Found cat (Photo: © WiSiTiA/aw)
When female lost and found cats are brought to an animal shelter, the question often arises whether the animal is already spayed or not. Since the surgical access for cats in Germany is usually chosen caudal to the navel, shearing of the corresponding area is usually sufficient to check for the presence of a scar. However, a scar is not always clearly visible and therefore misinterpretations are possible.
(aw) – According to a recent study by Lisa Morrow and colleagues from the University of Nottingham (Great Britain), another method with a high degree of certainty is the determination of the LH (luteinizing hormone) concentration by means of a rapid test. This is based on the experience that non-spayed females have very low LH blood concentrations. The intact ovaries provide the low LH concentration due to a negative feedback, therefore if the ovaries are removed, the LH concentration in the blood of female cats increases.
Low LH concentration = intact ovaries
Lisa Morrow conducted her research in the UK using the Witness LH rapid test from Zoetis, which is based on a semi-quantitative Rapid Immune Migration Assay and is actually designed to determine the timing of ovulation in bitches. If the concentration of LH in the blood sample is above 1ng/ml, a positive result is indicated. This test result means that the cat has been spayed or neutered. On the German market there are other rapid tests from other suppliers for LH determination, which are already approved for dogs and cats.
Specificity at 100 percent
The test found 79 spayed animals among the 236 female cats that were examined. No non-neutered cat was classified as neutered, thus achieving a specificity of 100 percent. Conversely, in addition to the 121 non-neutered cats, 36 animals were classified as non-neutered based on their LH levels, even though they were already neutered. Thus, the sensitivity of the test in the present study was 69%. This means that with the test a reliable detection of all non-neutered animals is possible. With regard to a placement of found cats and their potential reproduction, the result is therefore very good and saves in case of doubt the trial aparatomy. Already in 2003 there had been a similar study with a total of 50 cats and then the scientists Scebra and Griffin came to a specificity of about 92 percent and a sensitivity of 100 percent, because two cats were not neutered, although the test had predicted it. Conversely, all neutered cats were identified as neutered, hence the high sensitivity.
No additional burden for the cat
Since found cats brought to the shelter usually have blood drawn anyway to check FeLV and FIP status, the LH test is not an additional expense and provides a result within 20 minutes. The reliable result could save about 77 percent of the trial laparatomies that are routinely performed on found cats in UK shelters to determine the fertility status of female cats. In addition to the considerable cost savings, the blood test is much gentler for the animals and may also lead to faster re-homing. In the current test, cats with an age of less than four months, as well as pregnant and lactating animals, were excluded from the test.