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Factors Affecting the Incidence of Postpartum Fever in Heavy Draft Mares
Journal of Equine Veterinary Science xx (2014) 1–3
Contents lists available at ScienceDirect
Journal of Equine Veterinary Science journal homepage: www.j-evs.com
Short Communication
Factors Affecting the Incidence of Postpartum Fever in Heavy Draft Mares Takahiro Aoki DVM a, *, Kazuhiro Yamakawa DVM, PhD b, Mitsuo Ishii DVM, PhD a a b
Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan Yuubetsu Herd Management Service, Yuubetsu, Hokkaido, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 October 2013 Received in revised form 30 November 2013 Accepted 14 December 2013 Available online xxxx
Postpartum metritis is a common problem in many animal species. In equine medicine, sequelae of postpartum metritis vary from delay in uterine involution to development of systemic acute metritis (SAM), toxemia, and laminitis. Heavy draft mares potentially have higher risk of suffering from SAM than light breed mares. Postpartum fever (PF) mostly appears as a sign of SAM. The purpose of this study is to analyze the factors affecting the incidence of PF in 158 foalings from 62 heavy draft mares by multiple logistic regressions. The objective variable was the incidence of PF, and the explanatory variables were year foaled, month foaled, age of mare, breed of mare (crossbred heavy draft horse vs. Percheron), gestation length, foaling difficulty (easy delivery vs. dystocia), retained fetal membranes, stillbirth, and sex of offspring. Twenty-four out of 158 mares were diagnosed with PF. Stepwise regression analysis showed that breed of dams and foaling difficulty were significant risk factors for PF. Percheron mares had higher risk than crossbred mares (odds ratio: 3.4). Dystocia had higher risk than easy delivery (odds ratio: 3.3). Percheron mares had higher incidence of PF than crossbred mares even in the cases of easy delivery. Risks for damage and contamination of birth canal will be increased especially if the fetal delivery needs assistance. The results of this study suggest that it is necessary to consider the foaling difficulty and the breed of dams for earlier detection of PF in peripartum heavy draft mares. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Heavy draft horse Systemic acute metritis Postpartum fever Percheron Dystocia
1. Introduction Postpartum metritis is a common problem in many animal species [1–3]. In equine medicine, sequelae of postpartum metritis vary from delay in uterine involution to development of systemic acute metritis (SAM), toxemia, and laminitis [4]. Although the pathogenesis of toxemia and laminitis followed by SAM remains unproven, the longterm outcome is poor to moderate for mares that develop these stages. Systemic acute metritis and laminitis are commonly seen in heavy draft breeds, but rarely occur in * Corresponding author at: Takahiro Aoki, DVM, Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Nishi, Inada, Obihiro, Hokkaido 080-8555, Japan. E-mail address: [email protected] (T. Aoki). 0737-0806/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jevs.2013.12.011
Thoroughbreds and other light breeds [5]. Systemic acute metritis is often a result of nonhygienic manipulation during foaling and retained fetal membranes [6]. It has been reported that retained fetal membranes are likely to occur in heavy draft mares [7] and after dystocia [8]. Therefore, peripartum heavy draft mares potentially have higher risk of suffering from retained fetal membranes, SAM, and laminitis than light breed mares. The prognosis for future fertility is favorable if the affected mare is appropriately treated in the early stages, and therefore, early detection of SAM is very important. Postpartum fever (PF) is a general term for febrile diseases in puerperal period and mostly appears as a sign of SAM [4]. Postpartum fever is a useful indicator for early detection of SAM. Until now, there are no reports that performed an epidemiological and risk analysis of PF in the horse. The purpose of this study is to analyze the
