Hereditary deficiency of the enzyme catalase, which catalyses the breakdown of hydrogen peroxide into water and oxygen. Catalase is very abundant in erythrocytes and in many tissues, and its deficiency manifests as a characteristic biochemical alteration. Most affected animals are asymptomatic; homozygotes may present oral ulcers and periodontal problems due to reduced defence against bacterial peroxide. It is a classic biochemical trait described in Beagle lines.

Trait initially described in laboratory Beagle lines. Screening with genetic panels has also detected the allele in the companion Beagle (including a homozygote with oral gangrene) and in the American Foxhound, English Foxhound, Harrier, Miniature Poodle and Treeing Walker Coonhound (Donner et al., 2016, PMID 27525650; 2018, PMID 29708978; OMIA:001138-9615). There are no consolidated population frequencies for most breeds.

- Very low or undetectable erythrocyte catalase activity\n- In most cases, absence of clinical signs\n- Oral ulcers and gingivitis in susceptible homozygotes\n- Increased risk of periodontal infections\n- Occasionally, haemolysis after exposure to oxidants

Acatalasemia was recognised in the Beagle in the mid-20th century in research colonies, as one of the first Mendelian biochemical traits of the dog. Molecular analysis of catalase cDNA in the acatalasemic Beagle identified a single nucleotide substitution that changes alanine 327 to threonine; the mutant enzyme is thermolabile and undergoes accelerated proteasome-mediated degradation in erythrocytes (Nakamura et al., 2000; PMID 11137458). Screening with genetic panels confirmed the presence of the allele in the companion Beagle and in other scent hound breeds (Donner et al., 2016, PMID 27525650; 2018, PMID 29708978).

- Screen breeding animals from lines with a history before mating\n- Do not mate two carriers if testing is available\n- Monitor the oral health of homozygous animals and consider periodic dental prophylaxis\n- Inform the new owner of the animal's biochemical status

Acatalasemia is usually an incidental analytical finding when measuring erythrocyte enzyme activity. It should not be confused with G6PDH deficiency or with haemolytic anaemias due to defects of the glutathione axis. The diagnosis is confirmed by measuring catalase activity in red blood cells. Its clinical relevance is minor, but it should be monitored in carrier lines to avoid symptomatic homozygosity.

1. Nakamura K, et al. cDNA cloning of mutant catalase in acatalasemic beagle dog: single nucleotide substitution leading to thermal-instability and enhanced proteolysis of mutant enzyme. Int J Biochem Cell Biol 2000;32(11-12):1183-93. PMID: 11137458
2. Donner J, et al. Genetic panel screening of nearly 100 mutations reveals new insights into the breed distribution of risk variants for canine hereditary disorders. PLoS One 2016;11(8):e0161005. PMID: 27525650
3. Donner J, et al. Frequency and distribution of 152 genetic disease variants in over 100,000 mixed breed and purebred dogs. PLoS Genet 2018;14(4):e1007361. PMID: 29708978
4. OMIA:001138-9615 (CAT). https://omia.org/OMIA001138/9615/