The effect of dioestrus on the racing performance of Greyhounds

Payne, Richard

doi:10.1016/j.tvjl.2013.05.029

Cited by 6 publications

(7 citation statements)

References 20 publications

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“…However, similar protection is unlikely to have occurred in greyhounds during the current study as testosterone proprionate was permitted to prevent estrous in female greyhounds at that time ( 93 ). In Australia, female greyhounds are not permitted to race whilst in estrous or for 28 days post estrous ( 93 ) and reduced performance in the diestrous period of up to 91 days has been reported ( 94 ). Therefore, racing female greyhounds can be assumed to be in late diestrous or anestrous with relatively low levels of circulating estrogen and progesterone ( 95 ).…”

Section: Discussionmentioning

confidence: 99%

Influence of the Environment on Body Temperature of Racing Greyhounds

2016

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Heat strain is a potential risk factor for racing greyhounds in hot climates. However, there have been limited studies into the incidence of heat strain (when excess heat causes physiological or pathological effects) in racing greyhounds. The aim of this study was to determine if heat strain occurs in racing greyhounds, and, if so, whether environmental factors (e.g., ambient temperature and relative humidity) or dog-related factors (e.g., sex, bodyweight, color) are associated with the risk of heat strain. A total of 229 greyhounds were included in over 46 race meetings and seven different race venues in South Australia, Australia. Rectal temperatures of dogs were measured pre- and postrace and urine samples collected for analysis of myoglobinuria. Ambient temperature at race times ranged between 11.0 and 40.8°C and relative humidity ranged from 17 to 92%. There was a mean increase in greyhound rectal temperature of 2.1°C (range 1.1–3.1°C). A small but significant association was present between ambient temperature and increase in rectal temperature (r2 = 0.033, P = 0.007). The mean ambient temperature at race time, of dogs with postrace rectal temperature of or exceeding 41.5°C, was significantly greater than at race time of dogs with a postrace rectal temperature ≤41.5°C (31.2 vs. 27.3°C, respectively, P = 0.004). When the ambient temperature reached 38oC, over one-third (39%) of dogs had a rectal temperature >41.5°C. Over half of postrace urine samples were positive by Dipstick reading for hemoglobin/myoglobin, and of 77 urine samples positive for Dipstick readings, 95% were positive for myoglobin. However, urinary myoglobin levels were not associated with ambient temperature or postrace rectal temperatures. The mean increase in rectal temperature was greater in dark (black, blue, brindle) than light (fawn and white) colored greyhounds. The results suggest heat strain occurs in racing greyhounds, evidenced by postrace rectal temperatures over 41.5°C and postrace myoglobinuria. Risk of heat strain may be increased in higher ambient temperatures and in darker colored greyhounds. Further research into the incidence of heat strain in racing greyhounds, and longer term physiological responses to heat strain, are warranted.

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Section: Discussionmentioning

confidence: 99%

Influence of the Environment on Body Temperature of Racing Greyhounds

2016

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“…Analogues such as proligestone and MPA have side-effects in racing Greyhounds, most notably a reported drop in performance and weight gain, hence the original reason to use methyltestosterone. As far as performance animals are concerned, there are several consistent and fully reversible side-effects of progestogens, centred around weight gain and reduced exercise performance, effects which can be nulled by spaying (Payne, 2013a(Payne, , 2013b. Norethisterone has oestrogenic activity in dogs (unlike MPA), so the performance loss may be less, given that bitches coming into season run faster (Payne, 2013a), which matches the rise in oestrogen (Edqvist et al, 1975).…”

Section: Side-effects Of Progesterone Analoguesmentioning

confidence: 99%

“…As far as performance animals are concerned, there are several consistent and fully reversible side-effects of progestogens, centred around weight gain and reduced exercise performance, effects which can be nulled by spaying (Payne, 2013a(Payne, , 2013b. Norethisterone has oestrogenic activity in dogs (unlike MPA), so the performance loss may be less, given that bitches coming into season run faster (Payne, 2013a), which matches the rise in oestrogen (Edqvist et al, 1975). This is not proven to be a causative link, only temporally linked.…”

Section: Side-effects Of Progesterone Analoguesmentioning

confidence: 99%

“…The first level within the model was set as repeated races, with Greyhound identity as the second level. Models were built in a forward stepwise manner using distance (metres) as the main predictor, with weight (kilograms) and age (days) as confounders based on previous experience with modelling such data (Payne, 2013a). Spayed versus suppressed was indicated via a dichotomous variable (0,1).…”

Section: Statistical Analysis and Modellingmentioning

confidence: 99%

“…Cyclicity is normally restored when the Greyhounds retire (usually by five years old). Previous work by the author suggested that the layoff period should be nearer to 60-70 days (Payne, 2013a) in order to avoid the performance changes seen at 40-55 days post-oestrus. This performance change is presumed to be due to elevated levels of endogenous progesterone (P4).…”

Section: Introductionmentioning

confidence: 99%

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