• Coccidia
  • Liver fluke
  • Lungworm
  • Roundworm


​Dictyocaulus viviparous is the specie of lungworm that infects cattle.  This is different from the donkey lungworm (Dictyocaulus arnfieldi).  The first thing to realize is that these are two different lungworms, cattle lungworms do not infect horses and donkeys, and vice versa.  However, cattle lungworms do infect llamas and alpacas.  

​Cattle ingest lungworm third stage larvae while grazing.  Once ingested, the larvae are able to pass through the intestinal wall and migrate to the lungs.  About one week after the initial infection, the larvae will break into the alveoli, the part of the lung where gas exchange occurs.  As the larvae develops, they will pass deeper into the lung tissue, migrating through the bronchioles, up through the bronchi and trachea.  This is where they will mature to the adult worm stage.  Female worms produce eggs which will quickly hatch into the first stage larvae.  This larvae will either travel up the trachea, or are coughed up, before being swallowed and passed through the digestive tract with the feces onto the pasture.  While on pasture, this larvae develops through third stage larvae where they are able to be ingested and restart the cycle.

Clinical signs may vary anywhere from mild to severe within any group of affected animals.  Animals who are mildly affected tend to only cough occasionally, especially under times of stress.  Moderately affected animals will cough even at rest.  Their breathing will be more labored and faster than normal.  Severely affected animals will develop a rapid, labored breathing and frequently exhibit the classic 'air-hunger' position with the head and neck outstretched.  These animals usually have a deep, harsh cough with frothy mouths and often will not eat.  Although some animals may die, most cattle will recover although a complete return to normality may take up to several months.  It is not uncommon for animals to develop deadly secondary infections however, as bacteria and/or viruses capitalize on opportunities to infect damaged tissue.  Even after animals recover, it is common for significant lung damage to impact their productivity and profitability.  

Contact Triple Oaks for simple prevention and vaccination programs.  Treatments are available for animals already infected.  Effectiveness depends on a quickly administering the drugs after a positive diagnosis.

Horn Flies

Horn flies are small, dark gray flies which feed on cattle and occasionally horses.  Both sexes are blood feeders, taking 20 or more blood meals each day.  Irritations from the bites annoy animals and occasionally, the wounds may become infected.  

Horn flies inflict the greatest effect on growing animals with weaning weights significantly less than those of animals protected from horn flies.  The same type of impact has been seen on yearling cattle.  Horn flies stay on animals almost continuously.  They're easy to identify as they characteristically rest with their heads pointing toward the ground and their wings held at a 45 to 60 degree angle to their bodies. During extremely hot weather or rains, they will move to the lower sides and underside of the animal.  They fly up in swarms when disturbed but soon return to an animal.  Females leave only to deposit their eggs on manure before returning to the animals.

Horn fly maggots develop only in cattle manure, and they do best in the grass manure of pastured cattle.  The life cycle of a horn fly is completed in 10 to 14 days, however each female can lay up to 500 eggs so very large populations can build up quickly.  During the winter months, horn flies remain dormant in the pupal stage beneath manure pads or in the soil and develop into adults in late May.  Without some type of fly control program, every animal in a herd may have several hundred horn flies by mid to late summer with bulls usually carrying the heaviest infestations. 

Several species of predator beetles feed on horn fly eggs and maggots in cattle droppings and may reduce horn fly production by more than 90%.  Conditions that quicken the drying of manure, along with activities of dung beetles also can provide some natural control.

Several insecticide application options are also available: insecticide ear tags, dust bags, concentrated pour-ons, animal sprays, and oral larvicides are available.  Ear tags, pour-ons, and forced use dust bags have consistently given the best control but other methods can be effective, too. The choice can be made based on what works best with pasture layouts and herd management practices.  

​Contact Triple Oaks for simple prevention and vaccination protocols.  


Parasitic roundworms, or nematodes, can be found year-round in cattle. These parasites live in many sites such as the lungs, body cavity, tear ducts, beneath the skin, and the gastro-intestinal tract.  Each area is occupied by roundworms specific to those sites.

Cattle host over 14 different species of gastro-intestinal roundworms. Different species live in different locations in the intestine. As there are usually just a few of these roundworms present, the harm they cause is not always immediately apparent and can be difficult to assess.

Eggs produced by adult roundworms pass through an infected host and pass through in the manure.  Within a few days, a larvae hatches from the egg, this is the first larval stage.  The newly hatched larvae develops through a second and third stage where it becomes capable of infecting cattle.  As cattle graze on infected pasture or drink contaminated water they become infected with larvae.  The larvae mature in the body of the host and mate.  Roundworms have a lifespan of approximately one year in cattle.  New generations of parasites quickly replace the previous year's adults.  

