Sick Pigs: 9 Illnesses (Bacterial, Viral, and Parasitic)

Praziquantel can be used to eliminate adult worms DLX2 Final

When I started a piggery on my farm, I had no idea how many diseases and illnesses my pigs were susceptible to contracting. I had to closely monitor my pigs to see if they presented with any warning-bell symptoms when they seemed off.

For peace of mind, I approached my local vet about common pig illnesses. She gave me some good tips on how to avoid certain diseases, what symptoms to look out for, and how to treat them. I wanted to be more hands-on with caring for my sick pig.

So when my 3-year-old piglets broke out in patchy lesions all over their skin. I had all the information from the vet, and I could identify the bacterial disease immediately and get the correct treatment for them.

What common illnesses do pigs suffer? Pigs suffer from bacterial, viral, and parasitic infections, such as roundworm infestation, leptospirosis, and foot-in-mouth disease. Diamond Skin Disease, Swine Dysentery, Porcine Rotavirus Infection, and Pseudorables are common to swine. Since some of these illnesses can be confused, it’s important to watch for specific symptoms. 

This will help you quickly provide them with the correct treatment for their condition.

Let’s take a closer look at nine common illnesses of a sick pig and the steps you should take to treat them. This guide includes pigs’ bacterial, viral, and parasitic diseases for easy reference.

Bacterial and Fungal Diseases of Pigs

Bacterial diseases are treated differently than fungal diseases. The medicines for either won’t work on the other illness. So, it’s important to treat your pig with the correct medicine. You may have treated the wrong illness if you don’t see improvement. 

1. Leptospirosis: Reproductive Illness (Zoonotic) 

Leptospirosis is a common bacterial disease that causes abortions, stillbirths, and reproductive issues in pigs. It is caused by spirochaetes (a group of spiral-shaped bacteria). Leptospirosis occurs mainly in adult pigs. Sadly within 1 to 4 weeks after infection with the bacteria, a pig can experience abortion or the birth of weak piglets that die soon after birth.

Pregnant sows are at high risk for this disease. The bacteria enter the body through the pig’s mucous membranes and cause infection within the uterus. 

Leptospirosis is zoonotic, which means it can spread to humans, domestic animals, and wildlife. It causes serious diseases such as Lyme disease and syphilis in humans (study). It can also cause symptoms similar to the flu: fever, headaches, sore muscles, chills, and vomiting. So take extreme care to handle infected pigs with gloves and wash your hands immediately!

Causes of Leptospirosis

Infected or carrier pigs shed the organisms in their urine, which can spread quickly to the rest of the herd. Leptospirosis spreads through contaminated food or water. 

Humans are infected by consuming uncooked pork products, drinking contaminated water, or handling carrier pigs. The bacteria spread through the air from the urine droplets of infected pigs. So cover your nose and mouth with an N95 mask when working with ill pigs.

Symptoms of Leptospirosis 

If your pig is infected, it will show signs of anorexia, fever, and lack of energy. If your piglets are infected, they show signs of jaundice (although it is rare for piglets to be infected). 

If your pigs are experiencing stillbirth or giving birth to weak piglets (also known as squeakers), they may be infected. Symptoms of Leptospirosis in Pigs include:

  • Stillbirths
  • Weak piglets
  • Loss of appetite
  • Mild diarrhea
  • Weight loss 

Treating Leptospirosis 

Administer oral antibiotics as soon as possible to prevent further spread of the bacteria. Blood transfusions may also be necessary in severe cases.

Have your pigs vaccinated with a multivalent bacterin (such as Lepto-Eryvac) every six months as a preventative? Make sure there are no rats in your pig’s living environment, as they are also carriers of this disease. Secure pig feeds to prevent attracting rats.

Ensure your pigs have access to clean water. Disinfect the pigs living area regularly with products that contain sodium hypochlorite. Unfortunately, no confirmed safe vaccine is available for humans yet, so preventing human infection is vital.

Leptospirosis is a common bacterial disease that causes reproductive issues in pigs DLX2 Final

2. Diamond Skin Disease (Erysipelothrix rhusiopathiae infection- Zoonotic)

Diamond skin disease, also known as swine erysipelas, is an infectious disease caused by the bacteria Erysipelothrix rhusiopathiae. Diamond Skin disease is a skin disease named after the diamond patches it leaves on the pigs’ skin. It causes fever, skin lesions, blood poisoning, arthritis, and sometimes, sudden death. 

