- - AGRICULTURE CORE CURRICULUM - - (3000) Advanced Core Cluster: ANIMAL SCIENCE (CLF3350) Unit Title: LIVESTOCK PESTS ___________________________________________________________________________ (CLF3351) Topic: INTERNAL PARASITE Time Year(s) CONTROL 6 hours 3 / 4 ___________________________________________________________________________ Topic Objectives: Upon completion of this lesson, the student will be able to: Learning Outcome #: (F-1) - Draw the life cycle of an internal parasite that is specific for each of the following: horse, swine, cattle, sheep, poultry, and rabbits and show in the life cycle where each internal parasite can best be controlled. (F-3) - Develop a one-year worming and vaccination schedule for a student-owned, animal related SOE. (F-4) - Explain the value of pasture rotation in parasite control. (F-6) - Define drenching and demonstrate methods on three livestock species. Special Materials and Equipment: Blank paper and colored pens and pencils, soda bottles, a large dose syringe, or other drenching materials and a live sheep! References: Ensminger, M.E. THE STOCKMAN'S HANDBOOK. Ensminger, M.E. HORSES AND HORSEMANSHIP. Cheeke, Peter R. RABBIT PRODUCTION. Bundy and Diggins. LIVESTOCK AND POULTRY PRODUCTION. Evaluation: Quiz by instructor and grading of lifecycle drawings. TOPIC PRESENTATION: Internal Parasites A. Life Cycles and Control of Internal Parasites 1. Strongyles (bloodworms) a. Of the numerous parasites affecting horses, the most serious threat to the health and life of the horse kept in confinement is the strongyle. b. The lifecycle; 1) The eggs are passed in the feces. 2) Once they are on the ground or on herbage, the eggs hatch into the first stage larvae, then they develop into a second stage larvae, and finally develop into a third stage infective larvae, which do not feed, but wait for ingestion. This whole process takes about 7 days under favorable temperature and moisture conditions. 3) Next, the infective larvae crawl onto vegetation. 4) They are ingested when the horse feeds on the infected vegetation. 5) After ingestion, the larvae penetrate the wall of the small intestine, cecum, and colon; invade the walls of the small arteries in these organs and migrate along the anterior mesenteric artery and cause thrombi and aneurysms: a) thrombi - blood clots within a blood vessel, and b) aneurysms - permanent abnormal blood-filled dilatations of the blood vessel wall. 6) The larvae then move out into the blood vessel and lumen. They are carried by the bloodstream to the colon and cecum, where they migrate back through the walls to become adult worms attached to the mucosa lining of the cecum and colon. This entire migration and development, from ingestion to adulthood, takes six months. a) The worms suck blood from the cecum and colon, causing tissue damage at the site of the attachment and anemia. b) During this time of migration, the larvae are inaccessible to ordinary doses of many anthelmintics. c. Time and method of control: 1) before the larva penetrates the blood vessels, using anthelmintics, and 2) when eggs and larvae are on the ground or herbage -- using proper manure disposal, pasture rotation, and limiting the number of animals in the pasture. 2. Whipworm (Trichuris suis) a. Affects swine and causes: 1) slow weight gain, 2) feed inefficiency, 3) diarrhea, and 4) some deaths. b. Lifecycle: 1) The eggs are passed in the feces and are consumed by the swine. 2) The eggs then hatch and the larvae mature and live in the cecum. 3) The adult worms produce eggs which are then shed in the feces. c. Control: 1) when the adults are in the caecum, and 2) by using proper manure disposal and pasture rotation (not done that often with swine). 3. Lungworm (thread lungworm and hair lungworm) a. Found in cattle, sheep, and swine, but each species has a different species of lungworm that affects them. 1) They affect the circulatory and respiratory systems. 2) Symptoms include coughing, rapid breathing, open mouth with tongue hanging out, fever, and the animal looses its appetite - "off feed." b. Lifecycle: 1) Adult parasites live in the lungs and lay eggs in the bronchi which hatch to the first stage larvae in the lungs. 2) The eggs are coughed up, swallowed, and hatch in the intestines. 3) The larvae stages require a certain amount of warmth and moisture to survive. They pass through the intestine and are eventually eliminated in the feces. 4) Infective larvae are consumed in forage and migrate through the digestive organs, they then pass through the lymph stream, the heart, and the blood stream to the lungs where they mature, all in 25-30 days. c. Control: 1) the adults in the lung to decrease egg output. 2) the larvae before they reach the lungs since they damage lung tissue and may cause secondary pneumonia. 3) pasture areas to ensure that the animals do not occupy wet, swampy pastures. 4. Grubs (Heel Fly, warbles) a. Affect cattle. b. The grub stage or warble is the larval stage of this parasite and the heel fly is the external form (same stages as the bot fly in horses and the nose bot in sheep). c. Lifecycle: 1) The female fly deposits eggs on the hairs of the lower parts of the legs which irritate the cattle. 2) These eggs hatch and the larvae enter the body of the animal through the skin into subcutaneous tissues for 4-5 months. 3) The larvae then migrate through the body tissues for approximately 9 months and eventually arrive at the back area, and then live in the fat and in the subcutaneous tissues for two months. 4) The larvae lodge in the cattle's back, just under the skin causing a conspicuous, painful lump. There may be a small hole punctured through the skin at this stage. 5) After the second molt, the larvae pop out and drop to the ground and enter the pupa stage, where they reside for 1-3 months until spring by burrowing into the soil and finally emerging as the heel fly. d. Control: Apply a systemic insecticide to cattle as soon as the activity of the heel fly ceases and before they have reached the spinal cord, heart, or esophagus. This should kill the young larvae before they begin migrating through the tissues. 