STRONGYLES. Large strongyles

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1 Microorganism or Microbes Living forms that are too small to be perceptible by the human eye. The scientific study of these is called microbiology: bacterias, fungus, virus, protozoans?? Parasite An organism whose existence is at the expense of another living organism called the host. The scientific study calls these parasitology. Ectoparasites: these are located in the coat/skin or hair of the horse, for example fleas, ticks, lice, nits, flies and mites (scabies). They have no importance in cutaneous lesions, but they do produce itching and other effects. We must also take them into account as vectors or carriers of other diseases: Ex: The tick is an intermediate host in the cycle of babesiasis. (Blue-tongue) Endoparasites: Internal parasites that are the principle cause of colic in horses and they are often the causal factor that contributes in the presentation of various problems of respiratory types, digestive and zootechnical function loss. The five internal parasites that are more commonly found and represent major risk issues of health in horses are the large and small strongyles, large roundworms (ascaris), pinworms (oxyuris equi), and bots (gastrophilus larvae). STRONGYLES Large strongyles Large strongyles are referred to as a large group related amongst one another of internal parasites. Strongyles are also called blood worms or reddish filiform vermes. The life cycle of the strongyles begins in the intestinal tract, where the female worm deposits her eggs which are eliminated through the feces. Under ideal environment conditions (including heat and humidity), the eggs convert into larvae in the manure. The larvae infesters migrate to the pastures, where they remain until they are ingested by the horse. Then they develop as larvae parasites inside of the intestines and migrate along the arterial walls of various organs and eventually return to the large intestine in the young form of a parasite. Larva can cause extensive damage to the lining of the blood vessels.

2 Horses that are infested with large strongyles can lose their physical condition, become weak and can also present weight loss, anemia and colic. In extreme cases, the blood supply to the intestines can become completely blocked because of the strongyle, resulting in severe and even fatal colic. In horses infested with a large amount of strongyles, they may turn into formations of arterial aneurysms, which can cause sudden death if the artery ruptures in the area of the aneurysm. Small Strongyles Small strongyles differentiate from large strongyles in various aspects. Firstly, small strongyles do not migrate to half of the tissues as large strongyles do. Secondly, larva of small strongyles can come to form a cyst (encyst). This means that they can penetrate into the intestinal wall and remain inactive waiting on adequate conditions to emerge. During this period of isolation, contrary to adult parasites, small strongyle larvae are not susceptible to the majority of anti-parasitic suppressors. If numerous numbers of small strongyle simultaneously emerge from the intestinal wall, they can cause severe damage in the mucosa. Colic and diarrhea can be observed. Other signs of infestation from small strongyles include loss in physical condition, weight loss, lack of shine to the coat and hair and subnormality of its growth. ASCARIS: (roundworms) Ascaris or large roundworms, affect young horses more often than that of adult horses. Large roundworms are between 15 to 30 centimeters long and can be found in great quantities in the small intestine. Their presence interferes with a foals nourishment. Symptoms of colic, cough and diarrhea can be a result of ascaris infestation. Also, they can cause blockage in the intestines and emerge to the lungs causing pneumonia. Newborn foals pick up infestered eggs of the ascaris through the feces of other horses. The eggs that contaminate hay or water are ingested and occur in the intestinal tract. Larval forms of the parasite penetrate the intestinal wall, and take approximately one week before migrating to the lungs. From there the larval forms of the parasite travel to the trachea and into the mouth, where they are swallowed for the second time. There they mature in the intestine in two or three months, and then the eliminated eggs are deposited in the feces where once again the whole cycle will repeat all over again. Female roundworms may deposit up to 200,000 eggs per day. When foals are treated with an anti-parasitic suppressor for the first time, there can be symptoms of colic.

