Case Fi le: Recurrent Fevers of Unknown Origin

SIGNALMENT AND HISTORY• 9-year-old Quarter Horse gelding

• Used for competitive (Western) riding

• 7-month history of fevers that were, in general, ‘antimicrobial-responsive’

• Poor appetite and weight loss

• One-time colic event (mild) in July 2010.

REVIEW OF PREVIOUS CBCS AND DIAGNOSTIC PROFILES (TABLE 1)

Problem List (historical):

• anemia

• moderate leukocytosis

• hyperfibrinogenemia

• hyperglobulinemia

CONTACT INFOColorado State University

Veterinary Teaching Hospital

300 West Drake Road

Fort Collins, CO 80523-1620

Phone: (970) 297-5000

Fax: (970) 297-4100

csuvth.colostate.edu

Questions regarding this case file may be directed to:

Dr. Lutz Goehring, Equine Medicine

Dr. Eileen Hackett, Equine Critical Care

August2011• Volume2Appl ied Research for Today’s Equine AthleteDiscovery

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Table 1:

Date

PCV in % (normal: 32-45)

Total Protein in g/dL

(normal: 5.8-7.0)

Fibrinogen (normal:

200-400 mg/dL)

08/10/2110 23 8.8 750

08/12/2110 26 8.6 830

11/20/2110 29 8.3 500

02/22/2111* 33 8.8 900

* hospital admission

Additional information on ‘testing’ (Nov. 2010):

• M-protein titer (Strep. equi spp. equi): 1:200

• Synergistic Hemolysis Inhibition test (Corynebacterium pseudotuberculosis): 1:2

PHYSICAL EXAM• QAR

• Resp. Rate: 20 bpm; HR: 30 bpm; Temp: 99.8 degrees F

• BCS: 3/ 9, dull hair coat

• Mucous membranes: slightly pale, palpable lymphnodes ( Lnn. mandibulares): normal

• Auscultation of lungs (incl. ‘rebreathing’), heart and abdomen: normal

Observed and Historical Problem List:

• weight loss

• dull hair coat

• chronic-active inflammation

• fevers (not observed - but historical)

DIFFERENTIAL DIAGNOSES AND PLAN• Equine Infectious Anemia

- submit serum for AGID -EIA (Coggins’ Test)

• Septic process in abdomen

- transabdominal ultrasound, exam per rectum, abdominocentesis

• Septic process in thorax or valvular endocarditis

- repeat auscultation, thoracic radiographs

- repeat auscultation, cardiac ultrasound

- collect blood for blood culture during a fever spike

• Lymphoma or other neoplasia combined with paraneoplastic syndrome

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- transabdominal and transrectal ultrasound (focus on lymphoid structures - spleen, colonic and mesenteric Lnn

- submit serum for electrophoresis (distinguish between a monoclonal vs. a polyclonal gammopathy)

FIRST ROUND OF RESULTS1. Coggins Test: negative

2. Transabdominal ultrasound: normal, no increased amount of fluid

3. Exam per rectum: normal

4. Electrophoresis (Fig. 1) suggests polyclonal gammopathy

Fig. 1: Serum electrophorogram of the patient. Left to right: albumin peak, α1, α2, β1, β2 and γ globulin fractions. Note the pronounced α2 –spike representing acute phase-proteins and the β-γ ridge indicating chronic antigenic stimulation with excessive immunoglobulin production.

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INTERPRETATION OF COMPILED FINDINGSAnemia likely to be due to chronic-inflammatory disease. This is supported by the fibrinogen and globulin concentrations. Referring DVM ruled-out Strep. equi spp. equi and C. pseudotuberculosis as a possible cause for the chronic-active inflammation. EIA was ruled out by Coggins’ Test; however, equine lymphoma remains a possible differential diagnosis. Location of active inflammation needs to be determined.

FURTHER DIAGNOSTICS• Abdominocentesis: (procedure of penetrating the

peritoneal cavity appeared painful)

- nucleated cell count/uL: 14490

- 86 percent non-degenerate neutrophils

- Refractometer Protein: 4.4 g/dL

- no bacteria or neoplastic cells observed

• Interpretation: moderate exudate originating from an inflammatory process within the abdominal cavity

CHANGE OF DIAGNOSTIC PLAN: FOCUS ON THE ABDOMINAL CAVITY• Differential diagnoses and plan of action:

- Bastard Strangles (Strep. equi spp. equi) - abdominal abscess. Corynebacterium pseudotuberculosis - abdominal abscess. Although titers were already determined and considered ‘low,’ titers may need to be repeated in case these were false-negative results.

Fig. 2a and 2b: Radiographs of patient’s cranio-ventral abdomen. Arrows point to the two radiodense structures presumed in the sternal flexure of the ascending colon.

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- Foreign body - abdominal abscess. Historically ‘feeding out-of-a-tire’ has been implemented. Suggest abdominal radiographs searching for metal objects.

- Alimentary lymphoma. No strong indicators. However, the range how ‘Equine Lymphoma’ can present varies.

- Other form of alimentary neoplasm (adenocarcinoma, gastric squamous cell carcinoma, etc.). Hypoalbuminemia is suggestive for albumin loss or decreased albumin production (negative-inflammatory protein). Albumin loss is often associated with gastric squamous cell carcinoma. Suggest gastroscopy.

RADIOGRAPHIC INTERPRETATION• Two metal, filamentous structures in the cranial abdomen

(Fig. 2A and 2B)

PATHOGENESIS• With the practice of ‘feeding out of a tire’ it is likely

that the horse ingested pieces of metal (Fig. 6), which perforated or are currently situated in the colon wall (Fig. 4).

EVIDENCE-BASED MEDICINE AND SURGEON’S EXPERIENCEIf the foreign body in the abdominal cavity is identified early, within days of gastrointestinal penetration, surgery can be curative. When the diagnosis is delayed, chronic changes such as extensive abdominal abscessation and adhesions are difficult to treat. Though rare, in our hospital abdominal injuries outnumber pharyngeal perforating injuries following wire ingestion.

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Fig. 3 (left): Example of hay being fed out of a tire. Note the break-down of the tire material and the exposure of wires.

Fig. 4: Perforating wire through the colon wall.

Fig. 5 (right): Layers of fibrous tissue that formed around a wire that perforated the colon wall.

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OUTCOMEThe horse was euthanized three weeks later. A post mortem exam showed a chronic peritonitis with adhesions between the tip of the cecum and ventral colon, adhesions between spleen and liver. Two pieces of wire (7 and 10 cm) were recovered from the cranial wall of the sternal flexure of the ascending colon. One piece of wire had perforated through the colon wall into the spleen, and was embedded in a thick capsule of fibrous tissue. The second wire was pre-perforative and embedded in a thick fibrous capsule.

Fig. 6: Adhesions between spleen (top) and liver (bottom) in patient’s abdomen.

At Colorado State University equine veterinary care is delivered through the collaboration of three nationally recognized equine service centers: (1) Colorado State University Veterinary Teaching Hospital Equine Service; (2) Colorado State University Equine Reproduction Laboratory; (3) Colorado State University Orthopaedic Research Center. Equine treatment capabilities at CSU are at the forefront of equine veterinary medicine through the shared expertise of these organizations.

Fig. 7: Both wires removed from the tissue.

RESOURCES• Colorado State University

Veterinary Teaching Hospital: csuvth.colostate.edu