Copyright 2012 by Brenda Bishop, VMD. No portion of this publication may be without prior written permission of the author. Portions of this work have previously appeared in Natural Horse magazine: volume 12 issue 2 (2010) “Demystifying Equine Shivers” by Brenda Bishop, VMD and volume 5 issue 3 (2003) “Deciphering Equine Fibromyalgia Syndrome (EFMS)” by Brenda Bishop, VMD.

The most common zoonotic bacterial infection in the world is Leptospirosis. Due to its number one status, much is known about its appearance in humans, dogs, cats, cattle, sheep, pigs and goats. Comparatively little is known about its existence in horses. Of the many different serovars (there are over two hundred known to date) the serovar L. pomona is associated with two clinical entities in horses: equine recurrent uveitis (ERU) and spontaneous abortion in mares. ERU is considered to be an autoimmune problem by many scientists leptopirosis is suspected in mares that abort for no apparent reason. Both ERU and abortion represent consequences of previous (usually unrecognized) exposure to one or more Leptospira serovars. Whether the affected horse had a healthy immune system or a compromised one at the time of exposure, these horses have won the initial skirmish (acute infection) but lost the war, eventually suffering loss of one or both eyes or a fetus.

Bacteria that have a spiral shape, such as Leptospira and the Lyme disease spirochete Borrelia, have a predictable course of action once established in their respective hosts. They characteristically elicit a biphasic response the initial acute infection, which may or may not provoke a fever and general malaise, lasts a short time (days) the second phase takes weeks or months to manifest. The symptoms of this second phase are a reflection of an immune system struggling for control. When immune system imbalance goes on long enough, a certain threshold is reached wherein autoimmune conditions (such as Shivers) can result. Researchers have found that spirochete infections produce the same clinical pictures in various animal species and humans, some of whom develop ‘Persistent Human Leptospirosis’ (PHL). Horses are thought to be a reservoir in nature for certain Leptospira serovars it is known that wild animals shed Leptospira in their urine which can easily be ingested by grazing livestock. If in fact some horses embody a carrier state for the bacteria, these should not be confused with those individuals whose immune systems are engaged in an ongoing active battle with chronic infection.

The easiest way to envision this second phase is in terms of a prolonged allergic reaction. Unlike the initial acute phase which can be life threatening (due to lung, kidney and/or liver damage), this phase amounts to a progressive complex cascade of events which leave the affected host with a wide array of complaints. To further oversimplify the picture of how specific problems are created, it is helpful to consider the role of mast cells in the host horse’s body. An important but poorly understood part of the immune system, mast cells live abundantly in connective tissues (such as skin and ocular conjunctiva) and mucosal linings (respiratory, reproductive and gastrointestinal tracts). They cluster around nerve endings, the smallest of blood vessels and lymphatics. Another crucial part of the immune system, plasma cells, circulate freely and produce antibodies (immunoglobulins) such as IgG, IgM and IgE. Mast cells have an affinity for IgE which attaches to their surface. When leptospiral antigens make contact with this IgE, the mast cell becomes activated and explodes like a bomb. Among the many substances released into the surrounding tissues are histamine, prostaglandins, cytokines and leukotrienes. These in turn produce constriction of the airways, gastric acid secretion, spasms of the gastrointestinal tract, itching, irritated nerve endings, swollen blood vessels and lymphatics, and needless to say inflammatory pain.