3 OXYURIS EQUI (pinworms) Although these are less dangerous than other internal parasites, oxyuris equi (pinworms) cause discomfort in horses because they produce irritation in the anal. One of the characteristics of infestation by oxyuris is rubbing around the base of the tail and the anal region causing damage to the hair of the tail and apparition in the alopecic areas around the base of the same area. The parasite can infest the animal by the means of contaminated water, grains, hay or pasture. Larval forms of these pinworms mature in the big intestine in 3 to 4 months, adult pinworms crawl out of the anal deposit their eggs in the adjacent surface. The eggs develop out of the animals body and become infesters in a few days, however, they can remain without hatching for several months. CESTODES: (tapeworms) Existing forage mites in farms for foals can ingest the eggs that they find in infested feces. Horses grazing can ingest the mites and be infected by tapeworms. As a result of this infestation they can present colics of various intensities. Therefore, it is fundamental to include in the anti-parasitic schedule a specific treatment against cestodes. Because most existing anthelmintic products are not effective against tapeworms, it is necessary to add a specific taenicide to the anti-parasitic schedule of your horse. GASTEROPHILUS LARVAE (bots) Gasterophilus are larva of the common bot fly. These flies are frequently found in the middle of a horse's environment, it's almost impossible that the horse doesn't become infested. Life Cycle During the warm months, the ending of summer and the beginning of autumn, the adult bot fly deposits its eggs in different parts of the horse's body, especially in the pectoral areas, front limbs (cannon bone area), neck and muzzle. The larva develop stimulated by the horse's licking and penetrates into its mouth, where it resides in the tissue of the gums, cheeks and tongue. Approximately a month later, the larvae migrate to the stomach, where they are located on the inner wall thereof. It is not surprising that several hundred gasterophilus attach to the stomach, causing irritation, interfering with digestion and obstructing the opening or lumen of the small intestine. The gasterophilus larvae are excreted in the feces after 8 to 10 weeks, where they bury theirselves in the ground or manure, to hatch into adult bot flies approximately in one months time and where once again they are ready to start the whole cycle all over again by depositing their eggs in the horse's hair or coat.

4 Protozoan parasites Protozoa: single-celled beings with a complex metabolism that also produce parasitic diseases. In horses the more important are the ehrlichiosis and the piroplasmosis. Equine Piroplasmosis: Equine piroplasmosis (EP), as its name suggests, is a disease of equines (horses, donkeys, mules and zebras) caused by protozoan parasites that invade the red blood cells causing its destruction. There are two species of these protozoa, the Theileria equi (formerly known as Babesia equi) and the Babesia caballi that are present in 90% of the world inhabited by horses. Only Canada, The United States, Australia, Japan, England and Ireland are not considered endemic disease areas. The disease is transmitted through blood and is generally transmitted by ticks and other insects, however inadequate disinfection of hypodermic needles or other instruments can also cause mechanical transmission. Babesia Caballi causes a less severe disease as that only 1% of the red blood cells become infected. Infections may not be apparent, but may persist for up to 1 to 4 years, although at the end they are eliminated. They may associate poor appetite, poor work exercise and weight loss. Theileria equi (formerly Babesia equi) infect up to 20% of the red blood cells, producing clinical signs of fever, anemia, icterus, increase of respiratory and cardiac rhythm and enlargement of the spleen. Given that parasites destroy the red blood cells, anemia occurs and hemoglobin detachment which can produce liver disease and dark-colored urine. They can also come to the point of giving cases of colic, constipation followed by diarrhea, and swelling of the extremities. Foals can be infected inside of the utero, including risk of abortion or birth anemic and debilitation. Animals infected with Theileria equi (Babesia equi) become lifelong carriers. VACCINATION It is an antigen preparation that once inside the body triggers an attack response known as an antibody that eliminates the antigen. This response generates an immunological memory resulting in a higher or to the greatest extent possible against the antigen. The vaccine is preventive, never curative. DEWORMING Action and effect of removing a parasite. We're going to use it in a preventive way, but on occasions also as a curative. DISINFECTION Refers to the reduction of pathogenic microorganisms in a PREVENTIVE and CURATIVE manner used on the animal and for the environment. There are many types of disinfectants, some are used specifically in installations, others

