FDA clears canine-labeled cosyntropin injection for adrenal testing: full analysis

The FDA has approved CosACTHen (cosyntropin injection) for the evaluation of adrenal function in dogs, giving veterinarians the first cosyntropin product specifically labeled for canine use in the U.S. Dechra announced the approval on May 19, 2026, while FDA records show the original new animal drug application, NADA 141-576, was approved on December 18, 2025. The product is intended to support ACTH stimulation testing, a core tool in diagnosing and monitoring canine Cushing and Addison diseases. (animaldrugsatfda.fda.gov)

That approval lands in a familiar clinical space. ACTH stimulation testing has long been part of adrenal workups in dogs, especially when clinicians need to confirm hypoadrenocorticism, assess hyperadrenocorticism, or monitor response to trilostane. FDA consumer guidance on canine Cushing disease notes that pituitary tumors drive most cases through excess ACTH production, while adrenal tumors account for roughly 15% to 20% of cases, and that dogs starting therapy often need frequent blood tests and veterinary checkups early in treatment. Against that backdrop, a canine-specific cosyntropin product gives practices a labeled diagnostic input tied directly to adrenal function testing. (fda.gov)

According to FDA’s Freedom of Information summary, CosACTHen is supplied as a 0.25 mg/mL solution in a 1 mL clear glass vial and is dispensed by prescription only. The labeled dose is 0.25 mg, or 1 mL, per dog weighing 10 to 110 pounds, administered either intravenously or intramuscularly for the purpose of performing the ACTH stimulation test. FDA reviewed two well-controlled laboratory studies and one field study to support effectiveness. The field study enrolled 119 dogs, ages 20 months to 16 years, that were suspected of having hypoadrenocorticism or hyperadrenocorticism, across sites in Georgia, Michigan, Texas, Pennsylvania, California, and Missouri. (animaldrugsatfda.fda.gov)

In that field study, the FDA summary reported limited adverse reactions: two dogs vomited within eight hours of administration, and one developed a hematoma after IV injection. DailyMed adds that foreign post-approval experience has included lethargy, anxiety, muscle tremor or weakness, abdominal pain, anorexia, diarrhea, injection-site pain or bruising, lameness, and hypersensitivity reactions. Those reports don’t establish incidence, but they do give clinicians a fuller picture of what to discuss with pet parents and monitor after use. (animaldrugsatfda.fda.gov)

Dechra is framing the launch around endocrine workflow, especially for practices already using trilostane. In its announcement, the company said CosACTHen is meant to help veterinarians assess adrenocortical function and monitor dogs receiving Vetoryl capsules. dvm360’s coverage similarly emphasized the product’s role in diagnosis, confirmation, and monitoring of canine Cushing and Addison diseases. I did not find independent expert commentary from boarded internists or veterinary associations published alongside the announcement, so the public reaction available so far appears to be driven mainly by Dechra and trade-media reporting. (biospace.com)

Why it matters: For veterinary professionals, the practical significance is less about introducing a new testing concept and more about standardization, labeling, and supply confidence. A canine-specific, FDA-approved cosyntropin may simplify procurement and protocol discussions, particularly in general practice settings that need a clear labeled product for ACTH stimulation testing. It may also support more consistent conversations with pet parents when clinicians are explaining why a dog with suspected Addison disease, suspected Cushing disease, or trilostane follow-up needs repeat adrenal testing. That said, practices will still need to weigh cost, availability, turnaround logistics for cortisol testing, and how this product fits into existing internal medicine workflows. (animaldrugsatfda.fda.gov)

There’s also a regulatory angle. FDA’s recent animal drug approvals page lists CosACTHen among approved animal drugs, underscoring that companion animal endocrinology continues to attract formal label development, not just therapeutic expansion. In a market where many diagnostic workflows have historically relied on products or protocols adapted from outside species-specific labeling, this approval may signal more appetite for targeted veterinary endocrine products if uptake is strong. That inference is based on the approval pattern and Dechra’s positioning, rather than an explicit FDA statement. (fda.gov)

What to watch: The next questions are commercial and clinical: when U.S. clinics can reliably get product on shelves, whether specialty and primary care practices incorporate it into standard ACTH stim protocols, and whether post-launch experience changes how veterinarians think about testing frequency, administration route choice, or client acceptance in dogs being diagnosed with or monitored for adrenal disease. (animaldrugsatfda.fda.gov)