Porcine Quick Guides

Porcine Abortion

Specimens to submit: Entire fetuses with placenta, minimally contaminated, fresh/chilled are preferred specimens. Do NOT freeze. Send 4-6 representative fresh fetuses and all mummified fetuses. Alternatively, remove the following tissues from 3 fetuses per litter:

Brain

1/2 brain, fresh/chilled and formalin-fixed

Heart

1/2 of organ fresh/chilled, 1/2 cm slice formalin-fixed

Kidney

Fresh/chilled, formalin-fixed (1/2 cm slices)

Liver

Fresh/chilled (1/3 of organ), formalin-fixed(1/2 cm slice)

Lung

Fresh/chilled (1 entire lung), plus formalin-fixed (1/2 cm slice)

Placenta

Fresh/chilled and several pieces formalin-fixed

Sow serum

Optional, see notes on abortion serology. 1-3 ml from affected sows

Stomach contents

1-3 ml in sterile syringe or tube, fresh/chilled

Thoracic fluid

0.25 - 1 ml per aborted pig, may pool within litter for PRRS virus, PCV

Umbilicus

Formalin-fixed, several 1/2 cm slices

SAMPLING TECHNIQUES

1. Do NOT freeze tissue.
2. Submit placenta whenever possible
3. Thorough investigation of abortion should include serology. Submit dam's sera. Retain 1/2 of sample frozen.

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria

Arcanobacterium pyogenes, Bacillus spp., Brucella spp., E. coli, Salmonella spp., Streptococcus spp., etc

Viruses

Pseudorabies virus, PRRSV, porcine circovirus, parvovirus (see comments)

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

Leptospira

If leptospirosis is suspected, extra effort should be made to deliver freshly aborted, chilled fetuses directly to the lab. FA tests can be performed on kidney. Serology on sow sera is probably the most reliable method for diagnosing leptospirosis.

PRRS virus

Isolation for PRRS virus is not routinely conducted on tissues from aborted or stillborn pigs as viable virus is rarely present. Histopath may occasionally demonstrate lesions suggestive of PRRS virus in umbilical cords, lungs, heart or other tissues. Preferred samples are lung or serum from weakborn littermates or from pigs that develop pneumonia shortly after birth. PCR for PRRS virus nucleic acids in fetal thoracic fluid or serum from sick sows is often valuable. A serologic survey of the sow herd may be useful, but may be difficult to interpret in PRRS virus vaccinated herds.

Toxicosis

Carbon monoxide (heart blood in EDTA; clotted heart blood or thoracic fluid as second choice).

COMMENTS

• Fetal serology may aid in the diagnosis of porcine parvovirus, Leptospira and PRRSV.
• Parvovirus usually does not cause abortion, as defined by the presentation of dead or nonviable fetuses before term. Embryos or fetuses die in utero if infected early in gestation (<70 days). In the case of PPV, embryos may be reabsorbed or fetuses mummify, but gestation will usually go to term.

Porcine Central Nervous System Disorders

Specimens to submit: One or more acutely affected live pigs. Alternatively, tissues from field necropsy should include:

Brain (including brain stem)

Swab of brain stem and base of cerebellum (for bacterial culture)

1/2 brain divided longitudinally, fresh/chilled

1/2 brain, formalin-fixed

Intestine

Optional, edema disease.

One 10-15 cm slice of ileum and jejunum, fresh/chilled

Several 1/2 cm slices of ileum, formalin-fixed

Spinal cord

Optional, locomotor problems.

Entire carcass or vertebral column, fresh/chilled

Dissected cord, fresh/chilled

Cross-sections (1/2 cm slices) of cord from 4-5 levels, formalin-fixed

Spleen

Fresh/chilled and formalin-fixed

Tonsil

Fresh/chilled and formalin-fixed

SAMPLING TECHNIQUES

1. Entire head can be submitted. Chill before shipment if possible.
2. Do NOT freeze fresh brain or head.
3. Fresh half of brain should be packed carefully to avoid crushing.
4. Fixed half of brain should be incised transversely (not longitudinally) into the ventricle to aid in fixation if brain is large.
5. CSF can be collected prior to removing the skull. When a bacterial meningitis is suspected, CSF is an excellent sample as there is less opportunity for contamination compared to most methods of opening the skull.

