PIG Diseases

Question 1

How do you treat Erysipelas?

Answer 1

penicillin

Question 2

You are called to a farm to check some pigs that have severe respiratory problems and are not responsive to antibiotic treatment. These pigs are housed in an outdoor facility and are about 9 to 10 weeks old. The pigs have been vaccinated for PCV2 and Mycoplasma hyopneumoniae. What should be one of your top differentials?

Answer 2

The correct answer is Ascaris suum or the swine roundworm. A. suum larvae travel through the liver and into the lungs causing verminous pneumonia which is usually not responsive to antibiotics as the worm larvae continue to do significant lung damage. Raising pigs outdoors is a significant risk factor for roundworm infestation. PRRS does cause respiratory problems, but usually the secondary bacterial infections are controlled with antibiotics. None of the other parasites listed cause pneumonia. Trichuris suis is the pig whipworm, Oesophagostomum dentatum is the nodular worm, and Stephanurus dentatus is the kidney worm.

Question 3

A group of 3 month old pigs presents for soft yellow diarrhea in some and hemorrhagic diarrhea in others. They continue to eat well, but they are losing weight and are lethargic. Necropsy of one animal shows thickened intestines and curved bacteria inside enterocytes. What is the most likely diagnosis?

Answer 3

The correct answer is Lawsonia intracellularis infection. Lawsonia intracellularis is an intracellular Gram-negative bacillus anaerobe that causes soft buttery stool in some and acute hemorrhagic diarrhea in others. This disease most commonly occurs in weaned and older pigs. Weight loss is the most consistent sign, and the lesions are as described in the question. This disease is considered to be similar to Johne’s disease in cows. The other answer choices all more commonly cause diarrhea in unweaned and young piglets.

Question 4

A 2-month old pig is presented for evaluation of lesions on the ventrum. You find multiple raised circular lesions. You tell the farmer that you suspect the lesions will resolve without further treatment. 3 weeks later, he returns, thankful that his pig has gotten all better. What condition did the pig have?

Answer 4

The correct answer is pityriasis rosea, a disease of unknown cause. Pityriasis rosea occurs in pigs 3-14 weeks of age and is characterized by raised circular lesions on the ventral abdomen. Pityriasis rosea resolves on its own in a few weeks without any treatment.

Question 5

How do you treat diamond skin disease?

Answer 5

Penicillin for acute cases; cull chronic cases

Question 6

Fusobacterium necrophorum commonly contributes to which of the following diseases in young pigs?

Answer 6

The correct answer is necrotic rhinitis. Fusobacterium necrophorum is a gram negative anaerobe that causes hepatic abscesses in cows, gastroenteritis in ruminants, foot rot in pigs and ruminants, and metritis in cows. Pleuropneumonia in pigs is caused by Actinobacillus pleuropneumoniae. Necrotic rhinitis is a sporadic disease of young pigs in which they undergo necrosis of the snout when F. necrophorum enters a wound in the nasal or oral mucosa.

Question 7

At what age are piglets normally weaned on North American commercial swine farms?

Answer 7

The range throughout the world tends to be slightly greater at 14 to 28 days.

Question 8

You have been called to a large farm that just lost 60 pigs overnight. You decide to perform some necropsies to get a better feel for what is going on. How many pigs should you necropsy?

Answer 8

The correct answer is to keep necropsying dead pigs until you see a general pattern of what system(s) may be affected. Although untreated, acutely affected, euthanized pigs are the best for diagnostic sampling, since decomposition can distort or make difficult to identify some gross pathology, many times recently dead pigs can still provide enough information to help guide in figuring out what is causing the mortalities.

When dealing with large populations of animals you must be able to differentiate individual pig problems from population problems, therefore you need to necropsy more than one dead pig. It is not efficient to necropsy all pigs or even just select 30 head. Doing only 10 head may or may not provide you with a true picture of what is going on in the whole herd.

Diagnostic sampling (including correct animals to sample) and live pig evaluation will also be important in helping you figure out what may be causing the high mortality on this farm.

Question 9

Which of the following is the most common mode of transmission for Strongyloides ransomi in pigs?

