Case Studies

Aspergillosis Infection Causing Pyelonephritis and Ureteritis in a Cat.

Aspergillosis: Infection Causing Pyelonephritis And Ureteritis In A Cat


An unusual case, the Aspergillus infection appears to be localized solely to the left kidney and ureter with no respiratory component or signs of immune system compromise.

By Heather McDonnell Siemon, DVM
and Stephen Bilbrey, DVM, MS
Diplomate AVCS

1. Referral

Olive, a 7 year old female spayed domestic shorthair cat, was referred to the ASG internal medicine service for further evaluation of a suspected mass in her left kidney. She had presented to her primary veterinarian for weight loss and decreased appetite. Olive is an indoor-only cat with no recent travel history and up to date on vaccinations. The other cat in the household was healthy. Diagnostic investigations by the referring veterinarian including a CBC and urinalysis were within normal limits. Her biochemistry identified an elevated total protein of 9.1 g/dL and elevated globulin of 6.4 g/dL. Other diagnostic investigations including full-body radiographs, fecal analysis, FeLV antigen, and FIV antibody testing did not reveal any abnormalities. An abdominal ultrasound was also performed that identified a left renal mass effect and severe dilation of the proximal left ureter with no other identified abnormalities.

2. Physical Examination

At the time of her appointment with the ASG internal medicine service, Olive had been experiencing clinical signs of decreased appetite and weight loss for approximately 4 months. Olive was found to have a normal physical examination aside from a body condition score of 3/9. Thoracic radiographs were taken which showed a mild diffuse bronchial pattern but were otherwise unremarkable. A recheck CBC and biochemistry analysis were submitted and showed an elevated globulin level of 5.4 g/dL, elevated CK of 1190 IU/L, elevated white blood cell level of 27.8 103/uL, elevated neutrophils of 23352/uL. Urinalysis showed a urine protein level of 2+, with 2+ occult blood, 11-20 white blood cells/hpf, and 11-20 red blood cells/hpf.

Based on the ultrasonographic appearance of her left kidney and ureter as well as her history of weight loss and decreased appetite, Olive was referred to a veterinary surgeon for left nephrectomy. It was recommended that Olive undergo renal scintigraphy to assess the function of her right kidney prior to removing the left kidney. This test was declined by the owners, who elected to proceed directly with the nephrectomy.

3. Treatment

Olive was hospitalized the day prior to her planned nephrectomy. She was treated with intravenous fluid therapy at a rate of 1.5 times maintenance overnight and restricted from food in preparation for her surgery. On the day of her surgery she was prepared with routine skin preparation and anesthesia. A ventral midline incision was made and full abdominal exploration was performed. Her left kidney appeared grossly normal and the adjacent ureter appeared firm and severely dilated at the proximal aspect, tapering to a more normal diameter distally. Aspiration of the kidney revealed that it contained purulent material. Her liver appeared small and rounded. The rest of her abdomen was normal in appearance. A routine nephrectomy was performed with sharp and blunt dissection used to exteriorize the left kidney and ureter. The renal artery and vein and ovarian vein were double ligated. The ureter was double ligated at its entrance to the urinary bladder and transected. The abdomen was lavaged with sterile saline prior to routine closure. The left kidney was incised after removal and found to contain large amounts of purulent material in the renal pelvis. The left kidney and ureter were submitted for histopathology and a sample of the purulent material from the left renal pelvis was submitted for aerobic and anaerobic culture. Olive remained stable under anesthesia and recovered well. She remained hospitalized for 2 days after surgery receiving intravenous fluids, antibiotics, analgesia, and close monitoring. Her BUN and creatinine were monitored and remained normal throughout her hospitalization.

4. Diagnosis

The histopathology report showed “necrosuppurative, locally extensive, severe and chronic-active pyelonephritis and ureteritis with dense mats of fungal hyphae”. Further it was found that “the ureter and renal pelvis are distended by large amounts of necrotic debris and neutrophils with fewer eosinophils, all of which is variably admixed with dense mats of lightly basophilic fungal hyphae. (Fig 1)”

Aspergillosis: fungal hyphae

Figure 1: Arrows indicate fungal hyphae.

Although a specific fungus could not be identified on gross examination, the pathologist suspected aspergillosis based on the morphology of the observed fungal hyphae. Fungal culture was recommended. A sample was subjected to Grocott’s methenamine silver stain and was positive, indicating the presence of fungi (Fig 2).

Aspergillosis: Grocott’s methenamine silver stain

Figures 2

Aerobic, anaerobic, and fungal culture were all negative for growth. An additional urine fungal culture was submitted to the San Antonio Fungus Testing Lab that was negative for growth. Aspergillosis antibody via agar gel immunodiffusion was submitted and was positive.

