De Worming - Parasite Control : WORMS
By AKKPS Member Debra Allen of Allen's Acres
Yuck. No one wants to think about worms, much less talk about them. But unfortunately, all responsible animal owners must, at some time, do just that.
This article will hopefully share information on the internal parasites affecting pigs and how to eradicate them. (External parasites like lice and mites have a separate article). Always remember your best source of information is always your vet.
Disclaimer: it is against the law in the US for a non-veterinarian to give off label advice on any medication including dewormers. Giving ‘Off label’ advice means making suggestions of how to use any medication for a different species of animal than listed on the label, or giving the dosage by a different route if administration(orally vs injection).
Fast facts
- Worm infections can negatively affect growth performance, reproductive success, and decrease carcass value and overall health.
- In-feed or injectable medications can be used for a successful deworming program.
- Anthelmintics vary in efficacy and spectrum of activity.
- An effective control program depends on the specific worm problem, stage of production, and type of production system.
- Anthelmintics are classified as drugs and their use is regulated by the Food and Drug Administration.
- Some species of worms are transmissible to humans
- Proper terminology is to use ‘deworming’ for the act of ridding an animal of parasites. Not ‘worming’.
Worms and other internal parasites of pigs
Worms are parasites that reside in the stomach and intestinal tract of the pig, causing irritation, impaction, indigestion and lack of appetite. Parasites cause loss of nutrients from feed consumed, by competing with the host, and by causing poor digestion, gut ulceration and even blood loss. Even small numbers of the large roundworm, Ascaris suum, can depress feed intake and daily gain and cause a depression in gain:feed ratio. Some worm parasites may be found in the lungs, where they interfere with respiration. This in turn may result in pneumonia. Others are found in the kidneys and other organs.
Parasite control, in addition to control of viruses and bacteria, must be part of a comprehensive herd-health program in every swine production system. Gastrointestinal worm infections may result in significant economic losses. Signs of infection are general and not readily apparent, since worm infections rarely cause elevated mortality levels. Some worms commonly found in pigs are roundworms (Ascaris suum), nodular worms (Oesophagostomum species), intestinal threadworms (Strongyloides ransomi), whipworms (Trichuris suis), kidney worms (Stephanurus dentatus), and lungworms (Metastrongylus species), and hookworms (Necator sp.)
Knowledge of the specific parasites present in the herd and their life cycle is helpful in establishing an effective control program. Prepatent period (Table 1) refers to the period between the time when the infection occurs and when the adult worms begin shedding eggs. Some worms produce eggs several days after infection, while others take months to begin producing eggs. Most anthelmintics are not able to destroy the egg and larval forms that develop into adults after several days. The interval for repeating deworming can be determined on the basis of the prepatent periods. Deworming must be repeated before the minimum prepatent period to kill the adult forms and prevent them from laying eggs.
Types of Parasites:
Large Roundworms
Most hogs have Ascaris infections during their lifetimes. These roundworms are usually found in greatest numbers in pigs up to 2 to 3 months of age with a few in older pigs. Sows usually are not clinically affected, but serve as carriers. Roundworms are long (6 to 12 inches), stout, pinkish worms, sometimes with curved tails. The adults live in the small intestine, grazing on the gut lining and ingesting particulate and liquid materials from digesting food.
The adult females deposit round, microscopic eggs. Each female lays thousands per day beginning about two months after the pig becomes infected. Eggs may survive for 10 or more years and are quite resistant to cold and disinfectants. They can be destroyed by high-pressure steam heat and sunlight. Because they are sticky, eggs are easily transported by cockroaches, beetles, flies, birds and workers' boots and clothing.
Eggs become infective after being outside the pig for one month. When another pig swallows them, they hatch in the stomach or small intestine. The tiny larva that emerges penetrates the gut wall and is carried to the liver through the bloodstream. In the liver, larvae migrate for one-half to one week and then are swept through the bloodstream to the lungs. From there, the larvae are coughed up, swallowed and returned to the small intestine, where they grow and mature within two months. Thus pigs may be 1-1/2 to 2 months of age before eggs can be detected in fecal samples, but immature adult worms may be passed earlier. The significance of this is that clinical signs may occur before eggs are detectable in feces.
