Critical Thinking In Animal Science
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Critical Thinking In Animal Science

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    Critical Thinking In Animal Science Critical Thinking In Animal Science Document Transcript

    • 4/6/2010 CRITICAL THINKING IN ANIMAL SCIENCE Species: small ruminants Topic: parasite control SUSAN SCHOENIAN Extension Sheep & Goat Specialist Western Maryland Research & Education Center University of Maryland Extension sschoen@umd.edu - www.sheepandgoat.com WESTERN MARYLAND RESEARCH & EDUCATION CENTER Keedysville Washington County 491 acres Three units University of Maryland Extension 1. Administrative home for West region 2. Extension specialists 3. Ag experiment station 1
    • 4/6/2010 WESTERN MARYLAND RESEARCH & EDUCATION CENTER Research Education (Extension) Agronomy Ag marketing Forages Farm management Fruit Grapes and viticulture Horticulture Forestry/natural resources Small ruminants Nutrient management Viticutlure/enology Small ruminants WESTERN MARYLAND PASTURE-BASED MEAT GOAT PERFORMANCE TEST Established in 2006 to evaluate the performance of meat goats consuming a pasture-only diet with natural exposure to gastro- intestinal parasites. Up to 70 weanling male meat goats are tested per year. While on test, goats are evaluated for growth, parasite resistance (fecal egg counts) and parasite resilience (eye anemia scores and need for anthelmintic treatment). Early June – early October 2
    • 4/6/2010 CLASSIFICATION OF FARM ANIMALS By their digestive systems Monogastric Simple stomach Pigs and poultry (and people) Ruminant Cud-chewing 4 compartment stomach. - Cows, sheep, and goats Pseudo-ruminant (3 compartment stomach) - Alpacas and llamas Hind-gut fermenter Fermentation occurs in the caecum and/or large intestine Horses and rabbits SMALL RUMINANTS Sheep Goats Cervids (deer) Camelids (alpacas and llamas) 3
    • 4/6/2010 SHEEP AND GOAT PRODUCTION Meat Lamb/mutton Chevon/cabrito Fiber Wool Mohair Cashmere Dairy Milk Cheese Other Landscape management Goats – shrubs, trees, browse Sheep – weeds, grass Bio-medical/tech Research models Blood Pharmaceutical production SHEEP AND GOAT PRODUCTION World 1.93 billion sheep and goats China, Australia, India 6 percent of world meat consumption 3 percent of world fiber production 3.4 percent of world milk production United States 8.7 million sheep and goats Texas, California, intermountain states Less than 1% of livestock receipts in U.S. Per capita consumption of lamb is less than 1 lb. per person 4
    • 4/6/2010 SHEEP AND GOAT PRODUCTION IN MARYLAND 23,000 sheep Maryland Sheep & Wool Festival Maryland Wool Pool 14,900 goats 2,400 dairy goats < 6 certified goats/sheep dairies 12,500 meat/other goats Counties that raise the most sheep/goats are Frederick, Carroll, Garrett, Baltimore While there are some commercial and larger farms, most are lifestyle farms. Average producer has less than 30 animals. PARASITES – WHAT ARE THEY? An animal or plant that lives in or on a host (another animal or plant); it obtains nourishment from the host without benefiting or killing the host. A (generally undesirable) living organism that exists by stealing the resources produced/collected by another living organism. Parasitism is a type of symbiotic relationship between organisms of different species where one organism, the parasite, benefits at the expense of the host. 5
    • 4/6/2010 TWO KINDS OF PARASITES (ecto ecto) External (ecto) (endo endo) Internal (endo) EXTERNAL (ECTO) PARASITES Ticks Deer tick – lyme disease Ked - sheep tick Biting and sucking lice Mites Fleas Flies Nose bots Fly strike (maggots) Diseases with insect vectors Bluetongue virus Cache valley virus stillbirths and congenital abnormalities 6
    • 4/6/2010 SIGNS OF EXTERNAL PARASITISM Wool or hair loss Rough hair coat Itching Rubbing Scratching Skin discoloration Skin rash Tail wagging Distress Foul smell (wound) Visible signs of maggots Snotty nose Hold nose close to the ground Weight loss TREATMENT OF EXTERNAL PARASITES Insecticides Pour-on Sprinkle Spray Dust Dip (old-time, other countries) Some anthelmintics Macrocylic lactones only Ivermectin, doramectin, moxidectin Ivermectin is usually drug the of choice Organic treatments 7
