A 7-year-old neutered male Domestic Shorthair cat weighing 3.71 kg (8.2 lb), was presented to the Companion Animal Clinic at Midwestern University College of Veterinary Medicine (MWU-CVM) (day 1) with a 4-month history of sneezing, intermittent bilateral epistaxis and mucopurulent nasal discharge, progressive vision loss, as well as a 24-h onset of difficulty breathing, anorexia, and marked weakness. The cat was housed indoors only and had no contact with other animals. There was no known trauma or access to rodenticide. Two days before presentation, the primary care veterinarian performed coagulation testing (PT and PTT), serum biochemistry, and urinalysis, which were unremarkable. A complete blood count performed at that time revealed thrombocytopenia (23 x 103/muL; reference interval 151-600 x 103/muL) and a hematocrit within the reference interval (39%; reference interval 30-52%). A slide review with manual platelet count was not performed. In addition, the cat tested negative for feline leukemia virus (FeLV) antigen and feline immunodeficiency virus (FIV) antibody (IDEXX Laboratories, Inc., Westbrook, ME, USA). The cat also had a mean indirect systolic blood pressure measurement performed by Doppler ultrasonography that was unremarkable (149 mmHg; reference <160 mmHg).
Pertinent physical examination findings on day 1 included a rectal temperature of 103.5 F (39.7 C), heart rate of 220 beats per minute with a grade 2/6 systolic left parasternal heart murmur, respiratory rate of 35 breaths per minute with open mouth breathing as well as stertor and pale- pink oral mucous membranes. Ophthalmic examination performed by a boarded-small animal internist revealed bilaterally mydriatic pupils, intact pupillary light and palpebral reflexes, and an absent menace response. There was no evidence of intraocular or ocular surface inflammation. Intraocular pressure measurements performed with a tonometer (Icare TONOVET tonometer TV01, Vantaa, Finland) were unremarkable (OD: 15 mmHg, OS: 18 mmHg; reference range 10-25 mmHg). Indirect ophthalmoscopy was performed using a condensing lens and Finhoff transilluminator and revealed bilaterally swollen optic discs and prominent retinal vessels; there was no evidence of retinal detachment. There was a moderate amount of serosanguinous to mucoid nasal discharge and absent airflow bilaterally. The remainder of the physical examination revealed no additional abnormalities.
Clinically important complete blood cell count abnormalities performed at MWU-CVM were anemia (13%; reference interval 29-48%), reticulocytosis (81,200/muL; reference interval <45,000/muL), thrombocytopenia (57 x 103/muL reference interval 200-500 x 103/muL), leukocytosis (36.9 x 103/muL; reference interval 3.5-16 x 103/muL), neutrophilia (26.57 x 103/muL; reference interval 2.5-8.5 x 103/muL), with increased band neutrophils (1.1 x 103 /muL; reference interval 0.0-0.15 x 103/muL), monocytosis (5.2 x 103/muL; reference interval 0.0-0.60 x 103/muL), and total solids (5.8 g/dL; reference interval 5.2-8.8 g/dL). A blood smear reviewed by a boarded-clinical pathologist revealed an estimated manual platelet count of ~70 x 103/muL and infectious organisms were not identified. A biochemical profile was not performed at that time.
Based on the age of the cat, chronicity of bilateral epistaxis that coincided with the development of progressive vision loss, absence of nasal airflow, and severe anemia, the cat was suspected to have an aggressive infiltrative nasal disease process with secondary blood loss anemia. Differential diagnoses considered most likely at that time included primary nasal neoplasia (e.g., adenocarcinoma, squamous cell carcinoma, lymphoma), abcessation, or fungal rhinitis. Initial treatment consisted of a blood transfusion to address the severe anemia. The cat was blood typed (type A) and was administered 9.4 mL/kg of type A packed red blood cell transfusion IV over 4 h. An hour after the completed blood transfusion, PCV and total solids increased to 21% and 6.4 g/dL, respectively.
Computed tomography (CT; CT scanner, Syngo VC 40 16-slice, Siemens Healthcare, Germany) imaging of the skull was performed on day 2. Helical images of the skull were acquired with a slice thickness of 1.00 mm and a pitch of 0.85. Soft tissue filled the majority of the nasal passages bilaterally, was non-contrast enhancing, and caused displacement of gas. The non-contrast enhancing soft tissue contoured to the shape of the turbinates. There was diffuse contrast enhancement of the soft tissue that lined the osseous scrolls (Figure 1A). The nasal soft tissue extended from the nares caudally to the ethmoid turbinates and into the frontal sinuses and sphenoidal sinus (Figure 1B). The soft tissue within the frontal sinuses collected in the dependent portion with fluid wicking along the margins (Figures 1B,C). The choanae were filled with soft tissue obstructing the patency of the nasopharyngeal upper airway (Figures 1A-C). There was no lysis of the paranasal bones or nasal septum. There was focal enhancement within the posterior ocular globes within the region of the optic disc and the optic nerve heterogeneously contrast enhanced (Figures 1C,D). Rigid rhinoscopy (Karl Storz multi-purpose rigid scope 30 , Segundo, CA, USA) was then performed, which demonstrated hyperemic, vascular, and edematous nasal mucosa with moderate hemorrhage and mucus in both nasal cavities. No obvious mass lesions or fungal plaques were identified. Copious amounts of mucopurulent material and blood were visualized in the nasopharynx using a flexible endoscope (Karl Storz Flexible Silver Scope Small Flexible Gastrointestinal scope, Segundo, CA, USA). Importantly, a nasal foreign body was not identified. Moist laparotomy sponges were placed in the caudal pharynx and 60 mL of chilled sterile 0.9% sodium chloride was used to flush each nasal cavity (120 mL total).
