Case of the Month
October 2005

HISTORY

A herd of sheep and goats was confiscated for poor management/flock neglect. A ram was up and ambulatory on Thursday afternoon when it was presented to the VMTH.  Shortly after arrival, it laid down and would not rise. The students and clinicians performed a physical examination:

PHYSICAL EXAMINATION: 

•   T-102.5 P-120 R-36 down in lateral reluctant to move 
•   EENT: Pale mucus membranes, sclera not injected and slightly pale
•   Cardio: NSF
•   Resp: NSF
•   INT: Marked diarrhea staining on the rump and perineal area.
•   GI: Diarrhea with occult blood in feces. Later in the day blood clot feces, with little fecal material, then returned   to brown loose feces.
•   M/S: thin and down, no fractures or sores noted
•   Neuro: Obtunded
•   Lymph: NSF

BLOODWORK:

Blood was sampled and chemistries run (on a stall-side chemistry machine):

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QUESTIONS:

1. What are your differential diagnoses?

2. What would your treatment plan include? Your diagnostic plan?

3. Can you give the owner an idea of this animal’s prognosis?

TREATMENT

The next day (0800 hrs):

1. PCV=15, TP=15.6
2. PPG 4ml IM
3. at 2000 hrs: PCV=16, TP=6.3

The following day at 0800 hrs:

1. PCV=15, TP=6.0
2. PPG 4ml IM

      The following day – Ultrasound of the kidneys show enlarged with numerous masses within the cortex               (possible abscesses or cysts). The sheep was euthanized and the animal was submitted for a necropsy.

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PATHOLOGICAL FINDINGS

Examined is a 53.5 kg. male ovine (ram) in good post-mortem and poor nutritional condition. Most of the hair coat has been sheared. There is a small, circular, superficial cutaneous abrasion overlying the left elbow. There is a small patch of perineal fecal staining. The peritoneal cavity contains 100 ml of serous fluid. There is moderate to severe edema of numerous serosal surfaces, particularly notable throughout the abomasum. Dissection reveals marked mucosal and submucosal edema throughout the abomasum. Intestinal contents in the distal ileum and colon are dark brown to black. The liver is 1.1 kg. (2.1 % of body weight) with a diffuse, enhanced reticular pattern. The kidneys are markedly enlarged  (see Figure 1 and Figure 2). The left kidney measures 15 x 10 x 8 cm and the right kidney measures 18 x 12 x 8 cm. The cortices of both kidneys have almost been completely effaced by numerous, large spherical encapsulated lesions which are comprised of yellow to green semi-soft to caseous laminated material. These areas often coalesce particularly under the subcapsular surface. Some of these extend just deep to the corticomedullary junction, but the medulla in both kidneys is largely unaffected. Remaining areas of corticomedullary junction are frequently dark red. The heart is 0.81 kg. There is 45 mm of serous fluid in the pericardial sac. Numerous, mesenteric, sublumbar and renal lymph nodes are effaced and expanded by encapsulated lesions containing similar material to that described in the lesion of the kidney.

Figure 1

Figure 2

Questions: 

What is the yellow laminated material in the kidney?

Why is the liver weight given as a percentage of body weight?  What does 2.1% mean?

Why is there clear serous fluid in the abdomen and pericardial sac?  Why the edema?

Why are the digestive contents black?  Can you explain the physiology behind this?

Can you name the disease?  The likely etiology (causative agent)?

What do you expect the kidneys to look like histologically?

HISTOLOGY:

Following are photomicrographs of the kidney, along with some questions.  Think about what diagnoses you would use to describe what you see:

Figure 3.  2x view of the kidney from a sheep stained with Hematoxylin and Eosin (H&E).  Can you identify normal kidney (i.e. glomeruli, tubules, capsule)?  What does the large expansive area of dark blue and pink on the left represent? What about the pale blue solid area in the middle?

Figure 4.  20x view of the boxed region from Figure 3 (H&E).  What are the blue smudges on the lower left? 

What are the finely stippled blue cells in the middle?  What is the more pale blue staining region on the right with 

long slender cells?  Do these long slender cells suggest how long this disease process has been affecting this animal?

Figure 5.  A closer view (60x) of Figure 5 (H&E).  Any better idea what the blue smudges are in the lower left? 

What stain might help you?

Figure 6.  Brown and Brenn stain (a tissue Gram stain) of Figure 5.  What does this tell you about the blue smudges?

Figure 7.  10 x view of the more normal regions of kidney (H&E).  What is wrong with this “normal” section of kidney?  What is the deep eosinophilic homogenous material in the renal tubule?  Are the glomeruli normal?

Figure 8. 40 x view of a glomerulus (H&E).  What is abnormal about this glomerulus?  Is the abnormality 
intracellular or extracellular?  What stain(s) would help you determine what the lesion is?

Figure 9.  40x view of a Congo Red stained section of sheep kidney.  What material stains orange with the 
Congo Red stain?  What could you do to further prove your diagnosis?

Figure 10.  40 x view of a Congo Red stained section of sheep kidney under polarized light. 
What material gives off the apple green birefringence?

AND THE MORPHOLOGIC DIAGNOSES ARE!

·  KIDNEYS (CORTICES, BILATERAL): MARKED, CHRONIC, CASEOUS ABSCESSATION WITH 

INTRALESIONAL GRAM POSITIVE BACTERIA

·  KIDNEYS: MODERATE, GLOMERULAR AMYLOIDOSIS WITH MULTIFOCAL, CHRONIC VASCULITIS

·  LYMPH NODES (MESENTERIC, RENAL, SUBLUMBAR): SEVERE, CHRONIC, CASEOUS 

LYMPHADENITIS WITH MULTIPLE ABSCESSES

·  RUMEN: MILD, MULTIFOCAL, ACUTE, SUPPURATIVE PERIVASCULAR RUMENITIS

·  BODY AS A WHOLE: MARKED EDEMA

·  SPLEEN: MODERATE, LYMPHOFOLLICULAR HYPERPLASIA AND PLASMACYTOSIS

·  DISTAL ILEUM, COLON: MELENA

·  PERITONEAL, PERICARDIAL SPACES: MODERATE SEROUS EFFUSION

·  LIVER: MODERATE ATROPHY AND MILD, MULTIFOCAL LYMPHOPLASMACYTIC PORTAL HEPATITIS

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COMMENT:

This sheep had severe effacement of both renal cortices and some lymph nodes by large, coalescing caseous abscesses 
most consistent with Corynebacterium pseudotuberculosis infection (Caseous lymphadenitis). 
Only Arcanobacterium pyogenes was cultured, which is a common secondary opportunist to
C. pseudotuberculosis infections. The concurrent presence of C. pseudotuberculosis was supported by 
large numbers of gram positive short rods observed in the kidney on B&B gram stain.  Chronic inflammation 
likely led to AA amyloid deposition in the renal glomeruli.  Bleeding tendencies, anemia, hypoproteinemia, and 
edema are secondary to protein loss through the compromised leaky glomeruli as well as emaciation most likely from starvation.

REFENCES OF INTEREST:

Menusa, C, Carrasco, L, Bautista, MJ, Biescas, E, Fernandez, A, Murphy, CL, Weisse, DT, Solomon, A, Lujan, 
L. Pathology of AA amyloidosis in domestic sheep and goats. Vet Pathol. 2003. 40: 71-80.

Williamson, LH. Caseous lymphadenitis in small ruminants. Vet Clin North Am Food Anim Pract. 2001. 17:359-71.

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