Canine pyometra is an infectious and inflammatory disorder of the uterus typically occurring in adult, intact bitches during or immediately after the luteal phase of estrous cycle. There is accumulation of pus within the uterine lumen, typically occurring during or immediately following a period of progesterone dominance (Rubina et al., 2010; Kumar et al., 2016)). The elevated progesterone level, help to create the ideal conditions for infection and stimulate uterine glandular secretion within the uterus, which suppresses uterine contration (Cox, 1970).
Pyometra is specially more frequent in bitches over 8 years old and it develops in more than 50% of all intact female dogs ( Egenvall et al., 2000). The bitches that have not given any birth for a long time are more predisposed to pyometra (Lika et al., 2009). It is common in bitches within 8 weeks of oestrus cycle and also common in bitches of the following breed Rottweiler; Saint Bernard, Chow Chow, Golden Retriever are of high risk while breeds like German shepherd, Daschunds and Swedish hounds have low risk. (Rubina et al.,2012)
It can be classified as open or close cervix pyometra (Rubina et al., 2012); if it is open, pus will drain from the uterus through the vagina to the outside. It is often noted on the skin or hair under the tail or on bedding and furniture where the dog has laid. Fever, lethargy, anorexia, and depression may or may not be present.If the cervix is closed, pus that forms is not able to drain to the outside. It collects in the uterus causing distention of the abdomen.The bacteria release toxins that are absorbed into circulation.These dogs often become severely ill very rapidly. They are anorectic, very listless, and very depressed. Vomiting or diarrhea may be present.
Pyometra is often the result of hormonal changes in the reproductive tract. During estrus (heat), white blood cells are removed from the uterus to allow safe passage of the sperm. This lapse in protection often leads to infection. Also following estrus (heat), progesterone levels remain elevated for 8-10 weeks and thicken the lining of the uterus in preparation for pregnancy. If pregnancy does not occur for several estrus cycles, the lining continues to increase in thickness until cysts form within it. The thickened, cystic lining secretes fluids that create an ideal environment in which bacteria can grow. Additionally, high progesterone levels inhibit the ability of the muscles in the wall of the uterus to contract.
The pathogenesis of pyometra in the bitch involves estrogen stimulation of the uterus, followed by prolonged intervals of progesterone dominance. Progesterone results in endometrial proliferation and uterine glandular secretions and decreased myometrial contractions. Leukocyte inhibition in the progesterone primed uterus often supports bacterial growth. These effects are cumulative, with each estrous cycle exacerbating the uterine pathology. Thus, in the first half of diestrus, the suppressed activity of cellular immunity results from increasing progesterone concentration and minimal estrogen release (Sugiura, 2004).
Recent research involving the induction of canine pyometra by inoculating Escherichia coli into the uterus demonstrated that, on days 1120 and 2130 after the LH peak, the uterus was most susceptible to infection. The E. coli present in naturally occurring cases are also found in the urine and feces of affected bitches (Tsumagari, 2005). It appears that sub-clinical urinary tract infection is associated with pyometra where adherence through K-antigen seems to be important for colonization of the bacteria in the uterus (Sandholm, 1975). Exogenous estrogen therapy for mismating and progesterone therapy for estrus suppression have beenassociated with increased risk for pyometra.
The treatment of choice for older dog, ill bitches or those with closed Pyometra/cystic endoetrium hyperplasia is complete Ovariohysterectomy (MacInstire 2004)
Chemotherapy is done in a case that is not life threatening and the patient is still alert. The management procedures include: PGF2alpha which have been used successfully for treatment of pyometra. Natural prostaglandin @ 10-50 mg, 3-5 times daily for 3-7 days have been used (Nelson et al., 1982). In bitches, prolactin is an important luteotropic hormone. So Dopamine agonists or prolactin inhibitors such as bromocriptine (20 mg/kg) or cabergoline (@ 5 mg/kg) are used in combination with natural or synthetic Prostagalndin to treat pyometra (Meyers-Wallen et al., 1986). Antimicrobial treatment involves broad spectrum antibiotics necessary to combat the infectious agents (Rubina et al., 2010). Before starting treatment antibiotic sensitivity test should be done for selection of antibiotics. Antibiotics like amoxicillin, amoxicillin plus clauvanic acid and cephalosporins or potentiated sulfonamides are choice for initial treatment.
REFERENCES
Bigliardi, E. and Pamigiani, E. (2004). Ultrasonography and Cystic Hyperplasia-Pyometra Complex in Bitch. Reproduction in Domestic Animals, 39:136-240.
Chastain, C.B., Panciera, D. and Walters, C. (1999). Association Between Age, Parity, Hormonal Therapy and Breed and Pyometra in Finnish Dogs. Small Animal Endocrinology, 9: 8-17
Cox,J.E. (1970). Progestagens in Bitches.Journal for Small Animal Practice, 11:759-778.
Dennis, J., Lucas B. and Hamm (2012). Surgical and Medical Treatment of Pyometra. Veterinary Medicine, 3:45-57.
Douglas N., Benjamin D., Andrew J., John H., Ronald S. and Sally K (2004). Cyproheptadine in Cystic Fibrosis.Pediatric Pulmonology, 38: 129-134
Dow, C. (1957). The Cystic Hyperplasia Pyometra Complex In the Bitch. Veterinary Research, 69: 1409-15.
Egenval, A., Bonnett, B.N., Olson, P. and Hedhammer, A. (2000). Gender, Age and Breed Pattern of diagnoses for Veterinary Care in Insured Dogs in Sweden during 1996. Veterinary Record, 146(1): 551-7.
Ellen, D.D. (2014). Suture Material and Needle Option in Oral and Periodontal Surgery. Journal of Veterinary Dentistry, Vol.31, No.3.
Fingland, R. B. (1998) The Uterus. Current Techniques in Small Animal Surgery, 4:489-502.
Foster, S.(2012). Effects of Vitamin Bcomplex. Veterinary & Aquatic Services Department, 24: 154-176.
Hagman, R. (2017). Reproduction of Domestic Animals.Acta Veterinaria Scandinavica 12: 45-57.
Hagman, R., Kindahl, H. and Largerstedt, A.S. (2006). Pyometra in Bitches induces Elevated Plasma Endotoxin and Proatagladin F2& Metabolites Level. Acts of Veterinary Scandal, 47:55-68
Hallyer, P.W., Freeman, L.C. and Hubbel J.A.E. (1991). Induction of anaesthesia with Diazepam-Ketamine and Medizolamine-Ketamine in Greyhounds. Veterinary Surgery. 20:143-147.
Haskins, S.C., Favaer, T.B. and Patz, J.D. (1986). Cardiovascular Changes in Dogs given Diazepam as Diazepam-Ketamine. American Journal of Veterinary Researchers, 47:795-798.