Did you know?: 50% of the swine population carries this disease in their tonsils.

Swine erysipelas is zoonotic but can only pass to humans through cuts or skin punctures, so take care when handling raw pork. The bacteria infect all ages of pigs that don’t have a robust immune system. Pigs between three months to three years old are the most susceptible.

Unfortunately, this bacteria is resilient and can survive up to five days in contaminated drinking water and 35 days in sewage. Hygienic management of pigs is essential for prevention and treatment.

Causes of Diamond Skin Disease

Most diamond skin infections are caused when your pig ingests contaminated food, feces, or soil which causes the bacteria to grow in their gut or tonsils. 

Another cause of this disease is when pigs injure their feet or legs on damaged floor slates in their living space. Vector insects such as flies will then bite and feed on your pig’s open wounds, causing the bacteria to enter the pig’s body. foo

Symptoms of Diamond Skin Disease

Look out for these symptoms if you suspect your pig has Diamond Skin Disease:

  • Increasing fever
  • Slightly raised, diamond-shaped, purplish-red patches on the skin
  • Develops septicemia
  • Lack of energy
  • Painful joints
  • Anorexia
  • Vomiting
  • Diarrhea
  • Bristling of hairs where the lesions are going to form
  • Sudden death (in severe cases)

Treating Diamond Skin Disease

The most successful form of treatment is to administer Penicillin to your pig. Ask your vet for an antiserum to help with their symptoms in the early stages. Prevention is always better than cure, and it’s advised that you have your pigs vaccinated with a multivalent bacterin against this disease (such as Lepto-Eryvac) every six months.

3. Swine Dysentery 

Swine dysentery (SD) is a highly infectious disease caused by the bacteria Brachyspira hyodysenteriae. It causes diarrhea, often with blood in the stool. A loss of body weight, and listlessness, also accompany SD. This disease wreaks havoc on pig farms and is responsible for severe economic losses from infected herds (that must be isolated and receive costly medications). 

This organism thrives in cool and moist environments, and once the bacteria infects the pig, it breeds in their colon. The pig suffers from severe diarrhea and inflammation of the large colon. 

Humans aren’t affected by the Swine dysentery bacteria. However, they can carry the bacteria on their boots or clothing and pass it on to the pigs. Pigs of all ages can be infected with SD. However, it’s rarely seen in piglets under three weeks old.

Causes of Swine Dysentery

The leading cause of Swine dysentery is when pigs ingest contaminated feces. This bacteria can survive up to 2 months in moist feces. It’s essential to keep your pig’s living environment clean to avoid the spread of bacteria. Therefore, scrub your pig sties weekly with a strong disinfectant. 

Infected rats and mice can also carry this disease to your pigs. Other ways that this disease can be transmitted are by birds, flies, and mites. Carrier pigs can have the disease and spread it for almost 90 days.

Symptoms of Swine Dysentery

Pigs with swine dysentery often have wasting syndrome. They stop growing or lose weight, look lethargic, and may have blood in their stool. Pigs are often hunched, look haggard, and have sunken eyes or twitching tails. They will look ill. 

  • Yellowish-gray diarrhea that has a slimy coating or mucus
  • Fresh blood is present in the stool
  • Fecal material may ooze out of the anus and cover your pig’s hind legs
  • Twitching tail
  • Hunched over 
  • Haggard appearance
  • Sunken eyes
  • Loss of appetite
  • Severe cases can lead to sudden death

Treating Swine Dysentery

The infected pig or herd should be in quarantine for at least 30 to 60 days to avoid spreading the disease. Antibiotics such as Carbadox, Tiamulin, and Lincomycin need to be administered. Unfortunately, antibiotic resistance is increasing, which makes a long-term strategy difficult. 

Keep your pigs’ living area clean, and disinfect their pens regularly to avoid the growth of bacteria and further spread of the disease. Currently, there is no vaccine available for this disease. You will need to rely on antibiotics and preventative measures to keep this disease under control.

