Yellowstone River Whitefish PKD Tetracapsuloides bryosalmonae Epidemic

Montana Standard Article: Spread of pathogen in Montana Rivers requires a thoughtful and scientific response.

Preservation Medicine

Sid Gustafson DVM

Aquatic infectious disease is caused by a pathogen present in a river environment that achieves successful reproduction in a vulnerable host, often at the host’s expense.

An appreciation of the Yellowstone River whitefish epidemic requires consideration of three factors; 1) the host(s), 2) the warming river environment, and 3) the pathogen(s).
Epidemics—including the Yellowstone River whitefish Tetra epidemic—are preceded by essential predisposing conditions in all three.
The Yellowstone River and watershed activities compose the environment. Warming temperatures, low flows, silting, proliferation of the pathogen Tetracapsuloides bryosalmonae, diminished oxygenation, salinity, septic seepage, chemical runoff, altered riverbanks, recurrent contamination with pathogens and invasive species, river sporting, boating, and flyfishing, water diversion and irrigation, riparian residential, business, and agricultural practices are the primary environmental factors that facilitated this epidemic.
While all of the aforementioned factors play a role, the warming of the river was the critical factor in this epidemic. Had the river not warmed to the critical temperature, thought to be around 15 degrees centigrade, the epidemic would not have happened despite the presence of the pathogen and the vulnerable whitefish.
Tetracapsuloides bryosalmonae is a native North American pathogen that has resided in American rivers for centuries. The pathogen has spread to European rivers, as well as to the Yellowstone River. In the Yellowstone, this infectious agent has adapted to infect whitefish, finding them more vulnerable than trout. The native Yellowstone mountain whitefish, the salmonid Prosopium williamsoni is our host of concern. The fish is called the mountain whitefish because in cold mountain rivers this fish thrives.
The infective aquatic pathogen T. bryosalmonae is unusual among the myxosporea (of which the whirling disease pathogen is a relative) in that it requires a bryozoan as an intermediate host. The bryozoan in this case may be Plumatella fungosa. In this freshwater jellyfish, the Tetracapsula completes its life cycle. This jellyfish releases fish-infective spores into the river. When waters warm high enough to manifest disease, around 60 degrees F, these floating spores attach to the whitefish’s gills before proceeding to cause proliferative kidney disease
Depending on the fish’s health, resistance, environmental conditions, adaptability, infective dose, and immune status, the fish survives to perhaps be resistant to future infections, or she dies. As the fish dies, the pathogen enters the water. At this stage of this complex life-cycle, rather than finding another fish, the Tetra pathogen finds a fungosa to complete its lifecycle. In this process, the infectious organism begins to flourish in the river and gains momentum to create an epidemic.
Multiple measurable factors preceded the whitefish epidemic, an epidemic a long-time coming, an epidemic that veterinary medical technology had the ability to predict had aquatic veterinary medicine been employed to keep Montana rivers and their fish populations prosperous and healthy.
The hosts of this disease have historically been salmonids, whitefish among them. As any Yellowstone guide knows, a whitefish is no salmon. While considered undesirable by some, the whitefish is an indicator species reflective of river health. Like trout, whitefish and grayling are salmonids. Whitefish require pristine rivers. Grayling, the previous indicator species, were extirpated by sullied river systems. Historically, whitefish often come next.
To monitor and predict future epidemics, competent aquatic veterinarians sample, test, analyze and interpret the host health, river health, intermediate host presence, along with the pathogen load in the river system. With this information, aquatic veterinarians can manage the health of the watershed, river, and fish to minimize the impact of infectious disease. All of this ahead of time. The aquatic veterinary goal is to prevent epidemics, or at least predict them, something beyond biologists’ ability at this time. Veterinarians have a long and effective history of successfully managing the health of animal populations threatened by infectious disease, be they wild or domestic. Veterinarians have the appropriate knowledge and experience to sustain fish and river health. The time has come to look to veterinarians to manage river health in Montana as rivers are managed in progressive fisheries throughout the world where the economy depends on fish health and prosperity. There is a lot to learn about this epidemic, and veterinarians are the best learners regarding management and prevention of infectious disease.

