Olive, an approximately one-year-old spayed female ferret, presented after going missing for several days prior. Since coming home, she had mild intermittent diarrhea, decreased weight, and lethargy. Initial treatment for her gastrointestinal symptoms was started, including subcutaneous Lactated Ringer’s solution (30 mL/kg) and oral medications for GI upset. Broad-spectrum antibiotics consisted of enrofloxacin (10 mg/kg PO BID) and amoxicillin and clavulanate potassium drops (12.5 mg/kg PO BID), gastroprotectants in the form of sucralfate (150 mg/kg PO TID), and a recovery diet to be offered due to lean body condition. Olive returned to the clinic two days later for continued inappetence, diarrhea, and suspected fever. She was depressed but responsive with an elevated temperature (104.3 F), tachycardia (>300 bpm), 7-10 percent dehydration, and had a palpable abdominal mass in the right cranial abdominal quadrant. After initial triage and physical examination, a CBC, chemistry panel, and radiographs were performed. Blood work showed a mild leukocytosis (8.3 10^3/mL), elevated hematocrit (59 percent), low creatinine (0.1 mg/dL) and BUN (9 mg/dL), and an elevated cholesterol (365 mg/dL). Full-body radiographs revealed an abnormal contour of the right kidney as well as generalized dehydration, otherwise normal serosal detail, and no evidence of a foreign body or obstruction. Ventodorsal radiograph showing cystic changes to the right kidney and mild loss of serosal detail. Photo courtesy Dr. Cordell Rech Lateral radiograph showing mild loss of serosal detail with prominent kidneys, which were palpable on physical examination. Photo courtesy Dr. Cordell Rech Hospitalization and surgery Due to Olive’s lack of improvement on outpatient therapy, hospitalization was implemented to manage dehydration, reduce pyrexia, and treat for possible infectious etiologies. She had a 24-gauge intravenous catheter placed in a cephalic vein and was started on IV fluids at 150 ml/kg/day to restore hydration. Since Olive had already been started on oral medications and there was no history of emesis, the oral medications previously prescribed were continued, and meloxicam (0.3 mg/kg PO BID) was added as an anti-inflammatory. The patient was maintained on overnight fluids and hospitalization during which her fever dropped to 103.1 F, and her demeanor improved marginally to the point of voluntarily consuming small amounts of a high-calorie recovery canned food. Surgical positioning for exploratory laparotomy and nephrectomy via ventral midline approach. Photo courtesy Dr. Cordell Rech During continued hospitalization, Olive’s improvement plateaued. Since she was not getting any better, and there was a palpable mass effect, abdominal exploratory surgery was recommended to assess the cause of the mass and remove it if indicated. The owners approved this plan, and 48 hours after hospitalization, Olive underwent surgery. She was placed in standard dorsal recumbency and quarter-draped. The abdomen was opened in a standard midline approach, which revealed the right kidney to be diffusely covered in fluid-filled cysts with loss of normal architecture. No other abnormalities were seen. The right kidney was removed without complication, and hemostasis was managed by hemoclip placement across the renal artery, vein, and ureter. The right kidney intraoperatively showed cystic changes consistent with radiographic findings. Photo courtesy Dr. Cordell Rech Renal vessels occluded with hemoclips after nephrectomy. Photo courtesy Dr. Cordell Rech After sterile lavage of the abdomen, the body wall and skin were closed in three layers using a monofilament absorbable suture. The kidney was submitted for histopathology, and a sterile swab of several ruptured cysts was sent in for culture. Olive was discharged from the hospital 24 hours post-operatively. She was more active, eating well, and with a normal temperature (101 F). Histopathology results Histopathology and culture for the kidney returned, showing multifocal renal cysts, moderate chronic pyelonephritis with hydronephrosis, and pyogranulomatous peritonitis without evidence of bacteria or other infectious or neoplastic agents. After 96 hours, the renal culture returned negative, and although Olive had been on antibiotics for 24 hours prior to surgery, this was considered unlikely to have caused a false-negative culture given the number of cysts and the amount of inflammation present. Due to clinical history and diagnostic findings, it was concluded Olive’s abnormal kidney was an incidental finding and not a primary factor in her illness. Skeletal muscle biopsies showing suppurative and pyogranulomatous myositis consistent with disseminated idiopathic myositis. Image courtesy of Dr. Robin F. Lane, Avian & Exotics Consultant, Antech Diagnostic Laboratories Follow-up Olive returned one week post-nephrectomy due to worsening conditions, with 7-10 percent dehydration, returned pyrexia (104 F), anorexia, and severe lethargy. At this visit, the veterinary team’s differential list had been narrowed to include sepsis and disseminated idiopathic myofascitis (DIM). Blood work was repeated, and Olive had several changes considered to be caused by the recent nephrectomy: low HCT (32 percent), low RBC (6.3 x 10^6/mL), and low HGB (9.6 g/dL). Clinically significant changes to her blood work that gave indication to the primary disease process being DIM were a severe leukocytosis (32.2 x 10^3/mL) characterized by a severe neutrophilia with toxic changes (18,998/mL), severe lymphocytosis (11,914/mL), moderate thrombocytosis (680 x10^3/mL), low total protein (4.8 g/dL), low albumin (1.8 g/dL), and mildly elevated chloride (114 mEq/L). Due to the lack of response to treatment and the increasing suspicion of disseminated idiopathic myositis, the decision was made to switch Olive’s antibiotics and begin immunosuppressive steroids in an effort to improve her clinical signs: enrofloxacin was stopped and replaced with doxycycline (10 mg/kg PO BID), famotidine (0.5 mg/kg PO BID), and prednisolone (0.5 mg/kg PO BID). Over the next several days, Olive showed no improvement despite the changes to her treatment plan, and her quality of life continued to decline. Due to this, her owners elected humane euthanasia. Post-mortem After euthanasia, muscle biopsies were taken from the diaphragm, esophagus, and gastrocnemius muscles for histopathology. Histopathology showed severe suppurative esophagitis and myositis with pyogranulomas. DIM typically affects young ferrets less than 18 months old, is not contagious, and the onset is typically fast. Owners may report overnight changes to demeanor and behavior, as well as persistent but fluctuating fever. Initial bloodwork may show normal to mildly elevated white cell counts, as in Olive’s case, which can rapidly progress over 7-10 days, with up to 100,000 cells/mL of blood with toxic changes. Glucose is frequently elevated, and albumin levels are usually decreased, while creatine kinase (CK) is not elevated. Biopsy of the affected muscle typically reveals severe, widespread inflammation, often with suppurative changes, with the esophagus being particularly affected. The prognosis for this condition is poor, and the etiology is still unknown, but is suspected to be autoimmune. There have been some cases where systemic immunosuppression has caused remission using steroids and other immunosuppressants. Olive’s histopathology, combined with her history, is most indicative DIM and was her post-mortem diagnosis. Cordell Rech, DVM, enjoys the challenge and variety that exotic companion animals bring to general practice. Educating clients about their pets and helping prevent illness is rewarding and brings enthusiasm from staff and clients alike. He graduated from Texas A&M College of Veterinary Medicine and Biomedical Sciences in 2016 and completed two internships before moving into private practice. Dr. Rech would like to thank his fellow doctors for their assistance in hospitalization and management of this case while at South Wilton Veterinary Hospital at the time of this case: Raina Schunk, Clare Fahy, and Ryan Pelletier.
