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Internal / External Cow Parasites

Parasites in Cows

Table of Contents

Internal / External Cow Parasites

What is the Parasite?

Internal / External Cow Parasites – According to the centers for disease control and prevention,

“A parasite is an organism that lives on or in a host organism and gets its food from or at the expense of its host”

How many Types of Parasites are there in Cows?

Mainly there are two types of parasites in the cow.

  1. Internal parasites.
  2. External parasites.

How many Types of Internal Parasites are There in Cows?

There are three types of internal parasites present within the cow’s body.

  1. Roundworms.
  2. Tapeworms.
  3. Flukes.

1.   Roundworms:

There are several species of roundworms worthy of consideration.

Haemonchus contortus, Ostertagia ostertagi, and Trichostrongylus axei are found in the stomach.

The intestines are inhabited by varieties of genus Cooperia, the ruminant hookworm called Bunostomum phlebotomum and the nodular worms ( Oesoghagostomum radiatum). All these worms have similar life cycles, even though they vary in size from almost microscopic to about 1 ¼ inches long.

Mature roundworms live in the digestive tract, and the eggs produced there are eventually passed in the host animal’s droppings. Warm, humid weather favors conditions, the eggs soon hatch into larvae that are able to infect a new host within two to six days.

The infected roundworm larvae are able to migrate a short way up the blades of grass, and there they lie in wait until they either perish or some unfortunate beast comes along and takes them into its mouth with the desired forage.

Some of the more daring species of immature roundworms can even burrow through a host animal’s intact skin to gain entrance to its body. The larvae continue to develop after this entry and, in three to four weeks, become adults in the gut of the new host. At this time they begin egg production and the life cycle is reestablished.

2.   Tapeworms:

Tapeworms-flat, segmented, ribbon-like creatures that may be three-quarters of an inch wide and several feet long are rather more complicated than roundworms.

Ruminant Tapeworm Species:

Tapeworm species whose adult stages are present in the ruminant.

1.    Moniezia expansa and M. benedeni.

Do relatively little damage to mature animals and cases of symptomatic disease caused by them.

The head of the adult tapeworm attaches to the lining of the intestine and each segment of the creature is a separate reproductive unit. As they mature, the terminal segments are full of eggs that break off from the main body and expelled by the host with its feces.

The eggs next must be eaten by a free-living oribatid mite that frequents most moist pasture areas. Larval development takes place within the mite and, if the infected mite is then consumed by a ruminant, the larvae mature in the gut of the new host and the process begins anew.

The larvae then penetrate the afflicted cow’s gut wall and are carried by its bloodstream to selected sites in the body organs or muscles, where they form cysts. These cystic stages called Echinococcus granulosus and Cysticercus tenuicollis take the form of fluid-filled sacs up to one inch in diameter.

A common name for the sacs is hydatid cysts and they may or may not cause symptoms, depending on their location in the body. A canine becomes the new host for Taenia echinococcus and T. hydatigena by eating tissues containing these cysts.

The so-called “beef tapeworm of man” ( T.seginata) has a similar life cycle involving cattle and people. Cattle are subjected to T.seginata cystic infection after exposure to the tapeworm’s egg in feed or water contaminated with feces from people who consumed the cysts in improperly cooked meat.

The widespread use of flush-toilets has practically eliminated this parasite, but it is possible that it could again become a problem in some rural settings where human wastes are not disposed of properly.

See Our Guide – Ways to Make Money Cattle Farming

Flatworms or Flukes:

Only three kinds of liver flukes occur in the continental United States.

1.    Fascioloides magna:

Fasioloides magna is a natural parasite of deer, elk, and moose in many of the states bordering Canada.

2.    Dicrocoelium dendriticum:

The lancet fluke occurs only in a small area in central New York State.

3.    Fasciola hepatica:

The common liver fluke is found in the southwest, the Gulf Coast, parts of the Southwest, the Rocky Mountain region and Pacific Coast states. Where it has been found to infect deer, cattle, sheep, goats, rabbits, swine, horses and humans.

Fluke Morphology:

Flukes are flat leaf-like creatures that range in size from one-half inch up to four inches in length.

Flukes have a fascinating and very complex life cycle. The adults live in the bile ducts of the ruminant’s liver and pass their eggs into the intestines where they are voided in the host animal’s droppings.

In water, these eggs hatch into a larval stage called miracidia, which will perish unless they find within a few hours. Inside the snail, the miracidia grow and multiply and finally emerge as an intermediate stage called cercariae.

The cercariae form cysts on submerged plates or other objects and enter their new host with contaminated plants or water.

Once in the body, the parasites then migrate through the tissues until they finally find their way to the liver to complete the cycle.

Flukes are often responsible for poor gains in young animals and in older animals that have been undernourished. The greatest economic loss is from the livers that are condemned at slaughter because of enlarged bile ducts and other damage.

