Cattle drenching

Last updated
Angus weaners, approximately 6-9 months old, just taken off their mothers in Northern NSW Clarence Valley Angus weaners in Northern NSW Clarence Valley.jpg
Angus weaners, approximately 6-9 months old, just taken off their mothers in Northern NSW Clarence Valley

Cattle drenching is the process of administering chemical solutions (anthelmintics) to cattle or Bos taurus with the purpose of protecting livestock from various parasites including worms, fluke, cattle ticks, lice and flies. [1] Parasites hinder the production of cattle through living off their host and carrying diseases that can be transmitted to cattle. Cattle drenches can be applied through a solution poured on the back, throat or an injection. [1] [2] Cattle drenches are predominately necessary for young cattle with weaker immune systems that are susceptible to parasite infestation. [1] Drenching is a common method for controlling parasites in the meat and dairy industries. [1] Drenching cattle improves the health, condition and fertility of cattle leading to increased calving rates, weight gain, hide condition and milk production. [3]

Contents

Application of drenches

Pour-on (Back-spraying)

Pour-on drench is applied to the back of cattle and is the most common method used. [1] [4] The process involves a water-based chemical solution applied to the back of an animal through a squirting pump attached to a pack worn on the back of the operator. [4] The chemical then seeps into the skin on the back of the animal and into the bloodstream of the animal protecting and eradicating the parasites on the animal. [4] Pour-on options have now become the most popular option due to the speed of application allowing large numbers of to be processed quickly. [4] The amount of drench used depends on the weight of the cows; normally the drench is 1 or 2 mL per 10–20 kg. [5] Pour-on has, however, been one of the causes of increased resistance to drench products due to the process of back application which once dried allows flies and ticks to become accustomed to the chemical at a low effect level. [6]

Oral

The care of animals - a book of brief and popular advice on the diseases and ailments of farm animals (1905) (14782192692) Illustrating Oral Drenching The care of animals - a book of brief and popular advice on the diseases and ailments of farm animals (1905) (14782192692).jpg
The care of animals - a book of brief and popular advice on the diseases and ailments of farm animals (1905) (14782192692) Illustrating Oral Drenching

Using an oral drench gun attached to the back of the operator, anthelmintic chemicals which are in a pack worn on the back are administered down the throat of the animal. [1] [7] The operator must put the cows head in a head bail or crush and use one hand to pry open its mouth and the other to slowly release the drench into the throat. [7] Oral drenching can cause problems if the drench is administered to the wrong part of the throat causing the drench to go into the lungs. [1] This could potentially kill or make a cow seriously ill. The trachea leading to the lungs is located at the middle-back of the throat. [1] The oesophagus is in the back left and this is where the stomach is located and where the drench should be administered. [1] Care must be taken not to damage the tongue, gums or throat. [7]

Injection

Injection is applied through a syringe to the neck or shoulders of the cow. [1] [5] Depending on the type of chemical used it can either be injected into the skin or muscle of the neck. [5] The amount of drench used depends on the weight of the cows, but is usually between 2-5 mL. [5] No more than one dose should be administered, as two doses could lead to death or serious sickness. [5] Injecting cattle needs to be done carefully as irritation can cause large lumps on the side of the beast and be rendered ineffective. [5]

Cattle Parasites

Buffalo fly

The buffalo fly ( Haematobia exigua) is a very common pest among cattle producers. [2] The fly is a small blood sucking parasite that is widely considered the most serious health problem to cattle in warm and moist areas of the cattle industry. [8] Buffalo flies cause sores and ulcers causing large hide impairments on cattle as they rub themselves causing disturbances in feeding and hide quality reduction. [8] [2] Beef cattle can average a loss of 15 kg and dairy cattle 0.5 L of milk a day if untreated in a buffalo fly season. [8] Macrocyclic lactones and benzimidazoles in the form of pour on solutions are the most commonly used drench formula, however other drenches and fly tags are also used. [2] Buffalo flies impact cattle the most during spring-summer when temperatures are high and a wet summer will increase their impact due to prime conditions for breeding. [8] [2]

