Testing of dogs: MAC
Related tests
- Combination Schnauzer Miniature CMT + MAC + MC + PMDS+ PRA1 + SCD + vWDI
- MAC + PRA1 doubletest for Schnauzer Miniature for better price
- MC + MAC doubletest for Schnauzer Miniature for better price
Mycobacterium Avium Complex (MAC) in Miniature Schnauzer
Mycobacterium avium complex (MAC) is a group of mycobacteria that contains potentially pathogenic organisms. The MAC includes Mycobacterium avium and Mycobacterium intracellulare. These organisms are commonly present in the environment – in soil, water and air. Therefore, dogs are often exposed to this pathogen, however usually they are not at risk because dogs posses natural resistance to infection with MAC. But in susceptible patients these organisms are capable of producing generalized disease due to a defect in the immune system. It has been proven the importance of genetic factors in determining both susceptibility to infection and whether or not there is subsequent development of clinical disease.
The MAC infection is a life threatening disease. The primary sign is lymph node enlargement as well as liver and spleen enlargement. The affected dog is lethargic and shows further symptoms such as vomiting, anorexia, weakness and fever. The dogs may also suffer from runny nose, conjunctivitis, diarrhoea, blood in stool or respiratory problems. The infection is incurable and always fatal.
The genetic disorder causing susceptibility to MAC infections has been discovered in Miniature Schnauzer. All these affected dogs were related to a particular dog under suspicion of being a genetic source for the potential immune system defect allowing a MAC infection. The most cases were diagnosed in the USA and Canada, but some cases were reported from Poland and other parts of Europe. The occurrence of polymorphism carriers is approximately 10% in Europe and North America.
The polymorphism is recessively inherited. The increased susceptibility to MAC develops in dogs which inherit the variant gene from each parent. These dogs are designated as P/P (positive/positive). The carriers of the polymorphism are designated as N/P (negative/positive). The carriers inherited the variant gene from one parent only and are without clinical signs. However, they pass the disease on to their offspring. When mating two heterozygotes (N/P), there will be theoretically 25% of the offspring healthy, 50% of the offspring will be carriers and 25% of the offspring will inherit the polymorphism from both parents and will be in risk of MAC. Mating one healthy dog (N/N) with a carrier of this polymorphism (N/P) will theoretically produce 50% carriers and 50% healthy offspring. If a carrier (N/P) is mated with an affected dog (P/P), there will be theoretically 50% affected dogs and 50% carriers.
The increased susceptibility to pathogenic organisms M.avium and M. intracellulare is caused by gene variant in CARD9-gene that has an important regulatory function in cell apoptosis and plays an important role in natural immune response to pathogens such as, for example, yeasts.
MAC is potentially infectious for humans. The health of people is not at risk, because humans generally have the same innate immunity to this pathogen as dogs. However, persons with HIV/AIDS, diabetes, cancer or other immune system disorders should consult with their doctor if they have dog diagnosed with MAC.
.
Reference:
Errolyn Martin: Disseminated Mycobacterium Avium Complex Infection in Miniature Schnauzers
Keijiro Mizukami, Angella Dorsey-Oresto, Karthik Raj, Anna Erings, Eva Furrow, Gary S. Johnsom, Urs Giger: A codon deletion in CARD9 gene causes increased susceptibility to Mycobacterium Avium complex in Miniature Schnauzer Dogs: The 9th international conference on canine and feline genetics and genomics