Ontario Animal Health Network (OAHN)
Equine Expert Network
Quarterly Veterinary Report
Fecal Water Syndrome – what’s new?
Fecal water syndrome (FWS), also known as free fecal liquid or water (FFL or W) is a syndrome whereby feces are voided in two phases; solid and liquid. It affects adult horses of any age, breed or sex. It can last for from a few days, to months or even years and can vary in severity, be intermittent or continuous. It occurs most commonly in the winter, however, it can occur during the spring and fall depending on geographic location. Clinical signs are quite variable and may include dermatitis/scalding of the hindlegs/perineum, weight loss, poor condition and intestinal discomfort.
Over the last few years, and primarily coinciding with research into the equine microbiome, a few studies have been devoted to examining FWS. Although no specific cause has been identified these studies have shown that FWS is NOT caused by:
- Poor dentition / mastication
- Parasite load
- Dysbiosis (no change in fecal microbiota between cases and controls)¹,²
- ACTH level
- Altered hindgut fermentation
- Fecal sand
A recent study using 100 case-control pairs from Sweden, Norway and Germany³, demonstrated that feces from cases of FWS had lower water holding capacity. The authors opined that this may be related to the type and amount of fibre present in the feces. Individual variation with how horses digest fibre may account for the individual but sporadic nature of this syndrome.
Laustsen et al² recently showed clinical improvement in horses with FWS that received fecal transfaunation therapy. Interestingly, the improvement was not significant until 14 days post treatment. There was no change to fecal microbiota diversity so the researchers theorized that the improvement may be due to metabolites such as volatile fatty acids contained within the transfaunate. Butyric acid (butyrate) “enhances gut integrity and development, minimizes inflammation and alleviates leaky gut related issues.” The authors also opined that feces may not be representative of the gut site most affected by FWS and that future projects should involve microbial analysis of mucosal biopsies.
Anecdotally, the most consistent management change associated with positive results is switching from long stem hay to short fibres such as chopped hay, hay cubes, hay pellets or a complete senior feed. As well, there are several anecdotal reports from veterinarians citing success with gastric supplements containing psyllium, yeast, butyrate and /or DTO smectite.
- Dysbiosis is not present in horseswith fecalwater syndrome when compared to controls in spring and autumn. Schoster A, Weese JS, Gerber V, Nicole Graubner C.J Vet Intern Med. 2020 Jul;34(4):1614-1621.
- FreeFaecal Water: Analysis of Horse Faecal Microbiota and the Impact of Faecal Microbial Transplantation on Symptom Severity. Laustsen L, Edwards JE, Hermes GDA, Lúthersson N, van Doorn DA, Okrathok S, Kujawa TJ, Smidt H.Animals (Basel). 2021 Sep 23;11(10):2776
- Chemical composition and physical characteristics of faeces in horseswith and without freefaecal liquid – two case-control studies. Lindroth KM, Dicksved J, Vervuert I, Müller CE.BMC Vet Res. 2022 Jan 3;18(1):2.
Vitamin E Deficient Neurologic Disease:
equine neuroaxonal dystrophy (eNAD) / equine degenerative myeloencephalopathy (EDM)
Equine neuroaxonal dystrophy and equine degenerative myeloencephalopathy are clinically indistinguishable inherited neurodegenerative diseases which cause ataxia within the first year of life. eNAD and EDM are on a spectrum of neurologic disease with EDM being the more advanced form, particularly histologically, with lesions extending in to the ascending tracts of the spinal cord. Lesions with eNAD are limited to the medulla oblongata. Oxidative stress occurs in these areas. There is a human form of the disease called “human ataxia with vitamin E deficiency” (AVED) which is an inherited disease cause by genetic mutations in tocopherol transfer protein alpha and shares similar clinical and pathological features with eNAD/EDM. Dr. Finno’s group at UC Davis has identified aberrant vitamin E metabolism in Quarter Horses with eNAD/EDM causing a higher requirement for vitamin E in affected individuals.