The resolution of the Tetra epidemic could be similar to the resolution of the whirling disease epidemic. The whitefish and trout survivors will perpetuate offspring that are more resistant than their immunologically naïve predecessors. Disease resistance will develop. The fish will adapt to and/or find a balance with their pathogen and intermediate host. An equilibrium between pathogens and hosts emerges over time if the river system is kept healthy and cool. The trout may have previously acquired a resistance from their experience with the whirling disease organism, and now with this Tetra experience, the trout appear to be developing resistance to infective pathogens of various sorts.

Treatments:
An antimicrobial agent to kill the aquatic pathogen is not an available method of control or prevention, as the river environment would be further deteriorated by the drug’s side-effects and unintended victims.
The jellyfish host, Plumatella fungosa, could be medically manipulated, sterilized, or genetically altered to block the two-host disease transmission cycle, and that is a consideration.
The environment (the river et al) can be made healthier; water cooled, flow quickened, and oxygenation enhanced using progressive river management techniques (limiting water drawouts, averting septic and manure seepage, and halting chemically contaminated runoffs). The fish populations could be treated more kindly and carefully by educating guides and anglers on the principles of animal welfare (fish are sentient beings) and the principles of disease transmission. Fishing hooks, boats, gear, and fishermen transmit fish diseases near and far. This needs to be evaluated and addressed.
Fishing stress and disease vulnerability can be significantly reduced by regulating fishing and/or floating in consideration of the fish, rather than the fisherman, accountants, and irrigators. Catch-and-release practices and their relationship to perpetuating and spreading fish diseases require investigation. Harvesting can be considered a possible disease management measure. Stressed or injured fish should not be released back into the river.

Rest is the oldest remedy to manage disease. While naïve to the vagaries of infectious animal disease, the Montana FWP is to be commended for closing the river and giving her a long-needed rest. Periodic rest during critical times appears to be one solution of many. Whitefish populations can balance trout populations, and overpopulations, keeping fish numbers balanced and healthy. Pathogens often find imbalanced populations vulnerable. The microbe often has the last word (when the humans don’t pay attention). Aquatic veterinarians pay attention.



Recommended reading:

^ Hedrick R.; McConnell E.; de Kinkelin P (1993). "Proliferative kidney disease of salmonid fish". Annual Review of Fish Diseases. 3: 277–290. doi:10.1016/0959-8030(93)90039-E.
^ Kent, M.L. & R.P. Hedrick (1985). "PKX the causative agent of proliferative kidney disease (PKD) in Pacific salmonid fishes and its affinities with the Myxozoa". Journal of Protozoology. 32 (2): 254 260. doi:10.1111/j.1550-7408.1985.tb03047.x. PMID 4009511.
^ Korotneff, A. (1892). "Myxosporidium bryozoides". Z. Wiss. Zool. 53: 591–596.
^ Anderson, C.L., Canning, E.U. & Okamura, B. (1999). "18S rDNA sequences indicate that PKX organism parasitizes Bryozoa". Bulletin of the European Association of Fish Pathologists. 19: 94–97.
^ Canning, E.U., Curry, A., Feist, S.W., Longshaw, M., & Okamura, B. (1999). "Tetracapsula bryosalmonae n.sp. for PKX organism the cause of PKD in salmonid fish". Bulletin of the European Association of Fish Pathologists. 19 (2): 203–206.
^ Canning, E.U., Curry, A., Feist, S.W., Longshaw, M., & Okamura, B. (2000). "A new class and order of myxozoans to accommodate parasites of bryozoans with ultrastructural observations on Tetracapsula bryosalmonae (PKX organism)". Journal of Eukaryotic Microbiology. 47 (5): 456–468. doi:10.1111/j.1550-7408.2000.tb00075.x. PMID 11001143.
^ Kent, M.L. J. Khattra, R.P. Hedrick, and R.H. Devlin (2000). "Tetracapsula renicola (Myxozoa: Saccosporidae); the PKX myxozoan – the cause of proliferative kidney disease of salmonid fishes". Journal of Parasitology. 86 (1): 103–111. doi:10.1645/0022-3395(2000)086[0103:TRNSMS]2.0.CO;2. PMID 10701572.
^ Anderson, C.L., Canning, E.U. & Okamura, B. (1999). "18S rDNA sequences indicate that PKX organism parasitizes Bryozoa". Bulletin of the European Association of Fish Pathologists. 19: 94–97.
^ Henderson, M. & Okamura, B. (2004). "The phylogeography of salmonid proliferative kidney disease in Europe and North America". Proceedings of the Royal Society B. 271 (1549): 1729–1736. doi:10.1098/rspb.2004.2677. PMC 1691782. PMID 15306294.