Treatment of Diamond Skin Disease involves administering Penicillin DLX2 Final

Viral Diseases of Pigs

Viral infections are harder to treat because viruses cannot be controlled by antibiotics. The pig’s own immune system has to overcome the virus. But, in some cases, the virus is often accompanied by a secondary disease

In that case, you may need to treat your pigs with antibiotics, not to cure the original disease but to reduce the risk of secondary illnesses to your pig. 

Here’s a closer look at three common viral diseases of pigs:

4. Porcine Rotavirus Infection (Zoonotic)

Porcine rotavirus is a terrible infection for pigs and humans. It causes major viral gastroenteritis, or severe watery diarrhea, in suckling and recently weaned piglets (one to five weeks old). It causes frequent death, high levels of sickness, and is very contagious. This particular disease plays a massive role in financial losses for pig farmers. 

Unfortunately, this virus is resistant to most disinfectants, making it difficult to remove the virus entirely from the pig sty. Porcine rotavirus is zoonotic and causes severe gastroenteritis in young children especially.

Did you know?: Rotavirus is named after the wheel-like appearance of the virus seen under an electron microscope.

Causes of Porcine Rotavirus Infection

The main cause and spread of Porcine rotavirus are when a large swine herd is infected with the virus. The virus continues to multiply and infect the pigs as they move amongst each other. 

Young and growing piglets are therefore exposed to the virus from their mothers or carriers through urine and feces. 

Other causes include unhygienic living areas,  sudden, drastic changes in temperature, and humans wearing contaminated clothing and boots

Symptoms of Porcine Rotavirus Infection

Porcine Rotavirus infections cause the following symptoms in pigs:

  • Watery diarrhea that persists for 3 to 4 days
  • Dehydration
  • The skin around the rectum is wet
  • Sunken eyes
  • Depression 
  • Anorexia
  • White or yellow feces
  • Extreme dehydration can result in death

Treating Porcine Rotavirus Infection

Suppose your piglet contracts the virus. In that case, antibiotic therapy (such as Amoxicillin) is given by injection, orally, or added to their drinking water to help fight off secondary infections.

Ensure that your pig has plenty of water and electrolytes, such as dextrose or glycine, to counteract dehydration. Use the All-in-All-Out management system to break the infection cycle among the piglets. This system keeps the piglets in groups. Once one group moves out, you disinfect the area and rotate the next group in. 

The best way to protect yourself against this virus is to ensure that you and your family have been vaccinated against it. Your pigs can also be vaccinated against Rotavirus.

5. Foot-and-Mouth Disease (Zoonotic)

Foot and mouth disease (FMD) affects pigs of all ages and is a highly contagious infection. Pigs with FMD develop lesions, or sores, in the mucosa of their mouths. They may also develop fluid-filled blisters on their feet. Pigs will develop a fever, become lethargic, and may become lame or die.

The viral infection FMD is a zoonotic disease that can infect humans (especially young children). The virus presents as sores in the mouth and rashes on the hands and feet. If your pig becomes infected, this is a notifiable disease and must be reported to the authorities as it can spread quickly. 

Humans contract the virus by ingesting unpasteurized milk or uncooked pork. Direct contact with infected animals also passes on the virus. The United States has remained Foot and Mouth disease free since 1929.

Causes of Foot and Mouth Disease

Domestic pigs that are infected with FMD can excrete more than 1,500 times more virus as aerosols into the atmosphere than an individual cow or sheep over 24 hours. Packed piggeries are the most significant cause of FMD outbreaks, as the virus spreads quickly. 

Did you know: Your pig’s saliva contains the highest virus concentrations, which is easily passed through drinking water to other pigs. A pig’s water trough becomes a giant reservoir of the disease.

Symptoms of Foot and Mouth Disease

Foot and mouth disease causes the following symptoms in pigs:

  • Lesions or blisters on the snout, tongue, or lips
  • Foot lesions
  • Sudden lameness
  • After 24 hours, the lesions will begin to burst
  • High-grade fever
  • Chomping of jaws
  • Lethargy and depression
  • Cardiac arrest in piglets

Treating Foot and Mouth Disease

Sadly there is no effective treatment once a pig has contracted FMD. Cull infected pigs to prevent further spread of the disease. Vaccination is vital to prevent your herd from catching this virus.

Unfortunately, vaccines for pigs are short-lived and only last about six months. There are different strains of FMD; therefore, vaccines must be multivalent (several sites). Administering these vaccines can become costly to farmers when FMD becomes prevalent in their area.

