Ectopic Pregnancy in Two Cats
Authors: Zheng Jia-San , Wang Zheng , Zhang Jia-Ren , Qiu Shuang , Wei Ren-Yue , Nie Jing , Zhu Ting-Ting 
Published: May 2019

Background: Ectopic pregnancy mainly refers to tubal pregnancy and abdominal pregnancy. Tubal pregnancy presents as an implanted embryo that develops in the fallopian tubes, and is relatively common in humans. In animals, tubal pregnancy occurs primarily in primates, for example monkeys. The probability of a tubal pregnancy in non-primate animals is extremely low. Abdominal pregnancy is a type of ectopic pregnancy that occurs outside of the uterus, fallopian tube, ovary, and ligament(broad ligament, ovarian ligament, suspensory ligament).This paper describes two cases of ectopic pregnancy in cats.Cases: Cat 1. The presenting sign was a significant increase in abdominal circumference. The age and immune and sterilization status of the cat were unknown. On palpation, a 4 cm, rough, oval-shaped, hard mass was found in the posterior abdomen. Radiographic examination showed three high-density images in the posterior abdomen. The fetus was significantlycalcified and some feces was evident in the colon. The condition was preliminarily diagnosed as ectopic pregnancy. Cat 2. The owner of a 2-year-old British shorthair cat visited us because of a hard lump in the cat’s abdomen. The cat had a normal diet and was drinking normally. Routine immunization and insect repulsion had been implemented. The cat had naturally delivered five healthy kittens two months previous. Radiographs showed an oval-shaped mass with a clear edge in the middle abdominal cavity. Other examinations were normal. The case was preliminarily diagnosed as ectopic pregnancy, and the pregnancy was surgically terminated. The ectopic pregnancies were surgically terminated. During surgery, the structures of the uterus and ovary of cat 1 were found to be intact and the organs were in a normal physiological position.Cat 1 was diagnosed with primary abdominal pregnancy. In cat 2, the uterus left side was small and the fallopian tube on the same side was both enlarged and longer than normal. Immature fetuses were found in the gestational sac. Thus, cat 2 was diagnosed with tubal ectopic pregnancy based on the presenting pathology.Discussion: Cats with ectopic pregnancies generally show no obvious clinical symptoms. The ectopic fetus can remain within the body for several months or even years. Occasionally, necrotic ectopic tissues or mechanical stimulation of the ectopic fetus can lead to a systemic inflammatory response, loss of appetite, and apathy. The two cats in our reportshowed no significant clinical symptoms. To our knowledge, there have been no previous reports of the development of an ectopic fetus to maturity, within the abdominal cavity of felines, because the placenta of cats cannot support the growth and development of the fetus outside of the uterus. Secondary abdominal ectopic pregnancy, lacking any signs of uterine rupture is likely associated with the strong regenerative ability of uterine muscles. A damaged uterus or fallopian tube can quickly recover and rarely leaves scar tissue. In the present report, cat 1 showed no apparent scar tissue, nor signs of a ruptured ovary or fallopian tubes. It was diagnosed with primary ectopic abdominal pregnancy, which could arise from the descent of the fertilized egg from the fallopian tube into the abdominal cavity. There was an abnormal protrusion in left of the fallopian tubes in cat 2, to which the gestational sac was directly connected. Based on pathological examination of the uterus, fallopian tubes, and gestational sac, the cat was diagnosed with a tubal pregnancy. Placental tissues and signs of fetal calcification were observed in both the fallopian tube and gestational sac.Keywords: tubal pregnancy, abdominal pregnancy, feline, ectopic fetus, fallopian tube, gestational sac.