now lives on a retirement farm. She is exercised daily and used to train young riders. She has a good disposition and is amiable to her training… Due to her good genetics, she was bred often. Since arriving at her current home, she has put on a couple hundred pounds and now is at an ideal body weight. She has not been sweating normally for quite some time now according to the owner. An equine practitioner was out a few weeks ago to float the teeth but the lack of sweating was not addressed. The owner notes this improved her temperament and appetite. In order to address the decreased sweating, the owner has tried small amounts of exercise, dark beer and air conditioning. There was no improvement noted. The horse can be seen laying in a pond sometimes after exercising. The owner also notes that the mare seems to turn her right leg out when at a walk and has done this since she has owned her. She does not think it causes a lot of pain since she has never refused exercise. She lives in southwest Florida with access to a grass field and a dirt training arena. Her stall is adequately padded with pine bedding.”
“Upon [my] arrival, she was out laying down in the grass field. An exam at a distance was performed first. She ambulated slowly with her head held at a neutral position and bobbing slightly which correlated with placement of her right rear leg. Her right leg turned slightly valgus at the level of the stifle and she appeared to drag the right and left rear hooves with some steps. Pulse and respiration were within normal limits. A myofascial exam was performed next. Palpation of the temporalis muscle was within normal limits. A slight response was noted with palpation of the temporomandibular joint. The cleidocephalicus muscles and trapezius muscles palpated normally. Flexion of the neck was normal in all four directions. Supraspinatus and infraspinatus muscles palpated normally with no taut muscle bands. The left forelimb was sensitive to palpation around the insertion point of the brachialis. The pectoral muscles palpated normally. There was a significant reaction in palpation in the midthoracic to caudal thoracic spine. The hair in this area laid in different directions and there was some heat felt on the skin. Gluteal muscles palpated normally. Both hind limbs were resistant to lifting, flexion and extension. There was no pain associated with flexion of the base of the tail. The horse appeared anxious following the exam.”
“Anhidrosis was the most likely diagnosis at this time…Unfortunately, we were unable to definitively diagnose this without further diagnostics. If I had the chance to discuss this case with an equine practitioner, I would be interested in a full blood panel for her. My current understanding is that after a few other differentials are ruled out you are able to test for anhidrosis by performing an intradermal terbutaline sweat test. Furthermore, I would be interested in hind limb radiographs to definitively diagnose the hindlimb lameness.”
Acupuncture points stimulated on one or more sessions included the following:
Central nervous system points: BL 13, BL 17, BL 20, BL 21, BL 22, BL 23, KI 27, Bai Hui.
Peripheral nervous system points (with myofascial effects): GB 29, GB 30, BL 54.
Autonomic nervous system points: GV 20, GV 14, LI 16, HT 7. Additional points considered for future treatment included LU 11, LI 4, KI 7, and GV T.
Case #2. By Dr. Kelsey S. Pruitt
In excessive climatic conditions the ability of the equine sweat glands to function properly is often diminished. Sweat glands become desensitized to ß-adrenergic receptors over time. To restore optimal function of the nervous system acupuncture was performed in efforts to encourage neurovascular communication with the glands. Harmony’s treatment for anhidrosis included an array of acupuncture points to promote sweating, increase blood flow to the periphery, and create a more homeostatic environment within the body. Following acupuncture treatments combined with supplements and environmental alterations, she began to sweat more consistently. Acupuncture can be an effective form of treatment for anhidrosis when used in conjunction with other traditional remedies.
Harmony, a 17.5 yo, Halflinger paint mare, presented to Sun Dog Cat Moon’s ambulatory equine service with a chief complaint of anhidrosis for the past three summers. Other concurrent diagnoses include obesity and metabolic disease. She has a history of Degenerative Joint Disease (DJD) bilaterally in her hocks, secondary to metabolic disease. No joint injections were administered. Prior to presentation, she was on the following supplements: ½ scoop electrolytes two times per day, 2 scoops of One AC two times per day, ½ Guinness beer daily, equiwinner patches, 15 minutes of cool hosing and fans. Harmony is currently being ridden as a ground therapy and trail riding horse.
Physical Examination and Clinical Assessments
Upon physical examination, Harmony was bright and alert. All vital parameters were within normal limits. No abnormal findings noted on neurologic evaluation. No gait abnormalities appreciated on the lameness examination. She was consistently responsive on myofascial palpation at BL 11 bilaterally and BL 54 primarily on the left side.
