Mucopolysaccharidosis in Dogs – Vet Led Guide 2025 🐶🧬

By Dr. Duncan Houston BVSc

Hello, I’m Dr Duncan Houston, BVSc, founder of Ask A Vet. In this 2025 update, we dive into mucopolysaccharidosis (MPS)—a group of rare, inherited lysosomal storage disorders that affect dogs from puppyhood. These metabolic conditions cause progressive buildup of glycosaminoglycans (GAGs), leading to widespread effects. Though incurable, early diagnosis and thoughtful care can help affected pups live the best life possible. Let’s explore together! 🐾

🧬 What Is MPS?

MPS is a genetic disease resulting from missing enzymes in lysosomes—the cell’s recycling centers. When these enzymes can't break down GAGs, they accumulate in organs, joints, eyes, brain, and connective tissue, causing progressive dysfunction.

MPS is inherited in an autosomal recessive manner, meaning both parents must pass on a mutated gene. Carriers show no signs but can produce affected pups.

🧪 Types of Canine MPS

There are several canine MPS types, each with different enzyme deficiencies:

• MPS I: α‑l‑iduronidase deficiency—similar to human Hurler syndrome; affects breeds like Rottweilers, Boston Terriers
• MPS IIIA / IIIB: heparan sulfate deficiencies—neurologic disease in Huntaways and other working breeds
• MPS VI (Maroteaux‑Lamy): arylsulfatase B deficiency—documented in Miniature Schnauzers, Pinschers, Great Danes
• MPS VII (Sly syndrome): β‑glucuronidase deficiency—seen in German Shepherds, mixed breeds

🚩 Common Clinical Signs

Pups may appear normal at birth but develop signs within months:

• Growth retardation, short stature, broad chest, head enlargement (“coarse” facial features)
• Skeletal deformities—kyphosis, limb shortening, joint laxity
• Eye issues—corneal clouding, vision changes
• Organ enlargement—liver, spleen, heart disease
• Neurologic signs—ataxia, cognitive decline, seizures (MPS III)
• Respiratory difficulties due to airway shape changes
• Frequent infections from tissue and organ dysfunction

🔬 Diagnosis: How We Confirm MPS

1. Clinical exam + pedigree: Combined with dysmorphic features or breed risk.
2. Blood & urine testing: GAG spot test for excessive urinary GAGs.
3. Enzyme analysis: Confirm specific enzyme deficiency.
4. Genetic testing: Carrier vs affected status (e.g., SGSH for MPS IIIA, ARSB for MPS VI).
5. Imaging: X-rays for bone, spine; MRI for brain in neurologic types.
6. Histology: Lysosomal inclusions in biopsy confirm diagnosis.

💉 Treatment & Management Options

1. Enzyme Replacement Therapy (ERT)

ERT (like Naglazyme® for MPS VI) can reduce GAG buildup, improve joint mobility, reduce respiratory issues—but isn’t widely used in dogs due to cost.

2. Gene Therapy & Transplantation

Bone marrow or stem cell transplantation has had success in slowing progression.

Canine gene therapies (using viral vectors) show promise in lab studies, especially for cardiovascular and neurologic improvement.

3. Symptomatic Supportive Care

• Pain relief & joint supplements for mobility
• Antibiotics for recurrent infections
• Soft diets for oral/jaw issues
• Hydration & appetite stimulants
• Respiratory support for airway compromise
• Neurologic care: seizures, coordination support

📅 Prognosis & Lifespan

• Without treatment, most MPS pups show progressive decline and a lifespan <2–3 years.
• ERT or transplant can extend quality life into mid‑childhood.
• Neurologic types (MPS III) often progress rapidly once onset occurs.
• Supportive care can maintain comfort, mobility, and meaningful pet‑parent time.

🏡 Home Care & Quality‑of‑Life Tips

1. Provide padded bedding—support joint comfort.
2. Use ramps/low steps to ease mobility.
3. Feed soft, nutrient-rich diets; monitor weight.
4. Administer medications & supplements reliably.
5. Keep up safe oral hygiene with gentle tools.
   
6. Schedule frequent checkpoints with your vet—including progress testing.

🐾 Role of Ask A Vet

If your dog is diagnosed or at risk, chat anytime with Ask A Vet about testing, supportive strategies, or treatment progress.

✨ Key Takeaways

• MPS is a rare but serious genetic disorder causing multi-system dysfunction via GAG accumulation.
• Diagnosis requires clinical signs, biochemical, genetic, and imaging tests.
• While no cure exists, ERT, gene therapy, or transplant may slow progression in some cases.
• Supportive care and environmental adaptations are essential to maintain quality of life.
• Early detection, breeder testing, and compassionate home strategies help pups live their best lives.

If you suspect MPS in your dog or need help managing symptoms, contact your veterinarian or Ask A Vet. Let’s support your companion with love, science, and hope. 💛