Nov 132022

Microfilaria in Horses

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 other more effective, essential methods with which we can effectively control Microfilaria with the use of chemical dewormers and customised herbal formulations proven when combined simultaneously can make enormous differences to our horses health and well being, albeit it is an ongoing maintenance program, as we have no control over the ever progressing insect population.

Filariasis Symptom Check List 

 by Brenda Bishop, VMD

“Good observation is your best tool.” – Elaine Hammel, VMD 

“Birds of a feather flock together” as do Chronic Stealth Infections. Decades of routine chemical deworming delivered orally in paste form have contributed both directly (pastes and gels damage the immune system) and indirectly (drug resistant strains have had plenty of time to adjust and ultimately thrive) to the current state of affairs: horses carrying a wide array of opportunistic CSI’s. These infections can even be transmitted to foals via the placenta in utero. Where one or two stealth pathogens are present, there are many more hiding under the radar. Tape worms for example are next to impossible to test for, rarely seen in manure and survive in all kinds of weather. Worms with a microscopic filarial stage in their life cycle can reach epidemic proportions over a horse’s lifespan. Examples are Onchocerca spp, Oxyuris spp and Setaria spp. Like birds, blood sucking insects are ubiquitous team players. Mosquitos transmit Dirofilaria immitis (heartworm); sheep keds (blood sucking insects) are known to harbor both Bartonella and Wolbachia stealth bacteria. This fact alone links filarial worm populations with Bartonella presence. Wolbachia bacteria are distributed worldwide and promote fertility (production of microfilaria) from within adult heartworms, pinworms, threadworms, etc. The consummate team players, endosymbiotic Wolbachia strains modulate lipid metabolism (increase insulin sensitivity), alter mineral metabolism, and lurk in the background overshadowed by an array of protein aggregate, mitochondrial, and glycogen storage myopathies. Layers of symbiotic (mutually enhancing) relationships among a wide range of zoonotic stealth pathogens cannot be fully appreciated overnight. Knowing that ‘the horse will always tell you’, it falls on us to observe and interpret clues implicating CSI’s. Inevitably the Filariasis Symptom Check List and the Bartonellosis Symptom Check List will share a number of possible undesirable findings. 

Chronic Protein Deficiency
thin sparse short mane / thinning hair / short wispy tail thin hoof walls / thin soles / chronic foot soreness chronic toe cracks / quarter cracks
neurotransmitter imbalances 

delayed reactions / over reactions 

anxiety / ‘brain fog’
leaky gut syndrome (LGS) / protein losing enteropathy 

low serotonin levels (serotonin is made in the gut) ****depletion of vitamins B1, B6, iodine and glutamine food allergies
small fiber neuropathy (SFN) 

chronic cellular oxidative stress
low dopamine (dopaminergic neurons in the midbrain are stressed) low glutathione (a critical anti-oxidant) 

chronic fatigue syndrome (CSF) 

chronic obstructive pulmonary disease (COPD) skeletal muscle wasting (predominantly topline area) edema / fluid retention
fatty liver
periodontal disease / broken teeth
bone fractures / hairline cracks 

Drainage / Microcirculation Deficits
cold feet (feet should always be warm to the touch)
hypothermia / intense violent shivering (usually in cold rain / snow) necrosis of the collateral cartilage (‘quittor’)
frostbite (ears primarily)
swollen painful inguinal lymphatics (groin area)
swollen painful axillary lymphatics (elbow area)
chronic progressive lymph edema (CPL)
swollen painful parotid salivary glands (throat area)
swollen painful submandibular lymph nodes (lower jaw area) choke / slow to swallow food and water / epiglottis dysfunction dorsal displacement of the soft palate (DDSP)
patchy sweating / excessive sweating / anhidrosis
belching / burping (lower GI tract / liver)
lymphatic channel pooling and/or dehiscence / leaking 

poll evil
fistulous withers
hygroma / bursitis of the elbow (olecranon)
tender girth area (channel between the withers and elbow) swollen udder with or without discharge (mares)
swollen painful sheath (geldings and stallions)
swollen scrotum (stallions)
‘scratches’ (lower legs)
‘rain rot’ (predominantly topline, lower hind legs)
wind galls / wind puffs (suspensory / flexor tendons) chronic lacrimation (one or both eyes) 

Gravity Dependent Edema / Weakened Weight Bearing Posture
sway back / high head carriage / loss of topline musculature
pot belly (with or without bloating)
‘ewe neck’
dropped sternum
dropped head syndrome (head and neck fall down between the scapulas) collapse of ligamentum nuchae
tendon laxity (foals, young horses)
digital suspensory ligament desmitis (DSLD) (old horses)
sheared heels (usually in one or both front feet bearing 60% total body weight) pleural effusion 

