Reference interval for the C-ACT activated clotting time test in healthy dogs using a water bath and manual assessment of clot formation.

AIMS: To establish a reference range for the canine C-ACT activated clotting time (ACT) test using a water bath and visual clot assessment technique. METHODS: Healthy, privately owned dogs (n = 48) were prospectively recruited to the study. Blood samples were collected via direct jugular venipuncture for complete blood count, serum biochemistry analysis and measurement of prothrombin time (PT) and activated partial thromboplastin time (aPTT). Five animals with major abnormalities or who became agitated during phlebotomy were excluded. For the 43 remaining animals, 2 mL of blood was collected via the cephalic vein and added directly to a C-ACT tube that was shaken vigorously before being placed in a water bath at 37°C. Tubes were visually assessed for clot formation and C-ACT was recorded in seconds when the magnet within the tube lodged in the clot. RESULTS: The nonparametric reference interval (capturing the central 95% of the data) was 50-80 seconds, with a 90% CI for the lower limit of 50-55 seconds and a 90% CI for the upper limit of 75-80 seconds. The C-ACT ACT test had a positive correlation with aPTT (0.42; 95% CI = 0.13-0.64). There was no evidence of a correlation between C-ACT ACT and age, weight, PT, haematocrit, white blood cell count, platelet count or total protein. CONCLUSIONS AND CLINICAL RELEVANCE: The results of this study suggest that the normal reference interval for ACT in dogs using C-ACT tubes in a 37°C water bath is 50-80 seconds. Care should be taken extrapolating the results of this study to the general population, as the smaller study design had less control for confounders than a larger study. However, when using the described analytical methods, C-ACT tube ACT test results >80 seconds should be considered prolonged in dogs and should prompt further investigation.

Elective cricothyrotomy in a dog with transient laryngeal paralysis secondary to Australian paralysis tick (Ixodes holocyclus) envenomation.

The tube cricothyrotomy (CTT) has recently been introduced to small animal medicine as a viable surgical airway access procedure; however, there are no reports documenting its clinical use. The author's objective is to describe the clinical application, complications, and management of an elective CTT in a dog. Furthermore, the characteristics of CTT that may be clinically advantageous over temporary tube tracheostomy (TT) will be discussed. A 2-year-old female spayed German shepherd dog required mechanical ventilation (MV) due to unsustainable work of breathing as a result of tick paralysis and aspiration pneumonia. After successful weaning from MV, the dog was diagnosed with laryngeal paralysis. A surgical airway was performed using CTT to allow extubation and patient management whilst conscious. Complications included frequent tube suctioning due to accumulation of airway secretions in the tube and a single dislodgement event. The dog made an uneventful recovery with complete stoma healing by the second intention within 15 days. To the authors' knowledge, this is the first clinical report of an elective CTT performed to successfully manage upper airway obstruction in the dog. Its efficacy, clinical management and patient outcome are described.

The oxygen and volatile anaesthetic delivery characteristics during spontaneous ventilation using a non-rebreathing coaxial anaesthesia system.

The gas delivery characteristics during simulated spontaneous ventilation of a non-rebreathing adaptation of the Bain circuit were examined. Tidal volumes were varied from 200 to 600 ml and respiratory rate from 8 to 20 breaths per minute obtaining characteristics for a minute volume range from 2.4 to 12 litres/minute. The minimum inspired oxygen concentration with 1 litre/minute 100% oxygen fresh gas flow varied between 86 and 43% over the range of minute volumes. . The minimum inspired Sevoflurane concentration with a 4% vaporiser setting and a 1 litre/minute fresh gas flow varied between 3.4 and 1.3% over the range of minute volumes. Increasing minute volume was the primary determinant of decreasing minimum inspired concentrations with increasing respiratory rate having an independent but smaller effect in reducing concentrations. Thus this system was shown to be safe and economical for the use in spontaneous ventilation.