External Parasites:

The major external parasites that can infest dairy cattle are insects and arthropods.

The insects are including:

  • Stable flies
  • House flies
  • Horn flies
  • Face flies
  • Lice.

The Arthropods are including:

  • Ticks
  • Mites

1.   Stable Flies:

These flies are probably the most important pests of dairy cattle; yet, they are often unrecognized by the dairy producer. Stable flies closely resemble common house flies but have bayonet-like piercing-type mouthparts that project from the front of their heads. They feed head up and low on the animal around the hocks trying to rid themselves of this aggravation.

2.   House Flies ( Musca domestica):

House flies pose a major threat around dairy operations because of their potential to transmit disease organisms.

These insects’ active behavior and omnivorous feeding habits make it possible for them to carry disease organisms from material such as manure and garbage directly into the milk room, milking parlor, or human dwellings.

The result can be contaminated milking equipment, milk, or other foods.

House flies have been implicated in the transmission of organisms causing bovine mastitis as well as several of the organisms that cause enteric disease in humans.

House flies have sponging type mouthparts that they use to feed on a variety of foods. They fed on solid foods by dissolving them with regurgitated liquids, a habit that further spreads in humans.

Horn Flies ( Haematobia irritans)

Small, gray-black, blood-sucking flies about one-half the size of house flies, horn flies are primarily cattle pests. Horn flies usually are resting on the shoulders or backs of the cattle. However, during extremely hot weather or rainy periods, they will move to the underside of the animal.

When feeding, horn flies characteristically orient themselves with their heads pointing toward the ground and with their wings held at a 45- degree angle. They stay close to the host animal, leaving only to lay eggs or to fly to another animal.

Horn fly maggots develop in fresh cattle manure. Female flies lay their eggs in manure within 2 min after they are deposited on the ground. The maggots develop best in the grass-type manure of cattle that are on pasture. Their life cycle is completed in 10 to 14 days.

Face flies( Musca autumnalis)

About the same size and appearance as house flies, face flies have sponging mouthparts and usually are feeding on mucous secretions from the eyes and noses of cattle. They also feed on saliva or on blood oozing from wounds.

Face flies usually are seen feeding on cattle. Their feeding, especially that around the eyes, is irritating to cattle and causes them to toss their heads in an effort to dislodge the flies.

Face flies transmit the following disease:

  1. Moraxella bovis
  2. Infectious bovine rhinotracheitis virus.

These are the causative agent of pinkeye.

Unlike horn flies, face flies feed only during daylight hours and spend only a small portion of their time on the host animal. The remaining time is spent resting on weeds, grasses, fence posts, and other vertical objects.

Face fly maggots also develop in freshly deposited cattle manure. Female face flies most readily are attracted to grass-type manure and lay their eggs within 15 min after they are deposited. The face flies’ life cycle takes about 15 to 25 days.

Controlling Flies with Ear Tags

Lice ( Haematopinus eurysternus):

Serious lice infestations tend to be a problem during winter months when cattle have heavy hair coats, drier skin, and are in closer contact with one another.

Cattle-biting lice, Bovicola Bovis, are yellowish-white with broad, reddish heads. Biting lice do not suck blood but use their chewing mouthparts to feed on hair, bits of skin, dried skin secretion, dried blood, or raw flesh around wounds. These lice irritate cattle by their feeding and by their movements over the animal’s body.

Suckling lice are the most damaging. These lice are slate-gray and have narrow heads. As their name implies, suckling lice use their piercing-sucking mouthparts to feed on blood.

The heavy population of suckling lice can remove enough blood from cattle to cause severe anemia. Animals thus infested are less productive and more susceptible to diseases. Calves can be killed by heavy lice infestations.

Ticks ( dermacentor spp., Amblyomma sp., Ixodes sp., Boophilus sp., etc)

Ticks are not insects, but they are blood-feeding parasites closely related to mites. All adult members of this class have eight legs, which distinguishes them from six-legged insects. Ticks further differ from insects in having an oval, compact body with no distinct division between the head region and the rest of the body. They lack antennae and wings.

Life cycle:

There is four-stage in the life cycle of ticks:

  1. Egg, 2. Six-legged larva or seed tick, 3. Nymph and 4th is an adult.

Larvae, nymphs, and adults obtain food by piercing the skin of the animals and sucking blood. Eggs are laid on the ground, not on the host animal. Different species of ticks are referred to as being one, two, or three-host ticks, depending on how many animals the ticks parasitize during the life cycle.

A single animal can be infested with literally thousands of these pests causing severe blood loss and consequent reduction in the animal’s productive capabilities.

Ticks used as the vector for transmitting the following disease in cattle:

  1. Taxes cattle fever
  2. Bovine anaplasmosis
  3. Babesiosis etc.

Mites ( Psoroptes sp., Sarcoptes sp., Cborioptes sp., Demodex sp.,)

Mites are usually microscopic in size and are eight-legged as are the ticks to which they are related.