Horses in the early stages of persistent leptospiral infections demonstrate chronic fatigue, occasional toe dragging, itching body parts (mainly the head), depression and poor appetite. As time goes on, they might exhibit some of the following: urogenital discomfort, biting at themselves, transient peripheral lymphadenopathy, cording of the lymphatics, vasculitis in the hind legs, a mucoid nasal discharge, hyperventilation at rest, asthma, insulin resistance, difficulty standing up, hind leg gait deficits, anxiety and/or hallucinogenic behavior. Both allergic and autoimmune states reflect alterations of the immune system. If an allergic response lasts over a long period of time (weeks), IgE remains abundant and other immunoglobulins eventually enter the fray. Both Myasthenia Gravis and Lambert Eaton Myasthenic Syndrome involve antibodies of the IgG class, acetylcholine receptor antibodies and calcium channel antibodies respectively. (This is why a percentage of babies born to mothers with MG or LEMS have ‘neonatal MG’ or ‘neonatal LEMS’ until the antibodies from the mother’s blood disappear within the first week or two of life.) Both pre-synaptic (LEMS) Shivers horses and post-synaptic (MG) Shivers horses already have plenty of IgE MG is characterized by high levels of mast cell density in certain tissues and LEMS has been linked to mastocytosis (an excessive number of mast cells) in humans. Regardless of which came first, i.e., Leptospirosis or Shivers, for a Shivers horse dealing with a leptospiral infection, the stage is set for all the results of mast cell stimulation to escalate in intensity. Small animal veterinarians have observed that Leptospirosis vaccination appears to trigger mast cell tumors in some dogs there is no approved vaccine for horses.

Even though testing for up to seven serovars of Leptospirosis is available for horses, results are subject to personal interpretation. Another diagnostic challenge hinges on spirochete biology, namely an adaptive ability to morph into ‘round bodies’ (a different shape) when the local environment changes. Clarification of spirochete round body relationships with their vertebrate hosts will be lacking until sorely needed research regardless of species is accomplished. As with Fibromyalgia and systemic fungal infections, not all Leptospirosis horses develop Shivers nor do all Shivers horses have active Leptospirosis. If a horse displays signs of massive mast cell stimulation, with or without the presence of Shivers, Leptospirosis should be high on the list of possible scenarios. In the case of a horse with Shivers and a head that simply loves to be rubbed with a soft towel after exercise, Leptospirosis should be considered. Oral Doxycycline is one of the antibiotics of choice for spirochete infections. It has the added benefit of having an anti-inflammatory effect on immune mediated neuritis. (Immune mediated neuritis can manifest as mild itching, stringhalt, Shivers, head shaking, hypersensitivity to hot and/or cold weather or any number of other syndromes such as EFMS and/or any combination thereof.) For a horse with Leptospirosis the dose should be 5 milligrams per pound twice daily for up to sixty days. Ideally a blood sample is tested at the start and again after antibiotic therapy. Short term benefits can be obtained with antihistamines, aspirin and/or ibuprofen, however use of these drugs is like closing the barn door after the horse is out they have a place but are not practical for long term use.

With the exception of autoimmune hemolytic anemia, one drug that IS useful for maintenance of horses with a wide range of immune mediated problems such as Leptospirosis is Pentosan. Pentosan polysulfate sodium is gaining popularity in the treatment of several human diseases, among them Crohn’s disease (an autoimmune gastrointestinal disorder). It stabilizes mast cells by inhibiting allergic mast cell stimulation. This powerful effect results in reduced histamine release, an effect more potent than that of hydroxyzine, a drug that merely competes for histamine receptor sites on target cells and is often prescribed for horses with Cushing’s syndrome. An example of symptom overlap that can be addressed with Pentosan is the skin hypersensitivity common in Fibromyalgia horses. People with Fibromyalgia have up to four times the usual number of mast cells just below their skin surface. Imagine how much discomfort (itching and burning) such a horse would have upon being groomed with stiff brushes and/or heavy hands. Additionally Pentosan lowers intracellular calcium. An essential signaling molecule, calcium levels must be maintained in a precise balance, in a ratio of about twenty thousand times more outside than inside individual cells. When intracellular calcium rises, cells die and different neurodegenerative diseases result. One of the key regulators of intracellular calcium is the voltage gated calcium channel, which is dysfunctional in LEMS. Pentosan’s effects are dose dependent, appear quickly (24 hours) and last long after it has washed out of the body (weeks).

