This article starts with a review of the literature regarding the normal reproductive physiology of the mare, normal luteolysis, different causes of prolonged luteal phase and theories behind these. The article also presents a study where it was examined if treatment with human choriongonadotropic hormone (hCG) during the luteal phase induces prolonged luteal phase in mares, thus preventing estrus. The study consisted of two parts: one intensive study of eight mares at the former Department of Obstetrics and Gynaecology at SLU, Uppsala, Sweden and one field study of seven mares at a stud farm 70 km north of Uppsala. The mares in the intensive study were divided in two groups: one with four mares that were injected with hCG in luteal phase when they had a follicle of minimum 30 mm and a second group with four mares that were injected with sodium chloride at the same time. These mares were examined with ultrasonography and blood samples.

Det finns en direkt koppling mellan den allt högre mjölkavkastningen hos våra mjölkraser SRB och SLB och vissa reproduktionsstörningar. Posten fruktsamhet är idag den största utslagsorsaken i kokontrollen. Högre produktionsnivåer leder till kortare och mer svårupptäckta brunster eller t o m till att brunst helt uteblir. Det tar också längre tid för kon att komma i brunst efter kalvning. Allra tydligast ses detta hos gruppen förstakalvare.

Pyometra is a common and life threatening disease of intact bitches. The disease is caused by a hormonal influence on the uterus in combination with a bacterial infection. The most common treatment is ovariohysterectomy, but several medical options are available to maintain fertility or avoid surgery and anaesthesia. Drugs that can be used for medical treatment are for example Progesterone-receptor antagonists, prostaglandins and dopamine agonist. The present study focused on treatment with the Progesterone-receptor antagonistaglepristone in combination with antimicrobial therapy.

Many scientists agree that phytoestrogens could have an effect on the reproduction of an animal. The question is now why and what mechanisms that play an important role. This paper has been focusing on the estrus behavior of gilts by use of a behavioral study. Some of the gilts were given additional feed with the phytoestrogen genistein which commonly occurs in the feed as a part of soybean products. Blood samples were collected and analyzed for Progesterone and estradiol concentrations.

Dairy farmers using artificial insemination (AI) are dependent on effective oestrus detection. In Sweden, AI is used for a majority of all dairy cows and oestrus synchronisation with hormones is not allowed. There are reports of declining ability to express oestrus with higher levels of milk production. This makes oestrus detection more difficult. Several aids for oestrus detection have been developed, for instance pedometers and mounting detectors.

This is a literature study in which I investigate if there are scientific studies that form the basis of the Swedish dog world views concerning the spaying of bitches. The positive impacts are said to be reduced problems with pseudopregnancy, reduced risk of pyometra, reduced risk of mammary and uterine tumors, an earlier cease of bone growth, a more active and happier dog and a bitch who is more tolerant of other dogs. The negative consequences are said to be urinary incontinence, increased aggressiveness, lower metabolism and the increased risk of obesity, a more lethargic individual and altered coat.There are studies indicating that spaying reduces behavioral problems associated with heat and pseudopregnancy. Assuming no ovary tissue persists after the procedure, and there is no Progesterone production, the risk of pyometra decreases. Early spaying, before the first heat, reduces the risk of mammary tumors.

The presence of cystic ovarian follicles represents an important ovarian dysfunction and is a major cause of reproductive failure in dairy cattle. A cystic ovarian follicle is a persistent follicular-like structure on one or both of the ovaries. It is at least 2,5cm in diameter and it has to persist for at least ten days while a corpus luteum is missing. There are two kinds of cystic ovarian follicles, those who have a Progesterone production and those who have not. A clear definition for this condition is lacking, probably because the heterogeneity of the clinical signs and the complexity of the disorder.

Juvertumörer är de vanligaste tumörerna hos tikar och det finns olika typer av både benigna och maligna juvertumörer. De hormonella fluktuationerna som sker under östralcykeln driver utvecklingen av juvervävnaden och behandling med progestiner (syntetiska ekvivalenter till progesteron) för uppskjutande av löp har kopplats samman med förekomst av juvertumörer, vilket har lett till ett intresse för den hormonella påverkan på juvertumörutvecklingen. Hormonerna är i sin tur beroende av uttrycket av receptorer för att kunna ha effekt i vävnaden. Syftet med den här litteraturstudien är att utreda uttrycket av hormoner och receptorer för progesteron, tillväxthormon (growth hormone, GH) och insulinliknande tillväxtfaktor (insulin-like growth factor, IGF) i normal juvervävnad och i benigna och maligna tumörer, såväl som deras påverkan på juvertumörutvecklingen. De intracellulära signalvägarna för progesteronreceptorer (PR), GH-receptorer (GHR) och IGF-I-receptorn (IGF-IR) är kopplade till cellproliferation och genreglering. De komplexa nätverken av signalvägar interagerar med varandra och en obalans i uttryck och reglering av hormoner, receptorer eller molekyler i cellen kan leda till att tumörer uppstår. Vid progestinbehandling har ökade nivåer av GH och IGF-I uppmätts och högst nivåer sågs i maligna tumörer.