Answer 9

The correct answer is transcolostrally. Strongyloides ransomi are threadworms of pigs. They reside in the small intestine of suckling piglets. Pigs may not show any clinical signs with only light infections. Heavy infections can cause diarrhea, anemia, emaciation, and death. Diagnosis can be made by fecal flotation, by an intestinal mucosal scraping, or on necropsy. Benzimidazoles and ivermectin are effective in treating these worms. (Earthworms are the intermediate hosts of the kidney worm of pigs, Stephanurus dentatus, and the lungworm of pigs, Metastrongylus spp.)

Question 10

Which organism causes reproductive failure in pigs by an ascending infection of the reproductive tract?

Answer 10

The correct answer is E. coli. Other infectious agents that ascend the reproductive tract causing a metritis and reproductive failure in pigs include Streptococci, Staphylococci, Actinomyces spp., Pseudomonas spp., etc. The other answer choices listed cause reproductive failure via systemic infections. Other systemic agents causing reproductive failure include PRRS, pseudorabies, brucellosis, etc.

Question 11

You are investigating a case of high mortality in 14 week old pigs. You are suspicious of Porcine circovirus associated disease (PCVAD). What sample do you need to submit to a laboratory to confirm your diagnosis?

Answer 11

The correct answer is lymphoid tissue for histology. A diagnosis of PCVAD requires 3 parts:

1) at least a doubling of mortality (clinical history)
2) demonstration of lymphoid depletion (histopathology)
3) high number of PCV2 antigen in the lesion (immunohistochemistry on tissue)

Question 12

What is the approximate gestation length of pigs?

Answer 12

The correct answer is 115 days. A useful way to remember this is “3 months, 3 weeks, 3 days”.

Question 13

While working as a meat inspector you encounter a pig liver with several “milk spots”. This is grounds for condemnation of the liver, which can be of substantial economic impact. After asking around, you are able to obtain a fresh fecal sample from a live pig. You perform a fecal flotation (see image). What is your diagnosis?

Answer 13

The correct answer is Ascaris suum. This is a round worm and as part of its life cycle, it will migrate through the liver and cause characteristic “milk spots” which appear as subcapsular white spots on the liver.

Trichuris suis is a whipworm and has a characteristic double-operculated egg appearance. Isospora suis is responsible for coccidiosis in young piglets. Strongyloides ransomi is known as the thread worm in pigs and infects the pig by entering through the mucosa of the mouth. Lesions may be seen in the liver but are typically more prominent in the lungs.

Question 14

Fusobacterium necrophorum commonly contributes to which of the following diseases in young pigs?

Answer 14

The correct answer is necrotic rhinitis. Fusobacterium necrophorum is a gram negative anaerobe that causes hepatic abscesses in cows, gastroenteritis in ruminants, foot rot in pigs and ruminants, and metritis in cows. Pleuropneumonia in pigs is caused by Actinobacillus pleuropneumoniae. Necrotic rhinitis is a sporadic disease of young pigs in which they undergo necrosis of the snout when F. necrophorum enters a wound in the nasal or oral mucosa.

Question 15

Which of the following is a reliable indicator of estrus in a pig?

Answer 15

The correct answer is the sow stands while being mounted by a boar. The sow may allow mounting by other sows or try mounting other herdmates during both proestrus and estrus, but she will only allow mounting by a boar while in estrus. Increased vocalization and rooting occur during estrus as well, but they are not as reliable as indicators.

Question 16

A group of 3 month old pigs presents for soft yellow diarrhea in some and hemorrhagic diarrhea in others. They continue to eat well, but they are losing weight and are lethargic. Necropsy of one animal shows thickened intestines and curved bacteria inside enterocytes. What is the most likely diagnosis?

Answer 16

The correct answer is Lawsonia intracellularis infection. Lawsonia intracellularis is an intracellular Gram-negative bacillus anaerobe that causes soft buttery stool in some and acute hemorrhagic diarrhea in others. This disease most commonly occurs in weaned and older pigs. Weight loss is the most consistent sign, and the lesions are as described in the question. This disease is considered to be similar to Johne’s disease in cows. The other answer choices all more commonly cause diarrhea in unweaned and young piglets.

Question 17

A group of 3-day old piglets are huddled together in the farrowing house shivering. What disease should you suspect?

