Influence of a Single Dose of Meloxicam Administrated during Canine Estrus on Progesterone Concentration and Fertility—A Clinical Case Study

SIMPLE SUMMARY: The use of nonsteroidal anti-inflammatory drugs (NSAID) in medicine is mostly connected to pain relief, inflammation reduction, and treatment of fevers, but their benefits in the context of reproduction are also described in the literature. In female domestic dogs, the corpus luteum (CL) is the only source of progesterone (P4), an adequate level of which is required for the maintenance of pregnancy. Based on studies in a number of species, the use of NSAID can have both a positive and negative influence on female fertility by reducing inflammation, as well as by acting as a Cyclooxygenase 1 or 2 (COX 1 or COX 2) inhibitor and influencing the production of prostaglandins that regulate CL creation and function. In this paper, we present a case of decreased levels of progesterone measured in the peripheral blood of a female domestic dog after meloxicam administration. Our observations suggest an influence of meloxicam administration on CL function, based on decreased P4 levels. However, in contrast to observations in other species, there was no negative effect on fertility, as, despite the drop in P4 levels, the female still became pregnant and delivered puppies. This paper indicates the need for broader studies on the effect of meloxicam in canine females in the context of its safety for pregnancy (including route of administration, doses, and duration of treatment) and its effectiveness in improving fertility. ABSTRACT: This case report presents an observation of the influence of meloxicam administration, during the periovulatory phase, on corpora lutea function in the domestic dog (Canis familiaris). A 2 year old female German Shepherd dog, with a level of progesterone suggestive of the periovulatory period (5.97 ng/mL), received a single subcutaneous injection of meloxicam (0.2 mg/kg body weight). In this female, subsequent evaluation to detect the optimal time for mating revealed a strong decrease in P4 (2.77 ng/mL), although it increased to 13.98 ng/mL within the following three days. The same female conceived and delivered a litter of the same size as in a subsequent cycle where meloxicam was not administered. The use of NSAID (nonsteroidal anti-inflammatory drugs), and particularly meloxicam, as a COX-2 inhibitor that influences the production of prostaglandins has been reported as being potentially harmful for ovulation and pregnancy in various species, including humans. In dogs, the secretion of prostaglandin E (PGE) is thought to be important for ovulation and the formation of the corpora lutea, the only source of P4, which is required for pregnancy maintenance. Although previous case reports have indicated an influence of meloxicam administration on CL function in domestic dogs, here, the decreased progesterone level observed directly after a single dose of meloxicam was only temporary, with no negative impact on fertility. Based on our observations, further studies related to the influence of the timing of meloxicam administration on ovarian cycle advancement, as well as the influence of duration of treatment, dosage, and route of administration on progesterone levels, as an indicator of CL function, are required.