BRIEF COMMUNICATION Comparison of airway size with some phenotypic parameters in Dalmatian puppies: a practical method to estimate endotracheal tube size Sirri Avki* PhD, DVM, Kursad Yigitarslan* DVM & Ozcan Ozgel PhD, DVM *Department of Surgery, Faculty of Veterinary Medicine, University of Akdeniz, Burdur, Turkey  Department of Anatomy, Faculty of Veterinary Medicine, University of Akdeniz, Burdur, Turkey Correspondence: Sirri Avki, Department of Surgery, Faculty of Veterinary Medicine, University of Akdeniz, 15100 Burdur, Turkey. E-mail: sirriavki@hotmail.com Abstract Objective To determine the relationship between 16 phenotypic parameters and the diameter of the tracheal lumen and endotracheal tube size (ETS) in Dalmatian puppies. Study design A prospective nonblinded study. Animals Twenty-nine Dalmatian puppies, <5 months of age, referred to the Veterinary Faculty Clinics, Burdur, Turkey. Materials and methods The diameter of the tracheal lumen was assessed using lateral cervical radio- graphs and the ETS was determined for each puppy. The relationships between ETS and body mass, age, dimensions of carpal and digital pads of the thoracic limb, length of the philtrum and the distance between the philtrum and lateral nasal edges were analysed statistically. Results The linear relationships between the ETS and the vertical length of the fourth digital pad (r 2 ¼ 0.915), and body mass (r 2 ¼ 0.908) were higher than with other parameters. Two predictive formulae for ETS derived from regression lines are: ETS ± SE (0.20) ¼ [body mass (kg) · 6/10]+2.5 and ETS ± SE (0.19) ¼ [vertical length of fourth digital pad (cm) · 6] ) 2. Conclusions and clinical relevance These formulae provide a practical guide to ETS selection in Dalmatian puppies. Keywords dog, body mass, Dalmatian, digital pad, endotracheal tube size, radiography, tracheal dia- meter. Introduction Endotracheal intubation is an established prere- quisite to the administration of inhalant anaes- thetics to dogs (Hall & Clarke 1983; Hartsfield 1996). During maintenance of inhalant anaesthe- sia, the endotracheal tube should prevent the leak- age of anaesthetic gas into the environment (Hall & Clarke 1983). An airtight seal may be accomplished by inflating the endotracheal tube cuff. However, it is preferable to use uncuffed tubes in young dogs because their larger diameter reduces airway re- sistance. The likelihood of trauma to the tracheal mucosa – which is more fragile in puppies – is also reduced (Hall & Clarke 1983; Wong & Brock 1994; Hartsfield 1996). Several methods have been pro- posed to assist those performing endotracheal intu- bation in human beings to select appropriately sized endotracheal tubes (King et al. 1993; Shott 2000; Hofer et al. 2002). An age-based formula and selection based on the width of the child’s fifth finger are most widely recommended (King et al. 1993). 24 Veterinary Anaesthesia and Analgesia, 2006, 33, 24–27 doi:10.1111/j.1467-2995.2005.00200.x