Cattle inspected for ticks Cattle inspected for ticks.jpg
Cattle inspected for ticks

Cattle tick

Cattle ticks ( Rhipicephalus microplus ) feed on cattle by burrowing into their hide and accessing their blood. [9] Cattle ticks also cause tick fever triggering anaemia, high temperatures, and weakness which can potentially lead to death. [9] [2] Tick fever is caused by the diseases Babesia bigemina , Babesia bovis , or Anaplasma marginale which are transmitted by cattle ticks. [10] The disease initially causes anaemia, licking and rubbing at bite sites (tick worry), tick sores, ulceration and lack of energy. [2] [10] Heavy infestations over a period of time lead to rapid weight loss and potentially death. [2] Bos indicus (tropical breeds) are less susceptible to cattle ticks and build resistance quicker than Bos taurus (European breeds). [2] Drenches are used as both a repellent and eradicator of ticks; however, in some cases they may not kill the tick or stop them taking the host. [9] [2] Cattle ticks are found most commonly in warm bush areas and are most prevalent in late spring to early summer. [2]

Liver fluke

Liver fluke ( Fasciola hepatica ) is a parasite which is part of the Trematoda family. The fluke lives inside a cow's liver after they have hatched in water or swampy areas and grown. [11] Liver fluke cause a variety of diseases and health issues due to their migration from the liver causing blood loss and liver failure. [2] [11] The diseases caused by liver fluke include acute fasciolosis (short term), chronic fasciolosis (long term) and Black disease ( Clostridium novyi ). The health impacts include anaemia, loss of appetite, bottle jaw and liver failure, which can result in death. [2] [11] Liver fluke is most commonly found in areas with high rainfall due to their natural habitat patterns. [11] Cattle can lose 0.7-1.2 kg per week from liver fluke depending on the level of infestation. [11] Drenches that target liver fluke include triclabendazole, nitroxyni l or clorsulon; however, only triclabendazole will kill fluke at all stages in their life cycle. [2] It is recommended to drench for fluke in winter-early spring as only adult liver fluke will be present. [2]

Lice

Lice are the most commonly treated parasite due to the quantity and rate of infestations once infest a herd. [12] Lice cause cattle to rub, bite and scratch, causing disturbances in feeding and loss of hide quality. [12] [2] There are four types of lice that occur on cattle: biting lice ( Bovicola bovis ), short-nosed sucking lice (Haematopinus eurysternus) long-nosed sucking lice (Linognathus vituli), and small blue sucking lice ( Solenopotes capillatus ). [2] Sucking lice cause the most issues as they pierce the skin and suck blood from the host, causing the most irritation and resulting in loss in weight gain, condition and nutrition levels, especially in winter. [12] [2] The use of macrocyclic lactones in many large cattle industries has decreased levels of lice infestation and is an effective treatment if cattle show signs of lice activity. [12] Lice are more prominent during winter months due to the longer hair and often worse condition of cattle resulting in easier lice infestations. [2]

Small brown stomach worm

The small brown stomach worm ( Ostertagia ostertagi ) is present in large numbers of herds in cooler, high rainfall areas and is linked to high levels of production losses in weaners and young cattle. [2] [13] Small brown worms do not feed on blood but damage the lining of the stomach as they reach adulthood. [13] In more severe cases they cause death, collapses, weight loss, damage and inflammation of the gut resulting in diarrhoea and scours. [2] [13] Macrocyclic lactones are the most common form of drenches used in the pour on form; however oral benzimidazole (BZ) drenches provide similar control. [2] [14]