Answer 17

The correct answer is Escherichia coli. This question may seem vague but this is the kind of information you need to know. E. coli is most likely to occur at less than 5 days of age and sometimes from 7-14 days. Rotavirus often occurs in association with E. coli. TGE is a severe disease in piglets with 100% mortality in pigs less than 2 weeks of age; the most striking feature is the wet and dirty appearance of the litter due to profuse diarrhea. Salmonella is uncommon in piglets due to passive immunity from colostrum. Lawsonia is a slow growing organism and affects mostly older pigs and usually causes gradual wasting and diarrhea.

Question 18

Vesicular exanthema of swine affects swine and which other animals?

Answer 18

The correct answer is sea lions. Vesicular exanthema of swine is called San Miguel Sea Lion Disease in sea lions. It is caused by a calicivirus and affects swine, sea lions, several types of seals, and other marine mammals. Vesicular exanthema is not present in the USA, but San Miguel Sea Lion Disease is present in marine mammals off the coast of California. The disease is reportable.

Question 19

This 2-year old pot belly pig in the picture presents for eating a box of cooking salt. It is very thirsty at presentation, but otherwise clinically normal. Its blood sodium concentration is 175 mEq/dl. What is the best treatment for this pig?

Answer 19

The correct answer is to administer Normosol R IV slowly to decrease the blood sodium concentration. Salt poisoning in pigs occurs as a consequence of water deprivation (reduced amount of free water in the animal), or too much salt intake. When the blood sodium concentration is too high, water from the brain diffuses into the vasculature. The brain responds by forming hyperosmolar (idiogenic osmoles) particles to draw water back into the brain to prevent dehydration of its cells. Giving large amounts of free water in the form of drinking water or as a bolus of D5W intravenously will quickly drop the blood sodium concentration, causing a large amount of water to diffuse into the brain cells due to the hyperosmolar particles formed. Cerebral edema then ensues and neurologic signs result. Treatment should be aimed at slowly decreasing blood sodium concentration by about 1 meq/hr to prevent cerebral edema. This is best done by using a replacement fluid that approximates normal levels of sodium so as to not create too large of an osmotic gradient. Pigs showing clinical signs of brain disease usually die despite treatment.

Question 20

Which of the following is true about eperythrozoonosis in pigs?

Answer 20

The correct answer is it is often associated with anemia, fever, icterus, and reproductive failure. Eperythrozoonosis in pigs is caused by Mycoplasma suis (previously called Eperythrozoon suis), a disease vectored by biting insects. Clinical signs include anorexia, weakness, anemia, icterus, and reproductive failure. Younger pigs are more severely affected than older pigs. The treatment of choice for the disease is tetracycline antibiotics. Vaccines are not available for the disease.

Question 21

A litter of 2-week old piglets are presented for incoordination, salivation, opisthotonos, and seizures. You suspect pseudorabies and perform virus isolation to confirm your diagnosis. How will you treat these piglets?

Answer 21

The correct answer is there is no treatment for these piglets. Currently, all commercial US swine production is free of pseudorabies and therefore a confirmed diagnosis would require the immediate depopulation of the herd. Mortality in piglets this young with pseudorabies is near 100%. Piglets less than 3 weeks of age infected with pseudorabies often die in 1-3 days. Clinical signs include fever, anorexia, vomiting, blindness, convulsions, and neurologic signs. Pigs 3-9 weeks old have similar signs but their mortality rate is much lower. They also commonly show respiratory signs such as sneezing, nasal discharge, and coughing. Pigs older than 10 weeks infected with pseudorabies are more commonly affected with respiratory signs but may show CNS signs. Most of these pigs will recover in 7-10 days. Pregnant sows infected with the virus have reproductive failure including abortion, fetal resorption, and fetal mummification.

Question 22

You are visiting a swine farm in Oklahoma with no other known swine farms located within a 5 mile radius. The pigs weigh about 220 pounds (100kg). They are from a sow farm that has been testing negative for porcine reproductive and respiratory syndrome virus (PRRS) for the past 2 years. The pigs were doing quite well until 3 days ago when they started coughing. Today, over 90% of the pigs seem to be coughing. You take rectal temperatures of 5 clinically affected pigs and they all have temperatures greater than 105 degrees F (40.6 C). There is some sneezing and you note nasal discharge in over 60% of the pigs. This nasal discharge varies from clear to thick and white. What should you recommend?

