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Bovine Quick Guides

Quick Guides to sample selection for diagnosis of common conditions

The following ‘Quick Guides’ have been prepared to assist you in sample selection when a particular system is affected.  You may wish to provide copies to your technicians and keep copies at strategic locations for reference.

Bovine Abortion

Specimens to submit:  Tissues are received in best condition if removed at necropsy in the field.  Fetal tissues should include:
Brain Formalin-fixed (1/2 cm slice)
Dam's serum 3 - 5 ml from affected cows.  Optional, see notes on abortion serology.
Heart Formalin-fixed (1/2 cm slice)
Ileum Formalin-fixed

Kidney

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

Liver

Fresh/chilled (1/8- 1/4 of organ),  formalin-fixed (1/2 cm slice)

Lung

Fresh/chilled (1/8- 1/4 of organ),  formalin-fixed (1/2 cm slice)

Placenta (very important)

3 cotyledons, fresh/chilled;  2 cotyledons, formalin-fixed (please submit placenta when possible - this increases the diagnostic success rate)

Skeletal Muscle

Tongue and diaphragm formalin-fixed (1/2 cm slice)

Skin (lesions/ear notch)

Formalin-fixed (1/2 cm slice)

Spleen

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

Stomach contents

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

Thoracic fluid

1-3 ml in sterile syringe, fresh/chilled

Thymus

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

Alternatively, the entire fetus and placenta can be submitted.

SAMPLING TECHNIQUES

  1. Do NOT freeze fresh tissues.
  2. Always submit placenta if possible!  Failure to submit placenta severely diminishes the diagnostic success rate of bovine abortion cases.
  3. It may be useful to submit serum from affected and unaffected dams.

AGENTS DETECTED BY ROUTINE EXAMINATION OF FETAL AND PLACENTAL TISSUES

Bacteria

Trueperella (Arcanobacterium) pyogenesBacillus spp., Brucella spp., Campylobacter spp., Histophilus somnus, Salmonella, Listeria monocytogenes, etc.

Fungi

Aspergillus, Phycomycetes 

Protozoa

Neospora caninum (see comments), Toxoplasma gondii

Viruses

IBR, BVD

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

Bacteria

Leptospira (see comments below), Ureaplasma, Mycoplasma (culture)

Protozoa

Tritrichomonas fetus infection is best diagnosed by placing preputial wash or fetal fluids/stomach contents directly into TF pouch for culture

Eyeball (aqueous) Nitrate/nitrite

COMMENTS

  • If leptospirosis is suspected, extra effort should be made to deliver freshly aborted, chilled fetuses directly to the lab.  PCR and FA tests can be conducted on kidney.  Serology on dam sera is very helpful.  
  • Diagnosis of Neospora caninium abortion is based on histopathologic examination of brain, heart, skeletal muscle, liver, lung, and placenta for characteristic lesions.  Presence of the organism can be confiormed by immunohistochemistry.  Absence of serum antibody in the cow would rule out neosporsis.

 

Bovine Central Nervous System Disorders

Specimens to submit:  Tissues from euthanized or dead animals including:

Blood sample

EDTA tube for lead analysis or cholinesterase inhibition

Eyeball (aqueous)

Cations (calcium); nitrite

Brain (including brain stem)

1/2 brain divided longitudinally, fresh/chilled

1/2 brain, formalin-fixed

Colon

Optional, nervous coccidiosis.  Several partial loops with contents, fresh/chilled.  1 cm pieces of several loops, formalin-fixed

Liver

Optional, lead toxicosis.  Fresh/chilled.

Kidney

Optional, lead toxicosis.  Fresh/chilled.

Rumen contents

 

Fresh/chilled

Spinal cord

Optional, locomotor involvement

Entire carcass or vertebral column, fresh/chilled

Dissected cord, fresh/chilled

Cross-sections (1/2 cm) of cord from 4-5 levels, 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, at least once, transversely (not longitudinally) into the lateral ventricle to aid fixation if the brain is large.

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria

Histophilus somnus, Listeria monocytogenes, Arcanobacterium pyogenes, etc.