Categories of drenches

Anthelmintic is any drug that acts to expel parasites mainly helminths from the host's body through either stunning or killing the parasite. [15] They aim is to expel the parasite without causing harm to the host. [15] There are a wide range of anthelmintic drugs that can be used however three classes are available for sale on the livestock market including Macrocyclic Lactones, Benzimidazoles and Levamisole. [15] [2] However, anthelmintic chemotherapy is costly and all major parasites in all major agricultural hosts have varying degrees of resistance worldwide. [16]

Macrocyclic lactones (avermectins and milbemycins)

Macrocyclic lactones (avermectins and milbemycins) are chemical products of soil microorganisms developed in the 1970s/1980s for cattle use. [2] Macrocyclic lactones offer a wide range of internal and external parasite protection. [2] They are a commonly used drench and this is due to their low impact on cattle production and ability to expel adult parasites through to immature parasites (larvae). [14] Macrocyclic lactones also exhibit relatively long periods of persistent activity within cattle this is good for a long feeding season but leads to increased resistance. [14] They have been open to for producers for over 40 years in the commercial form and continue to be effective in expelling parasites even with the increasing resistance issues. [14] Five types of macrocyclic lactones active ingredients are used: eprinomectin, moxidectin, ivermectin, doramectin and abamectin. [2] All five ingredients can be administered through easy to use pour-on solutions (Back Spraying) and some oral drenches. [2] Macrocyclic lactones offer an overall protection from most parasites and a longer period then other drench formulas. [2]

Benzimidazoles

Benzimidazoles are another chemical family which is effective in the eradication of some parasite infections with particular focus on nematodes and trematodes. [17] The original benzimidazole was thiabendazole; however, other, newer chemicals have been introduced with a range of commercial names. [2] All but one benzimidazole product must be administered orally which has led to their reduction in use as pour-on drenches are more popular due to their easy administration. [2] The active ingredients used are albendazole, oxfendazole, triclabendazole and fenbendazole. [2] [14] Triclabendazole is the most commonly used drench for controlling liver fluke; it kills liver fluke at all stages of its life cycle. [2]

Levamisole

Levamisole is another chemical that has more impact in expelling the adult parasites in livestock however exhibits less effective rates in reducing larvae. [2] Levamisole is available for administration by injection, pour-on and oral routes which offers a variety of choice which is found in the commercial chemicals. [2] Some products use levamisole in conjunction with other chemicals. [2] Levamisole is most commonly used to treat fluke and worms. [18]

Biological impact

The main biological impact of drenches is the expelling of any parasites, flies, worms and other insects which come in contact with the cattle drenched. [2] This, in turn, impacts the number of parasites in their habitat and such flies, worms and other insects ability to reproduce and impacts the role that they play in the ecosystem. [14] Some parasites are vital in protecting some animals from diseases and bacteria. [14]

In addition, the chemicals used to expel parasites are often still present in faeces that is excreted by cattle the impact of this on the environment comes in a few forms. Many dung dwelling insects are adversely affected by the process as dung is a habitat and full of minerals needed by animals. Some chemicals once excreted from cattle are poisonous to dung beetles resulting in reduced habitat, less feeding and mating grounds and even mortality of some dung beetles. If dung beetles are impacted then the role in fertilising the land and spreading cow dung will be decreased. [14] In particular, ivermectin from treated cattle is still present in their faeces which reduces the invertebrate colonisation of faecal pats in both numbers and diversity, thus hindering the natural breakdown process. [19]

Some chemicals used infiltrate the meat and can stay in the system of the animal for a period of time. The chemicals which are applied to cattle may potentially thus need a period of time where the owners cannot sell, butcher or transport the cattle. These withholding periods are needed due to this infiltration of chemicals into the meat of cattle which need time to break down the chemical residues. Cattle may also be under an export slaughter interval which means they can not be transported or slaughtered overseas for a period of time. The potential impacts of an early kill or even a natural death followed by wildlife eating the animal would see the meat sold permeated with the chemicals causing sickness or death. [20]

