Chronic Lyme Disease in the Horse

Chronic Lyme Disease in the horse
This is long and technical article, but contains much useful information to help you recognize and treat this debilitating condition. Many veterinarians are unfamiliar with this disease, especially in parts of the country where it is uncommon. Others do not believe it is a problem. The truth is that this is a serious, widespread disease that is difficult to treat.
Joyce Harman DVM, MRCVS

The article is adapted from a paper presented at the American Holistic Veterinary Medical Association, 2010

Lyme disease (LD) has been recognized for about 40-50 years. It is now the most commonly reported tick-borne illness in the US and Europe and is also found in Asia. The Centers for Disease Control and Prevention (CDC), shows more than 35,000 reported human cases by 2008. The actual numbers are likely much higher as many cases go unreported. Most cases are concentrated in about 15 states, mostly on the east coast from Virginia north. However it can be found almost everywhere, so consider Lyme as part of any rule-out list.

The Lyme spirochete (Borrelia burgdorferi) is a very mobile, corkscrew-shaped bacteria. In nature the cycle of life involves ticks of the Ixodes ricinus on the East coast, with other species used in other parts of the US and world. Contrary to popular belief, deer are far from the only host for the infected tick, as the different tick species prefer different hosts. Many small mammals are part of the host cycle, from the white-footed mouse (the main one in the northeast) to the chipmunk, hedgehog and rats along with humans and dogs. The nymph stage ticks are the source of most infections while the adult tick, which is a little larger and easier to see, may be less important.

Spirochetes possess separate plasmids (DNA strands) and have an inner and an outer protein coat which is unusual in the bacterial world. The outside coat comes into contact with its host organisms and can be adapted to whichever host the spirochete comes in contact with.

There are many different outer protein coats, called Osp, and different portions of them are upregulated while the tick is eating its blood meal, even before the spirochete enters the body. A compound called decorin essentially hides the outer layer of the spirochete from the host immune system so that it can enter the body undetected. The spirochetes can then change themselves in a variety of ways so the immune system does not have one single thing to respond to. The spirochete cells also communicate between themselves and exchange information to evade antibiotics, an event that occurs with other resistant bacteria also.

While in the body the spirochetes continue to alter their structure from moment to moment. This probably contributes to the various symptoms that are part of the lyme picture as well as the resistance to treatment.

Spirochetes are attracted to different kinds of cells in the hosts, particularly collagen, so joints, aqueous humor of the eye, meninges of the brain, skin collagen and heart tissue (less so in the equine for an unknown reason) are all susceptible. Spirochetes actually travel faster in collagen then they do in the bloodstream. In Chinese medicine the Liver governs the collagen, sinews, tendons and ligaments so one of the most important factors in Chinese treatment will be to support the Liver.

Infection with Lyme as with many other chronic conditions causes or becomes an imbalance in the Th1 and Th2 immune complexes. The T helper cells (Th1) lymphocytes are characterized by the production of type I cytokines such as interleukin-2, tumor necrosis factor-beta and interferon gamma. The host produces a major Th1 response to try to deal with the acute infection; the side effect of this response can be inflammation. Th2 lymphocytes produce the cytokines interleukin (IL) 4, 5, 6, 10 and 13 and essentially help cool down the inflammation from the Th1 response. If either of these responses are out of balance, the spirochete can win the battle. The reader is referred to the references for more detailed explanation of the immune responses.

The spirochetes are clever opportunists responding to an assault from an antibiotic or the immune system by either changing their protective surfaces, entering a cell and even forming a protective coating inside the cell. Other evasion tactics are that they can create a completely different form usually referred to as a cyst, however there are also blebs and Spheroblastic L-forms. Blebs are partial pieces of material that are shed perhaps to confuse the immune system. Cysts go dormant but can re-activate when conditions are conducive to their reproduction. Antibiotic treatments often seem to change the spirochetes into abnormal motile forms, which can be a cyst or a Spheroblastic L-forms.

Lyme disease appears to actually suppress the body’s natural killer cells (NK) and clinically many horses seen with later stages of Lyme disease seem to mount a poor immune response. This frequently shows up as low white cell counts on a traditional CBC, and it is my personal thinking that this is one reason behind the common low to equivocal Lyme titers.

The longer the spirochetes are in the body prior to treatment the more adjusted they become to the specific immune situation in that host. An example of how this works is that the spirochetes may stay in the synovial lining of a joint, then evade the immune system or the antibiotic by entering the synovial cells. Once the antibiotics are out of the system or the immune system is weakened, the spirochetes reenter the joint.