There is a genetic susceptibility to eNAD/EDM with an autosomal dominant mode of inheritance with incomplete penetration found in Quarter horses, Appaloosas, Morgans and Standardbreds. As proprioceptive tracts are affected, the main clinical signs are symmetric four-limb ataxia with hypermetria exacerbated with head elevation. Clinical signs may occur as early as 1-2 months of age and progress until 2 years of age at which time they tend to stabilize. Some horses display a decreased or absent menace and/or a significant increase in hindlimb ataxia. Differential diagnoses for eNAD / EDM include; cervical vertebral instability/malformation, equine protozoal myelitis and equine herpes myeloencephalopathy.
The only definitive way to diagnose the disease is with post mortem histologic evaluation.
Alpha-tocopherol is the most bioactive form of Vitamin E and should be provided at the dose of 10 IU/kg/day to a suspect eNAD/EDM horse. Serum tocopherol supplementation may be indicated if the serum alpha-tocopherol levels are <2ug/ml and there is a history of neurologic disease in related individuals. Once clinical signs appear, treatment with vitamin E will not improve the signs but may prevent progression.
Prevention involves providing at risk-foals with vitamin E until they are three years of age and providing broodmares who have foaled at-risk foals, vitamin E during gestation. Grazing pasture provides some protective effect due to Vitamin E in green grass. Neurologic exams should be done in at-risk foals at 1 and 6 months and then every 6 months until 2 years of age. Serum alpha-tocopherol levels of foals should ideally by evaluated within the first week of life (at least before 4 months of age) as this is when the greatest difference in results occur between those which develop eNAD/EDM and those that don’t. Supplementation is indicated when serum concentrations are below 2 ug/ml in a pregnant mare. If NAD is suspected in a foal, the dam and offspring should be supplemented. Supplementation of the dam should begin at the start of the third trimester and end when foal is weaned. The foal should be supplemented from birth until the end of its 2 year old year.
Due to the genetic basis of disease, affected individuals should not be bred.
Increased alpha-tocopherol metabolism in horses with equine neuroaxonal dystrophy. Hales EN, Habib H, Favro G, Katzman S, Sakai RR, Marquardt S, Bordbari MH, Ming-Whitfield B, Peterson J, Dahlgren AR, Rivas V, Ramirez CA, Peng S, Donnelly CG, Dizmang BS, Kallenberg A, Grahn R, Miller AD, Woolard K, Moeller B, Puschner B, Finno CJ.J Vet Intern Med. 2021 Sep;35(5):2473-2485.
Increased alpha-tocopherol metabolism in horses with equine neuroaxonal dystrophy. Hales EN, Habib H, Favro G, Katzman S, Sakai RR, Marquardt S, Bordbari MH, Ming-Whitfield B, Peterson J, Dahlgren AR, Rivas V, Ramirez CA, Peng S, Donnelly CG, Dizmang BS, Kallenberg A, Grahn R, Miller AD, Woolard K, Moeller B, Puschner B, Finno CJ.J Vet Intern Med. 2021 Sep;35(5):2473-2485
OAHN Q4 Survey: Key Results
Thirty-one counties were represented by 26 veterinarians in this quarter’s survey.
