Effects of Oral Altrenogest on Sexual and Aggressive Behaviors and Seminal Parameters in Young Stallions

Johnson, N.N.; Brady, H.A.; Whisnant, C.S.; LaCasha, P.A.

doi:10.1016/s0737-0806(98)80141-x

Cited by 15 publications

(13 citation statements)

References 7 publications

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“…In comparison with testosterone altrenogest showed a 20-fold lower anabolic effect on M. levator ani in castrated rats (Peters, 1992). Contrarily longterm administration of altrenogest in male rats did not provoke an enhanced body weight gain (Kluber et al, 1985(Kluber et al, , 1988) and did not influence the body condition score in horses (Johnson et al, 1997;Hogson et al, 2005). These controversial informations on the anabolic efficacy of altrenogest have created some confusion.…”

Section: Altrenogestmentioning

confidence: 99%

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Pharmacokinetics of altrenogest in horses

Machnik

Hegger

Kietzmann

et al. 2007

Vet Pharm & Therapeutics

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The Federation Equestre Internationale has permitted the use of altrenogest in mares for the control of oestrus. However, altrenogest is also suspicious to misuse in competition horses for its potential anabolic effects and suppression of typical male behaviour, and thus is a controlled drug. To investigate the pharmacokinetics of altrenogest in horses we conducted an elimination study. Five oral doses of 44 mug/kg altrenogest were administered to 10 horses at a dose interval of 24 h. Following administration blood and urine samples were collected at appropriate intervals. Altrenogest concentrations were measured by liquid chromatography-tandem mass spectrometry. The plasma levels of altrenogest reached maximal concentrations of 23-75 ng/mL. Baseline values were achieved within 3 days after the final administration. Urine peak concentrations of total altrenogest ranged from 823 to 3895 ng/mL. Twelve days after the final administration concentrations were below the limit of detection (ca 2 ng/mL).

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Section: Altrenogestmentioning

confidence: 99%

“…Contrarily long‐term administration of altrenogest in male rats did not provoke an enhanced body weight gain (Kluber et al. , 1985, 1988; ) and did not influence the body condition score in horses (Johnson et al. , 1997; Hogson et al.…”

Section: Introductionmentioning

confidence: 99%

Pharmacokinetics of altrenogest in horses

Machnik

Hegger

Kietzmann

et al. 2007

Vet Pharm & Therapeutics

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“…For example, while there is a high degree of homology in the ligand‐binding domain of the AR of vertebrae species, including human and equine, the interaction of AR with its many cofactors could fine‐tune inter‐species responses. However, it is clear from equine administration studies that anabolic responses are affected by ALT, 4,15 and this study using our HEK293‐bioassay has clearly shown that ALT is a potent agonist of AR.…”

Section: Limitationsmentioning

confidence: 68%

“…Prolonged altrenogest, administered at a therapeutic dose, to sedentary mares had no effect on body score and no effect on socializing behaviour 2 . However, in both older (3–18 years) and younger (2–4 years) stallions, administration of altrenogest (0.088 mg/kg) decreased sexual and aggressive behaviours, reduced scrotal width, increased spermatozoal abnormalities while decreasing daily sperm production, circulating testosterone and luteinizing hormone levels 4,15 . For the younger stallions, further measurements obtained 8 weeks after the final ALT administration showed that scrotal circumference, and associated daily sperm production remained lower than prior to initiation of treatment 4 .…”

Section: Resultsmentioning

confidence: 99%

Unravelling androgens in sport: Altrenogest shows strong activation of the androgen receptor in a mammalian cell bioassay

Gillon

Chan

et al. 2020

Drug Testing and Analysis

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Altrenogest is a commonly used progestogen for the suppression of oestrus and associated distracting behaviours that interfere with training and performance of female racehorses. The steroid is derived from 19‐nor testosterone and is structurally similar to the anabolic androgenic steroid, trenbolone. In this study, the relative androgen potency of altrenogest was determined by a kidney (HEK293) cell androgen bioassay. The HEK293 bioassay shows that in its pure form, altrenogest has a high relative potency compared with testosterone but is not as strong as β‐trenbolone. Our results also show that altrenogest is able to activate the androgen receptor at the concentrations relevant to the administration regime of racehorses and retains its activity ex vivo. Thus, we show unequivocally that altrenogest, a progestogen used widely in female racehorses, acts as a strong androgen in a mammalian cell bioassay.

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“…While daily altrenogest at 0.044 mg/kg has no significant effect on reproductive behavior and semen parameters in stallions and zebra stallions [ 10 , 11 ], daily administration of 0.088 mg/kg altrenogest over a longer period to stallions significantly and reversibly reduces blood testosterone and luteinizing hormone concentrations, and induces a progressive decrease in testicle size and libido. Further, daily treatment with altrenogest at 0.088 mg/kg decreases the amount of ejaculate and the total sperm count in stallions throughout the treatment period [ 12 , 13 ]. On the basis of these previous findings, the present study examined whether the administration of 0.088 mg/kg altrenogest has similar effects on the gonadal function in goats.…”

Section: Introductionmentioning

confidence: 99%

Downregulation of testicular function in the goat by altrenogest

et al. 2021

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Background The present study investigated whether the administration of the progestin altrenogest provides noninvasive, temporary, and reversible suppression of gonadal function in the goat as a potential alternative to chirurgical castration, which is related with irreversibility, risks of complications till death of the animal and welfare issues. Eight sexually mature Peacock goats were randomly divided into two groups. The experimental group was administered altrenogest (0.088 mg/kg) orally once daily for 7 weeks. The remaining four goats received an oral glucose solution and served as the control group. After completing the administration period, the reversibility of the medication was evaluated for another 7 weeks (observation phase). The treatment effects were assessed by clinical examination; ultrasound examination of the testes, including one-dimensional grayscale analysis, blood testosterone levels, analysis of semen parameters and libido. At the end of the observation period, the animals were castrated and the testicles were examined histologically. Results Altrenogest treatment had no significant effect on the physical development of the goats, the sonographic appearance of the testes, the gray values measured in the ultrasound images, or the blood testosterone levels. The effects of treatment on the testicular and semen parameters varied widely in the experimental animals; the testicle volume was significantly lower and the number of pathologically altered sperm in the ejaculate was significantly higher in treated animals. Conclusion These findings indicate that daily altrenogest administration at a dose of 0.088 mg/kg does not reliably suppress gonadal function in the goat.

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Effects of Oral Altrenogest on Sexual and Aggressive Behaviors and Seminal Parameters in Young Stallions

Cited by 15 publications

References 7 publications

Pharmacokinetics of altrenogest in horses

Pharmacokinetics of altrenogest in horses

Unravelling androgens in sport: Altrenogest shows strong activation of the androgen receptor in a mammalian cell bioassay

Downregulation of testicular function in the goat by altrenogest

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