The characteristic bull’s-eye skin lesion is generally missing in the equine and dog, most likely due to their hair coat. One of the most common things we see is lameness that is difficult to specifically identify. In humans, cognitive problems, irritability, fatigue, headaches, disorganization, nerve pain, deficits in memory and retrieval of information, perceptual motor skills and problem solving are all serious issues. All of these likely exist in the horse though usually what we see is irritability, fatigue, lack of interest in work, perhaps a stubbornness, or perceived stubbornness, or a dullness, all of which are difficult to diagnose.

Arthritis attacks maybe periodic, and may wax and wane, being worse at a full moon. The wax and wane of the symptoms may have to do with the ability of the immune system to respond. Studies have shown that the primary factor leading to arthritic inflammation is the health of the immune system. Spirochete levels have been found to be irrelevant to the severity of the disease.

Cardiac issues do not seem to be a large problem with the equine, however some of our horses with cardiac issues may have Lyme in their background. Perhaps we should check for Lyme even with some of our sudden death cases if possible.

A combination of a thorough history along with a complete physical exam and blood work are required. The history often becomes the most important aspect. Many if not most of the horses show behavioral changes of various sorts, the most usual being lethargy, irritability or lack of interest in their surroundings. In some cases the behavioral changes are more towards the hyperactive or spooky side. The key is that there has been a significant mental change.

The physical part of the history can include shifting leg lameness, stiffness, poor performance, and reluctance to turn, poor jumping performance etc. In many cases, horses have been worked up for subtle lameness’s and have had traditional treatments such as joint injections and various anti-inflammatories but have not responded well. Diagnostic imaging may be inconclusive, or may point to joint inflammation yet treatment of that inflammation yields poor results.

Laboratory diagnosis
Laboratory diagnosis of Lyme disease can be very difficult even in humans where testing is significantly more sophisticated. This is in part due to the cleverness and changeability of the spirochete, and partly because the tests are not good enough yet. With the equine we have basically two tests, the ELISA and the Western Blot. The ELISA gives a positive range, a negative range and a gray area. The Western blot looks at staining characteristics of the reactive bands to give an idea of how likely it is to be Lyme. The tests leave many horses in a very gray area as far as confirming the disease.

Holistic diagnosis
Since Lyme disease has many manifestations there is not one clear-cut pattern from a holistic perspective. From a homeopathic perspective one needs to take a complete history and prescribe a constitutional remedy based on the animal’s presentation.

From a Chinese perspective the Liver meridian is the most affected directly and indirectly by the spirochete. Many horses will exhibit signs of Liver meridian dysfunction, however there is seldom one pattern for all horses. Wind invasion is common and many symptoms are related to that, with shifting signs. There may be Liver Qi Stagnation, Liver Heat rising, Liver Yin deficiency, Liver Blood deficiency and so on. These may be combined with other patterns, often made more complex by long-term drug use.

The real key is to approach each case as an individual, from your perspective and experience, and treat that which is in front of you. It may change from month to month as well as from year-to-year.

There are no vaccines approved for the horse. Canine vaccines are being used. It is my experience that the vaccine is very detrimental to the horse’s immune system and many horses will relapse post vaccination. This was the experience with a human Lyme vaccine that was removed from the market about three years after it was approved. Most horses do not seem to be able to handle much in the way of vaccination once they have Lyme disease.

One reason for the difficulty with the Lyme vaccine is that generally we do not want to vaccinate in the face of an infection (meaning when an infection is already present or could be incubating in the animal but have no symptoms showing). Since Lyme disease is difficult to detect and may be asymptomatic or unrecognized for a long period of time, many horses that were vaccinated likely were already harboring the disease. Most people desiring to vaccinate are in endemic areas, consequently the horses are likely to be infected or at least exposed.

This is the part where we wish we had a magic bullet but there is not one, at least not as I have found. The best approach is a multi-systemic one, using the best of all worlds: conventional, complementary and alternative. Most of the good human Lyme practitioners use antibiotics along with many immune supplements. The real key to treating Lyme is to help the immune system be as strong as possible, not just during the immediate treatment but over the long term. Due to Lyme’s ability to “recur” the immune system must be ready to go to work at a moments notice.

Part of the difficulty in treating Lyme disease is that the bug selectively adapts to the individual’s body, so what works well in one horse may or may not work as well in another.

