Defect in Mitochondrial NADH-Dehydrogenase Genes in Canine Mast Cell Tumours

Case report: Resolution of malignant canine mast cell tumor using ketogenic metabolic therapy alone

Background

Mast cell tumors (MCT) are common neoplasms in dogs and are similar to most other malignant cancers in requiring glucose for growth, regardless of histological grade. Ketogenic metabolic therapy (KMT) is emerging as a non-toxic nutritional intervention for cancer management in animals and humans alike. We report the case of a 7 years-old Pit Bull terrier that presented in 2011 with a cutaneous mast cell tumor under the right nostril.

Methods

The patient’s parent refused standard of care (SOC) and steroid medication after initial tumor diagnosis due to the unacceptable adverse effects of these treatments. Following tumor diagnosis, the patient’s diet was switched from Ol’Roy dog food to raw vegetables with cooked fish. The tumor continued to grow on this diet until July, 2013 when the diet was switched to a carbohydrate free, raw calorie restricted ketogenic diet consisting mostly of chicken and oils. A dog food calculator was used to reduce calories to 60% (40% calorie restriction) of that consumed on the original diet. A total of 444 kilocalories were given twice/day at 12 h intervals with one medium-sized raw radish given as a treat between each meal.

Results

The tumor grew to about 3–4 cm and invaded surrounding tissues while the patient was on the raw vegetable, cooked fish diet. The tumor gradually disappeared over a period of several months when the patient was switched to the carbohydrate free calorie restricted ketogenic diet. The patient lost 2.5 kg during the course of the calorie restriction and maintained an attentive and active behavior. The patient passed away without pain on June 4, 2019 (age 15 years) from failure to thrive due to an enlarged heart with no evidence of mast cell tumor recurrence.

Conclusion

This is the first report of a malignant cutaneous mast cell tumor in a dog treated with KMT alone. The resolution of the tumor in this canine patient could have been due to the diet-induced energy stress and the restriction of glucose-driven aerobic fermentation that is essential for the growth of most malignant tumors. Further studies are needed to determine if this non-toxic dietary therapeutic strategy could be effective in managing other canine patients with malignant mast cell tumors.

Molecular differences in mitochondrial DNA genomes of dogs with malignant mammary tumours

The aim of this study was to determine molecular defects in mitochondrial DNA (mtDNA) with the use of large-scale genome analysis in malignant canine mammary gland tumours and indicate whether these changes were linked with the carcinogenesis process. With the use of the NGS technology, we sequenced 27 samples of mtDNA isolated from blood and tumours obtained from 13 dogs with mammary gland tumours. The total number of mutations and polymorphisms in the analysed mitochondrial genomes was 557. We identified 383 single nucleotide polymorphisms (SNP), 32 indels (or length polymorphisms), 4 mutations, 137 heteroplasmic positions and 1 indel mutation. The highest variability (132 changes) was observed in the variable number of tandem repeats (VNTR) region. The heteroplasmy rate in VNTR varied among individuals and even between two tumours in one organism. Our previous study resulted in determination of a probable CpG island in this region, thus it is not excluded that these changes might alter mtDNA methylation. Only the ATP8 gene was not affected by any polymorphisms or mutations, whereas the COX1 gene had the highest number of polymorphisms from all protein-coding genes. One change m.13594G>A was detected in a region spanning two genes: ND5 and ND6, from which a deleterious effect was observed for the ND5 protein. Molecular changes were frequently observed in the TΨC loop, which is thought to interact with ribosomal RNA.