Blind biopsies were obtained from each nasal cavity for cytology (tissue impression smear preparations), histopathology, and aerobic/anaerobic bacterial and fungal culture with antimicrobial susceptibility. Cytology results described the nasal samples as containing numerous degenerative neutrophils frequently containing intracellular bacterial rods of varying morphology with rare bacterial cocci noted (Figure 2A). Subsequent management consisted of ampicillin with sulbactam (30.5 mg/kg, IV, q 8 h), enrofloxacin (Baytril, Bayer HealthCare Animal Health, Shawnee Mission, KS, USA; 5.0 mg/kg, IV, q 24 h), Yunnan Baiyo (Yunnan Baiyao Group Corp. Ltd, Kunming, China; 1 capsule, PO, q 24 h), nebulization with 0.9% saline (q 6 h), dexamethasone-sodium phosphate (0.1 mg/kg IV, administered once), and Lactated Ringer's solution (5.4 mL/kg IV q 1 h) with 20 mEq/L potassium chloride.
The next day (day 3), the cat was no longer febrile 100.7 F (38.1 C), but a marked anemia returned with a PCV and total solids of 12% and 4.8 g/dL, respectively. The cat was administered 11.1 mL/kg of type A packed red blood cells over 4 h following identification of a compatible cross-match donor. An hour after the completed blood transfusion, the PCV and total solids increased to 21% and 6.4 g/dL, respectively. On the day of discharge (day 4), the cat was bright, alert, responsive, afebrile, and had a normal appetite. The anemia persisted but remained static 24 h after the blood transfusion (PCV: 22%; total solids: 6.8 g/dL). Medical management at the time of discharge included prednisolone (0.7 mg/kg, PO, q 24 h), Yunnan Baiyo (1 capsule, PO, q 24 h), pradofloxacin (Veraflox, Bayer HealthCare Animal Health, Shawnee Mission, KS, USA; 7.4 mg/kg, PO, q 24 h), and nebulization with 3 mls of 0.9% saline (q 12 h). Histopathologic sections revealed dense sheets of an almost pure population of neutrophils in which there were a myriad of bacterial colonies that appeared to have a short rod and thin filamentous morphology (Figures 2B,C). Aerobic/anaerobic bacterial culture results returned on day 6 and indicated the presence of E. coli and Actinomyces spp. (Supplemental Table 1) with an absence of fungal growth (confirmed on day 33). The cat was diagnosed with severe bacterial CRS and presumed optic neuritis associated loss of vision. Based on the antimicrobial susceptibility panel, the antimicrobial spectrum was expanded to include amoxicillin-clavulanic acid (Clavamox, Zoetis Inc., Kalamazoo, MI, USA; 16.9 mg/kg, PO, q 12 h) in addition the previously prescribed pradofloxacin (7.4 mg/kg, PO, q 24 h) on day 6.
The cat was presented on day 17 and had an improved appetite, energy, as well as decreased frequency of sneezing and epistaxis. Physical examination revealed unchanged ophthalmic abnormalities, absence of nasal discharge, and improved stertor. A complete blood count was performed and revealed resolution of anemia (HCT: 37%). Medical management with prednisolone, amoxicillin-clavulinic acid, pradofloxacin, Yunnan-Baiyo, and nebulization with 0.9% saline remained unchanged. By day 30 the owner reported that the sneezing persisted but had decreased in frequency and the epistaxis had ceased. The cat's vision was reported to be improved but not yet normal. Physical examination revealed a lack of nasal discharge and normal airflow bilaterally. Ophthalmic examination showed bilaterally mydriatic pupils, intact pupillary light reflexes, and a menace response could be elicited from both eyes. Indirect ophthalmoscopy was performed using a condensing lens and Finhoff transillumintor and revealed unremarkable optic discs and retinal vessels. Due to the improvement of clinical signs, the amoxicillin-clavulinic acid, pradofloxacin, and Yunnan Baiyo were discontinued. Therapy with prednisolone (0.7 mg/kg, PO, q 24 h) and nebulization with 0.9% sodium chloride (q 12 h) was continued.
On day 70, the cat was presented for evaluation and the owner reported complete resolution of sneezing, nasal discharge, and continued improvement of vision. The frequency of prednisolone administration was decreased and subsequently discontinued along with nebulization of saline. Follow-up with the owner by phone at the time of this writing (day 330) revealed that the cat had no sneezing, nasal discharge, and had improved, but not yet normal vision.