Early exercise in the horse

Abstract: Across all equestrian disciplines, the single largest reason for wastage is musculoskeletal injury. It is, therefore, of importance that management and competition structures are in place to optimize the development of the equine musculoskeletal system to minimize wastage.Data from other species and, in particular, humans have demonstrated the benefit of early exercise and the dire consequences of inactivity. The horse has evolved as a cursorial animal capable of covering up to 10 km/d within 9 days of birth. Yet, modern equine management systems restrict, rather than promote, early exercise. Foals were shown to have a positive response to early preweaning paddock exercise (greater cartilage health), and more recent work has demonstrated that exercise over and above that normally occurring with pasture-reared foals, introduced as early as 3 weeks old, had positive effects on the equine musculoskeletal system. The response of juvenile horses to additional exercise is because of the tissue being responsive to priming. Epidemiological data indicate that the window for tissue modification may still be open when the horse is a yearling and even as a 2 year old.However, the method in which the exercise is applied may be of as much importance as the timing of the stimuli. A recent prospective study of both Thoroughbred and Standardbred horses demonstrated that the horses that entered training as 2 year olds had longer and more successful racing careers than those that entered training later in life. It would appear that even the initial stages of training are enough to provide a positive stimulus, as horses first registered with a trainer at 2 years old had the same advantages as those that raced as 2 year olds.The physiological, clinical, and epidemiological data indicate that, rather than restrict exercise and the use of horses at a young age, we should realign expectations with the capability of the horses’ musculoskeletal system and evolutionary template to maximize orthopedic health.

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Equine insect bite hypersensitivity: What do we know?

from pubmed: horse by Schaffartzik A, Hamza E, Janda J, Crameri R, Marti E, Rhyner C

Equine insect bite hypersensitivity: What do we know?

Vet Immunol Immunopathol. 2012 Apr 3;

Authors: Schaffartzik A, Hamza E, Janda J, Crameri R, Marti E, Rhyner C

Abstract
Insect bite hypersensitivity (IBH) is an allergic dermatitis of the horse caused by bites of insects of the genus Culicoides and is currently the best characterized allergic disease of horses. This article reviews knowledge of the immunopathogenesis of IBH, with a particular focus on the causative allergens. Whereas so far hardly any research has been done on the role of antigen presenting cells in the pathogenesis of IBH, recent studies suggest that IBH is characterized by an imbalance between a T helper 2 (Th2) and regulatory T cell (T(reg)) immune response, as shown both locally in the skin and with stimulated peripheral blood mononuclear cells. Various studies have shown IBH to be associated with IgE-mediated reactions against salivary antigens from Culicoides spp. However, until recently, the causative allergens had not been characterized at the molecular level. A major advance has now been made, as 11 Culicoides salivary gland proteins have been identified as relevant allergens for IBH. Currently, there is no satisfactory treatment of IBH. Characterization of the main allergens for IBH and understanding what mechanisms induce a healthy or allergic immune response towards these allergens may help to develop new treatment strategies, such as immunotherapy.

PMID: 22575371 [PubMed – as supplied by publisher]

 

Comment:  Progress on an old age problem.  Always known by deduction,  Culicoides spp. cause dramatic skin reactions in the horse.  The feeding process of Culicoides leaves some horses with profound swelling and intense itching.  To date, teh most effective tool has been exogenous steroid therapy.  As with many mysteries, the first step in the unlocking process is more understanding.  Perhaps hyposensitization therapy is in the future.

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Effect of livestock manures on the fitness of house fly, Musca domestica L. (Diptera: Muscidae).

from pubmed: horse by Khan HA, Shad SA, Akram W

Effect of livestock manures on the fitness of house fly, Musca domestica L. (Diptera: Muscidae).

Parasitol Res. 2012 May 11;

Authors: Khan HA, Shad SA, Akram W

Abstract
The house fly, Musca domestica L. (Diptera: Muscidae) is one of the major pests of confined and pastured livestock worldwide. Livestock manures play an important role in the development and spread of M. domestica. In the present study, we investigated the impact of different livestock manures on the fitness and relative growth rate of M. domestica and intrinsic rate of natural increase. We tested the hypotheses by studying life history parameters including developmental time from egg to adult’s eclosion, fecundity, longevity, and survival on manures of buffalo, cow, nursing calf, dog, horse, poultry, sheep, and goat, which revealed significant differences that might be associated with fitness costs. The maggots reared on poultry manure developed faster compared to any other host manure. The total developmental time was the shortest on poultry manure and the longest on horse manure. The fecundity by females reared on poultry, nursing calf, and dog manures was greater than on any other host manures. Similarly, percent survival of immature stages, pupal weight, eggs viability, adults’ eclosion, survival and longevity, intrinsic rate of natural increase, and biotic potential were significantly higher on poultry, nursing calf, and dog manures compared to any other livestock manures tested. However, the sex ratio of adult flies remained the same on all types of manures. The low survival on horse, buffalo, cow, sheep, and goat manures suggest unsuitability of these manures, while the higher pupal weight on poultry, nursing calf, and dog manures suggest that these may provide better food quality to M. domestica compared with any other host manures. Our results point to the role of livestock manures in increasing local M. domestica populations. Such results could help to design cultural management strategies which may include sanitation, moisture management, and manure removal.

