Canine Cushing's Case Files: The ins and outs of detection and treatment-Case file: Princess (Sponsored by Dechra Veterinary Products)

Hyperadrenocorticism affects many adult dogs. Whether the disease is pituitary-dependent (80% to 85% of spontaneous cases) or adrenal-dependent (15% to 20% of cases), the clinical and laboratory abnormalities associated with it result from chronic hypercortisolemia. Clinical signs of hyperadrenocorticism at the time of diagnosis can vary widely, and they develop so gradually that owners often mistake the signs for "normal" aging. Being aware of the more subtle signs of canine hyperadrenocorticism can be key to early diagnosis and initiation of therapy.

Whenever possible, pituitary-dependent hyperadrenocorticism and adrenal tumors should be differentiated to help guide therapy and patient monitoring. Early diagnosis and management of canine hyperadrenocorticism may not only improve the patient's clinical signs but may also keep the more severe consequences of Cushing's syndrome from developing.

COMMON CLINICAL SIGNS OF CANINE HYPERADRENOCORTICISM

CASE FILE: PRINCESS

13-year-old spayed female Maltese weighing 9.2 lb (4.2 kg)

Patient history

Princess has a five-year history of pedal pruritus that routinely appears in the summer and fall and responds to topical and oral antibiotic and corticosteroid treatment. About 18 months ago, Princess also developed facial pruritus, but her facial and pedal pruritus did not respond to this therapy, so she was referred for further dermatologic evaluation.

Referral evaluation

Princess' owners reported no behavior changes other than those associated with facial and pedal pruritus.

Physical examination findings

Physical examination revealed that Princess' popliteal lymph nodes were mildly enlarged. Her hair coat was diffusely thin, and she had a pot-bellied appearance. Her ventral abdominal skin was moderately striated with reduced elasticity. Numerous erythemic papules, pustules, and epidermal collarettes (variably crusted) were present over her entire body. The periocular regions and muzzle were the most severely affected (Figure 1). The dorsal, ventral, and interdigital aspects of all four paws were moderately alopecic and erythemic.

FIGURE 1. Princess before treatment for demodicosis, pyoderma, and hyperadrenocorticism. She exhibits perioral and periocular crusting, hyperpigmentation, erythema, and a pot-bellied appearance.

Diagnostic test results

Cytologic examination of skin scrapings were positive for all life stages of Demodex canis. Cytologic examination of impression smears and acetate tape preparation samples from the muzzle and abdomen revealed 1+ to 2+ cocci along with numerous degenerate neutrophils. Samples for fungal culture (dermatophyte test medium) were obtained to rule out dermatophytosis.

A complete blood count showed no abnormalities; a serum chemistry profile revealed elevated alkaline phosphatase (1,456 IU/L; reference range = 12 to 118 IU/L) and gamma-glutamyltransferase activities (62 IU/L; reference range = 1 to 12 IU/L). Princess' total T4 concentration was low at 0.8 µg/dl (reference range = 1.0 to 4.0 µg/dl), but her free T4 and TSH concentrations were within normal limits, indicating sick euthyroid syndrome.

Medical management of Princess' superficial pyoderma and demodicosis was initiated. However, at each of Princess' rechecks at three, six, and nine weeks, skin scraping results revealed that the Demodex species mite counts had not markedly decreased, despite appropriate treatment. The results of the previously submitted fungal culture were negative.

To determine whether hyperadrenocorticism was the underlying cause of Princess' adult-onset demodicosis, an adrenocorticotropic hormone (ACTH) stimulation test was then performed. Princess' baseline cortisol concentration was 2.7 µg/dl (reference range = 1.0 to 5.0 µg/dl) and her post-ACTH cortisol concentration was 47.3 µg/dl (reference range = 8.0 to 17.0 µg/dl). An abdominal ultrasonogram revealed bilaterally enlarged adrenal glands with no evidence of an adrenal tumor.

Treatment and follow-up

Treatment for pituitary-dependent hyperadrenocorticism (PDH) with VETORYL® (trilostane) Capsules was started at a dose of 2.4 mg/kg given orally once daily with food. The pyoderma treatment had been completed, and medical management of the demodicosis was continued.