Foal diseases/conditions (the number in parentheses represents the number of veterinarians reporting):
|INCREASED diseases/conditions in Q4||DECREASED diseases/conditions in Q4|
|Respiratory disease (3): URTI (2), Streptococcus zooepidemicus pneumonia|
|Diarrhea (2): Foal heat|
|Neurologic disease in weanlings: one confirmed with neuronal axonal dystrophy (NAD or EDM)|
|Lawsonia intracellularis infection (severe)|
|Failure of passive transfer|
Adult horse diseases/conditions (the number in parentheses represents the number of veterinarians reporting):
|INCREASED diseases/conditions in Q4||DECREASED diseases/conditions in Q3|
|Equine asthma (8)||Tetracycline-responsive diarrheas (3): PHF (2)|
|Respiratory disease (6): infectious (4), S. zooepidemicus (2)||Strangles, infectious respiratory disease, equine asthma, EHV-1, allergic dermatitis (sweet itch), distal limb cellulitis|
|Colic(4): medical, impaction|
|Strangles (2), rain rot (3), pastern dermatitis/cellulitis (3), melanoma (2), PPID (3)|
|Hoof abscesses (2)|
|Several down horses: 1) debilitated older horses and 2) slip-and-fall on ice with skull or limb fractures|
|Free fecal water syndrome (2)|
|Free fecal water syndrome (2)
Choke (1), diarrhea of unknown origin (1), coronavirus (1), epiglottic entrapment (1), allergies (1), dental fractures and sinusitis (1), EPM, circlers, WNV, Vit E deficient neuropathy, EEE, fungal type rashes ( racehorses) (1), feather mites (drafts), rain rot, insect bite hypersensitivity, cutaneous melanoma, staph dermatitis, late term EHV-1 abortion, post-breeding endometritis, mild arteritis-like symptoms (swollen legs, no fever), tick-borne with renal disease, FUO with mild liver involvement, OCD, canker, bone sequestrum,
New or interesting conditions or clinical signs without a diagnosis:
- Diagnosis of a confirmed neuronal axonal dystrophy case in a weanling STB filly; a handful of other weanlings/yearlings with low vitamin E and neurologic clinical signs
- One mare died within 12 hours of showing agitation, sweating, ataxia, salivation, and fever. She was unvaccinated and had shown signs of colic 6 days prior to the onset of neurological signs. She was negative for rabies, EEE, WNV, and EHV.
- Thoracic mass on ADR pregnant broodmare, dx on radiographs.
- Idiopathic laryngospasm/acute respiratory distress after NG intubation, not intubated in the lungs
- Multiple cases of gastroenteritis with no causative agent found.
- Several adult fevers or unknown origin – although I am not sure it is actually increased from last year as we always see a lot when the TBs come home from the track
- A very interesting case of a temporal dentigerous cyst was treated at our practice.
- Increase of cases surgically treated for sequestrum [facial, distal radius and canon bone].
- One case of stringhalt that was successfully treated at surgery but some mild gait alterations remained.
- 1) Through the Fall there were 8 horses, under 6 years of age, in different areas of the practice, that showed up with edema of the distal limbs either all four limbs or just hind limbs. 2 had fevers. No lameness or discomfort noted. All resolved with a week with either NSAID therapy and walking or corticosteroids
- 2) Many horses now are showing up passing water along with their normal formed fecal balls. Suspect it is due to colonic irritation and secretion of extra fluid – sometimes linked to transition from grass to long-stem hay in the late fall/winter
- Fever of unknown origin
Network Member Reports
|An informal poll of colleagues in neighbouring practices found that with one exception, the prevalence of equine disease seemed as expected for the time of year. The exception was equine neurological disease with high case fatality rate (over 80%), most of which was attributed to EEE. We had one acutely fatal case that was negative for all diseases tested, including rabies, in the area south of Orillia in Simcoe County. A colleague in Magnetawan (Parry Sound District) saw 12 cases of EEE, of which 3 were tested, and 11 of which were fatal. One case tested positive for both EEE and WNV. The fourth quarter is when we typically see most of our EEE and WNV cases, but case numbers for EEE were higher than in recent years. We have one breeding farm that has a higher number of upper respiratory cases in weanlings that are otherwise healthy, but they had more foals last year, so the population at risk is higher.|