http://echo.epfl.ch/page-114506-en.html


Fumagillin (or other effective drug)
Microsporidians (Loma salmonae, proliferative kidney disease, whirling disease, proliferative gill disease)/freshwater-reared finfish


Ray, R.A., R.W. Perry, N.A. Som and J.L. Bartholomew.  2014.  Using cure models for analyzing the influence of pathogens on salmon survival.  Transactions of the American Fisheries Society.  143(2):

Bjork, S.J., Zhang, Y.A., Hurst, C.N., Alonso-Naveiro, M.E., Alexander, J.D., Sunyer, J.O., and Bartholomew, J.L.  2014.  Defenses of susceptible and resistant Chinook salmon (Onchorhynchus tshawytscha) against the myxozoan parasite Ceratomyxa shasta.  Fish Shellfish Immunol. 1:87-95.

Gómez, D., Bartholomew, J., and Sunyer, J.O.  2014.  Biology and mucosal immunity to myxozoans.  Dev. Comp. Immunol. 43(2): 243-56.

Ray, A.R. and J.L. Bartholomew.  2013.  Estimation of transmission dynamics of the Ceratomyxa shasta actinospore to the salmonid host.  Parasitology.  140:907-916.

Bartošová, P., I. Fiala, M. Jirku, M. Cinkova, M. Caffara, M.L. Fioravante, S.D. Atkinson, J.L. Bartholomew and A.S. Holzer.  2013.  Sphaerospora sensu stricto:  Taxonomy, diversity and evolution of a unique lineage of myxosporeans (Myxozoa).  Molec. Phylogentics and Evolution.  68:93-105.

Ray, A.R., R.A. Holt and J.L. Bartholomew.  2012.  Relationship between temperature and C. shasta-induced mortality in Klamath River salmonids.  Journal of Parasitology.  98:520-526.

Ordás, M.C., R. Castro, B. Dixon, J.O. Sunyer, S. Bjork, J. Bartholomew, T. Korytar, B. Kollner, A. Cuesta and C. Tafalla.  2012.  Identification of a novel CCR7 gene in rainbow trout with differential expression in the context of mucosal or systemic infection.  Developmental and Comparative Immunology.  38:302-311.

Stinson, M.E.T. and J.L. Bartholomew.  2012.  Predicted redistribution of Ceratomyxa shasta genotypes with salmonid passage in the Deschutes River, Oregon.  J. of Aquatic Animal Hlth.  24:274-280.

Hallett, S.L., R.A. Ray, C.N. Hurst, R.A. Holt, G.R. Buckles, S.D. Atkinson and J.L. Bartholomew.  2012.  Density of the waterborne parasite, Ceratomyxa shasta, and its biological effects on salmon.  Applied and Environmental Microbiology 78:3724-3731.

Zielinski, C.M., H.V. Lorz, S.L. Hallett, L. Xue and J.L. Bartholomew.  2011.  Comparative susceptibility of Deschutes River (Oregon, USA) Tubifex tubifex populations to Myxobolus cerebralis.  Journal of Aquatic Animal Health 23:1-8.

Zhang, Y-A., I. Salinas, J. Li, D. Parra, S. Bjork, S. LePatra, J. Bartholomew and J.O. Sunyer.  2010.  IgT, a primitive immunoglobulin class specialized in mucosal immunity.  Nature Immunology 11:827-835.

Bjork, S.J. and J.L. Bartholomew.  2010.  Invasion of Ceratomyxa shasta (Myzozoa) and comparison of migration to the intestine between susceptible and resistant fish hosts.  International Journal for Parasitology, 40:1087-1095.

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Swift Dam, last best novel review

"Swift Dam," the new novel by veterinarian and writer Sid Gustafson, is a beautifully evocative exploration of memory and landscape, history and generational relationships. It is set on the Blackfeet Indian Reservation, where Sid grew up as part of the prolifically creative Gustafson clan.

http://www.open-bks.com/library/moderns/swift-dam/about-book.html

Order Swift Dam

The guts of the book are the ruminations of Oberly and Vallerone on life, love and mortality. Vallerone, apparently subject to some kind of sleep disorder, has trouble keeping his dreams separate from real life, or disentangling real history from myth and misremembrance.