Non-infectious

Polioencephalomalacia

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

Deficiencies

Magnesium (serum, entire eyeball, fresh/chilled), calcium (serum, fresh/chilled)

Parasites

Coccidia (flotation; feces, fresh/chilled) - NO lesions in brain

Toxicoses

Lead (whole blood in EDTA, liver, stomach contents, fresh/chilled), organophosphate (whole blood in EDTA, brain, rumen, fresh/chilled)
Sodium (whole blood in EDTA, brain, rumen, fresh/chilled)

Viruses

Rabies (FA), pseudorabies virus (FA, VI); bovine herpesvirus (brain, fresh/chilled)

COMMENTS

  • Cerebellum and brain stem are affected by most infectious causes of CNS disease and should always be included in submitted samples.
  • Many toxic, nutritional, and metabolic 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 rumen contents, complete feed, water and feed components, liver, kidney, and whole blood (in EDTA) as well as brain would include the tissues necessary for diagnosis. 

 

Bovine Enteritis - Calves < 2 Months of Age

Specimens to submit:  Antemortem fecal samples are of value if collected on the first day of diarrhea.  Alternatively, tissues should be removed from a euthanized calf. 

Abomasum

Fresh/chilled and formalin-fixed

Cecal contents

10 ml fluid contents, fresh/chilled

Ear notch

Formalin-fixed

Ileum

Two or three 10-15 cm segments, fresh/chilled
Three 1 cm pieces, formalin-fixed

Jejunum

Two or three 10-15 cm segments, fresh/chilled
Three 1 cm pieces, formalin-fixed

Liver

Fresh/chilled and formalin-fixed

Mesenteric lymph node

Fresh/chilled and formalin-fixed

Spiral colon

Several partial loops, fresh/chilled
Several 1 cm pieces, formalin-fixed

Spleen

Fresh/chilled and formalin-fixed

Because autolysis occurs very quickly in bovine intestines, samples removed at necropsy in the field are usually better than a whole dead calf 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 cm segments with scissors or forceps to expose mucosa as immersed.  Do not split open.
  4. Pool all formalin-fixed tissues from each calf in one bag; individual calves can be pooled or kept separate as desired.  Package fresh intestines separately from other tissues and each calf in a separate bag.  Chill fresh tissues before mailing.  Do NOT freeze. 

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria

E. coli, Salmonella spp., Clostridium spp., Enterococcus durans

Parasites

Cryptosporidia, Coccidia

Viruses

Rotavirus, bovine coronavirus

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

BVD virus

IHC on fixed ileum, colon, mesenteric lymph node, spleen, skin, and any gross lesions; VI on chilled mesenteric lymph node, spleen, kidney, thymus, and lung

COMMENTS

  • In cases of necrotic enteritis, submit both necrotic and adjacent non-necrotic segments fresh and fixed. 
  • In-house quick tests (acid-fast stained impression smears) may be of value for detection of cryptosporidia.  The preferred site for impression smears/mucosal scrapings for cryptosporidia is ileum.  As such, it is helpful if fresh ileum is submitted in a separate container. 
  • Colon is the preferred tissue in which to identify lesions of coronavirus enteritis and for laboratory confirmation with BCV IHC.  Colon should be submitted with all calf diarrhea cases.

 

Bovine Enteritis - Calves > 2 Months of Age, Feedlot Cattle, Adults

Specimens to submit:  Fecal samples may be of value if collected on the first day of diarrhea.  From euthanized or dead animals, tissues should include:

Abomasum

Fresh/chilled and formalin-fixed

Any other gross lesions

Fresh/chilled and formalin-fixed

Colon 10 ml fluid contents, fresh/chilled
Three 1 cm pieces, formalin-fixed
Colon contents 10 ml fluid contents, fresh/chilled
Ileum Two or three 10-15 cm segments, fresh/chilled
Three 1 cm pieces, formalin-fixed
Jejunum Two or three 10-15 cm segments, fresh/chilled
Three 1 cm pieces, formalin-fixed
Liver Fresh/chilled and formalin-fixed
Mesenteric lymph node Fresh/chilled and formalin-fixed
Rumen Fresh/chilled and formalin-fixed
Rumen contents Fresh/chilled for pH
Spleen Fresh/chilled and formalin-fixed

Samples removed in the field are better than a whole dead animal 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 cm segments with scissors or forceps to expose mucosa as immersed.  Do not split open.
  4. Pool all formalin-fixed tissues from each calf in one bag; individual calves can be pooled or kept separate as desired.  Package fresh intestines separately from other tissues and each calf represented in a separate bag.  Chill fresh tissues before mailing.  Do NOT freeze.

