Diagnostic Utility of Canine C-Reactive Protein, Haptoglobin, and 25-Hydroxyvitamin-D in Dogs with Nasal Cavity Disease

Simple Summary The diagnosis of nasal cavity disease (ND) in dogs typically requires comprehensive diagnostics under general anesthesia including cross-sectional imaging and rhinoscopy. Therefore, dogs with nasal discharge are often only presented for diagnostics after weeks of symptomatic or even antibiotic therapy, even though primary bacterial rhinitis is uncommon. In a previous study, the platelet-to-lymphocyte ratio (PLR) differed significantly between dogs with malignant tumors and benign pathology. To further investigate the value of blood tests for diagnosis, the aim of this second part of the study was to evaluate serum markers for their diagnostic utility and whether they may be helpful in making the diagnosis of ND quickly and cost-effectively. Dogs with additional diseases detected by a whole-body CT scan and blood tests were excluded. No significant differences were found between groups for the here evaluated markers C-reactive protein, haptoglobin, and 25-hydroxyvitamin-D.Abstract In this prospective blinded study, canine C-reactive protein (c-CRP), haptoglobin (HPT), and 25-hydroxyvitamin-D (25(OH)D) were investigated for their diagnostic value in 55 dogs with nasal cavity disease (ND). After comprehensive diagnostics including a culture-dependent microbiological examination (ME) of nasal swabs, 17 dogs were excluded due to additionally detected systemic diseases or steroid pre-treatment. Included were 25 dogs with malignant ND (13 carcinomas and 12 sarcomas) and 30 dogs with benign ND (7 benign tumors, 13 idiopathic rhinitis (IR), and 10 others), as well as 10 controls. In none of the 72 dogs with ND was primary bacterial rhinitis diagnosed. Although within the reference interval, compared to the controls, c-CRP was significantly higher in dogs with ND in general and in every subgroup except for benign tumors. Serum HPT concentrations were not different among groups. Compared to the controls, 25(OH)D concentrations were significantly lower (p = 0.041) in malignant ND and sarcomas (p = 0.025). Despite pre-treatment with antibiotics (40/54; 74.1%), in 23/51 (45%) dogs, the ME was positive. Cultivated bacteria did not differ significantly between nasal diseases. The serum markers were not significantly different regarding the positivity of ME. In conclusion, the investigated serum markers were not clinically useful for the reliable detection of canine ND, as was the ME. Because of the low number of dogs with IR and positive or negative ME, further studies regarding c-CRP are needed in a larger group of IR dogs without concomitant diseases to reliably evaluate its utility in IR dogs with suspected secondary bacterial nasal infection.