|This quarter our practice saw an uptick of neurologic cases not attributable to wobblers which responded to dexamethasone. Some may have been due to trauma. There were a number of down horses (fractures, skull fx) and debilitated/geriatric horses. A number of older horses with dental attrition (incisor disease) with extractions were seen as we do a lot more dentistry this time of year. We had a really stubborn canker in a draught horse, many foot bruises/abscesses due to the freeze/thaw cycle in the ground, a lot of track rash, wet heel scratches, random limb swelling/cellulitis, a significant drop in tetracycline responsive cases (PHF etc), an uptick of asthma cases (due to winter confinement) less strangles outbreaks in the barns, typical impaction colics but fewer “fevers of unknown origin. We also had an unusual case of suspected thymoma/lymphoma in a pregnant mare that is presently being managed until foaling.|
|This information was based on feedback from Woodbine backstretch veterinarians. Q4 was pretty quiet with nothing unusual from an infectious disease standpoint. Some individual horses had typical signs of respiratory disease for November. The track has set up a biosecurity fund to offset the cost of testing during disease outbreaks. A one time $25 fee at first start will be collected. All horses have to have been vaccinated against EHV-1 no less than 14 days and no greater than 90 days prior to entering the stabling area along with a negative EIA result and an up-to-date influenza vaccination. A veterinarian’s letter must be provided for horses coming from another province or country attesting to health status. In addition, there have been some rule changes addressing welfare including the prohibition of horses 7 years and older that are still maidens from stabling or racing at Woodbine.|
|We have seen the expected number and type of cases in Q4. There has been an increase in the number of cases/week since the beginning of December. These cases have included impaction colics due to water deprivation, teeth related, poor hay quality etc. Asthma cases are reduced in number but we are seeing an increase in infectious respiratory diseases ( S. zooepidemicus in a number of cases ) all of which have been responsive to ceftiofur. Clinical signs in these cases included a substantial cough, low grade fever, mild appetite reduction, mild colicky signs. Our clinic treated 6 horses on one day diagnosed with a primary strep infection (respiratory PCR panel). We also saw 3 horses with renal disease (clinical signs included increased kidney enzymes) which were positive for Lyme disease on SNAP 4Dx. All responded to oxytetracycline and recovered. We also had typical geriatric horses with arthritis , 3 were euthanized. Several horses had sole bruising due to the frozen ground. Pastern dermatitis was prevalent in late fall (wet) as was limb edema, all responsive to therapy. One barn in the Navan practice area had a case or two of FUO. The last case was referred and presented with an impaction but after minimal intravenous fluids broke with diarrhea , a sample of which tested positive for C. difficile on PCR panel. The horse responded well to treatment with metronidazole.|
|Ontario Veterinary College
|We have admitted a few horses with fevers of unknown origin this quarter. Some tested positive for coronavirus . We are also seeing issues with late pregnancy. We admitted a mare who succumbed to a broad ligament bleed. She was only 9 months pregnant as opposed to pre-partum. We had another mare with FUO and tachycardia that lost the fetus a week or so after treatment. Another mare had placental separation and the fetus has a high titre to leptospirosis. We have seen a number of colon torsions lately as well as weather related impactions. We admitted a horse with strangles with a draining dorsopharyngeal recess. One horse with acute leukemia is home and improving,|
|There was an unusual case of an ataxic senior pony which tested inconclusive on EHV-1 PCR on blood and nasal swab and on brain at post –mortem. The facility was managed like a the pony was a more typical EHM case although the risk to other from this pony was low given the fact that the pony was at a referral hospital and shedding low levels of virus. There was also a pregnant broodmare who tested inconclusive on EHV-1 PCR on blood and then positive on nasal swab. She is dealing with other health issues (possible lymphoma). The farm was managed with voluntary movement restrictions and biosecurity protocols.|
Laboratory Data – Highlights for Q4
Parasitology (AHL data only)
The number of fecal tests (fecal flotation and fecal egg counts) performed in Q4 2021 (261) was lower than that of Q4 in 2020 (380). The percentage of positive McMaster tests >500 epg 17.8% for Q4 2021 was lower than that of 29.7% in Q4 2020. The percentage of positive Wisconsin tests >500 epg was similar in Q4 2021 (19.8%) to that in Q4 2020 (19.3%).