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria

Salmonella spp., Clostridium perfringens

Parasites

Coccidia

Viruses

BVD virus (see comments below)

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

Bacteria

Culture of feces, mesenteric lymph nodes, and intestine; histopath and acid fast-stains on intestines and mesenteric lymph nodes

Parasites

 

Coccidia and GI nematodes; (feces, fresh/chilled for fecal flotation)
Viruses Bovine coronavirus (feces for EM and ELISA, fixed ileum and colon for histopath and IHC

COMMENTS

  • BVD mucosal disease diagnosis:  Fixed ileum, spleen, mesenteric lymph nodes, skin, heart, lung, and ANY GROSS LESIONS for immunohistochemistry.
  • Fresh/chilled spleen, lung, thymus mesenteric lymph node, and kidney for virus isolation.
  • Coccidiosis is a common cause of diarrhea in this age group.  It is necessary to submit feces and/or colon to diagnose coccidiosis.

 

Bovine Pneumonia

Specimens to submit:  From euthanized or dead animals, tissues should include:

Bronchial lymph node

Fresh/chilled only

Lung

Entire lung (one side), or generous portion of lesion and adjacent unaffected lung, fresh/chilled.  Sample 3-4 areas of lung, including both cranial and caudal lobes

Four or more thin slices (1 cm)  through affected and adjacent unaffected lung, formalin-fixed

Nasal swabs and/or
Deep naso-pharyngeal swabs and/or

Tracheal wash/lavage
(see a video onsampling techniques)

Use a long, Dacron-tipped swab that reaches deep into the nasal cavity

Swabs to be used for virus FA or PCR should penetrate the mucous layer to retrieve epithelial cells (rub hard, roll swabs on slides to deposit nasal mucosal epithelial cells for FA test). 

Submit separate swabs for bacterial culture and virus isolation in saline or transport media.  Do not freeze.

Swabs and/or lavage material can be submitted for PCR respiratory panel (bacteria and viral) as antemortem samples.

Serum samples Acute and convalescent serum from 5-10 affected and 5-10 normal calves.  Hold acute samples and submit with convalescent.
Trachea Optional, if lesions are observed.  Affected portion (10 cm) with larynx, fresh/chilled.  Several rings at edge of lesion, formalin-fixed.

SAMPLING TECHNIQUES

  1. Fresh tissues should be chilled before shipping.  Do NOT freeze.
  2. Samples for virus detection need to be taken from ACUTE animals at the onset of respiratory signs.
  3. Swabs must be kept moist and cold before and during shipment.

AGENTS DETECTED BY ROUTINE EXAMINATION

Bacteria Arcanobacterium pyogenes, Histophilus somnus, Mannheimia hemolytica, Mycoplasma bovis, Pasteurella multocida

Viruses

IBR, BRCV, BRSV, BVD, PI-3 (PCR on lung, swabs, and/or lavages, also FA, VI, IHC; lung, trachea, bronchial lymph node, fresh/chilled and formalin-fixed)

AGENTS REQUIRING SPECIAL TESTS (BY REQUEST)

Mycoplasma

Mycoplasma dispar, (Culture on fresh/chilled lung; histopath)

COMMENTS

  • Acute lesions are most likely to hold active causative agents are usually at the diseased/normal interface.
  • Chronic lesions in dependent tips or lobes may no longer hold primary pathogens.
  • Nasal swabs may pick up resident bacterial flora but may be of value in acute cases.  Nasal swabs may also be of value to identify viruses if sampled in the early stages (exhibiting serous nasal discharge).
  • Tracheal washes submitted on ice may be used for both virus and bacteria identification.