Resistance to drenching

Resistance to drenches occurs through a genetic feature of the parasite, fly or worm that results in minimal or zero impact by the drench. [6] Resistance to drenches first became known in the mid-1960s, however, widespread education was only used in the 1980s when farmers were educated on the unnecessary use of drenches in controlling parasites and to the need to create a wider range of drenches to stop resistance. [21]

Resistance to drenches has been controlled since however concerns about the build-up of these parasites with resistance in a colony is an issue. This occurs when the parasite survives and passes on their genes to the next generation. If the genetic selection becomes a major part of the gene makeup of the colony, then issues arise in controlling and new drenches must be manufactured. [6]

Resistance to drenching chemicals occurs due to over-drenching, under-dosing, long-acting treatments, low worm population treatment and consistent use of the same drench. Causing drench resistance is a common occurrence on smaller isolated communities and is an issue for agricultural industries that relies on clean cattle to trade. [6]

There are different management strategies to manage resistance to drenches including avoiding unnecessary drenching to older cattle, using shorter-acting drenches when possible and using the correct dose while varying the drench used year to year. [6] [21]

See also

Related Research Articles

<span class="mw-page-title-main">Fasciolosis</span> Parasitic worm infection

Fasciolosis is a parasitic worm infection caused by the common liver fluke Fasciola hepatica as well as by Fasciola gigantica. The disease is a plant-borne trematode zoonosis, and is classified as a neglected tropical disease (NTD). It affects humans, but its main host is ruminants such as cattle and sheep. The disease progresses through four distinct phases; an initial incubation phase of between a few days up to three months with little or no symptoms; an invasive or acute phase which may manifest with: fever, malaise, abdominal pain, gastrointestinal symptoms, urticaria, anemia, jaundice, and respiratory symptoms. The disease later progresses to a latent phase with less symptoms and ultimately into a chronic or obstructive phase months to years later. In the chronic state the disease causes inflammation of the bile ducts, gall bladder and may cause gall stones as well as fibrosis. While chronic inflammation is connected to increased cancer rates, it is unclear whether fasciolosis is associated with increased cancer risk.

<span class="mw-page-title-main">Ivermectin</span> Medication for parasite infestations

Ivermectin is an antiparasitic drug. After its discovery in 1975, its first uses were in veterinary medicine to prevent and treat heartworm and acariasis. Approved for human use in 1987, it is used to treat infestations including head lice, scabies, river blindness (onchocerciasis), strongyloidiasis, trichuriasis, ascariasis and lymphatic filariasis. It works through many mechanisms to kill the targeted parasites, and can be taken by mouth, or applied to the skin for external infestations. It belongs to the avermectin family of medications.

<span class="mw-page-title-main">Albendazole</span> Chemical compound

Albendazole is a broad-spectrum antihelmintic and antiprotozoal agent of the benzimidazole type. It is used for the treatment of a variety of intestinal parasite infections, including ascariasis, pinworm infection, hookworm infection, trichuriasis, strongyloidiasis, taeniasis, clonorchiasis, opisthorchiasis, cutaneous larva migrans, giardiasis, and gnathostomiasis, among other diseases.

<i>Haemonchus contortus</i> Species of roundworm

Haemonchus contortus, also known as the barber's pole worm, is a very common parasite and one of the most pathogenic nematodes of ruminants. Adult worms attach to abomasal mucosa and feed on the blood. This parasite is responsible for anemia, oedema, and death of infected sheep and goats, mainly during summer in warm, humid climates.

<i>Fasciola hepatica</i> Species of fluke

Fasciola hepatica, also known as the common liver fluke or sheep liver fluke, is a parasitic trematode of the class Trematoda, phylum Platyhelminthes. It infects the livers of various mammals, including humans, and is transmitted by sheep and cattle to humans all over the world. The disease caused by the fluke is called fasciolosis or fascioliasis, which is a type of helminthiasis and has been classified as a neglected tropical disease. Fasciolosis is currently classified as a plant/food-borne trematode infection, often acquired through eating the parasite's metacercariae encysted on plants. F. hepatica, which is distributed worldwide, has been known as an important parasite of sheep and cattle for decades and causes significant economic losses in these livestock species, up to £23 million in the UK alone. Because of its relatively large size and economic importance, it has been the subject of many scientific investigations and may be the best-known of any trematode species. F. hepatica's closest relative is Fasciola gigantica. These two flukes are sister species; they share many morphological features and can mate with each other.