    • 4/6/2010 FOUR KINDS OF INTERNAL PARASITES Nematodes (roundworms) Trematodes (flukes) Cestodes (tapeworms) Protozoa NEMATODES (ROUNDWORMS) Gastro-intestinal worms Lungworms Bunostomum sp. Dictyocaulus filaria Hookworm Muellerius capillaris Cooperia sp. Small intestinal worm Meningeal worm Deer / brain worm Haemonchus contortus Parelaphostrongylus tenuis Barber pole worm Nematodirus sp. Threadneck worm Ostertagia sp. Medium or brown stomach worm Oesophagostomum Nodular worm Trichostrongylus sp. Bankrupt worm, hair worm Trichuris ovis Whipworm 8
    • 4/6/2010 ROUNDWORMS ARE USUALLY THE MOST SIGNIFICANT HEALTH PROBLEM AFFECTING SHEEP AND GOATS Their grazing habits Sheep graze close to the ground. Goats are often forced to graze close to the ground (despite their preference for grazing high). Sheep and goats are often kept on small pastures with high stocking rates. Their fecal pellets disintegrate easily. They graze close to their feces. The primary parasite affecting sheep and goats is a blood-sucking killer! Haemonchus contortus (barber pole worm) ROUNDWORMS ARE USUALLY A MORE SERIOUS PROBLEM IN SMALL RUMINANTS THAN OTHER LIVESTOCK Immunity develops more slowly in small ruminants than other livestock. Females have relaxed immunity at the time of parturition. Few drugs are FDA-approved for small ruminants, especially goats. → The worms have developed resistance to drugs in all anthelmintic classes (more so than in any other species). ? Conflicting information. 9
    • 4/6/2010 LIFE CYCLE OF STOMACH WORMS BARBER POLE WORM Haemonchus contortus Lives in the abomasum (“true” stomach). Sucks blood from host animal. Clinical signs: anemia (pale mucous membranes), edema (bottle jaw), loss of body condition and weight, poor hair coat, lethargy, and death. 10
    • 4/6/2010 BARBER POLE WORM CONTROL: Pasture management Clean, safe pastures Pasture rotation/rest Minimum grazing heights > 3 inches Wait until dew has lifted before grazing Mixed-species grazing small ruminants cows, horses Alternative forages e.g. Sericea lespedeza Browsing Proper stocking rates BARBER POLE WORM CONTROL: other strategies Zero grazing Good sanitation Nutrition Protein supplementation Genetic selection Resistant breeds Hair sheep, Gulf Coast Native Kiko, Spanish, Myotonic Within breed selection The 80-20 rule 11
    • 4/6/2010 BARBER POLE WORM CONTROL Developed in South Africa: FAMACHA© = FAffa MAlan CHArt Selective deworming using FAMACHA© score plus . . . 1. Body condition score 2. Coat condition 3. Britch soiling/dags Evidence of scouring Consider host resistance • Species • Breed • Age • Status BARBER POLE WORM CONTROL: Fecal egg analysis Qualitative (simple fecal flotation) --of limited value. Quantitative (eggs per gram of feces) Modified McMaster technique (standard) → By itself, not a good indicator of the need to deworm. All strongyle eggs look the same (except nemotodirus) Different worms produce different numbers of eggs (barber pole worm is a prolific egg layer) What’s a high FEC varies by worm, season, and class of animal. Measure of pasture contamination. Do before and after fecal egg counts to determine drug effectiveness (resistance). 12
    • 4/6/2010 PROPER ANTHELMINTIC USE TREATMENT NOT PREVENTION 1. Dose according to weight. 2. Administer drugs orally (except Cydectin® injectable for goats). 3. Deposit drug into esophagus using oral dosing syringe with long, metal nozzle. 4. Higher doses for goats (except Cydectin® injectable for goats). 5. Deworm all new arrivals with drugs from two different chemical classes. 6. Do not dose everyone in the flock or herd. 7. Do not dose on a set schedule. 8. Test for drug resistance: FECRT - before and after fecal egg counts DrenchRite® / Larval development assay (LDA) WHAT ABOUT THE OTHER GI ROUNDWORMS? Usually secondary in importance. Usually part of mixed worm infections. Cause digestive disturbances, e.g. diarrhea. Same life cycle. Similar methods of control. Same anthelmintics. 13