The mites of most common concern to cattlemen are the skin parasites that cause mange and scabies. These mites live on or in the skin and may cause skin lesions, which are irritating to the host.

The severity, the parts of the animal attacked, and the type of skin reaction varies, depending on the type of mite and the kind of host animal.

Heavy infestations of mites can be severely debilitating to dairy animals causing drastic reductions in milk flow.

How can I find if my Cow is Suffering from Worms:

There are the following signs which help you to find the worm infestation of your cow:

1.   Bottle Jaw ( sub-mandibular edema)

Swelling under the jaw results from severe barber’s pole worm and liver fluke infections. The loss of blood results in anemia and less protein in the blood. This imbalance in the normal body fluids results in fluid accumulating under the jaw in some, but not all, affected animals.

2.   Ascites:

Abdominal swelling due to fluid occurs as a result of liver damage associated with liver fluke. Like bottle-jaw, it is the result of low protein in the blood causing body fluids to be out of balance and fluid to build up in the abdominal cavity.

3.   Coughing and Pneumonia:

The large lungworm infects the airways of cattle and causes the production of a frothy mucus that will cause the animal to cough; there may also be a nasal discharge. In heavy infections pneumonia( inflammation and infection in the lung tissue) may be evident, accompanied by rapid breathing.

4.   Lethargy and Collapse:

Lethargy and weakness can result from a severe infection of many worms. Liver fluke worm infections it is due to anemia and the lack of red blood cells to carry oxygen required for muscle function.

5.   Weight loss from decreased appetite:

Affected animals with worms lose weight and with severe infections can become emaciated and ultimately die. Worms burdens result in less muscle growth, and less milk produced by lactating cows.

6.   Damage and Inflammation of the Gut resulting in Diarrhea:

The presence of worms initiates a strong immune response from the host animals that damage the lining of the gut resulting in diarrhea. This will result in a loss of protein from the gut and lowered absorption of nutrients, in turn, this adds to weight loss.

With severe infections, animals can become emaciated and die.

7.   Potbelly:

The worms-infested cow will have a potbelly.

See Our Guide – Ways to Make Money Cattle Farming

How can I find if my Cow is Suffered from External Parasites?

There are the following symptoms that tell you that your cow is infested with external parasites.

  1. Mites cause mange. They infect the head, legs, body or tail region causing the skin to become crusted and cause loss of hair and wool. The infected area itches and the animal’s scratches.
  2. Lice also cause irritation of the skin and the animal scratches, rubs and bite the infected areas. The host loses, or does not gain weight, and looks in poor condition.
  3. Ticks are very important parasites. They bite the host and suck its blood and when full drop off onto the pasture where they can live for many months without feeding again. Animals can be poisoned or paralyzed by the bites of some ticks.

Treatment, prevention, and Control of Worms in Cattle:

  1. Treatment strategies:

The worm challenge on every farm is different and changes every year. Treatment plans should take into account unique factors such as farm location, disease history, current season/weather, and the type and age of stock.

General Use Wormers:

Deworming with one of several anthelmintics(wormers) approved for use in cattle is an effective preventive practice. Consult your veterinarian concerning strategic worming; timing the deworming to be the most cost-effective.

There are the following dewormers that are used for deworming:

Controlling Cattle Parasites

1.    Fenbendazole:

Fenbendazole is available as a stable suspension or granules. It is effective against roundworms in the gut, larval forms in the tissues, and lungworms. The withdrawal time to slaughter is 8 days.

2.    Ivermectin:

Ivermectin for cattle is an effective medication against internal worm parasites including lungworms as well as cattle grubs and sucking lice. It is available in injectable or pour-on formulations. The withdrawal time to slaughter is 35 days.

3.    Levamisole:

Levamisole is available in boluses, a paste for oral administration, as a pour-on or an injectable form.

Levamisole is effective against roundworms and lungworms. The withdrawal time is 2 days(orally) and 7 days ( injected).


Thiabendazole is available in paste or suspension. It is effective against all intestinal worms including tapeworms, and lungworms as well as liver flukes.

It has 27 days of withdrawal for slaughter. Not use in the first 45 days of pregnancy.


Oxfendazole is a new wormer that is effective against intestinal parasites including tapeworms. This wormer has injected directly into the rumen.

Prevention and Control Measures:

The various control strategies applied, on the host and of the host with or without chemicals will be useful for the sustainable production of farm animals as per agro-climatic conditions.

Housing Management:

  • The animals having good living conditions resist or tolerate better against internal parasites as compared to animals kept under poor housing conditions. The animal shed must be well ventilated and lighted to maintain the required humidity and air circulation.
  • Always keep the optimum number of animals in the animal shed as overstocking in animal shed causes a large number of livestock populations to have parasites at a time.
  • Feeders that cannot easily be contaminated with feces should be utilized for grain, hay, and minerals feeding.
  • Water should be clean.