Answer 22

The correct recommendation is to treat all pigs with oral antibiotics for 5 days. The rapid spread of the disease (90+% in just 3 days) and the high fevers are the classic clinical presentation of a swine influenza outbreak. Although antibiotics do not treat the viral infection, secondary bacterial infections almost always occur in conjunction with swine viral respiratory infections (porcine respiratory disease complex; PRDC). Prompt treatment for secondary bacterial infections is critical, and with 90+% animal affected, all animals need to be treated. The white nasal discharges support a bacterial component.

It is unlikely that PRRS is involved, since the pigs are from a negative sow farm and are well isolated from other pigs. Vaccination is not a good option at this time because all pigs are already affected (already naturally vaccinated). It is also important to note these pigs are large (220 lbs) and some pigs will be going to market in just 2 to 3 weeks, thus there is concern with vaccine slaughter withdrawal (usually at least 21 days for vaccines) as well as minimal time for any vaccine benefit.

Question 23

Which of the following organisms has been associated with spirochaetal colitis in swine?

Answer 23

The correct answer is Brachyspira pilosicoli. B. hyodysenteriae is the causative organism for swine dysentery. Lawsonia intracellularis causes ileitis. Trichuris suis is the porcine whipworm. Salmonella Typhimurium is associated with button ulcers in the colon.

Question 24

A herd of pigs is presented for multiple 1-2 cm round papules, pustules, vesicles, and scabs on their ventral abdomens. Young and growing pigs are most severely affected. What is the most likely diagnosis?

Answer 24

The correct answer is swine pox. The disease is caused by a pox virus that causes the skin lesions described in the question. All ages can be affected, but it is more commonly seen in young and growing pigs. The disease is often transmitted by biting insects, particularly lice. The disease usually does not require treatment, unless the lesions become secondarily infected. Broad-spectrum antibiotics may be helpful in this situation. Hog lice and insect vectors should be investigated and eliminated to help control swine pox. Erysipelas causes diamond-shaped skin lesions and necrosis of the ears and tail. Greasy pig disease or exudative epidermitis is caused by Staphylococcus hyicus. It causes dark, greasy, brown skin lesions in the axilla, groin, head, and face. Pseudorabies affects the CNS, respiratory system, and causes reproductive failure.

Question 25

A litter of 4 day old piglets presents for bloody diarrhea. Necropsy of one dead piglet reveals hemorrhagic and necrotic enteritis. There are many large gram positive rods in mucosal smears indicative of a Clostridium perfringens infection. What are the morbidity and mortality rates of Clostridium perfringens type C in piglets?

Answer 25

The correct answer is high morbidity and high mortality. Clostridium perfringens type C enteritis usually occurs in neonatal piglets less than 7 days old. The disease causes bloody diarrhea and is usually fatal. In acute outbreaks, some piglets may be found dead even before developing hemorrhagic diarrhea. The signalment, history, and clinical signs are suggestive of a diagnosis. Clostridium perfringens type C enteritis also occurs in neonatal lambs, calves, foals, and poultry.

Question 26

Testing for Classical Swine Fever can be complicated by the presence of which of the following viruses in swine?

Answer 26

The correct answer is Bovine Viral Diarrhea (BVD). Although BVD virus does not usually cause disease in pigs, pigs do get exposed to the virus and seroconvert. Both BVD and CSF are Pestiviruses from the family Flaviviridae. Antibody production in pigs to BVD can cross react with some CSF assays. This can create some problems because CSF is considered a foreign animal disease in the U.S.

Question 27

Transmission of brucellosis in pigs is often via which of the following routes?

Answer 27

The correct answer is venereal transmission, and through aborted fetuses. Pigs are often infected by ingestion of infected aborted fetuses, fetal membranes, and fluids discharged during abortion. Infection can also occur through infected semen via natural breeding, or poorly planned artificial insemination. Transmission is also possible through broken skin and mucous membranes.

Question 28

Which of the following is the most effective treatment for a leptospira infection in a growing pig?

Answer 28

The correct answer is long term use of tetracyclines. Vaccinations are usually only used in the breeding herd where bacterins, containing the appropriate serovar, can reduce the prevalence of infection and leptospirosis-induced abortions. Depopulation or euthanasia is not necessary as in growing pigs the clinical signs are not life threatening (leptospirosis-induced abortions is not a concern). Fluoroquinolone antibiotics are not useful against leptospirosis. Besides tetracycline antibiotics, other effective antibiotics include tylosin, erythromycin, and penicillins.