In the acute stages and generally upon initial diagnosis antibiotics are used by this author. Doxycycline is administered orally, consequently it is generally the starting point. Intravenous tetracycline does have research to prove that it works better than doxycycline, though clinically many horses seem to respond quite well to the doxy. The management issues with long-term intravenous therapy can be difficult in many situations. If management allows, it can be beneficial to start directly with intravenous treatment.

If doxycycline is used, the dose is about 10 mg/kg (50-55 100mg human tablets per 1200 lb horse) given twice a day. The idea behind any antibiotic use is to have the greatest effect at one time. Lower doses allow the spirochete to adapt and become resistant. If the horse responds well before 30 days, then doxycycline is all we use. After 30 days if the response is mediocre or not as good as we want, my preference is to go straight to the intravenous Tetracycline treatment if at all possible. There are many specific protocols, and I do not think there is one that is significantly better than any other.

The use of antibiotics does suppress the immune system in the gut particularly, and from a Chinese perspective damages the Spleen and Stomach due to the cold energy. So the rest of the treatment is designed to counteract those issues.

Horses presented in the later stages or those that have recurrences despite antibiotic usage are generally treated with herbal medicine and homeopathics preferentially. There are many more choices of antibiotics in human Lyme treatment then we have in the horse world.

Probiotics are an absolute necessity. There is certainly controversy about the timing of the probiotics, and there are many conventional practitioners who feel probiotics should not be given until after the antibiotics are finished. However, the only bug we are concerned about killing with antibiotics is the spirochete. Most other bacterial species are valuable assets. The antibiotics may very well kill off some of our probiotics, but that is why I will continue probiotics for several to many months after any antibiotic therapy is finished. ProBi from Advanced Biological Concepts and Digest Plus from Hilton Herbs are my probiotics of choice and often I will use them together for several months as they have different methods of action in the body.

Immune systems supporting compounds of many sorts are used. Many compounds that affect the immune system positively are very expensive so consideration needs to be given to the clients financial concerns. If finances are limited, select the most targeted compounds. Generally Chinese herbs and homeopathics are the most curative in this author’s hands. Many nutritional compounds are more supportive in nature, however they can be critical to the overall success.

Fortunately a few compounds are relatively inexpensive and can be quite helpful. Vitamin C is one such compound. It is readily available in bulk form and palatable with the dose of 4 to 8 gm being the most desirable. Vitamin C is well known for its action in collagen, which is one of the tissues particularly damaged by the spirochete. Camu camu (Myrciaria dubia) is an excellent source of natural vitamin C. Vitamin C mixed with bioflavonoids and quercetin is also a good source (Equilite).

Noni (Morinda citrifolia) contains many antibacterial, antifungal and anti-inflammatory compounds. Studies have shown it is particularly effective for many forms of arthritis and is also a very good immune regulator. In the fruit leather or powdered form it is relatively inexpensive, while in the juice form it can be quite expensive and contains a significant amount of sugar.

Omega-3 fatty acids are anti-inflammatory as well as supportive to the immune system. They can be obtained through feeding whole flaxseed (inexpensive), naturally stabilized ground flax, hemp seeds or Chia seeds (a very stable source of Omega 3’s). Flax or hemp oils can be used however they must be refrigerated during warm or hot weather. 3 to 6 ounces twice a day can be used with the seeds, less volume with the oils.

Medicinal mushrooms have excellent research showing their positive effects on the immune system with polysaccharides, glycoproteins, and anti-inflammatory compounds. There is also evidence they are beneficial in various arthritic conditions. They tend to be more expensive to use, however there immune modulating properties make them a beneficial addition. They are safe and can be used over a long term in a tincture or powder. One common formula used in this practice is a mixture of equal proportions of Cordyceps (Cordyceps sinensis), Reishi (Ganoderma lucidum), Maitake (Grifola frondosa), Shiitake (Lentinula edodes) and Turkey Tail (Trametes versicolor) (Mush™).

Glutathione is a powerful antioxidant present in every cell. It is particularly important in the liver and has some direct anti-inflammatory effects in arthritis. For many animals this may be one of the key ingredients in treating Lyme disease. Intravenous glutathione is available and can be given 2 to 3 times a week. This does require veterinary supervision and special ordering, however the actual injection can be given by experienced horse owners. It is very safe and may be able to be used in higher doses, however, a dose around 2000 mg in an adult horse seems to be effective. Precursors such as Alpha Lipoic Acid or N-Acetyl cysteine can also be used as well as some new glutathione products. The web store will keep up with the latest research on the best products.