5. Coccidiosis a. A parasitic disease caused by protozoan organisms that affect the intestine. In poultry, this disease is considered the most serious chick disease in this country. It is important to note that each class of animals harbors its own species of coccidia; thus there is usually no cross infection between animals. b. Lifecycle: 1) The immature coccidia organism (oocyst) is passed in the feces. 2) This organism them matures in 3 - 5 days outside the animal and is then ingested in contaminated feed or water. 3) Coccidia mature in the epithelial cells of the intestine and go through several cycles of multiplication, damaging the intestinal lining and causing bloody diarrhea. c. Control: 1) It is difficult to control. 2) The most effective time of control is when protozoa are passed in feces; thus manure control, sanitation, and prevention of crowding is very important. 6. Stomach worms a. These parasites are found in rabbits, swine, and all species of animals, with each species having its own type of worm. b. The Lifecycle: 1) The adult worms live in the stomach of the host. 2) The eggs are passed in the feces and are consumed by the animal in contaminated feed or during coprophagy, (the consumption of feces). c. Control: 1) can be done anytime during the life cycle using using anthelmintics. 2) should always include proper disposal of manure. __________________________________________________________ ACTIVITY: 1. Have students use blank paper and colored pencils to draw the lifecycles of these parasites. Students should indicate on each drawing where the lifecycle can be broken.( This may be assigned as homework since it will take some time.) __________________________________________________________ B. Vaccination/Deworming schedule for a market lamb 1. Vaccination schedule depends on: a. The location - 1) Diseases may be more common in certain geographical areas or when related to certain management practices. a) White muscle disease or muscular dystrophy in lambs is a problem caused by a selenium deficiency. Therefore, in Northern California where the soil is deficient in selenium, lambs are given a Vitamin E/selenium vaccination shortly after birth. The ewe can be administered an injection before lambing. b) Tetanus or lock jaw is common in lambs that are docked or castrated and can be prevented by vaccination. b. The flock - 1) Sore mouth is a contagious viral disease that can be prevented by vaccination. However, if your lamb came from an unexposed flock and/or this disease is uncommon in your area, you need not be vaccinated against sore mouth. c. The feed - 1) Some lambs are fed a high grain ration which can predispose the lambs to specific problems. a) Bloat and scours cannot be vaccinated against; however careful feeding can prevent these problems. b) Enterotoxemia, (Clostridium pertrindens), is an example of a disease that all market lambs should be vaccinated against since it is a noncontagious disease that affects healthy lambs on good feed. 2. Deworming a. The schedule is affected by the environment. 1) Internal parasite infestation is more likely to occur when animals (such as lambs) are confined to the same area year after year. a) Pasture rotation is a method by which land areas used for grazing are systematically changed so lambs are not in one area for a prolonged period. b) Since the life cycles of many internal parasites involve stages in the environment, one way to effectively interrupt the lifecycle is to reduce exposure to the host (the lamb) by moving it to another pasture. 2) Low, wet, and humid conditions favor the development of internal parasites. (These are good environmental conditions for the out-of-body stages of the life cycle of the parasite.) 3) As a general rule of thumb, market lambs are usually dewormed twice: a) shortly after weaning, and b) again 4 - 8 weeks later depending on the environment. b. Methods: 1) Drenching is a method of giving liquid medicine to animals. a) Sheep may effectively be dewormed using this method. b) Drenching has the advantage in that the handler insures that all the drug goes directly into the digestive tract. This is not always true of pastes and especially dewormers which are added to the feed. The handler never knows if the lamb received the entire dosage. c) Dose syringes are best used for administering liquids (or even soda bottles in a backyard situation). d) Drenching involves restraining the lamb, holding the head level, inserting the mouth of the bottle or tip of the dose syringe over the tongue and slowly pouring the liquid down the animal's throat. e) Drenching can be very dangerous if done too quickly or by tilting the head up. The animal may inhale the liquid which can cause pneumonia if the liquid enters the lungs or even drowning. 2) Injectable solutions are another popular method of application since.they require little labor and are very effective; however, currently none are approved for sheep. 3) Pastes and boluses are also commonly used but dosage may be less accurate and thus less effective. (Paste is difficult to measure and administer accurately and a bolus comes in a "one-size-fits-all" which as an application may not be accurate enough either. 4) Feed additives: a) require the least labor, and b) are the least effective since heavily infested lambs may consume the least amount of feed. If they don't obtain enough treatment in the feed, the internal parts are not killed. C. Residue Withdrawal 1. Handlers must read all pharmaceutical warnings to determine the residue withdrawal time. 2. For most medicines, there is a specific withdrawal or waiting period before the animal can be slaughtered for human consumption, before becoming pregnant, on before it's milk can be sold for human consumption. D. Herd Health 1. Internal parasites are a herd and flock problem, not just an individual animal problem. All animals should be treated for the parasite problems if it is to be controlled. 2. Signs of internal parasites: a. anemia, b. pale mouth and eyes, c. dull coat, d. scours, and e. slowing of weight gain, or even loss of weight,. __________________________________________________________ ACTIVITY: 1. Have students develop an actual 6 month vaccination and deworming schedule for a market lamb. 2. Demonstrate the proper drenching technique. If possible and have students practice.the technique on live animals or in a simulation. __________________________________________________________ 5/10/90sg #%&C