2
T. Aoki et al. / Journal of Equine Veterinary Science xx (2014) 1–3
factors affecting the incidence of PF in 158 foalings from 62 heavy draft horses by multiple logistic regressions. 2. Materials and Methods Data from a total of 158 foaling mares were used, which were recorded for peripartum events from 2009 to 2013. Mares (13 Percherons and 49 crossbred between Percheron, Belgian, and Breton heavy draft horses) were bred on three breeding stud farms (latitude 43 North) in Tokachi region of Hokkaido Island, Japan. Mares’ ages ranged from 3 to 19 years (mean standard deviation: 8.9 3.9) at the time of delivery. The following mares were excluded from the study: mares foaled with no witnesses, those undergoing cesarean section, those having preterm delivery (<300 days of gestation length), and those treated by veterinarians on the grounds of except retained fetal membranes. Prepartum mares with foaling signs were monitored, and foaling events were recorded. Dystocia was defined as occurring when it takes >30 minutes to finish second stage of parturition (from rupture of allantochorion to fetal delivery), and strong traction for expulsion of the fetus was needed. The mare, whose placenta was not discharged within an hour, was injected intramuscularly with 50 IU of oxytocin at hourly intervals until placental expulsion for the prevention of retained fetal membranes (this treatment is routinely carried out by the horse owner). Rectal temperature was recorded twice a day in puerperal period. We defined the mare as PF when the rectal temperature was >38.5 C within 96 hours after foaling. The objective variable was the incidence of PF, and the explanatory variables were year foaled, month foaled (from January to June), age of mare, breed of mare (crossbred heavy draft horses vs. Percheron), gestation length, foaling difficulty (easy delivery vs. dystocia), placental retention time (<3 hours vs. S3 hours), viability of neonate (alive vs. stillbirth), and sex of offspring. Stepwise regression analysis was performed using the SAS software (JMP version 5.1; SAS Institute Japan Ltd, Tokyo, Japan). Variables with <0.1 of a P value were considered significant. 3. Results Twenty-four out of 158 mares (15.2%) were diagnosed as PF. Stepwise regression analysis was performed to select the factors that had significant effects on the incidence of PF and showed that breed of dams (P ¼ .011) and foaling difficulty (P ¼ .074) were significant (Table 1). Percheron mares had significantly higher risk than crossbred mares (odds ratio: 3.4). The mare with dystocia had higher risk than easy delivery (odds ratio: 3.3). 4. Discussion The reason why Percheron mares have a higher risk for PF than crossbred mares remains unclear. There was no difference in the incidence of PF between crossbred mares and Percheron mares in dystocia cases; but on the other hand, Percheron mares had higher incidence of PF than crossbred mares even in the cases of easy delivery (crossbred vs. Percheron: 9.6% vs. 26.9%, P < .05, chi-square test).
Table 1 Factors affecting the incidence of postpartum fever in heavy draft horses (stepwise regression analysis) Explanatory variables Breed of mare Crossbred Percheron Foaling difficulty Easy delivery Dystocia Age of mare <10 y S10 y Primiparity (3–8 y) Placental retention time <3 hr S3 hr (Retained fetal membranes) Viability of neonates Alive Dead (stillbirth)
n
Significance Odds ratio
125 33 *P ¼ .011
1.0 3.4
141 17 *P ¼ .074
1.0 3.3
68 67 NS 23 NS 144 14 NS 151 6 NS
An asterisk indicates significant variable (P < .1). NS indicates nonsignificant variable (P S .1).