Medical Decision Making
Anhidrosis is defined by the inability to sweat, caused by a failure in the secretory process of the glands. The main stimuli of the body to produce sweat are via an increase in environmental temperature and exercise. Although to date, sweat glands are not considered innervated, it is important to note the close proximity of sympathetic innervation to the rich blood supply surrounding the equine sweat gland. Axons reside close to capillaries and other vasculature and are able to sense a change in temperature. The initial vasodilatory reflex response to an elevated body temperature leads to withdrawal of vasoconstrictor tone. This response is followed by a powerful compensatory decrease in vascular tone involving the release of neurotransmitters from the sympathetic nerves, such as adrenaline acting on ß2 adrenoreceptors. In climatic stress specifically, the ß2 adrenergic receptors have become desensitized or downregulated to increased circulating adrenaline, which in turn leads to a refractory condition within the sweat gland.
One way in which acupuncture can be effective in restoring a homeostatic environment to the autonomic nervous system, includes its effect on adrenergic receptors in the periphery. The axon reflex that is initiated following stimulation of the nervous system calls for a peripheral signal to travel the length of the neuronal cell body and allow for antidromic activity affecting surrounding connective tissue. There is still discrepancy on which catecholamines are released locally and have their effect on decreasing vascular tone. Secondary to their vasodilatory action, coupled with withdrawal of noradrenaline, a potentiated release of bradykinin and other neurotransmitters, such as Nitrous Oxide are released. These neurotransmitters play a major role in further local cutaneous vasodilation. The ability of the patient to sweat correlates with the cutaneous blood supply, which is upregulated by modulating the parasympathetic and sympathetic nervous systems via acupuncture; this in turn leads to a more homeostatic environment. Both the local and peripheral effects of acupuncture are essential to anhidrosis. During exercise, about 70% of heat dissipation occurs via sweating, while the remaining heat is alleviated by respiratory tract evaporation. Therefore, many of the points used during this specific treatment course for anhidrosis were also targeted to benefit optimal pulmonary function to aid in more efficient cooling of the equine patient.
Harmony’s treatment course was initiated by stimulating the cervicothoracic spinal nerve at GV 14 to alter immunologic dysfunction, as well as influence appropriate respiratory mechanisms to aid in cooling. BL 11 was used to influence the cervicothoracic spinal nerve and decrease tension along this channel to ensure optimal function of the respiratory system. The caudal thoracic spinal nerve at BL 20 was also needled for the same reasons. She was consistently responsive to palpation of BL 23, governed by the thoracolumbar spinal n., indicating a degree of lumbar and pelvic pain. Electrical stimulation was performed bilaterally from BL 11- BL 23. The mid-to-caudal lumbar spinal n. was influenced at Bai Hui for endorphin release and secondary pelvic limb pain, from previously diagnosed DJD bilaterally in hocks. In close proximity to the lumbar spinal nerves, Shen-shu, Shen-jiao, and Shen-peng were stimulated by electrical stimulation to aid in local lumbosacral and hindquarter pain relief. Severe sensitivity and discomfort was appreciated at BL 54 upon musculoskeletal palpation. The master point of the hindlimb is innervated by the cranial gluteal n. and dorsal rami of sacral spinal n., which were stimulated for relief of hip and gluteal pain. BL 40 and SP 6 innervated by the tibial n. were targeted for pelvic limb dysfunction and pain. LI 11 ( radial n.) and ST 36 (fibular n.) were needled for immunomodulation and anti-inflammatory actions. To directly promote sweating the radial n. was stimulated at LI 4 and the tibial n. at KI 7 for the regulation of water retention and anhidrosis. LR 3 was treated via acupuncture and acupressure by the owner for stagnation of blood flow. Harmony received a total of three treatments starting at two week intervals and progressing to four.
Outcomes and Discussions
Following the first treatment this summer, the owner reported that Harmony began to sweat a minor amount more than she had prior to acupuncture. With the second and third round of acupuncture treatment she became more consistent in her sweating and was no longer tachypneic. The latter treatment was toward the end of the summer, when the environmental temperature had decreased. In addition to acupuncture treatment, she was also on a Herbsmith Summer Heat formula, electrolytes, One AC, and Guinness beer daily. Environmental management was altered with fans and cooling protocols daily. No adverse side effects were noted from the acupuncture treatments. This case study has reinforced the importance of integrating all forms of medicine to treat the patient. There are still many unanswered questions on the pathophysiology of this disease. Though much research has been done on this condition, further investigation is warranted to produce an effective evidence-based treatment for anhidrosis.
