Canine Mucopolysaccharidosis

Different types have been described in dogs and cats. Type I occurs in Plott hounds and domestic cats. Type VI has been recognized in cats (Siamese) and dogs (Miniature Pinscher and Welsh Corgi). In cats it is caused by a deficiency of arylsulfatase B; in dogs it is the result of excessive dermatan sulfate. Dogs have an excessive amount of dermatan, heparan sulfate, and chondroitin sulfate in the urine. Affected animals are small and short and have facial (flattened faces) and skeletal abnormalities. Cloudy corneas occur in cats.

Signs of Canine Mucopolysaccharidosis

Canine Mucopolysaccharidosis (MPS) I is a condition caused by the deficiency of alpha-L-iduronidase and is most similar to human MPS type I. Dogs with MPS I appear normal at birth, also there is higher than normal incidence of umbilical hernia. Affected puppies remain generally healthy for 4-6 months and then show stunted growth, corneal clouding, and progressive, degenerative, noninflammatory joint disease caused by mucopolysaccharide deposition in synovial and periarticular tissues.

Joint laxity caused by abnormalities in lagaments and tendons is also common. Degeneration of intervertebral disks, collapse of disk spaces, vertebral and long-bone osteopenia and spondylosis also develop. Mucopolysaccharide accumulation in the heart valves and arteries can cause rapidly progressing heart failure. Affected dogs remain alert and responsive until their death by natural causes or euthanasia, usually between the ages of 2 and 3 years.

Canine Mucopolysaccharidosis VII

Canine Mucopolysaccharidosis VII is a condition caused by a deficiency of beta-glucuronidase which involves skeletal and joint abnormalities. Progressive noninflammatory bone and joint disease develops. By the age of 3-6 months, affected dogs are unable to stand and the muscles involved in movement waste. Corneal clouding can cause impaired vision in dogs with MPS VII, but the impairment is usually less severe than in dogs with MPS I At the age of 5-22 months, affected dogs often become lethargic and lose interest in their environment. Those signs might be associated with hydrocephalus.

Diagnosis of Canine Mucopolysaccharidosis

Diagnosis of mucopolysaccharidosis is made by physical examination, blood tests, and radiographic X-rays of the skeletal system. A special test that detects mucopolysaccharides in the urine (toluidine test) can also be employed. Unfortunately, there is no treatment for this disease. Because of the inherited nature of this disease, affected animals should not be bred.

References

1. Dogs By National Research Council Staff, Committee on Dogs, Committee on Dogs National Research Coun, Committee on Dogs, Institute of Laboratory Animal Resources, Commission on Life Sciences, Institute of Laboratory Animal Resources (U.S.), Inc NetLibrary, National Research Council Committee, National Research Council, National Research Council Committee, National Academy of Sciences
2. Thomas Carlyle Jones, Ronald Duncan Hunt, Norval W. King. Radiographic Interpretation for the Small Animal Clinician By Jerry M. Owens, Darryl N. Biery Veterinary Pathology