Susceptibility for PF in Percheron mares is considered to be a result of sensitivity to local contamination or inflammation of uterus and birth canal. A study reports that the high incidence of retained fetal membranes in Friesian horses is a result of inbreeding [9]. It will be necessary to examine genetic influences on susceptibility for PF in Percheron mares. Risks for damage and contamination of birth canal will be increased especially if the fetal delivery needs assistance such as strong traction and correction of fetal maldisposition. In our 17 cases of dystocia, the four cases were fetal maldisposition, and the others needed assistance because they could not get delivered on their own within 30 minutes. Results of this study support the previous reports that dystocia was a risk factor for SAM [1,4,6,10]. Dystocia occasionally causes laceration of the vagina [11]. Severe vaginitis that we did not examine might be present in this study. Although it is unclear whether vaginitis leads to fever, we have to carefully evaluate the cases for future study, including the examination of vaginal laceration. Retained fetal membranes were not a significant risk factor for PF in this study, but it was strongly related to the occurrence of SAM in many previous reports [1,5,6,11]. Incidence of retained fetal membranes in heavy draft mares was reported to be >50% [12] but only 8.9% (14/158) in our study. Gutjahr et al [13] reported that administration of exogenous oxytocin induces uterine contraction in the breeding mare. Another study reported that oxytocin administrations to the postpartum mare could hasten placental retention time [14]. Thirty-five percent (56/158) of the postpartum mare was given oxytocin hourly in this study. This treatment might have reduced the incidence of retained fetal membranes. Therefore, administration of oxytocin in early postpartum period has a possibility that it will also be effective for the prevention of SAM, not only retained fetal membranes. All mares used in this study developed a fever between 12 and 48 hours after the parturition, and therefore, the owners should monitor the body temperature of mares in postpartum 3 days at the least. The results of this study suggest that it is necessary to consider the foaling difficulty and the breed of dams for earlier detection of PF in peripartum heavy draft mares.
T. Aoki et al. / Journal of Equine Veterinary Science xx (2014) 1–3
Acknowledgments The authors would like to thank Takashi Taguchi for his assistance in writing the manuscript and Hirofumi Sasaki, Hajime Kaku, Masayori Nishimura, Yoshiharu Nishimura, and Shinichi Agemi for providing both the mares and the data used in this study.
References [1] Perkins NR, Frazer GS. Reproductive emergencies in the mare. Vet Clin North Am Equine Pract 1994;10:643–70. [2] Faro S. Postpartum endometritis. Clin Perinatol 2005;32:803–14. [3] LeBlanc SJ, Osawa T, Dubuc J. Reproductive tract defense and disease in postpartum dairy cows. Theriogenology 2011;76:1610–8. [4] Blanchard TL. Postpartum metritis. In: McKinnon AO, Squires EL, Vaala WE, Varner DD, editors. Equine reproduction. 2nd ed. Ames: Wiley-Blackwell; 2011. p. 2530–3. [5] Threlfall WR. Retained fetal membranes. In: McKinnon AO, Squires EL, Vaala WE, Varner DD, editors. Equine reproduction. 2nd ed. Ames: Wiley-Blackwell; 2011. p. 2520–9.
3
[6] Tibary A, Fite CL. Reproductive tract infections. In: Sellon DC, Long MT, editors. Equine infectious diseases. St. Louis: SAUNDERS; 2007. p. 84–103. [7] Jennings WE. Some common problems in horse breeding. Cornell Vet 1941;31:197–215. [8] Vandeplassche M, Spincemaille J, Bouters R. Aetiology, pathogenesis and treatment of retained placenta in the mare. Equine Vet J 1971;3: 144–7. [9] Sevinga M, Vrijenhoek T, Hesselinks JW, Barkema HW, Groen AF. Effect of inbreeding on the incidence of retained placenta in Friesian horses. J Anim Sci 2004;82:982–6. [10] Blanchard TL, Orsini JA, Garcia MC, Elmore RG, Youngquist RS, Bierschwal CJ. Influence of dystocia on white blood cell and blood neutrophil counts in mares. Theriogenology 1986;25:347–52. [11] LeBlanc M. Common peripartum problems in the mare. J Equine Vet Sci 2008;28:709–15. [12] Rapacz A, Pa zdzior K, Ras A, Rotkiewicz T, Janowski TE. Retained fetal membranes in heavy draft mares associated with histological abnormalities. J Equine Vet Sci 2012;32:38–44. [13] Gutjahr S, Paccamonti DL, Pycock JF, Taverne MA, Dieleman SJ, van der Weijden GC. Effect of dose and day of treatment on uterine response to oxytocin in mares. Theriogenology 2000;54:447–56. [14] Provencher R, Threlfall WR, Murdick PW, Wearly WK. Retained fetal membranes in the mare: a retrospective study. Can Vet J 1988;29: 903–10.
