Comparison of methohexital and propofol as induction agents for evaluation of laryngeal function in healthy dogs.

OBJECTIVE: To determine the influence of propofol or methohexital, with and without doxapram, on the examination of laryngeal function in dogs. STUDY DESIGN: Experimental study. ANIMALS: Forty healthy dogs randomly assigned to 4 groups: propofol with saline (n = 10), propofol with doxapram (n = 10), methohexital with saline (n = 10), or methohexital with doxapram (n = 10). METHODS: Propofol and methohexital were administered to effect. Investigators examined laryngeal function (initial) simultaneously with video laryngoscopy. Doxapram or saline was administered, and laryngeal function was reevaluated (second). Laryngeal motion, quality of laryngeal exposure, and the degree of swallowing, laryngospasm, and jaw tone were scored at each evaluation. Adverse events were recorded. Initial and second videos were evaluated by a masked observer, and still images obtained from both evaluations were evaluated for change in rima glottidis size by 2 masked observers. RESULTS: Administration of doxapram and saline was delayed with propofol (P = .001). Laryngeal function did not differ between dogs receiving propofol or methohexital, irrespective of doxapram administration. Doxapram improved breathing scores in both groups (P < .001). Jaw tone increased with propofol during the second evaluation (P = .049). Swallowing was more prevalent at initial examination (P = .020). Methohexital resulted in an increased heart rate (P < .001) compared with propofol. Twenty-five percent of dogs receiving methohexital developed seizure-like activity (n = 5/20). CONCLUSION: Evaluation of laryngeal function did not differ between healthy dogs anesthetized with propofol or methohexital. Methohexital provided shorter examination times with less jaw tone but was associated with adverse events. CLINICAL SIGNIFICANCE: This study provides evidence to recommend propofol over methohexital as an induction agent for laryngeal function examination.

Complex mammary carcinoma with metastases to lymph nodes, subcutaneous tissue, and multiple joints in a dog.

An 8-year-old, intact female, mixed-breed dog presented to the Oklahoma State University Boren Veterinary Medical Teaching Hospital for evaluation of progressive lameness and joint effusion of multiple joints. Physical examination revealed joint effusion of the elbow, hock, and stifle joints bilaterally, enlarged left axillary and right popliteal lymph nodes, a subcutaneous mass over the left elbow, and a subcutaneous mass involving the left second and third mammary glands. Cytologic examination of the mammary mass, enlarged lymph nodes, and joint fluid from most affected joints revealed a monomorphic population of loosely cohesive neoplastic epithelial cells. The patient was humanely euthanized, and subsequent necropsy with histopathologic examination revealed a complex mammary carcinoma with metastases to enlarged lymph nodes, subcutaneous tissue over the left elbow, and the synovium of multiple joints. Immunohistochemical stains were performed and showed diffusely positive pan cytokeratin, CK8/18, and CK19 staining in the neoplastic luminal epithelial cells of the mammary carcinoma, synovium, and lymph nodes, and showed diffusely positive vimentin staining of the myoepithelial cells. Myoepithelial calponin positivity was diffuse in the mammary mass and lymph nodes but minimal in the synovium. Only the mammary mass showed p63 positivity. Metastatic mammary neoplasia is relatively common in dogs; however, metastasis to the synovium has only been reported once previously in the literature. This is the first case utilizing immunohistochemistry for confirmation and characterization of metastases.