The point seems to be that we all are disordered when we try to reconstruct the past, that we all live to some extent in a waking dream.

The book is also full of veterinary particulars, which might sound dry but are anything but. Vallerone is an old-fashioned healer who does much of his diagnosis and doctoring with his hands—hence the nickname “Fingers”—and who is a proponent of the Blackfeet way of raising and caring for horses.

Sid, who in his own practice specializes in the care of thoroughbred race horses, goes into loving detail about the proper care of livestock, and he takes several detours to damn the damage done to animals by modern ranching techniques and the scourge of using drugs to treat every ailment.

Sid writes of veterinary medicine, and much else, with a poetic voluptuousness, as in this description of the aftermath of a cesarean birth: “The new mother heaves a sigh of relief as the calf exits her incised womb. Doc elevates the calf to drain her wet lungs, and lays the neonate out and revives the baby, too long inside. He clamps her umbilicus to make her inhale, and inhale the little creature does, taking in first air, continuing to inhale, gestating nine months to inhale. Fingers threads his needle with catgut suture and the newborn sits to her sternum and issues a faint bawl. He stitches the mother back together, the newborn flapping her ears, stars singing hallelujah.”

Sid also knows the Blackfeet, whom he grew up around up on the family ranch. He writes of Blackfeet past and present with a clear understanding of the indignities they have suffered, but also with an unsentimental appreciation of what they might teach those who care to listen.

Toward the end of the book, Vallerone “watches the new dam through the drizzle, his bones pained by the rain, joints in need of ambulation. He walks, walks to lubricate his joints, to stiffen his bones, to condition his muscles. He knows locomotion is the key to longevity. To keep living, one must keep moving. All of the animals taught him that to move is to live. All becomes dependent on locomotion in the end. When you stop moving, you stop living. When the water stops flowing, all is over.”

True words, for sure. The Gustafson children lost both their parents in the past few years, but Sid and his his siblings don’t seem to be slowing down in the least.

Details: “Swift Dam,” by Sid Gustafson, published by Open Books, 2016. 152 pages, $15.95; ebook, $6.99.

purchase Swift Dam

Dr Gustafson is a practicing veterinarian, equine behavior educator, and novelist. The application of behavior science enhances optimum health, performance, soundness, contentment, and longevity in animal athletes. Behavioral and nutritional strategies enrich the lives of stabled horses. Training and husbandry from the horse's perspective result in content, cooperative horses who are willing to learn and perform.

High Altitude Trouble in Dogs and Horses

High Altitude Disease in Dogs and Horses: Pulmonary Edema

Signs, Prevention, Treatment

Sid Gustafson DVM

Dog First Aid guide link

Practicing in Big Sky, at 6000-10000 feet and higher, our practice sees and treats many cases of pulmonary edema, altitude sickness, and heart disease in horses and dogs are exacerbated by the altitude.

Difficult Breathing is the first and most obvious sign.

Altitude Sickness

Pulmonary edema/altitude sickness can include swelling of the lungs or accumulation of fluid that interferes with effective breathing. Struggling for air is uncomfortable, and afflicted dogs and horses cannot catch their breath, even at rest.

Causes: Unacclimated to high altitudes accompanied by high altitude activity. Distressed, rapid, relentless, or difficult breathing may be associated with underlying med¬ical conditions such as heart disease, respiratory infection, asthma, collapsing trachea, etc. That said, the healthiest dogs and humans can succumb to the vagaries of altitude sickness from time to time. The body likes oxygen, and when oxygenation becomes impaired, breathing troubles can be intense. High temperatures contribute to the breathing distress. Make sure your dog and horse stay cool. 

Heart weaknesses and lung conditions contribute to the severity of the condition, as can allergies and infection. Gradual, measured acclimation to altitude is recommended. Subtle conditions not apparent at lower altitudes may present themselves clinically under the duress of altitude and exercise. Aging dogs become susceptible as time wears on. Just because Fido had an uneventful climb last year doesn't mean the trip will be a merry one this year. Don't forget your dog's annual physical before tackling the mountain peaks this year. Make sure your dog stays hydrated during mountain adventures.