PMID: 22576856 [PubMed – as supplied by publisher]

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Comment:  Finally, the horse is exonerated as the major cause of fly production!  This abstract gives good thought to manure management and whether chickens are worth having around, given the differential of fly generation.

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Dewormer comparisons – generic vs conventional.

Comparative performance of macrocyclic lactones against large strongyles in horses.

from pubmed: horse by Toscan G, Cezar AS, Pereira RC, Silva GB, Sangioni LA, Oliveira LS, Vogel FS

Comparative performance of macrocyclic lactones against large strongyles in horses.

Parasitol Int. 2012 May 8;

Authors: Toscan G, Cezar AS, Pereira RC, Silva GB, Sangioni LA, Oliveira LS, Vogel FS

Abstract
Several formulations of macrocyclic lactones (abamectin, ivermectin, moxidectin), including ivermectin combined with pyrantel (tetrahydropyrimidine) and ivermectin combined with praziquantel (pyrazinoisoquinolin derivative), were tested regarding their efficacy to control gastrointestinal nematodes of horses on a stud farm in southern Brazil. In addition, we tested a pharmaceutically produced generic paste containing ivermectin 4%. Similar formulations of avermectins had different efficacies measured by reduction of EPG. Levels of efficacy of the tested drugs varied against Strongylus edentatus, S. equinus and S. vulgaris. The generic paste (ivermectin 4%) was less effective than the conventional drugs.

PMID: 22580448 [PubMed – as supplied by publisher

 

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Comment:  Brand name dewormers are recommended over generic, inexpensive versions.  This study illustrates the potential outcome and difference between these two formulations.

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Electrolyte Supplementation in the Horse – is it effective?? Find comments after the abstract.

Gastric emptying and intestinal absorption of electrolytes,and exercise performance in electrolyte supplemented horses.

via pubmed: horse by Lindinger MI, Ecker GL on 5/17/12

Gastric emptying and intestinal absorption of electrolytes,and exercise performance in electrolyte supplemented horses.

Exp Physiol. 2012 May 11;

Authors: Lindinger MI, Ecker GL

Abstract
Horses lose considerably more electrolytes through sweating during prolonged exercise than can be readily replaced through feeds. The present study tested an oral electrolyte supplement (ES) designed to replace sweat electrolyte losses. We measured gastric emptying of 3L of ES (using gamma imaging of 99Tc- sulfide colloid), the absorption of Na+ and K+ from the g.i. tract using 24Na+ and 42K+, and the distribution of these ions in the body by measuring radioactivity within plasma and sweat during exercise. Three L of ES emptied from the stomach as fast as water, with a half time of 47 minutes, and appeared in plasma by 10 minutes after administration (n = 4 horses). Peak values of plasma 24Na+ and 42K+ radioactivity occurred at 20-40 minutes and a more rapid disappearance of K+ radioactivity from plasma was indicative of movement of K+ into cells (n = 3 horses). In a randomized crossover experiment (n = 4 horses), 1h after administration of placebo (water), 1 L or 3 L of ES containing 24Na+, horses exercised on a treadmill at 30% of peak VO2 until voluntary fatigue. 24Na+ appeared in sweat at 10 minutes of exercise, and when horses received 3L of ES the duration to voluntary fatigue was increased in all horses by 33+10 %. It is concluded that an oral ES designed to replace sweat ion losses was rapidly emptied from the g.i. tract, was rapidly absorbed in the upper intestinal tract and rapidly distributed within the body. The ES clearly served as a reservoir to replace sweat ion losses during exercise, and administration of ES prior to exercise resulted in increased duration of submaximal exercise.

PMID: 22581743 [PubMed – as supplied by publisher]

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Comments:

Electrolyte supplementation has been effectively used for many years in the equine sport of endurance riding and racing.  Though feeds provide the primary source, maximal exercise and sweating can create a substantial deficit in electrolytes, leading to possible gastrointestinal and muscle issues.  Any sport or circumstance that causes significant sweating deserves attention for possible supplementation.

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