5. Discharge

Olive was discharged from the hospital with oral buprenorphine pain relief, clavamox antibiotics, capromorelin appetite stimulant, and started on compounded itraconazole anti-fungal medication.

6. Discussion

Aspergillus is a type of ubiquitous saprophytic fungi that is found throughout the environment and thrives on a wide variety of organic material. Although infection with this organism is uncommon in cats, it has been implicated in two distinct types of infection: local sinonasal aspergillosis infection and disseminated aspergillosis1. Local sinonasal aspergillosis occurs when a focus of aspergillosis infection develops inside the sinonasal cavity. Because aspergillosis spores are easily aerosolized, most individuals will regularly inhale this organism in their lifetime and innate immune defenses will prevent infection from taking hold. Animals with compromised immune systems are more likely to develop sinonasal aspergillosis but this is not required for infection to take place and in particular is not critical for this infection to take place in cats. Sinonasal aspergillosis is more common in dogs than cats but in cats is associated with locally extensive invasion and destruction. In advanced cases, sinonasal aspergillosis can progress to sinoorbital aspergillosis when the infection extends through the orbital lamina2. Cats with sinonasal aspergillosis commonly present with sneezing and nasal discharge, more chronic cases show signs of facial swelling, prolapse of the third eyelid, and exophthalmos. Treatment of this condition may involve some combination of endoscopic debridement of fungal plaques and infusion of topical anti-fungal medications, as well as systemic anti-fungal medications which may require long courses of treatment. Sinonasal aspergillosis has a fair to guarded prognosis in cats1.

Disseminated aspergillosis is a condition in which the aspergillus organisms do not remain isolated in the respiratory anatomy but spread to other areas in the body. In cats this is commonly associated with immunosuppression including panleukopenia, FIV infection, FeLV infection, or in cats receiving medications which suppress the immune system2. Disseminated aspergillosis is very uncommon in cats and so is not well described. It is occasionally seen on necropsy with fungal plaques found in pulmonary, central nervous system, gastrointestinal, and urinary system tissues1.

Olive’s case is unusual because her infection appears to be localized solely to the left kidney and ureter with no respiratory component or signs of immune system compromise. Unfortunately, the organism failed to grow on culture so we lack information about the individual species of aspergillosis that infected Olive. Review of the literature reveals that focal isolates of aspergillus are rare outside of the nasal anatomy. A case described in Australia in 2011 details a case of aspergillosis isolated to a single pulmonary nodule which resolved after left pneumonectomy3. Two cases of mycotic cystitis have been described in which aspergillus was identified in the urine 4,5. Two cases of pulmonary aspergillosis were described in cats with poorly-controlled diabetes mellitus, which is theorized to have caused immunosuppression leading to infection in these cases 6. After review of the literature, a case of aspergillosis isolated to the kidney of a cat has not been identified.

7. Recovery

Olive presented to the internal medicine department for a recheck evaluation after approximately 8 weeks of itraconazole therapy. She was found to have gained weight during this time, from 2.8 kg to 3.12 kg. An aspergillus antigen enzyme immunoassay was submitted on both urine and serum and both were negative. “Olive” will be continued on itraconazole therapy for another month. Another aspergillus antigen enzyme immunoassay will be submitted at that point and if it is also negative Olive will be trialed without anti-fungal medication. Owners report that she is doing very well at home with good appetite.

Image of cat is not Olive.

REFERENCES: [1] Greene, Craig E. Infectious Diseases of the Dog and Cat. 4th ed., Saunders Elsevier, 2012; [2] Vanessa R. Barrs, Jessica J. Talbot,Feline Aspergillosis, Veterinary Clinics of North America: Small Animal Practice, 44:1, 2014: 51-73; [3] Hazell, K.L., Swift, I.M., Sullivan, N. Successful treatment of pulmonary aspergillosis in a cat. Aust Vet J. 2011; 89:101–104; [4] Kirkpatrick RM. Mycotic cystitis in a male cat. Vet Med Small Anim Clin 1982;77:1365–71; [5] Adamama-Moraitou KK, Paitaki CG, Rallis TS, et al. Aspergillus species cystitis in a cat. J Feline Med Surg 2001;3:31–4; [6] Leite-Filho RV, Fredo G, Lupion CG, Spanamberg A. Chronic invasive pulmonary aspergillosis in two cats with diabetes mellitus. Journ. Comp. Path, Vol 155: 2-3, Aug-Oct 2016: 141-144

Animal Specialty Group

DVM, MS, Diplomate American College of Veterinary Surgeons

Dr. Stephen Bilbrey has received multiple awards for academics and teaching, and has authored numerous scientific papers for veterinary surgery publications and textbooks. As a board-certified surgeon since 1991, his special interests include thoracic, abdominal, oncologic, plastic, and reconstructive surgery.