Several clinical events may occur in the infected pig. They include:
- Inflammation of the liver due to an allergic reaction to ascarid larva migration.
- "Milk spots" on the liver that usually disappear with time.
- Another allergic reaction occurs in the lungs as larvae move through the air spaces.
- The lung tissue becomes thick and wet, leading to inefficient respiration and "thumps." This process is made worse by dust, ammonia and bacteria.
- Colic or gut pain may result from worms in the small intestine grazing or nipping forcefully on the gut lining and stretching the gut wall as the worms grow.
- An impaction and even tearing of the gut may occur.
- Slow Weight Gain – Parasites can irritate the intestinal tracts of pigs, leading to impaction or indigestion and a lack of appetite. Plus, the hog becomes undernourished because the parasites compete for nutrition. All of this leads to insufficient weight gain.
- Scouring – Scours can present with parasite loads, especially in young pigs.
- Poor Feed Conversion – Less nutrition gets to the hog because the parasites compete for nutrition, again leading to a lack of weight gain even though the pig eats regularly.
- Coughing (with no fever)– Some worms attach to the lungs, causing a cough. This can lead to respiratory illnesses such as pneumonia.
- Unhealthy Looking – A hog with untreated worms will show signs of lethargy, hunch over, have dry skin, and seem droopy. They could become anemic and look pale.
- Worms in Feces – If you examine the feces of your pig, you may see worms. They look like white strings in the feces. Keep in mind few worms can be seen with the naked eye and no worm eggs.
- Pneumonia
- Rough hair coat (in the case of large roundworms)
- Pendulous or swollen abdomens
A United States study in 1987 showed losses due solely to lowered feed conversion from low-level ascarid infections were $155 million. Certainly, losses were far greater when scarred livers and other infections are taken into account.
Your veterinarian can diagnose this infection by taking fecal samples for microscopic examination. Whenever a pig dies, your veterinarian should necropsy it to determine parasitic infections by presence of ascarids in the small intestine and by milk spots on the liver surface.
Whipworms
The whipworm Trichuris suis is slender, 2 to 2-1/2 inches long, and found in the cecum and upper large intestine. The slender head end of this small worm penetrates the gut lining, causing irritation and some blood loss. Females worms sporadically produce microscopic eggs in pigs 3 months of age and older. Eggs are infective and capable of surviving long periods in soil or on dirt- and feces-covered slatted and concrete floors. When pigs ingest eggs, infections remain in the intestinal tract of the pig and larvae do not migrate. There is a period of three months from the time of infection to passing eggs; bloody scouring may occur during this period as well as during egg production.
Nodular worms
The name "nodular worm" stems from the nodules produced by a larval stage of Oesophagostomum.These nodules are formed as a fibrotic host response in the walls of the cecum and colon in an attempt to wall off the larvae. Larvae that escape nodule formation emerge in the gut and mature into adults less than 1 inch in length. The microscopic eggs are passed in the feces and hatch outside the pig. They survive on pasture for up to one year. Pigs usually become infected with these larvae while feeding. The worms are confined to the gut. Condemnation of the large intestine or colon at slaughter is an economic loss when these are used for sausage casings. In the live pig, scouring may result from infection.
Threadworm
This tiny intestinal worm, Strongyloides, occurs commonly in baby pigs. The adults (females only) are practically microscopic and live in the wall of the small intestine. Microscopic eggs are passed in the feces of pigs as young as 4 days of age. Farrowing pens, dirt lots and pastures become contaminated; larvae that are hatched may be ingested in water and feed or may penetrate skin. Most importantly, these infective larvae may be passed in sow colostrum so that infection takes place at first nursing. Prenatal infections can also occur. Heavy infections may cause intensive scouring in neonatal pigs, resulting in acute dehydration. Protective immunity develops rapidly in pigs not overwhelmed by this early infection.
Kidneyworms
The kidneyworm, Stephanurus, is a short (1 inch), stout, black and white worm found in the fat around the kidney and sometimes in the kidney. Mature infections are found primarily in sows, since it takes nine months to one year after infection before eggs are produced by adult kidneyworms. Because infection occurs in and around the kidneys, eggs are passed in the urine.