The little known herb Butterbur is a perfect therapeutic partner for Pentosan, useful because it is complementary at worst and synergistic at best. It is a natural beta blocker, i.e., it reduces spasms of capillary muscles and lowers blood pressure. Improved arterial blood flow results and is probably amplified in the presence of Pentosan which is heparin like. (It has been shown that Pentosan improves blood supply to subchondral bone in horses’ joints.) Butterbur gives dramatic relief to most sufferers of migraine headaches, one of many human diseases now viewed as ‘calcium channelopathies’. That a simple herb could give relief to throbbing blood vessels within the central nervous system suggests an exciting possibility for controlling spasms in the peripheral nervous system, an overlapping symptom of Leptospirosis, MG, LEMS and FMS. While Pentosan stabilizes mast cells, Butterbur lowers the effects of leukotrienes and prostaglandins which leak into tissues when mast cells do explode. Pain relief is the end result. For a thousand pound horse a dose of 300 milligrams Butterbur root extract added twice daily to the feed can be used until results are seen. Herbs can take weeks to garner improvement but provide a horse friendly alternative to aspirin or ibuprofen and like Pentosan can be pulse dosed over the long term. Horses allergic to daisies, chrysanthemums or marigolds should not be fed Butterbur, which belongs to the daisy family. Both Pentosan and Butterbur, used alone or together, appear to yield impressive clinical improvement by working at both the central (CNS) and peripheral (PNS) nervous system levels, a fact which lends excitement to this rapidly expanding field of twenty-first century research known as ‘autoimmune channelopathies’.


Copyright March 1, 2020 by Brenda Bishop, VMD All rights reserved.

No portion of this publication may be used without prior written permission of the author.

The author asserts her moral right to be identified with this work.

“When we know better we do better.”

-Maya Angelou-

Shining the light of our awareness into historically dark corners is a metaphor for the shifting paradigms we as horse owners face in this new year of 2020. Traditional linear thinking has served us up to a point and now it is time to take an accounting and ponder the gaps in our knowledge regarding horse health care. Prevailing mindsets have become comfortable with using drugs for anything and everything that amounts to a problem. This approach chooses “better living through modern chemistry” over broader mindfulness of deeper implications and fails to serve the whole horse. All the humans in horses' lives have become drug buyers and/or drug sellers. Equine supplements alone have become a multimillion dollar industry in a relatively short time. A small minority of horse people outside this grid fall into the network called healers. “Healers don't heal anyone. They re-balance.” (Abraham Hicks) Re-balancing centers around three principles: the principle of contraction, the principle of expansion and the principle of plurality.

Horses are by nature peaceful grazing prey animals. They are born equipped to run away from predators. When this ability is hampered by unsoundness of limb or limbs they become fearful and naturally prone to panic. Shortened forward phase of stride, delayed forward extension, flexors restricted by inflammatory agents, delayed over-extension (for example clicking heels), hypermetric gaits with spasms in abductor muscles (for example stringhalt, shivers), postural tremors, contracted heels, etc. are examples of contraction leading to tendon sheath rupture, suspensory strain and untold anxiety. The mental stress alone contributes to multisystem dysfunction such as gastrointestional ulcers, adrenal exhaustion syndrome, and increased permeability of the blood brain barrier. The principle of contraction is (from the horse's point of view) characterized by fear and potentially self destructive behavior. In order to re-balance it is necessary to get the horse's body and mind back to a natural neutral state of well-being.

The principle of expansion is essentially a one way street. “The mind, once stretched by a new idea, never returns to its original dimensions.” (Ralph Waldo Emerson) Healing takes place from the inside out when any and all impediments, restrictions, obstacles are removed. If the horse's garbage cans (lymphatics, liver, kidneys) are brimming with toxic debris, infection, parasites, etc. a cleansing is required to open (expand) the channels. If the lungs are not able to expand after contraction with each breath, the stress level is exponential. The interconnectedness of all things dictates that multiple systems will come into play on the path to well-being. The brain and central nervous system can compensate for small neuronal deficits but eventually imbalance will create downstream issues. Questionable integrity of the blood brain barrier is something healers tend to think about and factor into their protocols because it is so fundamental and necessary for promoting good health going forward.