The best advice is to keep in contact with local farmers and veterinarians to ensure you find out quickly if FMD is spreading in your area.

6. Pseudorabies (Zoonotic)

Pseudorabies is also known as Aujeszky’s disease or the “Mad Itch,” and it is a DNA herpes virus that affects a pig’s respiratory, nervous, and reproductive systems. It causes high death rates, coughing, sneezing, circling, and a lack of coordination. It can cause paralysis, fevers, and difficulty breathing.  Young pigs are at high risk for catching this disease, and almost all piglets under seven days old that are infected die.

Pseudorabies hinders the body’s ability to process and destroy bacteria, resulting in death if not caught in time. Many studies consider Pseudorabies not to be transmittable to people, but at least one study has looked at the ability of the virus to infect humans. Pseudorabies disease always originates with pigs but is highly contagious to almost all other mammals and many birds.

There is no effective treatment once a pig has contracted FMD DLX2 Final

Causes of Pseudorabies

The Pseudorabies virus transmits through nose-to-nose contact or the ingestion of feces or contaminated manure. The virus is airborne. It can transmit as an aerosol for up to 1.24 miles (without strong wind).

This virus can also survive for almost 7 hours in drinking water, two days in feces, and three days in pelleted pig feed. This particular virus can also survive for four days in straw bedding.

Symptoms of Pseudorabies

Look out for these symptoms if you suspect your pig has pseudorabies:

  • Intense pruritus (itching skin)
  • Circling
  • Paralysis
  • Fever
  • Breathing difficulties
  • Coughing
  • Sneezing
  • Abortions
  • Stillbirth
  • Mummified piglets
  • Pneumonia

Treating Pseudorabies

There is no specific treatment for acute infections with the pseudorabies virus, but vaccination can help prevent the symptoms. It would be best to vaccinate all of the pigs in the herd with a modified live virus vaccine.

Vaccinations help reduce viral shedding and spread to other pigs. Luckily, the virus from the vaccine is spread at such low levels that it’s virtually impossible to transmit it. Regular vaccinations will help to control the disease.

Parasitic Diseases of Pigs

Parasites are usually easier to treat and can often be prevented or the effects minimized. Good husbandry is critical in maintaining healthy pigs. Here’s a closer look at three common parasitic diseases of pigs:

7. Roundworm Infection (Ascariasis – Ascaris Suum) Zoonotic

Ascariasis (Roundworm infection) is a parasitic disease that occurs when a pig is infected with roundworm (Ascaris suum). This can cause hepatitis and pneumonia. A mature roundworm (ascarid) is about 0.78 inches long with a round body and can lay up to 2 million eggs daily.

An adult roundworm can survive in a pig’s body for almost six months, and some survive longer than a year. A single pig can have an infestation of hundreds of roundworms in their intestines.

Roundworm parasites can spread to humans by accidentally ingesting soil or sand contaminated by infected animal feces (not washing hands and touching your mouth). Regular deworming of your pigs is advised so that people aren’t infected..

Causes of Ascariasis

Roundworm infection in pigs is caused by ingesting Ascarid eggs. Infected pigs, dust, pig manure, and insects transport the eggs. The most common infestation cause is contaminated feces in the pigs living area. 

Eggs hatch in the pig’s intestine once ingested. The larvae pass through the bloodstream to the liver and other sites. Once the larva arrives in the lungs (approximately 10 days later), they are coughed up and re-swallowed. 

The worms then lay further eggs in the intestine, and the cycle continues, and eventually, the pig has a roundworm infestation. The spread to other pigs occurs when farmers unknowingly place the herd in an infected area on the farm. 

Symptoms of Ascariasis

Ascariasis infestations cause the following symptoms in pigs:

  • The pig’s hair is rough
  • Battles to put on weight
  • Coughing
  • Lack of energy
  • The abdomen seems to be hanging
  • Appears hungry
  • Pneumonia
  • Severe infestations can result in death
  • Difficulty breathing

Treating Ascariasis

Medications such as Ivermectin (Ivomec) and Benzimidazoles can be administered to pigs through an injection to the neck. This medication paralyzes and kills the parasites. Add Hygromycin to the pigs’ feed.