Wooded lots and shaded farrowing pens often become contaminated areas where larvae hatch from eggs and enter the soil. Pigs may become exposed to infective larvae by ingestion, skin penetration and ingestion of infected earthworms. Larvae then move from the small intestine and eventually into the liver, where they remain for two to four months.
Other organs such as the lungs and spleen may also be infected. From the liver, larvae migrate to areas around and in the kidneys and even into back muscle. Most of the damage is found in the liver, which becomes heavily scarred, and in nearby muscle tissue. Outbreaks have occurred in southern Missouri with both breeding stock and market-weight pigs involved.
Lungworms
Photo: University of Pennsylvania
Lungworms, Metastrongylus, are short (1 to 2 inches), slender and white and occur in clusters deep in the respiratory tract (bronchioles). Eggs are coughed up, swallowed and passed in the feces. Lungworm eggs are ingested by earthworms, allowing easy exposure to hogs that root in the soil and eat infected earthworms. Larvae are circulated by the lymphatic system from the small intestine, through the heart and then into the lungs. "Thumping" or coughing with pneumonia is common in infected pigs. Pigs may pass eggs one month after infection. Pigs on pasture are at highest risk. Lungs should be dissected at postmortem to determine the presence or absence of lungworms.
Hookworms
Hookworms are small (less than 0.5 inches long) parasitic worms that can cause infections in the small intestines. The major species of hookworms associated with infections are Necator americanus and Necator suillus. They get their name from the teeth (“hooks”) or cutting plates in their mouths by which they attach themselves to the intestinal wall.
Hookworms are not as common in swine as in dogs and some other species (like camels), however historically, hookworm disease has caused the most devastation in humans. Please click link for a history of the disease in humans in the US.
Hookworms · USDA's Contributions to Veterinary Parasitology (click here)
It is still fairly common for visitors to tropical or subtropical vacation destinations to return home and later find themselves victims of a hookworm infestation. Feral swine that roam freely on beaches can deposit hookworm eggs in the sand. The larva burrow into the soles of human bare feet and eventually grow and migrate into the intestines.
Coccidia
Neonatal (baby pigs) coccidiosis caused by Isospora suis is found wherever pigs are raised in confinement. Clinical signs of yellowish or gray pasty to liquid diarrhea appear at 1 to 2 weeks of age with dehydration evident even though nursing continues. Infection occurs in cells lining the small intestine. Oocysts (microscopic egglike forms) are passed five days after infection. Oocysts mature in 12 hours in the farrowing crate, and disease and mortality are directly proportional to the number of infective oocysts ingested. There has been no good evidence that sows are carriers and pass oocysts to their piglets. The source for this coccidian is still not known.
The other coccidia, Eimeria, which are found in weanling and older pigs, apparently cause little or no damage. Differentiation of Isospora from Eimeria can be made microscopically by your veterinarian but coccidiosis in baby pigs is apparently Isospora only. Unfortunately, none of the anticoccidial drugs is effective against Isospora, but sanitation of farrowing areas by thorough cleansing can be successful in its control. Control is best achieved by:
- Thorough cleaning and sanitation between each farrowing
- Monitoring of movement of personnel and supplies
- Control of pests and rodents to reduce mechanical transmission of the oocysts.
Treatment
Anthelmintics or “dewormers” are chemical substances that can be added to pig diets or administered, to control parasitic infestations
When deworming your animal, there are a number of products available to use and most of these can be found at your local feed store or agriculture supply store. Deworming medication can be given via injection, orally (in the feed or water) and topically, although topical wormers are not very effective on swine, because they do not have enough hair follicles for absorption of the medication. It is important to evaluate each of these products to make sure you are using the best possible method for deworming your pigs. Below is a summary of some of the deworming products commonly found in feed supply stores and agriculture supply stores.
Safe-Guard (Fenbendazole)
- Is an orally fed product, which comes as a pellet when labeled for swine.
- Controls lung worms, stomach worms, nodular worms, round worms, and kidney worms.
- Safe-Guard pellets are meant to be top-dressed or mixed into swine feed and fed for a period of 3-12 days, depending on the rate at which it is mixed.
