The single-pair diagnostic study combined clinical examinations, ultrasonography, hormone and blood analyses, semen assessment and cytogenetic screening, so it could not establish how common these findings are among captive jaguars or establish a population-wide cause of reproductive failure. The animals had lived together since they were five months old and had mated repeatedly for four years without a recorded pregnancy. The female had never produced a litter and, to the investigators’ knowledge, had never been pregnant.

Both were selected for breeding through the European Association of Zoos and Aquariums’ European Endangered Species Programme on the basis of a low inbreeding coefficient. They shared an outdoor and indoor enclosure totalling 900 square metres, received water ad libitum and were fed twice weekly with red meat supplemented with a commercial carnivore vitamin and mineral preparation. Their management context matters because the programme seeks to retain genetic diversity in a self-sustaining population, but incomplete pedigree records prevent mean-kinship and inbreeding coefficients from being used universally in pairing decisions.

The study’s reproductive assessment began with anaesthesia and included external and internal clinical examinations, transabdominal ultrasonography and blood collection. The female was examined 14 days after her last oestrous period, while the male’s penis, prepuce and testes were inspected and measured. The female’s non-seasonal oestrous cycle lasted 54 to 62 days, with behavioural oestrus lasting nine to 12 days and mating occurring multiple times per hour.

Ultrasound identified small follicular structures measuring 2 to 3 mm in both ovaries but no pathological uterine changes. Her serum progesterone concentration exceeded the assay’s upper reporting limit of 40 ng/mL, a result interpreted as a non-pregnant luteal phase consistent with recent ovulation and active luteal function. Digital examination of the female did reveal a circumferential mucosal fold at the junction of the vestibule and vagina that admitted only one finger.

The investigators considered that it might be a normal anatomical variant or mild congenital stenosis, but said it was not likely to prevent the vaginal stimulation required for mating-induced reflex ovulation. They flagged potential relevance to a future pregnancy and to transcervical insemination, noting that vaginoscopy under anaesthesia would be needed for further characterization. Apart from this finding, the female’s clinical and ultrasonographic results were unremarkable.

Her progesterone profile indicated that the hypothalamic-pituitary-gonadal axis was functioning, while the absence of pregnancy indicated that ovulation was occurring without successful fertilization and implantation. The male’s testes had normal texture on palpation and no pathological changes on ultrasound, and his penis could be protruded normally with the spines expected in jaguars. Semen nevertheless showed severe abnormalities.

Electroejaculation under anaesthesia yielded 1.3 mL containing 33 million spermatozoa per millilitre, for a total of 42.9 million cells per ejaculate. Subjective assessment found 10% motility and a progressive status score of 2 on a five-point scale. Morphological examination of 200 spermatozoa identified only 5% as normal.

Abnormal midpieces and bent or coiled tails can be associated with mitochondrial dysfunction and impaired flagellar movement, both of which can hinder sperm penetration. These semen measurements were below the published reference ranges given for electroejaculated captive jaguars, which have reported total motility of 57% to 77% and between 27% and 81% morphologically normal spermatozoa. Extreme teratozoospermia alone does not always prevent a jaguar from producing offspring: a previous report described a male with only 10% normal sperm that successfully fathered young, apparently because his sperm concentration was sufficient.

The combined findings in the present male—low concentration, markedly reduced progressive motility and 95% of spermatozoa with abnormal morphology—therefore represented a more substantial reproductive limitation than abnormal shape alone. The study identified the semen abnormalities as the principal factor associated with the pair’s failure to conceive, while not establishing their underlying cause. Blood measurements supplied additional clinical context but did not reveal a defined reason for the poor semen quality.

Both animals had elevated amylase concentrations—2,242 U/L in the female and 1,966 U/L in the male—and lipase concentrations of 112 to 113 U/L. These values can accompany pancreatitis, but neither jaguar displayed clinical signs of that condition. The investigators proposed that a high-fat meal shortly before blood collection might have contributed to the results and noted that future sampling would require a standardized fast of at least 12 hours.

The male’s serum testosterone concentration was 4.74 ng/mL, within the domestic-cat interval used because no jaguar-specific interval was available, but a single sample could not represent endocrine status because testosterone fluctuates over time. His free thyroxine was below the domestic-cat lower limit, although he had no clinical signs of hypothyroidism and no jaguar-specific reference interval was available for definitive interpretation. Cytogenetic analysis found no evidence that a chromosomal abnormality explained the reproductive outcome.

Both animals had 2n = 38 chromosomes in the standard feline arrangement, comprising autosomal groups A1–A3, B1–B4, C1–C2, D1–D4, E1–E3 and F2–F3, together with one pair of sex chromosomes. G-banding produced corresponding patterns in the male and female apart from the more homogeneous male Y chromosome. C-banding identified heterochromatic sex chromosomes and two pericentromeric blocks on chromosome pair E1.

Reversed CMA3/DAPI staining revealed GC-rich telomeric regions, while telomeric fluorescence in situ hybridization showed normal terminal distribution of TTAGGG repeats without interstitial signals that would indicate cryptic rearrangements. A 28S ribosomal DNA probe and silver staining of nucleolar organizer regions located the active nucleolar organizer region on the short arm of chromosome pair E1. According to the authors, the work provided the first molecular cytogenetic characterization of Panthera onca incorporating C-banding, CMA3/DAPI staining, telomeric fluorescence in situ hybridization and ribosomal DNA probes.

It supplies a reference baseline for comparative studies of chromosome evolution in felids and for diagnostic karyotypic screening in captive jaguars. The study did not find compelling evidence that these European captive-born animals had a karyotype categorically distinct from the standard feline arrangement reported previously. Differences in centromeric index noted against an earlier jaguar report could reflect chromosome selection, preparation quality or genuine population-level variation, but the two-animal sample was too limited to distinguish among those possibilities.

The findings leave the assisted-reproduction prognosis uncertain rather than definitively excluding it. Severe semen abnormalities constrain natural breeding, and jaguar sperm cryopreservation remains difficult: a review of six independent trials found post-thaw motility ranging from 4.3% ± 2.5% to 46.0% ± 7.7%, with most protocols below 30% even when fresh motility exceeded 90%. Sperm-selection techniques might enrich the small motile and morphologically normal fraction, and intracytoplasmic sperm injection could theoretically bypass some barriers associated with poor semen quality, but neither had been reported in jaguars.

The study itself was limited by its examination of only one pair, a single semen collection, subjective motility scoring, the absence of faecal glucocorticoid measurements and reliance on some domestic-cat reference intervals. Repeated semen evaluations and objective computer-assisted sperm analysis were described as necessary follow-up measures, alongside functional testing of acrosome integrity and DNA fragmentation.

Subject of Research: Reproductive and cytogenetic investigation of infertility in one captive jaguar breeding pair

Article Title: Integrated Reproductive and Cytogenetic Assessment of Infertility in a Captive Jaguar (Panthera onca)

Article References: Altmanová, M., Strand, J., Kirchhoff, K. T., & Majtánová, Z. (2026). Integrated Reproductive and Cytogenetic Assessment of Infertility in a Captive Jaguar ( Panthera onca ). Veterinary Medicine and Science, 12(6), Article e71192. https://doi.org/10.1002/vms3.71192

Image Credits: AI Generated

DOI: 10.1002/vms3.71192

Keywords: captive jaguar, infertility, semen analysis, teratozoospermia, sperm motility, cytogenetics, karyotype, conservation breeding, assisted reproduction, wild felids, Integrated, Reproductive