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria

Streptococcus suis, Haemophilus parasuis, Arcanobacterium pyogenes, E. coli (intestine, edema disease)

Viruses

Pseudorabies virus, PRRS virus, Porcine Circovirus type 2

Non-infectious

Water deprivation

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

Toxicosis

Selenium (liver and spinal cord - lumbar intumescence, fresh/chilled)

Organophosphate (whole blood in EDTA, brain, stomach contents, fresh/chilled)

Viruses

Rabies (FA on brain), Hemagglutinating encephalomyelitis virus (VI on fresh/chilled brain), porcine enterovirus (VI on fresh/chilled brain and spinal cord), paramyxovirus (VI on fresh/chilled brain)

COMMENTS

• Cerebellum and brain stem are affected by most infectious causes of CNS disease and should always be included in submitted samples.
• Many toxic causes of CNS disease do not induce lesions in the brain and must be diagnosed by analysis of other tissues. For most toxicoses, submission of stomach contents, liver, kidney, feed, water, and whole blood (in EDTA), as well as brain, would include the tissues necessary for diagnosis.

Specimens to submit: The best specimen is an acutely-ill (<24 hours) live untreated pig(s). Alternatively, tissues should be removed from a euthanized pig.

Colon and cecum

Entire organ, fresh/chilled

Several 1 cm pieces, formalin-fixed

Ileum

10-15 cm segments, fresh/chilled

Three 1 cm pieces, formalin-fixed

Jejunum

10-15 cm segments, fresh/chilled

Three 1 cm pieces, formalin-fixed

Lesions

10-15 cm segments, fresh/chilled

Several 1 cm pieces, formalin-fixed

Samples removed at necropsy in the field are better than a whole dead pig submitted to the lab.

SAMPLING TECHNIQUES

1. Samples must be taken as soon after death as possible (within minutes).
2. Intestines do not need to be tied off at the ends.
3. Flush intestinal segments for histopathologic examination with formalin and drop in fixative. Or, gently open ends of 1/2" segments with a scissors or forceps to expose mucosa as immersed.
4. Pool all formalin-fixed tissues from each pig in one bag; individual pigs can be pooled or kept separate as desired. Package fresh intestines separately from other tissues and each pig in a separate bag. Chill fresh tissues before mailing. Do NOT freeze.
5. Do not send whole, dead pigs (intestines autolyze quickly).

Bacteria

Brachyspira (Serpulina) spp., Clostridium spp., E. coli, Enterococcus durans, Lawsonia intracellularis, Salmonella spp.

Parasites

Coccidia, Cryptosporidia

Viruses

Rotavirus, TGE virus, PRRSV

comments

• In cases of necrotic enteritis, submit both necrotic and adjacent non-necrotic segments, fresh and fixed.
• Except for TGEV PCR and fecal flotation for parasites, fecal samples are of limited value and should be used only when tissues are not available. Results (both positive and negative) may not be completely definitive and must be evaluated with consideration of clinical signs. Samples (10-20 ml) should be taken on the first day of diarrhea. Brachyspira hyodysenteriae can occasionally be isolated from feces (swabs are even less reliable). Salmonella spp. are difficult to recover from feces and/or rectal swabs.
• Wet mounts of colonic mucosal scrapings or fecal flotation may be of value for quick in-house detection of Coccidia, whipworms, etc.
• In cases where mesocolonic edema is prominent, Clostridium difficile is a differential and the entire colon or colon contents should be submitted for a C. difficile toxin ELISA.

Specimens to submit: The best specimen is an acutely-ill (<24 hours) live untreated pig(s). Alternatively, tissues may be removed from a euthanized pig.

Colon and cecum

Entire organ, fresh/chilled

Several 1 cm pieces, formalin-fixed

Feces

2-5 ml fluid contents, fresh/chilled

Ileum

10-15 cm segment, fresh/chilled

Three 1 cm pieces, formalin-fixed

Jejunum

10-15 cm segment, fresh/chilled

Three 1 cm pieces, formalin-fixed

Lesions

10-15 cm segment, fresh/chilled

Several 1 cm pieces, formalin-fixed

Samples removed at necropsy in the field are often better than a whole, dead pig submitted to the lab.