<span class="mw-page-title-main">Triclabendazole</span> Chemical compound

Triclabendazole, sold under the brand name Egaten among others, is a medication used to treat fascioliasis and paragonimiasis. It is very effective for both conditions. Treatment in hospital may be required. It is taken by mouth with typically one or two doses being required.

<span class="mw-page-title-main">Moxidectin</span> Chemical compound

Moxidectin is an anthelmintic drug used in animals to prevent or control parasitic worms (helminths), such as heartworm and intestinal worms, in dogs, cats, horses, cattle and sheep. Moxidectin kills some of the most common internal and external parasites by selectively binding to a parasite's glutamate-gated chloride ion channels. These channels are vital to the function of invertebrate nerve and muscle cells; when moxidectin binds to the channels, it disrupts neurotransmission, resulting in paralysis and death of the parasite.

<i>Dicrocoelium dendriticum</i> Species of fluke

Dicrocoelium dendriticum, the lancet liver fluke, is a parasite fluke that tends to live in cattle or other grazing mammals.

<span class="mw-page-title-main">Levamisole</span> Chemical compound

Levamisole, sold under the brand name Ergamisol among others, is a medication used to treat parasitic worm infections, specifically ascariasis and hookworm infections. It is taken by mouth.

<span class="mw-page-title-main">Deworming</span> Use of anthelmintic drugs

Deworming is the giving of an anthelmintic drug to a human or animals to rid them of helminths parasites, such as roundworm, flukes and tapeworm. Purge dewormers for use in livestock can be formulated as a feed supplement that is eaten, a paste or gel that is deposited at the back of the animal's mouth, a liquid drench given orally, an injectable, or as a pour-on which can be applied to the animal's topline. In dogs and cats, purge dewormers come in many forms including a granular form to be added to food, pill form, chew tablets, and liquid suspensions.

<span class="mw-page-title-main">Anthelmintic</span> Antiparasitic drugs that expel parasitic worms (helminths) from the body

Anthelmintics or antihelminthics are a group of antiparasitic drugs that expel parasitic worms (helminths) and other internal parasites from the body by either stunning or killing them and without causing significant damage to the host. They may also be called vermifuges or vermicides. Anthelmintics are used to treat people who are infected by helminths, a condition called helminthiasis. These drugs are also used to treat infected animals, particularly small ruminants such as goats and sheep.

<span class="mw-page-title-main">Oxfendazole</span> Chemical compound

Oxfendazole is a broad spectrum benzimidazole anthelmintic. Its main use is for protecting livestock against roundworm, strongyles and pinworms. Oxfendazole is the sulfoxide metabolite of fenbendazole.

Paramphistomum cervi, the type species of Paramphistomum, is a parasitic flat worm belonging to the class Trematoda. It is a tiny fluke mostly parasitising livestock ruminants, as well as some wild mammals. Uniquely, unlike most parasites, the adult worms are relatively harmless, but it is the developing juveniles that cause serious disease called paramphistomiasis, especially in cattle and sheep. Its symptoms include profuse diarrhoea, anaemia, lethargy, and often result in death if untreated.

Amphistomiasis is a parasitic disease of livestock animals, more commonly of cattle and sheep, and humans caused by immature helminthic flatworms belonging to the order Echinostomida. The term amphistomiasis is used for broader connotation implying the disease inflicted by members of Echinostomida including the family Paramphistomidae/Gastrodiscidae ; whereas paramphistomiasis is restricted to that of the members of the family Paramphistomidae only. G. discoides and Watsonius watsoni are responsible for the disease in humans, while most paramphistomes are responsible in livestock animals, and some wild mammals. In livestock industry the disease causes heavy economic backlashes due to poor production of milk, meat and wool.