Regularly deworming your herd is vital to prevent infestation and the spread of the parasites. Unfortunately, the eggs are resistant to disinfectants, and the most successful way to destroy them is by steam cleaning or prolonged exposure to full sunlight.

The Pseudorabies virus is airborne DLX2 Final

8. Trichinellosis (Trichinella Spiralis) Zoonotic

Another common parasitic disease in pigs is Trichinellosis caused by the parasite Trichinella Spiralis, found in warm-blooded animals worldwide. These parasites invade the skeletal muscles and muscle fibers around the pigs’ rib cage and their eyes. 

The disease is zoonotic and spreads to man when consuming infected or undercooked pork (the larva is encysted in the muscle of the meat). Trichinellosis can cause severe illness in humans, and it’s important to deworm your pigs regularly and your family if you keep a pet pig.

Causes of Trichinellosis

Female Trichinellosis worms can produce between 500 to 1000 larvae over a period of six weeks. The larvae will pass into their small intestine if your pig eats garbage or scraps containing infected meat. Another cause is when pigs bite the tails of infected pigs when playing or fighting. 

Once the larvae mature, they will mate, and the female worms will move into the lymphatics or leave the body through feces. Once the larva penetrates muscle fiber, it can live up to 11 years!

Symptoms of Trichinellosis

Look out for these symptoms if you suspect your pig has Trichinellosis:

  • Diarrhea
  • Vomiting
  • Sweating
  • Poor vision
  • Deafness
  • Extreme muscle pain
  • Noticeable decrease in weight
  • Dehydration

Treating Trichinellosis

The most effective way to treat Trichinellosis is to kill the parasites, preventing further infestation in your pig. Antiparasitic medications such as Mebendazole and Albendazole work well for treatment.

Cook any leftover meat or carcasses before disposal. Pigs love to scavenge and eat anything. Rats are also responsible for spreading this disease, so make sure your pig’s living area is rodent-free and hygienic. 

9. Taenia Solium (Pork Tapeworm) Zoonotic

Taenia Solium, also known as pork tapeworm or armed tapeworm, is a common parasite that affects pigs. The adult tapeworms are found in the small bowel of a pig and can reach a length of 26.24 feet. These parasitic worms can produce up to 50,000 eggs.

Tapeworm infestation is zoonotic, and humans contract it when eating poorly cooked pork.

Causes of Taenia Solium

The infection starts when pigs live closely together, where sanitation is questionable.

Pigs are infected with the parasite when they eat the parasite’s eggs through fecally contaminated food. Once ingested, the eggs will hatch, and the tapeworm will penetrate the intestinal walls and eventually go towards the pig muscles.

Symptoms of Taenia Solium

A few symptoms of Tapeworm infestation are:

  • Vomiting
  • Abdominal pain
  • Hunched over
  • Diarrhea
  • Loss of weight
  • Loss of appetite

Treating Taenia Solium

As a single dose, Praziquantel can be used to eliminate adult worms. Your vet will request a stool sample from your pig to verify if the treatment is working. 

You can also give your pigs a single dose of Niclosamide, which is four tablets. Give your pig four tablets to chew, one at a time, with a small quantity of water. Humans must take medication such as Biltricide to paralyze and kill the tapeworm. Vaccine studies are underway

Regularly deworming your herd is vital to prevent infestation and the spread of the parasites DLX2 Final


It’s critical to recognize and know the symptoms of pig illnesses. This can help you to save your herd and prevent an outbreak. Often acting quickly is essential to reduce casualties and expenses. 

If it wasn’t for the guidance and advice from my vet, I am sure I would have missed the vital symptoms my pigs were showing. At first, I thought my pigs had a viral disease, but I quickly realized it was a bacterial disease requiring very different treatment.

I was able to treat my pigs at the homestead, and they are now running around happily again. I am grateful that I now know the difference between the different types of illnesses, and I feel confident that I will administer the correct treatment for my pigs.

Talitha van Niekerk

Hi, I’m Talitha van Niekerk, and I made the leap to farm animal ownership when I decided to fulfil my lifelong passion to own horses. Now, over a decade later, I run a public stable facility on 180 acres of land, caring for over 75 horses of all breeds and sizes. I love to write about my experiences, sharing the knowledge I have gained and helping others achieve their life’s passion to live on the land. See my about page here.

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