Signs: Difficult and labored breathing caused by airway inflammation or fluid in the airways and/or lungs. Your horse or dog tires easily and requires frequent rests, refuses to continue (can’t continue); relentless panting fails to diminish with rest.The dog may refuse to sit or lie down, as those postures makes breathing more difficult. As the condition worsens, coughing and blood-tainted spittle accompany shortness of breath. Milder cases of altitude sickness manifest as coughing at night, often beginning a few hours after activity has subsided. The dog may prefer a sitting position with the elbows held wide and head stretched out, refusing to lie down. Other signs include a worried expression, distressed eyes and unremitting panting. When horses pant, the condition is sever. In young dogs and horses, the cause can be congenital heart disease or anemia from internal parasites. Older or heavy dogs and horses may suffer from congestive heart failure. that is severely worsened with exercise at altitude. Backup of fluid into the lungs from a weak or aging heart is aggravated by strenuous or even mild activity at high elevations. Intake of untoward amounts of salt can aggravate heart disease and pulmonary edema. Many aging dogs should be on a low sodium, or sodium-free diet. Adequate hydration and maintenance of normal electrolyte levels becomes compensated at high elevations, and medical problems ensue on several levels.

Prevention: Careful conditioning and gradual acclimation to high altitudes are recommended before all high altitude trips. Proper medical treatment of underlying health conditions can prevent exercise-associated breathing complications at any altitude. Avoid strenuous exercise—especially at high altitudes—to which your dog is not accustomed, difficult snow (deep, wind-pressed, crusted) and extremes of hot or cold weather. See your veterinarian for a physical exam and consultation prior to departure. He or she will discuss proper conditioning and consider the need for administration of preventive and ameliorative medications, which can be critical as pulmonary edema and altitude sickness can be life-threatening. Retreating to a lower altitude is always recommended and often required for the breathing to return to normal. Avoid salt, and salty treats, bacon, ham, and cheap dog treats, as these cause additional fluid retention and contribute to pulmonary edema. Many dogs coming to altitude manifest symptoms of underlying heart disease that was asympotamtic at sea level. Weak hearts and lungs become even weaker at altitude. It is possible to prevent lung and heart issues with medication prescribed by your veterinarian.

Treatment: Discontinue activity. Transport the dog to a lower altitude in a manner that allows easy breathing. If the gums become pale or purple, mouth-to-nose breathing may be necessary until the gums regain their normal color and refill time. Administer oxygen if available, which it often is at high altitudes. I recommend that you bring oxygen for yourself and your dog if you plan to travel at unaccustomed elevations where there could be problems. Simply allow the oxygen to flow near your dog's nostrils, rather than into the mouth, in a wind- free environment.

Seek veterinary care if breathing difficulty doesn't improve with rest or the return to a lower elevation. Subsequent or underlying lung disorders or infections and aggravation of pre-existing medical conditions can complicate altitude sickness. See your veterinarian if your dog experiences difficulty breathing or tires easily on high altitude hikes. Furosemide is a commonly employed pharmaceutical treatment. It is a diuretic which lowers the arterial blood pressure in the lungs. Side effects include electrolyte imbalances and dehydration. Other preventive medications include triamcinolone. Cortisones that have a fluid retention effect should be avoided (prednisone and the like).

Dr Gustafson is a practicing veterinarian, equine behavior educator, and novelist. The application of behavior science enhances optimum health, performance, soundness, contentment, and longevity in animal athletes. Behavioral and nutritional strategies enrich the lives of stabled horses. Training and husbandry from the horse's perspective result in content, cooperative horses who are willing to learn and perform.

Locomotion: Essential Horse Health

Horses in natural settings forage two thirds of the time, walking and grazing together. in constant communication and group-survivalist harmony. The key to keeping confined horses healthy is to re-create this scenario in the stable as best one can manage. All systems of the horse are dependent on miles of daily locomotion for proper function. Digestion, respiration, metabolism, behaviour, learning, training, and hoof health are all dependent on abundant daily locomotion. Horses are born to move, and move they must to maintain health and prosperity. The last place a horse evolved to live is in a stall. When horses are stalled, natural must be re-created for them.

 Movement is necessary for normal, optimal digestion. Roughage is the diet of preference, and horses in natural settings arrange their lives to generally always have grass roughage in their stomach and grass roughage before them. Horses at pasture move most all the time. In caudal cecal grazers such as horses, digestion is linked to locomotion. Digestion is dependent on locomotion accompanied by near-constant grazing.