<i>Parascaris equorum</i> Species of roundworm

Parascaris equorum is a species of ascarid that is the equine roundworm. Amongst horse owners, the parasites are colloquially called "Ascarids". This is a host-specific helminth intestinal parasite that can infect horses, donkeys, and zebras. Horses up to six months of age are the most susceptible to infection. After this time, infection rates begin to decline and is extremely uncommon in horses over twelve months of age. It cannot infect humans or other animals. It is yellow-white in color, and females can become as large as 15 inches (38 cm) in length. Found worldwide, P. equorum is one of the most difficult equine parasites to kill, requiring larger doses of more powerful anthelmintic medications than are needed for other equine parasites.

<i>Cooperia oncophora</i> Species of roundworm

Cooperia oncophora is one of the most common intestinal parasitic nematodes in cattle in temperate regions. Infections with C. oncophora may result in mild clinical symptoms, but can lead to weight loss and damage of the small intestine, especially when co-infections with other nematodes such as O. ostertagi occur. Infections are usually treated with broad-spectrum anthelmintics such as benzimidazole, but resistance to these drugs has developed in the last decades and is now very common. C. oncophora has a direct life cycle. Infective larvae are ingested by the host. The larvae grow to adults, which reproduce in the small intestines. Eggs are shed onto the pasture with the faeces, which leads to new infections. Co-infections with other gastro-intestinal nematodes such as O. ostertagi and H. contortus are common.

Ostertagia ostertagi, commonly known as the medium stomach worm or brown stomach worm, is a parasitic nematode of cattle. O. ostertagi can also be found to a lesser extent in sheep, goats, wild ruminants, and horses. It causes ostertagiosis, which is potentially fatal in cattle. It is found worldwide and is economically important to cattle industries, particularly those found in temperate climates.

<span class="mw-page-title-main">Nitroxinil</span> Chemical compound

Nitroxinil is an anthelmintic, a veterinary medicine against parasitic worms in sheep and cattle. The substance is active against the liver fluke the Fasciola hepatica and to a lesser extent against thread worms in the gastrointestinal tract. Brand names include Fluconix, Dovenix and Trodax. Nitroxynil is also used against strains of the red gum worm that have become resistant to benzimidazoles.

<span class="mw-page-title-main">Beef cattle vaccination in Australia</span>

Vaccinations for cattle involves the process of applying subcutaneous injections of biological microorganisms in a weakened state to help the immune system develop protection by providing active acquirement of immunity to a particular disease. Cattle are bovine livestock and are thus very susceptible to diseases. Vaccinations for cattle are widely used in the livestock industries of the Australian agriculture sector by farmers to prevent harmful and deadly diseases from infecting their livestock, avoiding any economical or biological harm. Farmed livestock industries account for 45% of the gross value of Australian agricultural output, beef cattle being the largest farmed livestock nationally with around 26.2 million head of cattle nationwide. The beef industry within Australia generates a gross value of approximately $8 billion AUD in beef exports and a total gross value of $11.4 billion in farm production (2017–18). Thus, vaccinations play a vital role in protecting, sustaining and growing the beef cattle industry in the Australian agriculture sector.

Wolves may suffer from various pathogens, both viral and bacterial, and parasite, both external and internal. Parasitic infection in wolves is of particular concern to people. Wolves can spread them to dogs, which in turn can carry the parasites to humans. In areas where wolves inhabit pastoral areas, the parasites can be spread to livestock.