Contents lists available at ScienceDirect
Journal of Equine Veterinary Science journal homepage: www.j-evs.com
Short Communication
Factors Affecting the Incidence of Postpartum Fever in Heavy Draft Mares Takahiro Aoki DVM a, *, Kazuhiro Yamakawa DVM, PhD b, Mitsuo Ishii DVM, PhD a a b
Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan Yuubetsu Herd Management Service, Yuubetsu, Hokkaido, Japan
a r t i c l e i n f o
a b s t r a c t
Article history: Received 14 October 2013 Received in revised form 30 November 2013 Accepted 14 December 2013 Available online xxxx
Postpartum metritis is a common problem in many animal species. In equine medicine, sequelae of postpartum metritis vary from delay in uterine involution to development of systemic acute metritis (SAM), toxemia, and laminitis. Heavy draft mares potentially have higher risk of suffering from SAM than light breed mares. Postpartum fever (PF) mostly appears as a sign of SAM. The purpose of this study is to analyze the factors affecting the incidence of PF in 158 foalings from 62 heavy draft mares by multiple logistic regressions. The objective variable was the incidence of PF, and the explanatory variables were year foaled, month foaled, age of mare, breed of mare (crossbred heavy draft horse vs. Percheron), gestation length, foaling difficulty (easy delivery vs. dystocia), retained fetal membranes, stillbirth, and sex of offspring. Twenty-four out of 158 mares were diagnosed with PF. Stepwise regression analysis showed that breed of dams and foaling difficulty were significant risk factors for PF. Percheron mares had higher risk than crossbred mares (odds ratio: 3.4). Dystocia had higher risk than easy delivery (odds ratio: 3.3). Percheron mares had higher incidence of PF than crossbred mares even in the cases of easy delivery. Risks for damage and contamination of birth canal will be increased especially if the fetal delivery needs assistance. The results of this study suggest that it is necessary to consider the foaling difficulty and the breed of dams for earlier detection of PF in peripartum heavy draft mares. Ó 2014 Elsevier Inc. All rights reserved.
Keywords: Heavy draft horse Systemic acute metritis Postpartum fever Percheron Dystocia
1. Introduction Postpartum metritis is a common problem in many animal species [1–3]. In equine medicine, sequelae of postpartum metritis vary from delay in uterine involution to development of systemic acute metritis (SAM), toxemia, and laminitis [4]. Although the pathogenesis of toxemia and laminitis followed by SAM remains unproven, the longterm outcome is poor to moderate for mares that develop these stages. Systemic acute metritis and laminitis are commonly seen in heavy draft breeds, but rarely occur in * Corresponding author at: Takahiro Aoki, DVM, Department of Applied Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, 2-11 Nishi, Inada, Obihiro, Hokkaido 080-8555, Japan. E-mail address: [email protected] (T. Aoki). 0737-0806/$ – see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.jevs.2013.12.011
Thoroughbreds and other light breeds [5]. Systemic acute metritis is often a result of nonhygienic manipulation during foaling and retained fetal membranes [6]. It has been reported that retained fetal membranes are likely to occur in heavy draft mares [7] and after dystocia [8]. Therefore, peripartum heavy draft mares potentially have higher risk of suffering from retained fetal membranes, SAM, and laminitis than light breed mares. The prognosis for future fertility is favorable if the affected mare is appropriately treated in the early stages, and therefore, early detection of SAM is very important. Postpartum fever (PF) is a general term for febrile diseases in puerperal period and mostly appears as a sign of SAM [4]. Postpartum fever is a useful indicator for early detection of SAM. Until now, there are no reports that performed an epidemiological and risk analysis of PF in the horse. The purpose of this study is to analyze the