Initial follow-up visits

After 14 days, Princess' baseline cortisol concentration was 2.7 µg/dl, and her post-ACTH cortisol concentration was 10.3 µg/dl, which was above the value (> 9.1 µg/dl) suggested for increasing the VETORYL Capsules dose. However, Princess was doing well clinically, so it was decided to continue to monitor her at the same dose. Princess also continued to receive treatment for demodicosis.

In 45 days, the Demodex canis counts had decreased significantly to a few dead mites. At 90 days, Princess' skin scraping results were negative, and treatment for demodicosis was discontinued. Her lymphadenopathy had resolved, new hair growth was present, and the owners reported Princess exhibited minimal pruritus.

Princess continued to receive 10 mg of VETORYL Capsules daily, and ACTH stimulation tests were performed as recommended and the results were within normal limits. The owners declined a follow-up thyroid hormone panel as well as serum chemistry profiles as a component of monitoring.

Princess' long-term response

Five months after her initial referral presentation, Princess was presented again for evaluation of facial crusting and pruritus. Her owners had been out of town, and Princess had stayed with relatives who had discontinued her VETORYL® (trilostane) Capsules for 30 days before this examination.

VETORYL® (trilostane) Capsules

Results of skin scrapings and cytologic examination once again revealed demodicosis and a superficial bacterial infection. Treatment for pyoderma and demodicosis was reinitiated, and treatment for PDH with VETORYL Capsules 10 mg was again instituted.

Two weeks later, Princess's baseline cortisol concentration was 1.7 µg/dl and her post-ACTH cortisol concentration was 7.0 µg/dl. Follow-up skin scrapings and an ACTH stimulation test were scheduled for one month later, but Princess was lost to follow-up after this visit.

Dr. Thompson's perspective

As is frequently the case, client compliance is a key to effectively managing patients with hyperadrenocorticism. Owners or caretakers may easily become complacent about administering medications for chronic diseases, and demodicosis and hyperadrenocorticism are no exceptions. Once the pet looks and starts acting normal again, owner compliance may suffer despite the veterinarian's best efforts to educate their clients.

It is also easy to see the rapid effects of discontinuing VETORYL Capsules. Maximal plasma levels of trilostane occur within 1.5 hours, returning to baseline levels within 12 hours, although large inter-dog variation occurs. In Princess' case, demodicosis recurred rapidly after she stopped receiving VETORYL Capsules to treat her PDH.

Providing client literature that explains hyperadrenocorticism and the necessity for long-term medical management (see www.dechrace.com for client brochures), holding conferences in which all family members are educated about how the disease must be managed, and ensuring follow-up by the veterinarian and veterinary team (via phone calls or emails; also go to www.dechrace.com for "Team meeting in a Box: Coping with Cushing's Syndrome") will likely enhance your opportunities for successful treatment.

Lori Thompson, DVM, DACVD

After working several years in human resources, Dr. Thompson returned to veterinary school and earned her DVM degree. She then completed a three-year residency in veterinary dermatology. She currently practices as a board-certified veterinary dermatologist in indianapolis, Ind.

Learn more with these ONLINE RESOURCES

Go to the dechra Veterinary Products CE Learning Center at www.dechrace.com and choose one of the online CE modules to learn the latest on managing feline hyperthyroidism and canine hyperadrenocorticism. Plus earn free CE!

• Diagnosing and treating canine hyperadrenocorticism

Presented by Audrey K. Cook, BVM&S, MRCVS, DACVIM, DECVIM, and David S. Bruyette, DVM, DACVIM

• Cushing's disease: Inside and out

Rhonda Schulman DVM, DACVIM, and John Angus, DVM, DACVD

• Diagnosing and treating feline hyperthyroidism

Presented by Andrew J. Rosenfeld, DVM, DABVP

Then get your whole team on the same page, by visiting the Team Meeting in a box section at www.dechrace.com

Coping with Cushing's syndrome

Pets with Cushing's syndrome suffer from a chronic illness that will be managed throughout the pet's life, not cured. This Team Meeting in a Box will help you deliver a successful team-wide approach.

Stop getting burned by ear infections

How you handle otitis externa and ear infections can make or break client bonds—and dogs' well-being. Use this Team meeting in a Box to create a team approach to help pet owners and heal patients.

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