- There is no withdrawal time for the safe-guard product and it can be fed up to slaughter.
- Please note, Safe-Guard does not address external parasite issues (lice or mange).
- Safe-Guard comes in many different strengths. Only use the ones labeled for swine and read label directions carefully for directions on using or mixing. Many people find the directions confusing. Ask for help when in doubt.
Ivomec (Ivermectin)
- Can be found as an injectable, or oral (premix) at most stores. It can also be purchased online from animal supply companies like Valley Vet, PBS Animal Health, or Jeffer’s.
- Controls gastrointestinal (large roundworm, red stomach worm, nodular worm, thread worm) worms, lung worms, lice and mange mites in swine.
- Ivermectin injectable should be injected subcutaneous under the skin, in the neck of the animal.
- Withdrawal time is 18 days pre-slaughter for injected product or 7 days for the oral product.
Noromectin (Ivermectin)
- This product is the same as ivermectin, the label name is different.
- All of the above information for ivermectin applies.
- Withdrawal time is 7 days for the product when given in feed.
Dectomax (Doramectin)
- Is an injectable product labeled for swine.
- Controls round worms, lung worm, kidney worm, lice and mange mites.
- Dectomax should be injected intramuscularly, in the neck of the animals.
- Withdrawal time is 24 days pre-slaughter
- Causes less injection site pain than ivermectin.
- Because it’s injected IM, it’s often easier to give than ivermectin, which is given SubQ.
Wazine (Piperazine)
- This product is given orally and mixed with the animals drinking water.
- Controls round and nodular worms.
- Withdrawal time is 21 days pre-slaughter.
- Can be difficult to use in larger groups of pigs
Chart of dewormers indicated for swine:
The frequency with which you should deworm your pigs will vary depending on several factors.
It can be tough to establish a totally worm-free living environment. Pigs that are raised outdoors as well as those raised exclusively in confinement are equally susceptible to worms. Therefore, you will want to work closely with a veterinarian to come up with a worm management plant that will address all the needs of your pigs.
Adult pigs (those older than 12 months) should be treated with a dewormer on a twice-yearly basis. If you have a breeding herd of sows and gilts, you should worm them about two to three weeks before farrowing. This can prevent worms from spreading to newborn piglets.
Younger growing pigs require more frequent deworming than adults because they are more susceptible to damage from intestinal dog worms. Treat them when they’re six to eight weeks old – even if you wormed their mothers prior to farrowing – then once every two months.
How Do You De Worm a Pig?
Here are some tips to help you deworm your herd – the right way!
- Choose the Right Dewormer
There are many ways to deworm livestock, and for pigs, the most common methods are by oral or injectable options
There are also deworming feeds you can use. These complete feeds have all the nutritional requirements your pigs need to be healthy along with a dewormer added right in. These can be used as the sole ration to reduce the population of common parasites. Purina Nature’s Match Complete with Deworner is one product.
Once you decide on the form of dewormer you’d like to use, know that there are several different drugs that can be used. The most common are ivermectin (also known as Ivomec or Noromectin) along with fenbendazole (also known as SafeGuard).
However, Safe-Guard or fenbendazole, is especially approved for tapeworms, ascarids, and whipworms.
It is important to note that both ivermectin and fenbendazole are safe for pregnant or lactating pigs. Don’t deworm young piglets until they are at LEAST six weeks old.
- Administer the Dewormer
If you’re giving an injectable dewormer, you will need to check the instructions on the medication to make sure you have the proper dosage. You’ll also need your know your pig’s weight. Here’s an article on weighing Kunekunes:
Weighing KuneKunes (click here)
Usually if you’re administering with food it’s at roughly the same ratio, but again, check the instructions on the label to make sure you aren’t overdosing or underdosing your pigs. Underdosing deworming medication is one of the leading causes of worm resistance!
You may have to repeat doses, at 10-14 days apart. Be sure to check expiration dates on the medications you use, too.,
How do you decide whether you should go with an injectable or oral dosing system? It can be tough to decide.
Obviously, an injectable is good if you want to be able to know with 100% certainty that all of the medication was absorbed – if you go the oral route, there’s a chance that your pigs will spill some of the feed on the ground and miss some of the medication.