Jenkinson, David McEwan, Hugh Y Elder, and Douglas L. Bovell. “Equine Sweating and Anhidrosis Part 1: Equine Sweating.” Veterinary Dermatology 17.6 (2006): 361-92. Web.
Jenkinson, David McEwan, Hugh Y Elder, and Douglas L. Bovell. “Equine Sweating and Anhidrosis Part 2: Anhidrosis.” Veterinary Dermatology 18.1 (2007): 2-11. Web.
Robinson, Narda. CuraCore VET / Medical Acupuncture for Veterinarians Course Notes.
Case #3. By Dr. Jake Jensen
A gelding with a history of anhidrosis and poor performance during warm weather, which was unresponsive to oral supplement therapy, demonstrated increased sweating and improved performance following acupuncture therapy.
Gabe is a 12 year old, bay Warmblood gelding who is used as a hunter jumper. He stabled in central Indiana and has a several year history of anhidrosis, lethargy, and poor performance during the summer. His respiratory rate and temperature remain elevated for an extended period (>30 minutes) following exercise, and he sweats very little compared to other horses in the barn doing similar work. He received 1 teaspoon of the supplement One AC by mouth twice a day the previous summer with no observable change in sweating or performance. He began showing signs of anhidrosis again in May of 2016 as the seasonal temperature began increasing.
Physical Examination and Clinical Assessments
Gabe presented for evaluation and acupuncture treatment on 5/31/16. His physical exam at rest was within normal limits and he was observed to be sound at a trot in a straight line and on the lunge in both directions.
Medical Decision Making
The pathophysiology of anhidrosis in the horse is complex and still not entirely understood, however it is believed that excessive adrenaline secretion over time leads to desensitization and eventual failure of the glandular secretory process.1 Acupucture points were selected to modulate the autonomic nervous system and attempt to restore the balance between the sympathetic and parasympathetic nervous system in order to decrease adrenaline secretion and stimulation of beta-adrenergic receptors. This can be achieved through long loop peripheral nerve reflexes to the nucleus tractus solitarius and stimulation of the parasympathetic cranial nerves.
Acupuncture treatment on 5/31/16 consisted of GB 21, LI 11, TH 17, PC 6, BL 13, BL 20, ST 36, LR 4, and BL 40 bilaterally as well as GV 14 and Bai Hui. 40mm Seirin J-type 0.25mm diameter dry needles were used on points except for TH 17, PC 6, and LR 4 where 20mm Seirin J-type 0.2mm diameter needles were used. The needles were left in place for 15 minutes. The same treatment protocol took place on 7/5/16 and 8/22/16.
Outcomes, Discussions, and References
In the first week following acupuncture treatment, Gabe exhibited an observable increase in sweating, a decreased respiratory rate during similar work, and a quicker return to normal body temperature following exercise. Despite higher than normal average temperatures throughout the summer, he was able to continue training and showing during times of the year that he had not been able to perform in previously. The only variable that changed in his management was acupuncture. Many studies in humans have evaluated the ability of acupuncture to influence the autonomic nervous system and measured outcomes such as blood pressure, gastric motility, heart rate variability, and skin temperature2,3,4. This case suggests that anhidrosis in the horse may be another example of an autonomic nervous system dysfunction that responds favorably to treatment with acupuncture and warrants further research.
- Jenkinson DM, Elder HY, Bovell DL. Equine sweating and anhidrosis Part 2: anhidrosis. Vet Dermatology. 2007 Feb;18(1):2-11
- Haker E, Egekvist H, Bjerring P. Effect of sensory stimulation (acupuncture) on sympathetic and parasympathetic activities in healthy subjects. Journal of the Autonomic Nervous System. 2000;79(1):52–59.
- Sakatani K, Kitagawa T, Aoyama N, Sasaki M. Effects of acupuncture on autonomic nervous function and prefrontal cortex activity. Advances in Experimental Medicine and Biology. 2010;662:455–460.
- Li Q-Q, Shi G-X, Xu Q, Wang J, Liu C-Z, Wang L-P. Acupuncture Effect and Central Autonomic Regulation. Evidence-based Complementary and Alternative Medicine : eCAM. 2013;2013:267959. doi:10.1155