Abstract
Dear Editors, — The recent review of reproduction control methods by Dr Goericke-Pesch provides a timely update on non-surgical options that have become available to the feline clinician. 1 As the author discusses, GnRH and melatonin implants offer new alternatives for contraception in queens, without the risk of severe side effects associated with progestins, which have been the traditional alternative to surgical gonadectomy. That risk is well established in the literature. One such case report, published in this journal, documents multiple pathological abnormalities (bilateral ovarian cysts, cystic endometrial hyperplasia and pyometra, mammary adenoma, fibrosarcoma and cystic-papillary adenocarcinoma) in a queen after long-term (in this case 9 years) administration of medroxyprogesterone acetate (MPA). 2 It is an interesting report, I must say. However, a very important piece of information — the weight of the queen — is missing! Without the weight, it is impossible to make a general discussion on the risk of side effects of MPA when administered at a much greater than normal dose. The proper dosage in a queen is 2.5 mg/kg. If that queen was, say, 5.0 kg, she would have received just over double the dose, while if she was 8 kg she would have received 3.1 mg/kg. That is still a high dose, but is one that is frequently (albeit erroneously) given to queens.
Surgical gonadectomy, of course, remains the mainstay approach to reproduction control in cats, and raises concerns of its own. One such issue is well highlighted by another publication in this journal: ‘Pyometra in a 13-year-old neutered queen’, authored by Vanessa de Faria and Gary Nosworthy. 3 The case is well described (weight is clearly indicated), the literature is reviewed fully and properly, etc, but what strikes me is one of the final conclusions of the authors: ‘Moreover, (this case) serves to emphasize the importance of carrying out a total ovariohysterectomy when neutering cats.’
This is a controversial statement. The issue of whether to perform ovariectomy (OVX) or ovariohysterectomy (OVH) in dogs and cats has been a subject of debate over the past few decades. The ‘Anglo-Saxon’ or ‘British’ approach of removing everything is based on the concept that what is removed cannot cause disease, while the ‘Latin’ approach has always been that of removing only the ovaries since the uterus quickly undergoes atrophy following OVX, and perhaps the risk of developing urinary incontinence (uncommon in cats, admittedly) could be lower because of anatomical reasons. Research done in Utrecht in which 138 bitches that underwent OVH and 126 bitches treated by OVX were followed up for 8–11 years clearly showed that, between the two groups of dogs, there was: (a) no difference in short-term or long-term surgical complications; (b) no difference in the incidence of cystic endometrial hyperplasia, pyometra or any other uterine disease; and (c) no difference in the incidence of urinary incontinence. 4
As a matter of fact, the only differences between the two approaches are the degree of invasiveness and length of the surgery, and therefore length of anaesthesia, each of which is higher in the case of OVH. This results in a higher risk of surgical complications and a higher stress for the animal, as well as a higher cost for the owner. The conclusion of the study authors, Okkens et al, that: ‘There is no indication to remove also the uterus in elective castration procedures of healthy bitches, and therefore ovariectomy is to be considered the procedure of choice’ 4 is currently shared by the majority of US as well as European authors. 5–7
I am certainly not assuming that queens behave just the same as dogs. However, by the same token, one cannot assume that the opposite is true for cats. Indeed, the fact that no equivalent data has ever been produced for cats should prompt authors and editors alike to be somewhat cautious in making drastic statements. The case report from de Faria and Nosworthy 3 would have benefited from some reasoning around this issue, providing readers with insights into this debate, prompting some forward thinking and perhaps stimulating researchers to consider embarking on research in feline neutering similar to that which Okkens and colleagues published in 1997 on canine neutering. 4 The fact that many authors consider it unethical to perform OVH in bitches without any specific health reason should prompt us to discuss whether this could be true also for queens, given, among other things, the incidence of problems such as reported by de Faria and Nosworthy.