    • 4/6/2010 LUNGWORMS Found in lungs and bronchial tissues. Some speceis require intermediate host (snails, slugs) to complete life cycle. Larvae are coughed up, swallowed, and passed in feces. Common in wet areas. Diagnose by fecal exam (first stage larvae in feces) and necropsy. Difficult to diagnose. Common anthelmintics are effective against lungworms. MENINGEAL WORM Parasite of white-tail deer Primarily harmless. Sheep, goats, alpaca, llamas, moose, and horses are unnatural hosts. Causes damage to central nervous system death. Snails and slugs are intermediate host. Larvae reach CNS 10-14 days after ingestion of snail or slug. Common in wet areas and where there are a lot of deer. 14
    • 4/6/2010 MENINGEAL WORM Diagnose based on clinical symptoms and necropsy. Many differential diagnoses. Treat with high, repetitive doses of anthelmintics and anti- inflammatory drugs. Ivermectin and fenbendazole are drugs of choice. Treatment may or many not be effective. Prevent by keeping sheep and goats away from snail and slug habitats and deer. CESTODES (TAPEWORMS) Host Moniezia sp. Intermediate host Echinoccus granulosus Hydatid disease Taenia ovis Ovine cysticerosis Sheep measles 15
    • 4/6/2010 TAPEWORMS – MONIEZIA EXPANZA Require an intermediate host (soil/pasture mite) to complete their life cycle. Mature tapeworms shed segments (proglottids), which are filled with eggs. TAPEWORMS – MONIEZIA EXPANZA Tend to be non-pathogenic. Tend not to cause any problems, especially in adult animals. Research shows no benefit to treatment. Extreme cases… Blockage in large intestines. Ill thrift and poor growth in young animals. Only certain dewormers are effective against tapeworms. Benzimidazoles Safeguard®, Valbazen® Praziquantel 16
    • 4/6/2010 TAPEWORMS – SHEEP MEASLES Sheep and goats serve as intermediate host. Do not affect health of sheep or goat, but can cause cysts in meat and result in carcass condemnation Not harmful to people Dogs (wild and domestic) are definitive hosts. Few symptoms in the dog. Control by deworming dogs and preventing dogs (wild and domestic) from eating carrion or raw meat. TREMATODES - FLUKES Common liver fluke Fasciola hepatica Lives in bile ducts Causes liver damage → death Similar symptoms as barber pole worm 2-3 month life cycle. Snail serves as intermediate host Common in wet climates: Gulf states, California, Pacific Northwest, and Great Lakes region. Diagnose by fecal analysis and necropsy. Treat with albendazole (Valbazen®) and clorsulon (Ivermec Plus) 17
    • 4/6/2010 PROTOZOA – SINGLE CELL ORGANISMS Eimeria spp. Coccidia Cryptosporidia sp. Giardia sp. COCCIDIA – EIMERIA SP. Species-specific. All adult sheep and goats have coccidia in their guts. Primarily affects weanlings. Caused by stress, overcrowding, and poor sanitation. Damages lining of small intestines; damage can be permanent. Subclinical or clinical disease Primary symptom is diarrhea (smeared with blood or mucous). 18
    • 4/6/2010 COCCIDIA – EIMERIA SP. Diagnose with fecal analysis and clinical symptoms. Difficult to diagnose because… Many causes of diarrhea Limitation of fecal analysis Not all coccidia are pathogenic. Significant damage can occur before oocytes are shed in feces. Clinically normal animals have oocytes in feces. COCCIDIA – EIMERIA SP. Prevent with good sanitation and management. Dewormers have no effect on coccidia. Prevent with coccidiostats* in feed, mineral, or water. Rumensin® Bovatec® Deccox® Corid Treat with Corid or sulfa drugs (requires veterinary rx). *Can be toxic to equines. 19
    • 4/6/2010 PARASITE CONTROL (GI NEMATODES) Complex problem. There is no magic bullet or recipe. Requires an integrated approach. animal - parasite - pasture Recent changes in philosophy . . . Treatment not prevention Control parasitism + manage drug resistance Requires critical understanding and thinking. Thank you for your attention. Any questions? 20