From the FDA Drug Label
In a toxicity study in juvenile dogs treated with fosaprepitant from postnatal day 14 (equivalent to a newborn human) to day 42 (approximately equivalent to a 2 year old human), decreased testicular weight and Leydig cell size were seen in the males at 6 mg/kg/day and increased uterine weight, hypertrophy of the uterus and cervix, and edema of vaginal tissues were seen in females from 4 mg/kg/day
The use of fosaprepitant in dogs has been associated with changes in reproductive organs.
- Key findings in juvenile dogs include:
- Decreased testicular weight and Leydig cell size in males
- Increased uterine weight, hypertrophy of the uterus and cervix, and edema of vaginal tissues in females 1
From the Research
Fosaprepitant dimeglumine is not recommended for use in dogs due to the lack of veterinary research and clinical experience, and its use would be considered experimental. Instead, more established options for antiemetics in dogs include maropitant (Cerenia) at 1 mg/kg IV or 2 mg/kg orally once daily, ondansetron at 0.1-0.2 mg/kg IV every 8-12 hours, or metoclopramide at 0.2-0.5 mg/kg every 6-8 hours, as these medications have established safety profiles and dosing regimens for canine patients 2, 3, 4, 5, 6. The mechanism of fosaprepitant involves blocking substance P from binding to NK1 receptors in the brain's vomiting center, but without specific canine studies, its pharmacokinetics, efficacy, and safety in dogs remain largely unknown. Some key points to consider when evaluating the use of fosaprepitant in dogs include:
- The lack of veterinary research and clinical experience with fosaprepitant in dogs
- The availability of more established antiemetic options for dogs, such as maropitant, ondansetron, and metoclopramide
- The potential risks and uncertainties associated with experimental use of fosaprepitant in dogs
- The importance of consulting with a veterinarian before using any medication, especially one that is not approved for use in dogs. It is essential to prioritize the safety and well-being of canine patients and to rely on evidence-based medicine when making treatment decisions. In the absence of specific canine studies, it is not possible to recommend a specific dosage or protocol for fosaprepitant in dogs, and any use would require careful monitoring and veterinary guidance. Overall, the use of fosaprepitant in dogs is not supported by current evidence and should be approached with caution.