Behavior Abnormalities (frequently worse around a full moon)
intense itching/ scratching (with or without nocturnal periodicity) 

head (near poll / eyes / sinuses / facial crest) rectal area / tail head area
upper ribs
lower back / sacroiliac area 

ventral midline
chest area / ventral lower neck udder area / sheath area
groin area (high inside hind legs) 

random violent stomping one or more legs (usually the right hind)
dribbling urine / straining to urinate / hematuria
sporadic explosive outbursts / running straight backwards violently / bolting violent spasmotic dorsiflexion of lower back (bucking)
jittery, nervous habits (usually wax and wane)
holding one deep breath while running
ear pinning flat back against poll area / anger
ear sensitivity / tinnitis
head pressing / headaches
head shaking (guardian mask can differentiate photic vs nonphotic)
bruxism (teeth grinding)
cribbing (synonomous with severe depletion of dopamine and glutathione) depth perception deficits / ‘my space – your space’ issues
altered / sporadic estrus cycles
failure to thrive (foals)
depression / dull facial expression
adverse IV drug reactions
adverse vaccination reactions
hypersensitivity to sedatives with or without hematuria
biting insect allergies
hypersensitivity to light / moon blindness (ERU)
hypersensitivity to electromagnetic fields
sensitivity to freezing weather, rain, snow (excessive shivering)
balance problems / falling down in a moving horse trailer
rearing / falling over backwards / pulling back violently while tied
random transient ischemic attacks (TIA’s) / sudden collapse
seizures (see SLE symptom check list) 

Wolbachia spp (thousands of strains in nature) / endosymbionts of filarial worms Bartonella spp (discovery of new species is ongoing) / Bartonellosis
Borrelia spp (at least 50 species in nature) / Lyme Disease
Babesia spp / Equine Piroplasmosis
Ehrlichia equi / Anaplasmosis
Neorickettsiae risticii / Potomac Horse Fever
maggots (in dark low oxygen locations such as feet, inner sheath, tail bones) Leptospira serovars (discovery of new species is ongoing) / Leptospirosis Toxoplasma spp (intracellular protozoal parasites) / Toxoplasmosis
Sarcocystis spp (intracellular protozoal parasites) / Equine Protozoal Myelitis Corynebacterium pseudotuberculosis / Pigeon Fever
Candida and numerous other fungal species 

Localized filarial cysts / nests / ‘dormant abscesses’ / nodules / protein aggregates cystic ovaries / ovarian pain 

adrenal glands / adrenal exhaustion syndrome
lungs (coughing, small amounts of mucous) / COPD
upper airway obstruction / recurrent airway disease (RAD) / wheezing nasal polyps / progressive ethymoid hematoma
gutteral pouch infections / abscesses (unilateral or bilateral)
sinusitis (exacerbated on exercise)
lower legs 

collagenous tissue disruption (tendons, ligaments, suspensory apparatus)
carpal tunnel and/or check ligament deficits
extensor rigidity (shortened forward phase of stride)
flexor contraction and/or rupture (ex: curb) / displacement (ex: Achilles tendon) chronic foot abscesses / subsolar abscesses / false soles 

navicular abnormalities / digital cushion abnormalities contracted heels (usually in front feet)
club feet (one or both front feet) 

pituitary gland dysfunction (‘Cushing’s syndrome’) / pituitary ‘tumor’ 

thyroid gland dysfunction / ‘goiter’
‘ vitreous floaters (detached collagen fibers) with or without ERU (uveitis) 

keratitis that waxes and wanes (usually middle age and older horses) ‘parasitic’ / ‘eosinophilic’ keratitis
immune mediated keratitis (IMMK)
keratitis with secondary fungal overgrowth 

carbuncles 1 to 2 centimeters in diameter with central bulls eye (sheath area) acquired white spots / multiple polka dots (‘birdcatcher spots’) / ‘skunk tail’ disseminated granulomatosis (see SLE symptom list) 

autoimmune myopathies 

myasthenia gravis (Shivers)
systemic lupus erythematosis (SLE) (see SLE symptom check list) equine recurrent uveitis (ERU) (spasms in ciliary bodies)
transverse myelitis / myositis consistent with thiamine (B1) depletion 

glycogen storage myopathies
polysaccharide storage myopathy (PSSM) type 2 (increased insulin sensitivity) equine polysaccharide storage myopathy (EPSM) 

exertional myopathies
recurrent exercise induced rhabdomyolysis (RER)
exercise induced pulmonary hemorrhage (bleeding from the lungs) 

mitochondrial myopathies consistent with Wolbachia presence insulin resistance (IR) 

myopathies reflecting abberations in
macronutrient metabolism, mineral micronutrients, cofactors, hormone biosynthesis pathways 

generalized exercise intolerance / chronic fatigue syndrome (CFS)
chronic regional pain syndrome (CRPS) / ‘kissing spines’ / chronic topline pain