Question 29

A 3 month old pig is presented for an abnormal gait and lameness of both pelvic limbs. Your history reveals the pig has been gaining weight quickly and is on a high-energy diet. There is no history of trauma, although the pig is usually unsupervised outside. What is the most likely diagnosis?

Answer 29

The correct answer is osteochondrosis. Osteochondrosis is a common disease in young, rapidly-growing pigs. Lesions include ulcerations or defects in articular cartilage. Lesions are often bilateral and symmetric. Common sites of the disease in pigs include the medial femoral condyle, humeral condyle, humeral head, glenoid of the scapula, distal ulna, and lumbar vertebrae.

Question 30

What is the cause of Porcine Stress Syndrome (PSS), a condition which can result in poor meat quality where the meat is pale, soft and sour? It can also result in increased body temperature, dyspnea, or death during transport stress.

Answer 30

The ryr-1 (Ryanodine receptor) gene is the locus responsible, and homozygous animals will have PSS. The industry has made a concerted effort to test pigs and eliminate the gene, and the prevalence is now low in most countries.

Question 31

How is African swine flu transmitted?

Answer 31

soft tick

Question 32

Testing for Classical Swine Fever can be complicated by the presence of which of the following viruses in swine?

Answer 32

The correct answer is Bovine Viral Diarrhea (BVD). Although BVD virus does not usually cause disease in pigs, pigs do get exposed to the virus and seroconvert. Both BVD and CSF are Pestiviruses from the family Flaviviridae. Antibody production in pigs to BVD can cross react with some CSF assays. This can create some problems because CSF is considered a foreign animal disease in the U.S.

Question 33

A number of young growing pigs on a commercial hog farm are experiencing head tilt, incoordination, reduced weight gains, and weak rear limbs. Most have normal vital signs, and you suspect a nutritional deficiency. Which of the following deficiencies might cause such clinical signs?

Answer 33

A shortage of vitamin A in the diet can lead to these signs in young pigs, especially an increase in middle ear infections, as also seen in turtles. In sows it can cause embryonic mortality and congenital defects in their offspring

Question 34

You have been called to a farm to fix several rectal prolapses in a group of 60 lb pigs. The pigs are not coughing and you notice that several of the gilts in the group also have reddened and enlarged vulvas. What could be causing both problems?

Answer 34

The correct answer is zearalenone. This estrogenic effect of this mycotoxin causes edema of the vulva and sometimes edema of the rectum predisposing to rectal prolapses. There are some suspected genetic predispositions for rectal prolapses, but not for the enlarged reddened vulvas.

Calcium and phosphorus balance has no effects on either of the clinical presentations described. Severe diarrhea cause by salmonellosis can lead to rectal prolapses, but diarrhea or coughing (systemic manifestations) will be common.

Question 35

At what age are piglets normally weaned on North American commercial swine farms?

Answer 35

The range throughout the world tends to be slightly greater at 14 to 28 days.

Question 36

You are called to a farm that is experiencing sudden death in a group of pigs that are scheduled to go to market in 10 days. Upon performing a necropsy, you find large amounts of blood in the small intestine and spiral colon. The blood is red and clotted. There is no gross thickening of the intestinal mucosa. Your diagnosis is which of the following?

Answer 36

The correct answer is proliferative hemorrhagic enteropathy or PHE. Acute ileitis or PHE is caused by Lawsonia intracellularis. The name PHE can be deceiving as its acute nature does not always allow for gross evidence of proliferation. Lesion location in the small intestines as well as indications of red clotted blood is almost pathognomonic for the condition. Hemorrhagic bowel syndrome and intestinal torsion are not associated with intraluminal coagulated blood on necropsy. Digested blood is a sequelae to stomach ulcers. Erysipelas does not cause enteric pathology.

Question 37

You identify a pig with skin lesions characteristic of Pityriasis rosea. What should you do next?

Answer 37

The correct answer is to do nothing. Pityriasis rosea is a skin condition in pigs of unknown etiology. It is not a contagious condition and therefore pigs do not need to be separated from the rest of the herd. It is non-pruritic and resolves on itself with time. Almost all pigs fully recover with no effects on health or growth performance.