The principle of plurality incorporates aspects of expansion and contraction from a higher perspective. Linear thinking is useful but it falls short when the rubber meets the road on the path to lasting balance an expanded paradigm is required. Standing at the bottom of a mountain we can only see a short distance up standing at the top allows us to see everything below. This higher view organizes horse keeping into more obvious groups of choices. If we simply focus on three areas of healthcare (nutrition, chronic infection status and parasite status) the convoluted puzzle pieces will fall into place. When the inside of the horse is right the outside takes care of itself. Horse nutrition has been very well researched and can be learned by anyone taking the online course given by Eleanor Kellon, VMD, a pioneer in this field. Chronic stealth infections such as Borrelia (Lyme) and Bartonella operate in relative darkness due to lack of funding for needed research. (See Frequently Asked Questions on the Bartonella page of this website.)

Plurality is analogous to a modern Physics term for explaining the inter-relatedness of the distant parts of a phenomenon, 'entanglement'. Linear thinking cannot get there from here. Entanglement deals with answers which generate whole new lines of questions. We know that chronic bacterial stealth infections are synonymous with multiple system overlap. But we frequently fail to realize that chronic zoonotic parasitic infections are usually part of the total picture we label immune system compromise. Layers of infection are inevitable the longer a body is out of balance. Healers like to think of their work as 'peeling the onion'. One layer that grows more omnipresent over time is that of worms with a filarial stage in their life cycle. Examples are Onchocerca cervicalis, Oxyuris equi and Setaria equina. Because these worms live under the skin conventional “fecal exams are not worth the paper they are printed on” (Marvin Cain, DVM) when it comes to these parasites. Additional concerns arise by virtue of the fact that systemic filariasis is perpetuated courtesy of a symbiotic bacteria (Wolbachia) belonging to the same phylogenetic class as Bartonella spp., an avenue currently being explored by the World Health Organization.

New questions we should be asking ourselves go something like this: are frequent draining foot abscesses and/or subsolar abscesses bacterial, microfilarial or both? Are ill defined (dormant) cysts seen on diagnostic imaging of stifles, hocks, fetlocks, navicular areas microfilarial? Are horses diagnosed with COPD harboring millions of microfilaria in their lungs? Are seasonal skin pruritis problems linked to microfilarial populations positioning themselves to be siphoned off by blood sucking insects? Are club feet associated with small vessels clogged with microfilaria acquired through the placenta? Are microfilarial parasites inhabiting the pituitary in IR and/or Cushings horses? Are a horse's “Lyme/Bart” symptoms worse during a full moon because unrecognized microfilaria become active during certain lunar cycles? Are my horse's symptoms consistent with 'nocturnal periodicity' typical of microfilariasis? Is there a symbiotic relationship between this group of parasites and chronic stealth bacteria? What role do microfilaria play in acute onset co-infections such as tetanus, neurologic herpes and so-called protozoal myelitis? What are the inter-relationships between chronic Lyme disease, brain fog and filariasis? A review of the Symptom Check List under Bartonellosis will spark a plethora of additional questions for the reader.

Parasite resistance to chemical dewormers (drugs) is a well documented phenomenon in horses. Traditional deworming plans almost never take into account the possibility of worms with microfilarial stages. Fortunately there are a number of effective options that should be considered on a case by case basis. These include but are not limited to the following: resveratrol, arnica, Para-X (Omega Alpha), silicia, Silver Lining Maintenance, BVC (Advanced Biological Concepts), Source Micronutrients, dandelion root, white sage, prebiotics (garlic, bananas, custard apples, watermelon), and custom herbal Parasite Blends made specifically for addressing filariasis. Deworming strategies such as custom blends paired with nutritional balancers maximize blood brain barrier integrity by incorporating vitamins B6, B9, B12, resveratrol, curcumin, vitamin C, and anti-oxidants (green tea, raw barley, raw oats, Colloidal Silver, vitamin E). Stress reduction can be achieved with balanced targeted nutrition, chronic stealth infection and parasite elimination, and by limiting exposure to electromagnetic fields. Ideally we should remove anything electronic from our horses' immediate environment. This requires a return to natural environments far away from high voltage power lines and turning off the barn radio.