Roundworms can cause damage to cattle and your production rate.  Roundworms can puncture the small blood vessels of the abomasum and feed on blood.   If an animal is infected with large numbers it can cause anemia, poor growth and, occasionally, death.  Some roundworms, particularly the brown stomach worm, can penetrate into the wall of the abomasum. This causes damage to the glands producing the digestive juices necessary to break down food before it can be absorbed by the intestine. The damage may cause diarrhea, malnutrition and poor growth.

Symptoms may include loss of appetite, poor condition, scours, lethargy, and poor growth rate.  Prevention includes good pasture management and vaccination programs.  Contact Triple Oaks for simple prevention and vaccination protocols.  Treatments are available for animals already infected.  Effectiveness depends on a quickly administering the drugs after a positive diagnosis.

Bovine Parasites

  • Grubs
  • Horn flies
  • Lice

Liver Flukes

The liver fluke is a parasite which affects a range of livestock.  Grazing cattle, sheep, alpacas and deer are a few of the mammals who are susceptible to the liver fluke.  Herds grazing on low, wet areas are held at higher risk.

Liver flukes costs millions of dollars each year in lost production, stock deaths, and costs of treatment. Most of the economic cost is associated with production losses from infection.

In infected deer, adult flukes produce eggs within the bile ducts of the liver.  These eggs flow within the bile to the intestine.  There, the eggs are passed through the digestive tract with the feces.  Once passed, the eggs hatch in wet areas on the pasture.  Fluke larvae invade the snails which are the intermediate hosts.  Once inside the snail, larvae develop and multiply thousands of times.  The replicated, tadpole-like larvae leave the snails and encyst on vegetation.  This is the infective stage of liver fluke.

This is the point where the larvae is ingested by grazing animals. The young flukes penetrate the intestinal wall, make their way to the liver, and then migrate through the liver tissue for 6–7 weeks before entering the bile ducts to become adults.  Cattle are a "dead end host" for liver flukes.  Only deer will pass fluke eggs in their feces.  This means  infected cattle cannot infect other cattle, but animals grazing on the same pastures will ingest the fluke larvae deposited from deer.  

Disease can occur due to haemorrhage and tissue damage from migrating immature fluke and from damage to bile ducts and blood loss due to adult flukes.  Some symptoms include anaemia, jaundice, abdominal pain, loss of appetite, reduced growth rate, reduced milk production, reduced fertility, and death.

Unfortunately, liver flukes are not the only issue of concern with a liver fluke infection.  Secondary clostridial disease are a major concern for animals with liver flukes.  The damages made to the liver make animals much more susceptible  to these deadly disease.

Prevention through pasture rotation can be effective against flukes, as this prevents cattle grazing  down to the snail habitat. If possible, keep cattle from grazing on wet areas such as pond margins, river banks and marshy ground.  An appropriate deworming regime is also very effective.  Contact Triple Oaks for simple prevention and vaccination programs.  Treatments are available for animals already infected.  Effectiveness depends on a quickly administering the drugs after a positive diagnosis.

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Coccidia is not a bacteria, it is a single-celled parasite (known as a protozoa) which lives in the soil.  Coccidia causes coccidiosis, a disease of the intestines which causes damage to the cells lining the intestine resulting in diarrhea.  Coccidiosis is particularly common in calves between three weeks and six months, although it is seen in animals up to two years of age.  Young cattle become infected when living in environments contaminated by older cattle, or other infected calves.  Coccidial eggs require warmth and moisture to become infective, this commonly happens indoors on bedding or outdoors around feeding or drinking troughs.  Poor health, poor nutrition, poor hygiene, and high stocking density will all contribute to a calf picking up the parasites and acquiring the disease.  

Symptoms are not always specific to coccidiosis, however common signs are:

  • Diarrhea
  • Dysentery (blood stained feces)
  • Weight Loss
  • Poor Growth
  • Depression
  • Loss of Appetite

Death is rare, nevertheless, infections commonly result in reduced growth and weight gain.  Good management and proper hygiene is vital to achieve effective control of coccidia.  Young animals should be kept clean and dry; feeding and watering equipment should be cleaned regularly.  Avoid feeding cattle on the ground to prevent manure from contaminating the feed.  Pens with excessive moisture should be drained.  Try to keep grazing to a minimum in areas where cattle congregate (by the waterer) and avoid forcing animals to graze down the roots of plants to reduce the number of parasites consumed.  If possible, infected animals should be quarantined to avoid exposure to other animals.  Contact Dr. Matt to learn more or to set up a prevention plan.