Supplements to support joint health are important for any horse that has shown signs of joint related discomfort. These include glucosamine-based supplements, hyaluronic acid, glycosaminoglycans, and green-lipped mussels among others. Western herbal anti-inflammatories can also be used. Chinese herbal arthritis formulas based on the imbalances shown can also be useful, particularly alternating with some of the active Lyme herbs as discussed below. If an herbal formula being used as a primary Lyme treatment, general joint support is better done through nutritional supplementation to avoid an overload of herbs.

Main treatments

Homeopathics should be prescribed constitutionally. However, there are several remedies that fit many of the Lyme symptoms quite well. Ledum is one of the major remedies for Lyme disease; its symptoms include effects from toxic puncture wounds as well as insects. A tick bite is both of those. Rhododendron and Kalmia as well as remedies in those families are worth considering.

Western herbal protocols such as those used by David Winston have been used successfully. His formulas alternate every 2 weeks and have to be prescribed by a veterinarian.

Chinese medicine offers one of the best modalities to treat Lyme disease in this author’s hands. Acupuncture is excellent for pain control, immune stimulation, relieving Blood stagnation or pain and moving or tonifying Qi. Among many points that are useful (always treat the pattern the animal presents) are LIV 3, LIV 8, ST 36, KI 3, LI 4, LI 11, LI 10, BL 23, BL 26, SI 3. Acupressure can be also be used at these and other points that your acupuncturist may find beneficial for your horse.

Chinese herbal medicines are effective in both the early and late stage Lyme cases depending on the pattern presented. Many herbs that have direct action against the spirochete are also Chinese herbs that clear toxins, move Blood, expel Wind, Damp and strengthen Qi. Since the spirochete has such an ability to change and adapt to treatment, some of the current thinking is to change formulas on a regular basis.

One way to approach the Chinese treatment is to use a formula geared towards clearing spirochete for two weeks, and alternate with a formula that fits the main pattern the horse exhibits. So one horse may have SP Qi deficiency signs with lethargy and loose stool, so one could use a Lyme formula and alternate with a Qi Tonic and add a different spirochete clearing herbs such as Cat’s claw (Uncaria tomentosa) for two weeks. Or a horse showing signs of Liver Qi and Blood stagnation could receive a formula for that and Cat’s Claw for those two weeks. Horses with body pain, Blood and Qi stagnation or Blood Stasis can receive a pain formula. A holistic veterinarian with experience in Chinese herbs can select the appropriate formula for your horse.

Other treatment suggestions
Other compounds can be helpful depending on the symptoms the horse has. Magnesium is a mineral that is frequently deficient in human Lyme patients and is easy to supplement to the horses with magnesium citrate (1 to 3 g per day). Curcumin is an herb that shows excellent anti-inflammatory effects on joints as well as being supportive to the liver. Hyperbaric oxygen therapy, if it is available has been shown to be helpful in humans as has heat therapy. Horses that live outside in the sunshine may actually have increased body temperatures for a portion of the day, however in the wintertime that can be difficult to achieve. Garlic may be beneficial, it may also help keep some ticks away and is a good tonic herb. Coenzyme Q10 (100-300 mg per day) is a fat-soluble antioxidant that may be beneficial.

Herbs to support general gut health can be beneficial, especially after prolonged courses of antibiotics. Slippery Elm, marshmallow, meadowsweet are examples. Hilton Herb’s Digest Support contains these herbs.

Exercise at the level the horse is comfortable with is important on many levels. It is good for the immune system; it is helpful for the horse mentally and the Liver needs to move to avoid Liver Qi stagnation. There is no benefit to pushing the horse beyond what is comfortable and if he’s having a bad day, just go for a short walk.

Stress is a huge factor in the recovery from Lyme disease. Herbs can be used to help counteract stress and from many horses once they have recovered and gone back to competition it is beneficial to maintain them on adaptogenic, stress relieving herbs such as APF or Eleutherococcus (Siberian ginseng). Also important to pay attention to the amount of rest the horse actually gets at a barn. It has been shown that at many busy barns, horses actually get very little rest and sleep. This adds to stress and we know that stress suppresses the immune system.

The treatment of Lyme disease is complex and requires the willingness to keep reevaluating the progress. Most of the horses can be returned to full performance even with chronic Lyme disease, but many will require ongoing maintenance.

Zhang, Q and Zhang Y. Lyme Disease and Modern Chinese Medicine. Sino-Med Research Inst. NY, NY 2006.
Buhuner, SH. Healing Lyme. Raven Press. Silver City, NM. 2005.
Singleton, SB. The Lyme Disease Solution. BookSurge Publishing, Charlston SC. 2008.





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