Nutritional Management:

  • Type of diet and availability of vitamins, minerals, and other nutrients are directly related to the susceptibility of the animal to the parasites. Vitamin A, D and B complexes are essential in developing immunity against parasites.
  • Minerals like zinc, iron, cobalt, sodium, potassium, phosphorus, etc. are very essential for the proper functioning of immunological phenomena going inside the animal’s body to develop functional immunity against parasites.

Pasture Management:

  • Regular burning of old or grazed pasture should always be practiced to obtain parasites free pasture land.
  • Overstocking of animals in a small piece of land increase the concentration of parasite. So, allow the optimum number of animals to graze in a given piece of land.

Pasture Rotation and Rest:

Pasture rotation or intensive grazing is optimum use of grass by distributing the pasture into parcels of land of varying sizes called paddocks and frequently moving the livestock from one paddock to another.

The main objective of pasture rotation is not to put the animals back into the same field until the risk of infection has diminished.

Theoretically, this means that parasitism will decrease if the number of parcels of land and rotation time is increased.

The rest of 3-6 months is required for an infected pasture to return to a low level of infectivity.

As the density of parasites is generally at a maximum in the rainy season and at a minimum in the summer/winter, it is preferable to limit grazing to the summer/winter months to diminish the level of ingestion.

The risk of infection is greatly lowered by allowing animals to graze only dried grass and not wet grass.

Treatment, Prevention, and Control of External Parasites in the Cow:

Controlling Parasites Naturally

Homemade Treatment:

Homemade Tick and Insect Repellent:

Try this simple recipe.

  • 9 drops citronella essential oil
  • 6 drops tea tree essential oil
  • 6 drops peppermint essential oils
  • 1 tablespoon almond oil or jojoba oil.

Eucalyptus Oil:

Eucalyptus oil is known as an effective tick repellent and killer. It just combines 4 ounces of purified or distilled water to a small spray bottle along with 20 drops of eucalyptus essential oil. Shake before using and spray on skin, pant cuffs, and shoes.

Neem Oil:

Neem oil is used as a natural remedy to repel and remove ticks. To use, add several drops to the palm of your hand and rub on exposed skin. It can also be diluted and mixed with almond or other light carrier oil.

Eat Garlic:

we all know that garlic has excellent health benefits, and now we can add one more to the list. Regular consumption of garlic or garlic capsule reduces the risk of tick bites and tick-borne diseases.


There are different medicines that are used to treat external parasites.


Ivermectin is probably one of the most widely used antiparasitic drugs worldwide, and its efficacy is well established.

It is neurotoxic to parasites by potentiating glutamate-gated chloride ion channels in parasites. Paralysis and death of the parasite are caused by increased permeability to chloride ions and hyperpolarization of nerve cells.

Ivermectin is highly effective against many arthropod parasites of domestic animals such as ticks, biting flies, and parasitic dipteran larvae.

Doramectin 1%:

Doramectin is indicated for the treatment of gastrointestinal roundworms, lungworms, sucking lice and mange mites in cattle.

Ivermectin and Closantel:

It is indicated for the treatment of mixed trematode and nematode or arthropod infestations due to gastrointestinal roundworms, lungworms, eyeworms, warbles, mites, and lice of cattle.

Preventive Action:

  • Seal with cement or mud all cracks in the floor and walls of livestock housing.
  • Keep housing clean each day.
  • Spray housing with appropriate pesticides every two weeks if possible.
  • Rotate the land where livestock graze.
  • Wash animals regularly.
  • Make ash from dry neem leaves, mix into a paste with water and smear this on the animal every two weeks to prevent parasites.

Control Methods:

A number of different control methods are available to prevent and/or treat ectoparasites.

These control methods can be broadly split into chemical or cultural. Here we are discussing only the chemical methods for controlling the external parasites of the livestock.

These are:

1.    Cypermethrin:

It is a synthetic pyrethroid, indicated for the treatment and control of ectoparasites like ticks, mites, midges, all types of flies and lice in livestock.

Cypermethrin is recommended to be applied as spray or dip in the following dilution.

Cattle 1.5ml/liter of water.

2.   Diazinon 60%:

It is an organophosphate and used topically to control ticks, lice, mites, flies,

Mode of Action:

Neuromuscular paralysis of ectoparasites.

Animals Spray dilution Dip dilution
cattle 1:1000 1:1000

Amitraz 12.5%

Amitraz is the only formamide used topically to control the external parasites such as ticks, mites, and lice on cattle.

Recommended Usage:

For cattle, it is recommended 1- liter amitraz per 500 liters of water for dipping and spraying