Additional Reading:

http:// biodiversity-and-what-lies-beneath-the- connection-to-equine-diseases-2-2-2/ agricultural-and-biological-sciences/ onchocercidae

Microbial population analysis of the midgut of Melophagus ovinus via high-throughput sequencing Parasites and Vectors 2017 PMID 28793927 PMC106837/ Zoonotic Filariasis PMC4893572 A Rare Case of Ovarian Filariasis

Filariasis Symptom Check List

Systemic Lupus Erythematosus (SLE)
Symptom Check List

(updated 09/01/2021)

Copyright September 1, 2020 by Brenda Bishop, V.M.D. All rights reserved.

No portion of this publication may be used without prior written permission of the author.

The author asserts her moral right to be identified with this work.

Simultaneously as filarial parasites infiltrate horses' bodies via the circulation into every available nook and cranny within soft tissues (preferentially tissues built upon a collagen matrix), a certain percentage of horses escalate from chronic immune suppression to self destructive overdrive their immune systems start attacking themselves. Consequently autoimmune conditions tend to co-exist some examples are autoimmune hemolytic anemia, pemphigus, immune mediated keratitis, inflammatory bowel disease (IBD), cutaneous lupus and systemic lupus erythematosus (SLE). Unfortunately for affected horses, SLE is rarely recognized for two reasons every case is uniquely different symptom-wise (NO TWO CASES ARE ALIKE), and repeated exposure to specific high risk factors is commonplace. Many possible indicators of autoimmunity, convoluted in and of themselves, are challenging to appreciate due to layering of systemic stealth bacteria, filarial worm loads, mycoplasmas, biofilms, viruses, and so on. The following list of diagnostic criteria reflects a considerable amount of symptom overlap with Filariasis and Bartonellosis. Helping a compromised immune system is akin to closing the barn door after the horse is out. For veterinarians trained in developing a linear differential diagnosis list it doesn't help matters that autoimmune states tend to cluster, more or less superimposed upon each other reflecting multidimensional dysfunction.

Indices of Suspicion

__age of onset (early adulthood, 5 to 10 years)

__breed predilection (none however larger individuals are at higher risk)

__sex predilection (mares appear to be at higher risk due to presence of estrogen)

______(see Drug Induced Lupus below)

__history of malnutrition and/or repeated vaccinations early in life

__history of months or years living in tropical / subtropical climates

__history of stress followed by sudden hair loss (around eyes / total head / total body)

__history of repeated exposure to high risk factors

______feeds containing soy (soy is estrogenic and estrogen makes lupus worse)

______supplements containing garlic (many insect control products)

______alfalfa products (hays / cubes / pellets / sprouts / powder)

______sulfamethoxazole / trimethoprim (antibiotics)

__food allergies (allergy panel is exceedingly useful if in doubt)

Lupus Flares

__hypersensitivity to strong UV light (consider face masks in summer)

__livedo reticularis (plain zinc oxide paste is the ideal sunscreen for faces)

__rapid shallow breathing / fluttering nostrils at rest

__spontaneous periodic deep hyperventilation at rest (5 to 20 minute episodes)

__depression / eyes half closed / ocular pain

__hypersensitivity reactions to vaccines / drugs

__hypersensitivity reactions to alfalfa (organic and GMO)

__hypersensitivity reactions to garlic

__hypersensitivity to lectins (contained in grains such as corn, oats, barley)

__hypersensitivity to coconut oil

__deterioration on feeds containing soy

__lupus nephritis / frothy urine / blood in urine (hemoglobinuria)

Neuromuscular Predilections (that wax and wane randomly)