References

  1. 1 2 3 4 5 6 7 8 9 10 "VY-51". www.extension.purdue.edu. Retrieved 2019-05-21.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 "The Cattle Parasite Atlas". Meat and Livestock Australia. 17 May 2019.
  3. ↑ Priority list of endemic diseases for the red meat industries. North Sydney NSW 2059: Meat & Livestock Australia Limited. 20 March 2015. pp. 2–4.{{cite book}}: CS1 maint: location (link)
  4. 1 2 3 4 Fivetanimalhealth.com. (2016). Correct Methods of Drenching – Cattle | Fivet Animal Health. [online] Available at: http://www.fivetanimalhealth.com/management-articles/correct-methods-drenching-%E2%80%93-cattle [Accessed 2 Apr. 2019].
  5. 1 2 3 4 5 6 "Giving cattle injections? Do it right". Beef Magazine. 2016-10-31. Retrieved 2019-05-21.
  6. 1 2 3 4 5 "How does drench resistance come about?". WormBoss. Retrieved 2019-05-21.
  7. 1 2 3 "Drenching and mouthing". www.dpi.nsw.gov.au. 2018. Retrieved 2019-05-21.
  8. 1 2 3 4 "Farm Animal health Solutions & Livestock Products | Bayer Grow Solutions". www.growsolutions.com.au. Retrieved 2019-06-07.
  9. 1 2 3 Dpir.nt.gov.au. (2019). [online] Available at: https://dpir.nt.gov.au/__data/assets/pdf_file/0016/233143/721.pdf [Accessed 7 Jun. 2019].
  10. 1 2 "Tick fever of Cattle". www.dpi.nsw.gov.au. 2018. Retrieved 2019-06-07.
  11. 1 2 3 4 5 "Liver fluke". WormBoss. Retrieved 2019-06-07.
  12. 1 2 3 4 Dpi.nsw.gov.au. (2019). [online] Available at: https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0017/104066/Cattle-lice.pdf [Accessed 7 Jun. 2019].
  13. 1 2 3 "Brown stomach worm". WormBoss. Retrieved 2019-06-07.
  14. 1 2 3 4 5 6 7 8 "Macrocyclic Lactones - Pharmacology". Veterinary Manual. Retrieved 2019-05-21.
  15. 1 2 3 "Anthelmintic Drugs | Basic Concepts in Pharmacology: What You Need to Know for Each Drug Class, 5e". accesspharmacy.mhmedical.com. Retrieved 2019-05-21.
  16. ↑ Coltman, D. W.; Wilson, K.; Pilkington, J. G.; Stear, M. J.; Pemberton, J. M. (May 2001). "A microsatellite polymorphism in the gamma interferon gene is associated with resistance to gastrointestinal nematodes in a naturally-parasitized population of Soay sheep". Parasitology. 122 (Pt 5): 571–582. doi:10.1017/s0031182001007570. ISSN   0031-1820. PMID   11393831.
  17. ↑ "Benzimidazoles - Pharmacology". Veterinary Manual. Retrieved 2019-05-21.
  18. ↑ Berger, H.; Garces, T. R.; Wang, G. T.; Gale, G. O.; Steller, W. A.; Simkins, K. L. (January 1984). "Anthelmintic efficacy, safety, and residue evaluation of levamisole gel formulation in cattle". American Journal of Veterinary Research. 45 (1): 162–164. ISSN   0002-9645. PMID   6703451.
  19. ↑ Iglesias, L. E.; Saumell, C. A.; Fernández, A. S.; Fusé, L. A.; Lifschitz, A. L.; Rodríguez, E. M.; Steffan, P. E.; Fiel, C. A. (2006-12-01). "Environmental impact of ivermectin excreted by cattle treated in autumn on dung fauna and degradation of faeces on pasture". Parasitology Research. 100 (1): 93–102. doi:10.1007/s00436-006-0240-x. ISSN   1432-1955.
  20. ↑ "Chemical residues in livestock". www.agric.wa.gov.au. Retrieved 2019-05-21.
  21. 1 2 "Drench resistance - so what?". WormBoss. Retrieved 2019-05-21.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.