Vet360 Vol 4 Issue 4 August 2017 Vet 360 - Page 10

REPRODUCTION terone assays can be used to determine whether she is currently in dioestrus and the owner missed the pre- vious signs of oestrus or whether a luteal cyst is pres- ent whereby progesterone concentrations will persist beyond the 70-90 day lifespan of a normal CL. 16 An ultrasonographic examination of the reproductive tract should also be performed with special attention paid to the ovaries to check for cystic structures. In a pregnant bitch, progesterone levels drop to below 5 nmol/L about 24-48h prior to partus and can be used to determine readiness for whelping. A decrease in plasma progesterone to less than 3 nmol/L in preg- nant bitches may indicate impending abortion. 17 Re- cent work by De Cramer et al will assist us in more accurately determining the optimum day for elective caesarian sections in dogs. agnosis of cryptorchid stallions. AMH is secreted by the sertoli cells and the granulosa cells in the ovary and a measurable concentration of AMH indicates the presence of testicular or ovarian tissue. 19 An AMH test would therefore also be useful to determine the repro- ductive status of dogs or bitches. The test is currently available at the Veterinary Population Management Laboratory at Onderstepoort, however, it is very costly at this stage. Relaxin Ovarian remnant syndrome In dogs and cats, the hormone relaxin is secreted by the placenta and a qualitative relaxin assay (WITNESS® available on request from Zoetis South Africa ) can be used to diagnose pregnancy from about, 16-22 days after the first day of cytological dioestrous in dogs (D1) or 22-28 days after ovulation and about 31 days after mating in cats. In dogs, prior to establishment of the placenta, a false-negative result may be obtained Ovarian Remnant Syndrome (ORS), is defined as func- tional ovarian tissue present in a previously ovariec- tomized patient. ORS is an iatrogenic condition that results from failure to remove all ovarian tissue dur- ing ovariohysterectomy. This is most often due to surgical error such as incomplete ovary removal or auto-transplantation of dropped ovarian tissue. It has been shown that ovarian tissue placed free in the ab- domen can become re-vascularized and functional, In the majority of reports of ORS, residual ovarian tissue is found located in the region of the ovarian pedicle so incomplete ovary removal is suspected in most cas- es. 20, 21 Another reported explanation for ORS is the presence of extra-ovarian tissue such as ectopic ovari- an tissue or an accessory ovary that is not identified at the time of surgery. Accessory ovaries have been re- ported in cows, women and cats and in most reports, located in the proper ligament. 22 Accessory ovaries have not been reported in dogs. Testosterone Testosterone can be used in the diagnosis of bilateral cryptorchidism in the dog or in unilateral cryptorchid- ism where only the descended testis has been re- moved. In “castrated” male dogs with unknown back- grounds, that are exhibiting intact male characteristics such as urine marking, aggression and interest in fe- males, various diagnostic options are available. The undescended testis may be present anywhere from the caudal pole of the kidney to the inguinal canal and a dedicated ultrasonographic abdominal examination may be instrumental in identifying the cryptorchid tes- tis. Cryptorchid testes remain hormonally active but lose spermatogenic capability and are therefore more likely to undergo neoplastic change with sertoli cell tumours having the higher incidence in cryptorchid testes. Due to the episodic release of LH and therefore tes- tosterone, as well as the low systemic concentration of testosterone, a hCG or GnRH -stimulation test with subsequent measurement of testosterone will give a better indication of whether or not testicular tissue is present. The baseline value will be more than double if testicular tissue is present. 18 Owing to the overlap of resting ranges between cryptorchid and neutered males, LH is not accurate for the identification of cas- trated males In the future, Anti-Mullerian Hormone (AMH) assays may be more accurate for the diagnosis of crytor- chidism in dogs and are already being used in the di- vet360 Issue 04 | AUGUST 2017 | 10 In cats, the presence of spines on the penis indicates the presence of testosterone-secreting tissue. These spines atrophy about 6 weeks post castration and pro- vide a very convenient means of determining the pres- ence of cryptorchid testis/es in the tomcat prior to the use of hormone assays or ultrasonography. Clinical signs of ORS are consistent with pro-oestrus or oestrus and include vulvar discharge (serosanguin- ous or purulent), vulvar swelling, mammary gland en- largement, behavioural signs such as attracting males and postural behaviour in cats. 23 Polyuria and polydip- sia, weight loss, alopecia and poor coat have also re- ported ][[[X[][[ܙH[ۙH[KB[Yۋ H[YH[X[YۜY\H[\BܙX]KۙHYHYH[HوۙH[۝[YX\]HYYX[[YHXYۛ\و M[۝˂[[X[][\Xݘ\X[\YKX\ܘ[KBH[[[\ZHۙ\\[][X[Yۜ]H\ܝYYYX[[\[وM[۝ˈ ]Ԕ]HY[ۈ][ݘ\X[[\\ ˎ JH[ܙH\]Y[H[[XŠ IJK LXYۛ\وԔ[HYX[X]\HHݘ\KB[\YHX^HH\HX[ \H\H]\[\XYۛHݘ\X[[[[[H]Y[][X[YۜˈH\HX\Y\[X\H\\ܛBY[[]H\[Yۜو\\[