__non-specific muscle spasms tetanic in nature

__recurrent exertional rhabdomyolysis (RER) (commonly in young nervous mares)

__lower back / sacroiliac area chronic regional pain (CRPS) / transverse myelitis

__postural tremors (difficulty holding legs up against gravity )

__proximal suspensory desmitis (PSD) / suspensory strain

__cold hind legs / cold feet

__swollen joints (hocks, stifles)

__spasms of diaphragm (thumps aka hiccups)

__cardiac conduction disturbances (dropped beats / atrial fibrillation)

__pericarditis / transient ischemic attacks / sudden collapse / chest pain

__chronic fatigue (CFS) / fibromyalgia (EFMS) / poor exercise tolerance




______liver dysfunction / burping (not to be confused with thumps)

______endocrine imbalance

__ulcers (gastric, hind gut and frequently both)

__leaky gut syndrome (LGS) (manure can be normal, tight or loose) / IBS / IBD

______chronic protein deficiency

______loss of gut integrity / loss of glutamine (siphoned off by microfilaria)

__chronic oxidative stress / improvement on antioxidants

__biofilms / fungal overgrowth / Candida overgrowth

__'protein losing enteropathy' (poor haircoat, poor hoof quality)

__sensitivity to glyphosate contaminated feeds (soy / alfalfa / corn / beet pulp)

__multiple food allergies / improvement on elimination diets

Central Nervous System / Cranial Nerve anomalies

__'lupus psychosis' / immune mediated neuritis (multiple expressions)

__sporadic hallucinations

__brain fog that waxes and wanes

__optic neuropathy / uveitis (ERU) / keratitis (IMMK)

__hypersensitivity to sound

__dry mouth and/or dry eyes

__random seizures

__dizziness (during and after transport and/or repetitive forced exercise

__autoimmune transverse myelitis

Multiple Co-infections

__filarial parasites

______Onchocerca cervicalis (thread worms)

______Oxyuris equi (pin worms)

______Dirofilaria immitis

______Setaria spp.

__chronic stealth bacterial infections

______Wolbachia spp (see Filariasis Symptom Check List)

__________chronic cellular oxidative stress

__________unusual skin changes / chronic 'rain rot'

__________disseminated granulomatosis

__________semicircular white hair spots (shoulders / torso / thighs)

__________sweet itch (face, chest, ventral midline, neck, groin, tail head, lower legs

______Bartonella spp (see Bartonellosis Symptom Check List)

______Borreliosis (lyme disease)

______mycoplasmas (numerous)

______biofilms (respiratory and/or digestive and/or urinary tracks)



__Piroplasmosis (Babesia spp)

__Anaplasmosis (Ehrlichia equi)

__Potomac Horse Fever (Neorickettsiae risticii)

__Sarcocystis spp (Equine Protozoal Myelitis)

__Corynebacterium pseudotuberculosis (Pigeon Fever)

Neonatal Lupus (history of)

__neonatal myasthenia gravis (Shivers)

__failure to thrive (foals)

__orphan foals / foals weaned too early

Dermatologic Lupus

__disseminated granulomatosis

__alopecia areata (around eyes)

__sudden total hair loss on entire head and/or entire body

Drug Induced Lupus (history of)

__minocycline (antibiotic)

_sulfamethoxazole (antibiotic)

__butazolidin (non-steroidal anti-inflammatory)

__phenothiazines (tranquilizers)


______fluphenazine (illegal antipsychotic)

______chlorpromazine (illegal antipsychotic)

__________tissue residues persist for long periods (years)

__________**males are more prone to chlorpromazine induced lupus than females

__________lingering hypotension, pseudoparkinsonism, spasms, restlessness

__omeprazole (proton pump inhibitor / ulcer preventative)

__synthetic progesterone (exogenous hormone withdrawal / endocrine imbalance) ​


Brenda Bishop,VMD

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