5 are toxic and others are tolerable for applying on the animal. Be sure to make the correct choice when using an antimicrobial agent. DEINSECTIZATION Action and effect to eliminate insects from the animal as well as its surroundings. Can also be used in a curative and preventative way. The same as disinfectants, the products that are going to be used have to be chosen carefully. Commercial brands that are mostly used are Barricade and Arpon for applying on animals and Zotal for installations, although the other two brands can also be used for installations. VACCINATION SCHEDULE Equine Flu Equine influenza (or equine flu) is a viral disease, highly contagious, characterized by dry cough, nasal discharge and fever; it spreads quickly in any populated area not immunized. In animals that are partially immunized these signs may not be observed and the clinical manifestation of the disease is not evident, for this reason it is essential to perform a diagnosis that will differentiate it from a respiratory illness. These animals can secret the virus without manifesting clinical signs. The agent of this disease is a type-a orthomyxovirus and has two subtypes that have been recognized as: H7N7(A/equi1) and H3N8(A/equi2) formerly known as A/equine 2). This disease does not affect other species of animals or people. Equine influenza is an obligated declaration in this country and must be reported to the World Organization for Animal Health, OIE ANNEX V VACCINE AGAINST THE EQUINE FLU The vaccination document of a FEI or LIC passport, issued to all horses and ponies, must be signed and stamped by a non-owner veterinarian. This visa certifies that two injections have been administered to the horse as a primary vaccination against the equine influenza in a period of not less than 21 days nor more than 92 days. A reminder injection is administered in each successive period every (6) months after the second primary vaccination injection. However, this period may be extended for 6 months to not interrupt the intervention of the horse when in competition, up to a maximum of 21 days or three weeks. None of these injections should be administered 7 days prior to an event or admission in the stables of competition. The previous rules constitute the minimum indispensable. As much as for the basic vaccination, as for a reminder to follow the recommended vaccination protocol that usually corresponds to the rules stated above.

6 TETANUS Tetanus is the result of an infection by the bacterium Clostridium tetani. This microorganism, which can be found on the ground, synthesizes a powerful toxin that causes muscular paralysis. The treatment is expensive and difficult, and is often impossible to save the life of the animal, but the disease is preventable with a simple annual vaccination. Prevention is essential, as the horse is an animal very prone to tetanus. In the environment in where horses move around at, it is very easy that any type of wound is invaded by Clostridium tetani spores. These spores germinate and multiply and produce a powerful toxin that affects the nervous system and produces a progressive muscular paralysis. All muscles are seen affected and come to produce a respiratory paralysis that destroys the life of the animal. Annual vaccination and primary vaccination for 1 to 3 months. RHINOPNEUMONITIS A horse viral disease produced by the herpesvirus. They also have similar symptoms to that of the equine influenza with manifestations that are more devastating because of outbreaks of abortions, perinatal mortality in foals or nervosity symptoms. These three clinical forms can cause outbreaks and produce great economic losses. The risk of the herpesvirus strain (EHV1) in a group of horses is high, because it is treated as a highly contagious disease, the outbreak advances rapidly and a great number of clinical cases can be expected. Annual vaccination (recommended biannual). Primary vaccination for 1 to 3 months. For vaccinating pregnant mares using specifically Pneumabort-K in the 5th, 7th and 9th month of gestation. DEWORMING SCHEDULE An adequate deworming schedule reduces considerably the appearance of colics by four times as other problems such as weight loss, anorexia, anemia, tail scratching, ectoparasites and respiratory problems. A quarterly deworming schedule should be considered for horses (four times a year) by varying the active ingredient that is carried out. A good guideline would be to use an avermectin (ivermectin or moxidectin) two times a year, benzimidazole once a year and pyrantel pamoate or pyrvinium pamoate once a year. Author: Alvaro Vázquez/Pablo Adrados EQUISAN Veterinaria Equina Integral