2
T. Aoki et al. / Journal of Equine Veterinary Science xx (2014) 1–3
factors affecting the incidence of PF in 158 foalings from 62 heavy draft horses by multiple logistic regressions. 2. Materials and Methods Data from a total of 158 foaling mares were used, which were recorded for peripartum events from 2009 to 2013. Mares (13 Percherons and 49 crossbred between Percheron, Belgian, and Breton heavy draft horses) were bred on three breeding stud farms (latitude 43 North) in Tokachi region of Hokkaido Island, Japan. Mares’ ages ranged from 3 to 19 years (mean standard deviation: 8.9 3.9) at the time of delivery. The following mares were excluded from the study: mares foaled with no witnesses, those undergoing cesarean section, those having preterm delivery (<300 days of gestation length), and those treated by veterinarians on the grounds of except retained fetal membranes. Prepartum mares with foaling signs were monitored, and foaling events were recorded. Dystocia was defined as occurring when it takes >30 minutes to finish second stage of parturition (from rupture of allantochorion to fetal delivery), and strong traction for expulsion of the fetus was needed. The mare, whose placenta was not discharged within an hour, was injected intramuscularly with 50 IU of oxytocin at hourly intervals until placental expulsion for the prevention of retained fetal membranes (this treatment is routinely carried out by the horse owner). Rectal temperature was recorded twice a day in puerperal period. We defined the mare as PF when the rectal temperature was >38.5 C within 96 hours after foaling. The objective variable was the incidence of PF, and the explanatory variables were year foaled, month foaled (from January to June), age of mare, breed of mare (crossbred heavy draft horses vs. Percheron), gestation length, foaling difficulty (easy delivery vs. dystocia), placental retention time (<3 hours vs. S3 hours), viability of neonate (alive vs. stillbirth), and sex of offspring. Stepwise regression analysis was performed using the SAS software (JMP version 5.1; SAS Institute Japan Ltd, Tokyo, Japan). Variables with <0.1 of a P value were considered significant. 3. Results Twenty-four out of 158 mares (15.2%) were diagnosed as PF. Stepwise regression analysis was performed to select the factors that had significant effects on the incidence of PF and showed that breed of dams (P ¼ .011) and foaling difficulty (P ¼ .074) were significant (Table 1). Percheron mares had significantly higher risk than crossbred mares (odds ratio: 3.4). The mare with dystocia had higher risk than easy delivery (odds ratio: 3.3). 4. Discussion The reason why Percheron mares have a higher risk for PF than crossbred mares remains unclear. There was no difference in the incidence of PF between crossbred mares and Percheron mares in dystocia cases; but on the other hand, Percheron mares had higher incidence of PF than crossbred mares even in the cases of easy delivery (crossbred vs. Percheron: 9.6% vs. 26.9%, P < .05, chi-square test).
Table 1 Factors affecting the incidence of postpartum fever in heavy draft horses (stepwise regression analysis) Explanatory variables Breed of mare Crossbred Percheron Foaling difficulty Easy delivery Dystocia Age of mare <10 y S10 y Primiparity (3–8 y) Placental retention time <3 hr S3 hr (Retained fetal membranes) Viability of neonates Alive Dead (stillbirth)
n
Significance Odds ratio
125 33 *P ¼ .011
1.0 3.4
141 17 *P ¼ .074
1.0 3.3
68 67 NS 23 NS 144 14 NS 151 6 NS
An asterisk indicates significant variable (P < .1). NS indicates nonsignificant variable (P S .1).