Triple Oaks Equine LLC


Lice are small, flat-bodied insects with legs developed for grasping hair.  Lice can cause significant irritation for cattle, causing them to bite, scratch, and rub.  There are two types of lice:

Sucking lice
These have relatively small narrow heads designed piercing the skin and sucking blood. In large numbers they can cause anaemia. They are usually found around the head and neck of cattle
Biting lice
Biting lice have larger rounder heads. They feed on skin debris, blood and scabs. Despite being apparently less invasive than sucking lice, it is biting lice that produce the most severe irritation. There is one species of biting louse found throughout the world. It is a reddish-brown louse about 2 mm long with a brown head. It is mostly found on the neck, shoulders, back and rump.

The eggs (also known as nits) of both types are glued to individual hairs and hatch in about 14 days. The nymphs (immature stages) resemble the adults but are smaller.  The nymphs mature in about three weeks.  Once the adult stage is reached, lice can live two to three weeks and the females will lay about one egg per day. 

Cattle with a lice infestation will show signs of rough coats, raw skin, rubbing, hair loss, biting, and scratching.  They may cause damage to fences, yards or trees that they use as rubbing posts.  Lice can be an important cause of economic loss when cattle are in poor condition or if infestations are heavy. 

Insecticides can be used to treat infected cattle. However they may not be as effective on louse eggs. This means that after treatment, eggs can still hatch and continue the infestation. With some insecticides, a follow-up treatment 2–3 weeks later is necessary. This time interval is critical to achieve control, as it allows time for the eggs to hatch but not to mature into adults which will lay eggs themselves.  Different treatments and preventative measures are available including pour-ons, sprays, ear-tags or injection as well as basic bio-security to prevent outbreaks. 

​​Contact Triple Oaks for simple prevention and vaccination protocols.  

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Cattle Grubs (Heel Flies)

Cattle grubs or heel flies are large, robust flies similar in appearance to a bumblebee.  The adult female seeks out a host and attaches her eggs to the hairs on their hind legs.  The larvae then emerge and burrow under the skin of the host.  Cattle grubs are a major economic pest of cattle and cost the industry several million dollars each year in hide loss, decreased weight gain, tissue/meat damage and carcass downgrading. 

The eggs will incubate for 3-7 days on the hair before the larvae emerge.  The newly emerged tiny larvae crawl to the base of the hairs and penetrate through the host’s skin.  The larvae will spend 4-6 months burrowing through the connective tissues of  the host.  During the winter months the larvae will cluster either along the esophagus or along the spinal column, depending on the species of grub.  When spring arrives the larvae move away from the cluster to the back of the animal.  At this point each larvae will cut a small air hole in the skin of the host with which to breathe.   The larvae remain along the back until they finish developing.  Upon completing larval development, the larvae will crawl out of the hole and fall to the ground where they will transform into an adult fly.

Significant loss to the cattle industry due to damaged hides, reduced weight gains, lowered weaning weights, tissue/meat damage and carcass downgrading at slaughter and self-injury by panicked cattle running to escape females laying eggs.

Cattle grubs can be fatal to the host if treated for larval infestations at the improper time.  When treating for cattle grub infestations with a systemic product, it is unadvisable to treat when the larvae are clustered near the esophagus or the spinal column with a systemic product.  The ensuing death of the larvae can lead to tissue inflammation that could cause the animal to suffocate or become paralyzed.

Contact Triple Oaks for simple prevention and vaccination protocols.

The economic losses from parasite infections in cattle can be significant.  Calves under one year of age are of most concern since they have not developed any degree of immunity yet.  Keeping your whole herd healthy and parasite free will increase weaning and yearling weight and make your herd more profitable overall.

With proper preventive and treatment methods, cattle producers can control many common internal and external parasites. 

Common internal parasites include:

​​​Common external parasites include:

The lifecycle of most cattle parasites involves an adult worm producing eggs that are passed in the manure. The eggs hatch into larvae that develop and move up onto the pasture grasses where cattle consume them.  Eggs can survive the winter and hatch out with warm weather.  Infection is most likely to occur when temperatures are between 60° and 80°F and there is adequate rainfall.  Deworming prior to the grazing season will greatly reduce the contamination of pastures during the grazing season.  Cows dewormed in the fall usually have a higher conception rate the next breeding season, winter better and wean heavier calves.  Contact Triple Oaks to create the best parasite program for your herd.