Nutrients (normal range: selenium 0.12 – 0.18 ppm, vitamin E 4.6 – 23 umol/L)
The number of selenium tests performed in Q4 2021 (97) was increased to that in Q4 2020 (77). The percentage of tests with selenium concentration below 0.12 ppm in Q4 2021 (40.2%) was marginally higher than that of Q4 2020 (38.9%).
The number of vitamin E tests performed in Q4 2021 (122) was higher than the number performed in Q4 2020 ( 70). As well, the percentage of serum samples in Q4 2021 with concentrations below 4.6 umol/L was 42.6% compared to 21.4% in Q4 2020. For a refresher on Vitamin E testing and supplementation please refer to OAHN veterinary report Q1 2017.
More information on vitamin E: School of Veterinary Medicine – Vitamin E In Horses (ucdavis.edu)
In Q4 2021, the number of bacterial isolates reported (423) was increased when compared to the number performed in Q4 2020 (212). The number of Staphylococcus aureus and Streptococcus zooepidemicus isolations remain high relative to other isolations.
There number of Strangles (Streptococcus equi. subsp equi) PCR tests performed in Q4 2021 (160) was similar compared to Q4 2020 (165).. The percent of positive tests (23.8%) was higher than in Q4 2020 (14.5%).
There were zero Salmonella sp cultured and 0 PCR positives from 15 tests performed.
There was 1 positive and 2 inconclusive (non-negative) PCR test for EHV-1 this quarter, from 121 AHL tests performed compared to 0 PCR positive from 24 tests performed in Q4 2020. See OMAFRA’s report further on in this report.
There were no horses positive for Lawsonia intracellularis on PCR or IHC from 5 tests requested. However practitioners reported “Lawsonia” in horses with testing done at other laboratories. In Q4 2020 there were 5/9 tests positive for Lawsonia sp.
There was 1 tests positive for Potomac Horse Fever from 60 tests processed.. In Q4 2020 there was 1 test positive for PHF from 17 tests processed.
There were 10/22 tests positive for Lyme disease (Borrelia burgdorferi) multiplex this quarter compared to 1/13 tests positive in Q4 2020.
There were 0 foals positive for rotavirus on PCR reported this quarter.
No positive tests for coronavirus were reported this quarter.
- There were 122 postmortem and histopathology examinations performed in Q4 2021 compared to 117 in Q4 2020.
- There were 8 abortions (7 in Q4 2020). The majority were due to umbilical torsion however there was 1 due to leptospirosis.
- There were 7 horses diagnosed with neurologic disease.
- There were 26 cases of gastrointestinal disease, compared to 26 in Q4 2020. Of those, 11 were gastrointestinal accidents, 7 were enteritis/colitis cases and 2 were due to C. perfringens.
- Twenty-three cases of neoplasia were reported, with 6 cases of sarcoid and 4 cases of squamous cell carcinoma of the eye.
- There were 8 cases of respiratory disease as a primary finding on postmortem examination. In Q4 2020 there were 3 cases of respiratory disease.
Equine Research from Ontario and Around the World
Fragment size is associated with post-operative complications following elective arthroscopy of the tibiotarsal joint of horses. Merchán A, Koenig J, Côté N, Cribb N, Monteith G.Can Vet J. 2022 Jan;63(1):74-80
Bronchial brush cytology, endobronchial biopsy, and SALSA immunohistochemistry in severe equine asthma.Lee GKC, Beeler-Marfisi J, Viel L, Piché É, Kang H, Sears W, Bienzle D.Vet Pathol. 2022 Jan;59(1):100-111 Free PMC article
Around the world
Monitoring Performance in Show Jumping Horses: Validity of Non-specific and Discipline-specific Field Exercise Tests for a Practicable Assessment of Aerobic Performance. Kirsch K et al. .Front Physiol. 2022 Jan Free PMC article
The granulation (t)issue: A narrative and scoping review of basic and clinical research of the equine distal limb exuberant wound healing disorder. Anantama NA et al..Vet J. 2022 Jan 27:105790
Investigation of the use of serum amyloid A to monitor the health of recently imported horses to the USA. Middlebrooks BT, Cowles B, Pusterla N.J Equine Vet Sci. 2022 Jan 27:103887. doi: 10.1016/j.jevs.2022.103887
Caudal foot placement superior to toe elevation for navicular palmaroproximal-palmarodistal-oblique image quality. Peeters MWJ, Thursby JJ, Watson HE, Berner D.Equine Vet J. 2022 Jan 29. doi: 10.1111/evj.13563
Effects of a Bio-Electromagnetic Energy Regulation Blanket on Thoracolumbar Epaxial Muscle Pain in Horses. King MR, Seabaugh KA, Frisbie DD.J Equine Vet Sci. 2022 Jan 23:103867. doi: 10.1016/j.jevs.2022.103867.