Here’s an article on how to give shots:
Giving Shots By Deb Allen (clcik here)
Monitor Your Pig
After deworming your pig, keep a close eye on them to make sure there aren’t any additional problems and that they are reacting well to the medication. You may see a large flush of worms coming out in the manure – that’s okay. It simply means your pigs are shedding the parasite load from their bodies.
If you aren’t sure that the parasites were eliminated, you can do a fecal egg count a week or so after you administer the dewormer.
Also, be aware that most chemical dewormers have withdrawal periods. This is important if you are raising pigs for meat. This is the amount of time it takes for a pig’s body to clear the medication from its tissues. You can’t take a pig to market until the medication has cleared.
Preventing Worms in Pigs
The easiest way to address worms is to prevent them.
Keep your barn as clean as possible. This can be challenging when you’re raising pigs, but cleaning out any old or used bedding from the pig pen can go a long way in preventing pig parasites. Scrape out and replace the bedding often to prevent infestation of your pigs.
Pig parasites can be spread in numerous ways, but the most common is through direct contact with another pig or the pig’s feces or mucus or urine. You may also find that your pigs pick up parasites when using a paddock that was previously inhabited by a pig that shed parasite eggs. Therefore, rotating pastures regularly is essential.
Parasites can even be spread via mechanical transfer methods, such as birds or rodents visiting the paddock with parasite eggs on their feet. Because of this, it’s a good idea, again, to keep the area as clean as possible. Remove spilled feed and messes promptly. Feed at dawn or dusk so the pigs can eat before birds start frequenting the paddock.
Organic parasite treatments
These items have been used in various ways to treat parasites in pigs. Research shows that all of these are very much less effective than chemical means, at worst ineffective and at best are weakly preventative and not effective for actual treatment of worm infestations. That’s why it’s included in this section on preventatives.
- Pumpkin seeds
- Garlic
- Apple cider vinegar
- Diatomaceous earth
- Cayenne pepper
- Charcoal
- Wood ash
- Various herbs
- Tobacco
- Ground cinnamon
Myths and Mis-Information:
No article about dewormers is complete without discussing the myths and mis-information propagated by social media, and some mini pig or pet pig groups.
Repeating this again:
It is against the law in the US for a non-veterinarian to give off label advice on any medication including dewormers. Giving ‘Off label’ advice means making suggestions of how to use any medication for a different species of animal than listed on the label, or giving the dosage by a different route if administration(orally vs injection).
There are other forms of the deworming medications mentioned above. In particular, ivermectin is available in other forms to control parasites in other species. Two such forms are the cattle pour-on and the ivermectin horse paste.
The cattle pour on is dangerous to pigs. Period. It can kill them. It can damage pig skin causing secondary bacterial infections, and/or permanent scarring. Don’t use it.
Horse paste is, by its make-up, not homogeneous. It’s designed to give large quantities to an animal that weighs over 1,000 pounds, and it doesn’t matter if the concentration of drug varies from gram to gram. Giving small quantities to pigs is guess work at best, often leading to underdosing. Underdosing means your animal may not receive an effective dose. Underdosing may also result worms developing resistance to the drug.
Another myth is that injectable dewormers can be given orally. Never do this. There is a long scientific explanation for why this is a poor choice. Short version…anything given by mouth goes thru what’s called “the first pass effect” where drugs are weakened by action in the liver, even before getting to tissues where it’s supposed to work, thereby reducing effective dose. In some cases, the dose is reduced to ineffectiveness. These facts have been corroborated by professors at veterinary universities and by swine specialist veterinarians.
In conclusion:
Coming up with an effective deworming plan is the most effective thing you can do to keep your pigs healthy. Inspect pigs carefully when introducing them to the herd and keep records of when and how your pigs were wormed last. Don’t forget to deworm new pigs during quarantine.
Worm control is an important component of every herd-health program. Many anthelmintics are effective against different types of worms. Therefore, selection of an appropriate anthelmintic will depend on the type of worm to be controlled. Also, use of anthelmintics must not be relied on as the sole approach in controlling worms, but must be combined with good sanitation and production practices to be successful.