Skeletal muscle composition in various breeds of domestic dogs: (A comparative study)

• Main Author: van Boom, Kathryn
• Other Authors: Kohn, Tertius, Schoeman, Johan
• Format: Master Thesis
• Language: English
• Published: Faculty of Health Sciences 2019
• Subjects: sports medicine; Canis lupus
• Online Access: http://hdl.handle.net/11427/31125; https://open.uct.ac.za/bitstream/11427/31125/1/thesis_hsf_2019_van_boom_kathryn.pdf

The rising rate of insulin resistance and type 2 diabetes in humans over the past two decades have been linked to increasing rates of obesity, aging and urbanisation. A similar pattern is occurring in domestic animals, specifically cats and dogs. Skeletal muscle is a vital organ in the regulation of blood glucose. Its composition in terms of muscle fibre type, metabolism and contractility can differ substantially between species, but is poorly studied in the domestic dog, in particular the various breeds. It was hypothesised that insulin resistance and type 2 diabetes may be associated with muscle fibre type, in particular, muscle with a low type I fibre content being a predisposing factor. Therefore, the aims of this study were to investigate the skeletal muscle fibre composition and metabolic profile in the Triceps brachii (TB) and Vastus lateralis (VL) of 16 breeds of domestic dogs (Canis lupus familiaris). A secondary aim was to correlate the skeletal muscle composition with breeds reported as having a high incidence of diabetes. Skeletal muscle samples were collected post mortem from the TB and VL of 38 dogs from different breeds, age and sex, and analysed for fibre type composition, fibre size, oxidative and glycolytic metabolic capacity (citrate synthase (CS), 3-hydroxyacetyl co A dehydrogenase (3-HAD), creatine kinase (CK) and lactate dehydrogenase (LDH) enzyme activities). There was no significant difference between the TB and VL in any of the measurements. Type IIA was the predominant fibre type for both muscle groups (TB: 43%; VL: 44%) followed by type I (TB: 33%; VL: 38%) and type IIX (TB: 24%; VL: 18%). The cross sectional area (CSA) of the fibres were all smaller compared to humans and other wild animals. Surprisingly, there was no difference in the CSA between the fibres types and muscle groups: Type I: TB: 1740 µm2 VL: 1712 µm2 , Type IIA: TB: 1690 µm2 VL: 1720 µm2 , Type IIX TB: 1726 µm2 VL: 1791 µm2 ). Metabolically, the muscle of the dog displayed a high oxidative capacity with high ...