Colic is often initiated by deprivations of locomotion. Digestion is locomotion dependent. For the horse's gut to move, the horse must move, abundantly. Stalled horses require miles of daily walking to maintain digestive health. When stalled they should have constant access to appropriate forage. Bedding stalled on horses on clean straw helps re-create the constant moving and grazing horses are won't to do. Horses bedded on straw (with 24/7 access to hay), spend hours moving about, head down, lipping, and tonguing through the straw. Straw encourages the constant movement that aids digestion in a big way. It is relatively easy to keep stabled horses' stomachs full with roughage. Appropriate hay should always be present, in addition to the straw bedding. The straw bedding needs cleaned of manure and fluffed several times a day.

Behaviourists know stomach volume, and so now do all of you, 1-4 gallons. How easy is it to keep a horse's stomach full of a gallon or two of hay? Quite easy

Listen to McGreevy: Lack of forage is the most important management factor causing the development of stereotypic behaviours. 

Please understand horse's dependence on roughage, and please come to fully appreciate that the horse did not evolve to assimilate grains or concentrated protein, please. And for goodness sake, do not feed locomotion deprived horses grain, as the practice is detrimental. Only moving horses can handle grain. Long-standing horses fed grain develop obesity, and metabolic syndrome, laminitis follows, keeping the veterinarians busy, and the horse owner bank accounts depleted.

Tell me the ways that horsefolk in-the-know provide stabled horses roughage to graze two thirds of the time, and the necessary movement and locomotion to digest and assimilate the roughage.

Of course, by now we all know what failing to provide these simple roughage and stomach-content requirements causes in horses (poor learning ability, stereotypies, lack of motivation to perform, lameness, tying -up, ulcers, more veterinary bills...)

Oh, and do not forget water. And where the water is placed.

Tell me the reasons why when you lead a horse to water she will not drink the water, please, and remember horses will seldom eat when they start to become dehydrated (when they are thirsty), or after you clip their vibrissae.

Remember horses' good and essential friend, salt. Lead a horse to salt and she will lick and later drink. Make sure salt always travels with your horse. It seems lack of salt while traveling causes a lack of hydration, which leads to colic. Horses require salt and water 24/7 as they do forage and locomotion.

Minerals may also be required to be supplemented, and of course the most important minerals after salt are calcium and phosphorus, balanced please. Calcium and phosphorus make up bone, and bone makes a horse durable and sound. Do not forget the bone minerals, please.

Healthy horses make happy and willing partners.

When we have problems with a horse in this class, we all know to first make sure that the forage, friends, and locomotion are adequate, plentiful, and appropriate before devising some heavy handed training strategy. Unhappy horses are hard to train, yes, as are horses who are not pairbonded to their trainer.

When confronted with a horse with behaviour or training issues, we have all learned to first consider stabling as a primary factor in teaching, learning, and training. The proper method to address training issues is to first address stabling and socialization issues. 

Locomotion is also essential for pulmonary health. Horses locked down all day bleed into their lungs when exercised strenuously, as in a race. The leading cause of bleeding in racehorses is a lack of abundant daily locomotion. 

Metabolic disease and laminitis are caused by a lack of adequate locomotion. Colic is caused by a lack of locomotion. Obesity is caused by a lack of locomotion. Tying up is caused by a lack of locomotion. Bucking is caused by a lack of locomotion. Cribbing is caused by a lack of locomotion and constant chewing and grazing. Take locomotion away from a horse and she will give movement back to you in the arena in ways you do not prefer.

Happy horses train up happily. Set yourself and your horses up to succeed, please. Keep your horses happy with friends, forage, and locomotion, and grooming. 

Stalled horses require movement. For horses unable to move because of injury, we must re-create movement with massage and passive flexion of all the limbs.

Dr Gustafson is an equine veterinarian, veterinary behaviorist, and novelist. Applied veterinary behavior enhances optimum health, performance, soundness, contentment, and longevity in animal athletes. Natural approaches to development, training, nutrition, and conditioning sustain equine health and enhance performance.
Behavioral and nutritional enrichment strategies enhance the lives of stabled horses. Training and husbandry from the horse's perspective result in content, cooperative horses.