Sclerosis

Sclerosis – the word sounds serious, and sometimes it is. It refers to a hardening or stiffening of tissues and organs: instead of elastic fibres, fibrous connective tissue accumulates, gradually displacing healthy tissue. In dogs, this can affect the eyes, blood vessels, skin or nervous system. Whether and how severely a dog suffers from it depends entirely on which tissue is affected – the range extends from barely noticeable signs of ageing to serious diseases.

What is sclerosis?

The term comes from Greek and simply means “hardening”. In veterinary medicine, it stands for a whole group of pathological changes in which normal tissue is replaced by fibrous or hardened connective tissue – and thus loses its original function.

Which form actually occurs depends on which organ is affected. In dogs, the main distinctions are: atherosclerosis (hardening of the arterial walls), nuclear sclerosis (age-related changes in the lens of the eye) and multiple sclerosis – a disease of the central nervous system that is well known in humans but extremely rare in dogs.

Types of sclerosis in dogs

1. Nuclear sclerosis (lenticular sclerosis): This form affects the lens of the eye and is encountered mainly in older dogs. The inner lens fibres harden over time – the result is a characteristic clouding that at first glance resembles cataracts. The crucial difference: vision is significantly less impaired.
2. Atherosclerosis: Fat, cholesterol and other substances accumulate on the vessel walls and cause the arteries to stiffen. In dogs, this is rarer than in humans – but it can occur if diabetes or hypothyroidism are present simultaneously.
3. Otosclerosis: A hardening in the area of the inner ear that can lead to hearing loss. It is rare in dogs; if it does occur, it noticeably impairs hearing.
4. Scleroderma: This rare autoimmune disease causes the skin and connective tissue to harden. Possible consequences are skin problems, movement disorders and significantly reduced tissue elasticity.

Causes of sclerosis in dogs

Depending on the form of sclerosis and the tissue affected, the triggers vary. The following factors are most commonly involved:

1. Aging: Many forms – above all nuclear sclerosis – are simply age-related. Over the years, tissue loses its elasticity, and hardening is the result.
2. Chronic inflammation: Persistent inflammatory processes damage the tissue and drive connective tissue production excessively. Infections, autoimmune reactions or permanent irritation may lie behind these inflammations.
3. Genetic predisposition: Certain breeds are more susceptible to sclerotic changes, especially if autoimmune reactions or metabolic disorders are known in the lineage.
4. Metabolic disorders: Diseases such as diabetes or hypothyroidism attack blood vessels and connective tissue – and can thus lay the groundwork for atherosclerosis.

Symptoms of sclerosis

What a dog shows depends on the affected area – therefore, it is worth looking at each form individually.

Nuclear sclerosis:

• A slight, often bluish or greyish clouding of the lens.
• Slight visual impairment, which may become noticeable particularly in poor lighting conditions.
• Many dogs show no further complaints and continue to see well – especially with near objects.

Atherosclerosis:

• Cardiovascular complaints: weakness, unusual tiredness or breathing difficulties.
• High blood pressure or heart problems as a direct consequence of hardened arteries.
• Less enthusiasm for exercise and rapidly declining stamina under physical strain.

Otosclerosis:

• Hearing loss or significantly slowed reaction to sounds.
• In rare cases, the dog appears dizzy or shows balance problems.

Scleroderma:

• Noticeable hardening of the skin and connective tissue, which can cause stiffness and pain.
• Restricted mobility, particularly in the joints.
• Visible skin changes such as thickening or darkening of the skin.

Diagnosis of Sclerosis in Dogs

How the vet proceeds depends on which body region is affected. Typically, several methods are employed:

1. Clinical examination: First, the dog is thoroughly examined physically – eyes, blood vessels and ears are palpated and assessed for hardening.
2. Eye examination: If nuclear sclerosis is suspected, the vet uses an ophthalmoscope to assess the lens directly. As lenticular sclerosis is easily confused with cataracts, this detailed examination is crucial.
3. Blood tests: If there are indications of atherosclerosis or a metabolic disorder, blood tests provide information on cholesterol levels, blood sugar and thyroid hormones.
4. Imaging techniques: X-rays or ultrasound provide insight into blood vessels and heart structure if atherosclerosis is suspected.
5. Hearing tests: If otosclerosis is suspected, special hearing tests can determine the extent to which hearing is actually impaired.

Treatment of Sclerosis in Dogs

There is no blanket therapy – what helps depends on the type of sclerosis and the severity of the symptoms:

1. Nuclear sclerosis: In most cases, no special treatment is necessary because vision is only minimally affected. Only when a significant visual impairment becomes apparent does the vet rule out other causes such as cataracts and discuss further steps.
2. Atherosclerosis: Here, treatment of the underlying condition is central. If diabetes or hypothyroidism is present, their therapy and adapted nutrition are key. Heart medication can additionally be prescribed to alleviate symptoms and stabilise cardiovascular function.
3. Otosclerosis: There is currently no curative treatment. The vet relies on supportive measures that help the dog adapt to reduced hearing.
4. Scleroderma: Anti-inflammatory medications and painkillers can noticeably alleviate symptoms. Physiotherapy helps maintain joint mobility for as long as possible.

Prognosis

How a dog fares in the long term cannot be generalised – the type and severity of the disease are decisive. Age-related forms such as nuclear sclerosis hardly burden daily life and often require no treatment. In more severe forms such as atherosclerosis or scleroderma, the prognosis depends closely on how well the underlying conditions can be managed.