OBJECTIVE To determine whether the degree of CT attenuation of muscle would differ between healthy old and young dogs.
ANIMALS 10 healthy old (> 8 years old) and 9 healthy young (1 to 5 years old) Labrador Retrievers with a body condition score of 5 or 6 on a 9-point scale.
PROCEDURES CT was performed with the dogs mildly sedated. A freehand closed polygon tool was used to define the outer margin of the left epaxial muscles on each transverse image obtained from the cranial to caudal endplates of T13. The CT attenuation values from every voxel from within these regions of interest were exported from DICOM software as a single dataset in an extensible markup language file. From these data, mean CT attenuation values were calculated for each dog and these mean values were compared between age groups.
RESULTS Mean CT attenuation values for the epaxial muscles were significantly lower in old dogs than in young dogs. A significant negative correlation (r = –0.74) was identified between mean CT attenuation values and dog age.
CONCLUSIONS AND CLINICAL RELEVANCE In addition to loss of skeletal muscle mass, low muscle CT attenuation values suggested that the old dogs in this study also had greater muscle fat content than did young dogs. Additional studies are warranted to evaluate qualitative and quantitative muscle changes in old dogs.
Objective—To evaluate clinically applicable methods of assessing lean body mass in dogs and compare muscle mass and inflammatory markers in healthy young and old dogs.
Animals—9 healthy young (1 to 5 years old) and 10 old (> 8 years old) Labrador Retrievers with a body condition score of 5 to 6 of 9.
Procedures—Radiography of the thoracolumbar region was performed for measurement of epaxial muscle height at the level of T13–L1. Computed tomographic images were obtained for the measurement of the epaxial and temporal muscles. Ultrasonography also was performed for regional muscle measurements at these same sites and the quadriceps muscle. Serum C-reactive protein, insulin-like growth factor-1, and tumor necrosis factor-α concentrations also were measured, and dogs' activity for 14 days was assessed with an activity monitor.
Results—Mean epaxial muscle area measured by ultrasonography was significantly lower in the old group, compared with the young group, whereas epaxial muscle area measured by CT was only significantly lower in the old group after normalization for vertebral height. Neither temporal and quadriceps muscle measurements nor serum C-reactive protein or insulin-like growth factor-1 concentrations were significantly different between age groups. Tumor necrosis factor-α concentrations were undetectable in all dogs.
Conclusions and Clinical Relevance—This study documented reduced epaxial muscle area in healthy old Labrador Retrievers, consistent with the syndrome of sarcopenia. Ultrasonography and CT were feasible methods of measuring epaxial muscle area, but much additional research is required to assess this method. A better understanding of underlying mechanisms of sarcopenia as well as methods for slowing progression is needed.
Case Description—An 8-month-old male Saint Bernard developed tetanic seizures and hyperthermia during evaluation of bilateral osteochondritis dissecans of the shoulder joints. Further investigation revealed that the dog was receiving an unbalanced homemade diet.
Clinical Findings—Preliminary evaluation of the dog revealed bilateral signs of pain and mild muscle wasting in the shoulder joint areas. Serum biochemical analysis revealed severe hypocalcemia, hyponatremia, hypochloremia, hyperphosphatemia, vitamin D deficiency, and taurine deficiency. Diffuse osteopenia was identified on radiographs of the mandible and long bones, confirming bone demineralization. Analysis of the homemade diet revealed that the dog's diet was severely deficient in a variety of nutrients.
Treatment and Outcome—The dog responded positively to treatment for hypocalcemia, hyperthermia, and seizures. The dog's diet was changed to a complete and balanced canine diet formulated for growth. Body weight and body condition were monitored, and dietary intake was adjusted to achieve optimal body condition during growth. After initial evaluation, serial monitoring of serum calcium and taurine concentrations revealed that values were within reference limits and the dog had no further clinical signs associated with dietary deficiency.
Clinical Relevance—Findings in this puppy highlight the risks associated with feeding an unbalanced homemade diet during growth and the importance of obtaining a thorough dietary history from all patients. For owners who elect to feed a homemade diet, it is critical to have the homemade diet carefully formulated by a veterinary nutritionist to avoid severe nutrient imbalances, especially in young, growing dogs.