SAMPLING TECHNIQUES

1. Samples must be taken as soon after death as possible (within minutes).
2. Intestines do not need to be tied off at the ends.
3. Flush intestinal segments for histopathologic examination with formalin and drop in fixative. Or, gently open ends of 1/2" segments with a scissors or forceps to expose mucosa as immersed.
4. Pool all formalin-fixed tissues from each pig in one bag; individual pigs can be pooled or kept separate as desired. Package fresh intestines separately from other tissues and each pig in a separate bag. Chill fresh tissues before mailing. Do NOT freeze.
5. Do not send whole, dead pigs (intestines autolyze quickly).

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria

E. coli, Salmonella spp., Clostridium perfringens, Enterococcus durans, Brachyspira (surpulina) spp. Lawsonia intracellularis

Parasites

Coccidia, roundworms, whipworms

Viruses

Rotavirus, TGE virus, PRRSV, PCV2

COMMENTS

• Colitis associated with Brachyspira hyodysenteriae and Brachyspira pilosicoli should be confirmed by culture for a definitive diagnosis.
• In cases of necrotic enteritis submit both necrotic and adjacent non-necrotic segments, fresh and fixed.
• Porcine Proliferative Enteritis associated with Lawsonia intracellularis can be confirmed by immunohistochemistry.
• Except for TGEV PCR and fecal flotation for parasites, fecal samples are of limited value and should be used only when tissues are not available. Results (both positive and negative) may not be completely definitive and must be evaluated with consideration of clinical signs. Samples (10-20 ml) should be taken on the first day of diarrhea. Brachyspira hyodysenteriae can occasionally be isolated from feces (swabs are even less reliable). Salmonella spp. are seldom recovered.
• Ill-defined conditions such as dietary hypersensitivity or nonspecific colitis may be implied but cannot be confirmed by routine diagnostic investigations.
• Wet mounts of colonic mucosal scrapings or fecal flotation may be of value for quick in-house detection of Coccidia, whipworms, etc. Victoria Blue staining of mucosal scrapings is useful for a preliminary diagnosis of spirochetal colitis. Histopathology and culture are needed for confirmation.

Porcine Multisystemic Disease Investigations

Specimens to submit: The best specimen is a live untreated pig(s). Alternatively, tissues should include:

Brain

1/2 Fresh and 1/2 formalin-fixed

Colon and Cecum

Entire organ, fresh chilled

Several 1 cm pieces, formalin fixed

Heart

Fresh/chilled and formalin-fixed

Intestine

Two 10-15 cm slices of ileum and two jejunum, fresh/chilled

Several (6-10) 1/2 cm slices ileum and jejunum, formalin fixed

Kidney

Fresh/chilled and formalin-fixed

Liver

Fresh/chilled and formalin-fixed

Lung

Entire lung (one side) or generous portion of lung containing the lesions and adjacent unaffected lung, fresh/chilled

4-6 thin slices (1 cm) through affected and adjacent unaffected lung, formalin-fixed

Lymphoid tissues

Spleen, tonsil, and lymph nodes

Fresh/chilled and formalin-fixed

Spinal cord

Entire carcass or vertebral column, fresh/chilled, or

Dissected cord, fresh/chilled

Cross-sections (1/2 cm slices) of cord from 4-5 levels, formalin-fixed

sampling techniques

1. Fresh tissues should be chilled before shipping. Do NOT freeze.

2. Do not submit fresh lung in glycerin. Glycerin has not proven to be of value and prevents freezing of sections for FA tests.

3. Pool all formalin-fixed tissues from each pig in one bag; individual pigs can be pooled or kept separate as desired. Package fresh intestines separately from other tissues and keep each pig in a separate bag.

agents detected by routine examination

Bacteria

Pasteurella multocida, Streptococcus suis, Actinobacillus pleuropneumoniae, Actinobacillus suis, Arcanobacterium pyogenes, Bordetella bronchiseptica, Haemophilus parasuis, Salmonella spp., E. coli, Clostridium perfingens type A and C, Enterococcus durans, Lawsonia intracellularis, Brachyspira (Serpulina) spp.