Susceptibility for PF in Percheron mares is considered to be a result of sensitivity to local contamination or inflammation of uterus and birth canal. A study reports that the high incidence of retained fetal membranes in Friesian horses is a result of inbreeding [9]. It will be necessary to examine genetic influences on susceptibility for PF in Percheron mares. Risks for damage and contamination of birth canal will be increased especially if the fetal delivery needs assistance such as strong traction and correction of fetal maldisposition. In our 17 cases of dystocia, the four cases were fetal maldisposition, and the others needed assistance because they could not get delivered on their own within 30 minutes. Results of this study support the previous reports that dystocia was a risk factor for SAM [1,4,6,10]. Dystocia occasionally causes laceration of the vagina [11]. Severe vaginitis that we did not examine might be present in this study. Although it is unclear whether vaginitis leads to fever, we have to carefully evaluate the cases for future study, including the examination of vaginal laceration. Retained fetal membranes were not a significant risk factor for PF in this study, but it was strongly related to the occurrence of SAM in many previous reports [1,5,6,11]. Incidence of retained fetal membranes in heavy draft mares was reported to be >50% [12] but only 8.9% (14/158) in our study. Gutjahr et al [13] reported that administration of exogenous oxytocin induces uterine contraction in the breeding mare. Another study reported that oxytocin administrations to the postpartum mare could hasten placental retention time [14]. Thirty-five percent (56/158) of the postpartum mare was given oxytocin hourly in this study. This treatment might have reduced the incidence of retained fetal membranes. Therefore, administration of oxytocin in early postpartum period has a possibility that it will also be effective for the prevention of SAM, not only retained fetal membranes. All mares used in this study developed a fever between 12 and 48 hours after the parturition, and therefore, the owners should monitor the body temperature of mares in postpartum 3 days at the least. The results of this study suggest that it is necessary to consider the foaling difficulty and the breed of dams for earlier detection of PF in peripartum heavy draft mares.
T. Aoki et al. / Journal of Equine Veterinary Science xx (2014) 1–3
Acknowledgments The authors would like to thank Takashi Taguchi for his assistance in writing the manuscript and Hirofumi Sasaki, Hajime Kaku, Masayori Nishimura, Yoshiharu Nishimura, and Shinichi Agemi for providing both the mares and the data used in this study.
References [1] Perkins NR, Frazer GS. Reproductive emergencies in the mare. Vet Clin North Am Equine Pract 1994;10:643–70. [2] Faro S. Postpartum endometritis. Clin Perinatol 2005;32:803–14. [3] LeBlanc SJ, Osawa T, Dubuc J. Reproductive tract defense and disease in postpartum dairy cows. Theriogenology 2011;76:1610–8. [4] Blanchard TL. Postpartum metritis. In: McKinnon AO, Squires EL, Vaala WE, Varner DD, editors. Equine reproduction. 2nd ed. Ames: Wiley-Blackwell; 2011. p. 2530–3. [5] Threlfall WR. Retained fetal membranes. In: McKinnon AO, Squires EL, Vaala WE, Varner DD, editors. Equine reproduction. 2nd ed. Ames: Wiley-Blackwell; 2011. p. 2520–9.
3
[6] Tibary A, Fite CL. Reproductive tract infections. In: Sellon DC, Long MT, editors. Equine infectious diseases. St. Louis: SAUNDERS; 2007. p. 84–103. [7] Jennings WE. Some common problems in horse breeding. Cornell Vet 1941;31:197–215. [8] Vandeplassche M, Spincemaille J, Bouters R. Aetiology, pathogenesis and treatment of retained placenta in the mare. Equine Vet J 1971;3: 144–7. [9] Sevinga M, Vrijenhoek T, Hesselinks JW, Barkema HW, Groen AF. Effect of inbreeding on the incidence of retained placenta in Friesian horses. J Anim Sci 2004;82:982–6. [10] Blanchard TL, Orsini JA, Garcia MC, Elmore RG, Youngquist RS, Bierschwal CJ. Influence of dystocia on white blood cell and blood neutrophil counts in mares. Theriogenology 1986;25:347–52. [11] LeBlanc M. Common peripartum problems in the mare. J Equine Vet Sci 2008;28:709–15. [12] Rapacz A, Pa zdzior K, Ras A, Rotkiewicz T, Janowski TE. Retained fetal membranes in heavy draft mares associated with histological abnormalities. J Equine Vet Sci 2012;32:38–44. [13] Gutjahr S, Paccamonti DL, Pycock JF, Taverne MA, Dieleman SJ, van der Weijden GC. Effect of dose and day of treatment on uterine response to oxytocin in mares. Theriogenology 2000;54:447–56. [14] Provencher R, Threlfall WR, Murdick PW, Wearly WK. Retained fetal membranes in the mare: a retrospective study. Can Vet J 1988;29: 903–10.