Investigating the pathogenesis of high-serum gamma-glutamyl transferase activity in Thoroughbred racehorses: A series of case-control studies. Mann S et al. .Equine Vet J. 2022 Jan;54(1):39-51
Genome-wide association analyses of osteochondrosis in Belgian Warmbloods reveal candidate genes associated with chondrocyte development. Drabbe A et al. .J Equine Vet Sci. 2022 Jan 21:103870.
Equine proliferative enteropathy in weanling foals on a German breeding farm: clinical course, treatment and long-term outcome. Dohrmann J et al. .J Equine Vet Sci. 2022 Jan 21:103873.
Repeated nasopharyngeal lavage predicts freedom from silent carriage of Streptococcus equi after a strangles outbreak .Pringle J, Aspán A, Riihimäki M.J Vet Intern Med. 2022 Jan 24. doi: 10.1111/jvim.16368
A Novel Approach to Minimising Acute Equine Endometritis That May Help to Prevent the Development of the Chronic State. Morrell JM, Rocha A.Front Vet Sci. 2022 Jan 6;8:799619 Free PMC article
Performance of Swedish Warmblood fragile foal syndrome carriers and breeding prospects. Ablondi M et al..Genet Sel Evol. 2022 Jan 21;54(1):4. Free PMC article
Bacterial Toxins from Staphylococcus aureus and Bordetella bronchiseptica Predispose the Horse’s Respiratory Tract to Equine Herpesvirus Type 1 Infection. Van Crombrugge E et .Viruses. 2022 Jan 14;14(1):149 Free PMC article
Racing-associated fatalities in Norwegian and Swedish harness racehorses: Incidence rates, risk factors, and principal postmortem findings. Hellings IR et al..J Vet Intern Med. 2022 Jan 21.
Collagen and Microvascularization in Placentas From Young and Older Mares. Neto da Silva AC et al Front Vet Sci. 2022 Jan 4;8: Free PMC article
Occurrence and Antimicrobial Susceptibility Profiles of Streptococcus equi subsp. zooepidemicus Strains Isolated from Mares with Fertility Problems. Nocera FP et al. .Antibiotics (Basel). 2021 Dec 27;11(1):25. Free PMC article
Ivermectin (IVM) Possible Side Activities and Implications in Antimicrobial Resistance and Animal Welfare: The Authors’ Perspective.Piras C et al. .Vet Sci. 2022 Jan 11;9(1):24. Free PMC article
The Effect of Rider:Horse Bodyweight Ratio on the Superficial Body Temperature of Horse’s Thoracolumbar Region Evaluated by Advanced Thermal Image Processing. Domino M et al Animals (Basel). 2022 Jan 13;12(2):195
Incidence of superficial abdominal organ identification is similar using high-frequency linear (transrectal) and low-frequency curvilinear (abdominal) transducers in clinically healthy horses: A pilot study. Haardt H et al.Vet Radiol Ultrasound. 2022 Jan 20.
ResearchONequine.ca is a website developed by the Ontario Animal Health Network equine network to help increase research awareness and to connect researchers from academia, industry and government with the ultimate goal of improving the lives of all equines. It was supported by OAHN and the Ontario Association of Equine Practitioners.