What Are the Symptoms of Cushing’s Disease in Dogs?

Hyperadrenocorticism, also known as Cushing’s disease, is a condition affecting many older dogs that can significantly impact their quality of life if left untreated. This condition results from an excess of the hormone cortisol in the body. Cortisol, often referred to as the “stress hormone,” plays a crucial role in a dog’s response to stress, metabolism, and immune function. However, when produced in excessive amounts, cortisol can lead to various health issues. Recognising the symptoms of Cushing’s disease in your dog is essential for early diagnosis and effective management. This article will help you understand the most common symptoms of Cushing’s disease and what to do if you suspect your dog may be affected. 

Types of Cushing's Disease in Dogs

There are two main types: 

• Pituitary-Dependent Cushing’s Disease (PDH): This is the most common form, where a tumour in the pituitary gland causes an overproduction of adrenocorticotropic hormone (ACTH), leading to excess cortisol.
• Adrenal-Dependent Cushing’s Disease (ADH): This form occurs when a tumour in one of the adrenal glands directly produces excess cortisol.

Both types result in the following symptoms: 

1. Increased Thirst and Urination

One of the hallmark signs of Cushing's disease is an increase in thirst and urination. Dogs with Cushing's disease may start drinking more water than usual, often leading to more frequent trips outside to urinate. This symptom, known as polydipsia and polyuria, occurs because the excess cortisol affects the kidneys' ability to concentrate urine properly. You may notice that your dog’s water bowl empties faster, or they may have accidents indoors if they can’t make it outside in time.

2. Increased Appetite

An unusually high appetite, or polyphagia, is another common symptom of Cushing's disease. This increased hunger occurs because cortisol stimulates appetite. Dogs with Cushing's often appear ravenous, eating their meals faster and sometimes showing interest in foods they previously ignored. However, despite eating more, they don’t always gain weight proportionally. In some cases, they may even lose weight over time due to muscle wasting despite an increased food intake.

3. Weight Gain and a Pot-bellied Appearance

Dogs with Cushing's disease often develop a “pot-bellied” appearance due to fat redistribution and muscle weakness caused by excess cortisol. This belly enlargement is particularly noticeable in dogs that previously had a more athletic or slender build. While their appetite increases, their limbs might remain thin as fat collects around their midsection. This abdominal enlargement, combined with muscle wasting, is a classic sign of Cushing’s disease.

4. Thinning Hair and Skin Issues

Cushing’s disease can cause a range of skin and coat changes, which are often some of the more visible signs. Dogs may experience hair thinning or patchy hair loss, especially along the body, neck, and sides. Unlike other conditions, hair loss in Cushing’s disease is usually not accompanied by itching or scratching. Skin changes, such as thin, fragile skin that bruises easily, may also occur. Additionally, due to immune suppression, dogs with Cushing’s are more susceptible to skin infections, which may present as red, inflamed areas, especially on the belly and armpits.

5. Excessive Panting

Excessive panting is often observed in dogs with Cushing’s disease, even when they are at rest or in cool environments. This symptom can be uncomfortable for dogs and concerning for pet owners. The panting is likely due to multiple factors, including muscle weakness, fat accumulation, and cortisol’s effect on the respiratory system. Increased panting may also result from anxiety, which can accompany hormonal imbalances in Cushing’s disease.

6. Muscle Weakness and Lethargy

Cushing’s disease can lead to muscle wasting and weakness, making affected dogs appear less energetic or more reluctant to engage in physical activity. If your dog once loved long walks but now seems to tire more quickly or has difficulty jumping onto the sofa or climbing stairs, Cushing’s-related muscle loss could be the cause. This decrease in strength and energy can be gradual, making it easy to dismiss as normal ageing, but it is worth noting as a potential symptom of the disease.

7. Behavioural Changes

Some dogs with Cushing’s disease exhibit changes in behaviour, such as restlessness, irritability, or anxiety. While less common than the physical symptoms, some dogs become more easily startled or seem more on edge. Excess cortisol can affect a dog’s mood, leading to behaviours like pacing or increased vocalisation, especially during rest periods. If behavioural changes are unusual for your dog, it may be worth discussing them with your vet.

8. Slow Wound Healing and Frequent Infections

Cortisol plays a role in regulating the immune system, and when levels are too high, a dog’s immune function can become compromised. Dogs with Cushing’s disease may be more prone to skin, ear, and urinary tract infections, which can appear persistent or difficult to treat. Additionally, wounds may take longer to heal because cortisol impairs the body's ability to repair itself. This can lead to a cycle of infections and delayed recovery, especially if the dog also has thin or fragile skin.

9. Darkening of the Skin (Hyperpigmentation)

In some cases, dogs with Cushing’s disease develop areas of darker pigmentation on their skin, particularly on the abdomen. This darkening is often subtle initially but may become more pronounced over time. Although hyperpigmentation is not present in all cases, it may indicate a hormonal imbalance in dogs with other symptoms of Cushing’s disease.

What to Do If You Notice These Symptoms

If your dog is displaying multiple symptoms of Cushing’s disease, it’s essential to seek veterinary advice. Cushing’s disease is complex, and several other conditions can mimic its symptoms, so a professional diagnosis is necessary. Your vet will likely conduct a series of blood and urine tests to assess cortisol levels and may use imaging techniques, such as ultrasound, to evaluate your dog’s adrenal and pituitary glands.

Final Thoughts

While Cushing’s disease is a challenging condition, understanding the symptoms can help you seek early diagnosis and treatment, which can improve your dog’s quality of life. If you notice signs such as increased thirst, appetite changes, or changes in appearance, consult with your veterinarian to discuss testing and management options. Early intervention can make a significant difference in helping your furry friend enjoy a comfortable, healthy life.