Parasites

Coccidia, Cryptosporidia, round worms, whip worms

Viruses

PRRS virus, porcine circovirus type 2, swine influenza virus, cytomegalovirus/inclusion body rhinitis (only if turbinates are submitted), pseudorabies virus, rotavirus, TGE virus.

Mycoplasma

Mycoplasma hyopneumoniae (FA, IHC, PCR).

Non-infectious

Water deprivation

comments

PRRS virus is often best isolated from lung lavage fluids. The lung can be lavaged (with cell culture growth media or Lactated Ringers Solution) and the fluid submitted or the lavage can be done at the lab if at least one half of the lung is submitted without holes or slices in it.

Specimens to submit: Live acutely affected pig(s). Alternatively, tissues should include:

Brain

1/2 fresh, and 1/2 formalin-fixed

Lung

Entire lung (one side) or generous portion of lesion and adjacent unaffected lung, fresh/chilled

4 to 6 thin slices (1 cm) through affected and adjacent unaffected lung, formalin-fixed. At least 3-4 cross sections through anteroventral lung are recommended

Nasal swab

Swab of deep airway, chilled (Dacron-tipped, slightly moistened, for bacterial and viral cultures)

Snout or turbinate

Turbinate scroll from one side removed at junction with midline

septum, formalin-fixed

Tonsil

1/2 fresh, and 1/2 formalin-fixed

sampling techniques

1. Fresh tissue should be chilled before shipping. Do NOT freeze.

2. Do not submit fresh samples in glycerin (glycerin has not proven to be of value and prevents freezing of sections for FA tests).

3. Samples for virus detection need to be taken at the onset of respiratory signs.

4. Nasal swab preservation: swabs must be kept moist and cool before and during shipment.

5. Fixed turbinate must be submitted to confirm the presence of porcine cytomegalovirus (inclusion body rhinitis)

agents detected by routine examination

Bacteria

Pasteurella multocida, Streptococcus suis, Salmonella choleraesuis, Actinobacillus pleuropneumoniae, Actinobacillus suis, Arcanobacterium pyogenes, Bordetella bronchiseptica, Haemophilus parasuis

Viruses

PRRS virus, porcine circovirus, swine influenza virus, cytomegalovirus/inclusion body rhinitis (if turbinates are submitted for histopath)

Mycoplasma

Mycoplasma hyopneumoniae (FA/IHC/PCR). See additional information under Comments.

agents requiring special tests (by request)

Viruses

Porcine respiratory coronavirus (VI on nasal swabs, lung tissue, IHC on formalin-fixed lung). See additional information under Comments.

Swine influenza virus (VI, PCR, ELISA on nasal swabs, lung tissues). See additional information under Comments.

PRRS virus genomic sequencing.

comments

Cultures for Mycoplasma hyopneumoniae can be done on fresh/chilled lung. However, isolation studies for Mycoplasma hyopneumoniae are not routinely conducted because of the difficulty of recovering these fragile organisms in the presence of heavy contamination or concurrent bacterial or other mycoplasmal infection.

Porcine respiratory coronavirus is more readily isolated from nasal swabs than lung tissues. High serum antibody titers to TGE virus in herds with no evidence of TGE diarrhea also may suggest the presence of PRCV. A differential ELISA serology test is available through the VDL.

PCR (non-differential) and antigen-capture ELISA can be used on nasal swabs or lung tissues for detection of swine influenza virus. Subtype-specific PCR can be used on lung or isolates to determine hemagglutinin (H) and neuraminidase (N) subtypes. The PCR can also be used directly on nasal swabs or lung tissue, but sensitivity is lower than other methods of detection.

PRRSV is often best isolated from lung laval samples. The lung can be lavaged (with cell culture growth media or Lactated Ringers Solution) and the fluid submitted. Lung lavages can be done at the lab if at least one half of the lung is submitted without holes of slices.