Roczniki Naukowe Polskiego Towarzystwa Zootechnicznego, t. 5 (2009), nr 3

Thoroughbred foals' mortality causesduring first six months of life.Part II. Diseases and injuries

Maria Kulisa, Katarzyna Makieła, Bogusława Długosz, Magdalena Gaj

University of Agriculture in Kraków, Department of Horse Breeding,al. Mickiewicza 24/28, 30-059 Kraków

The aim of the study was to analyze Thoroughbred mortality caused by diseases or injuriesduring the first six months of life. Causes of foals' deaths from birth until weaning wereanalyzed. Data were collected at one of Polish Thoroughbred National Studs. Twelve bree-ding seasons were analyzed during which 395 foals were live-born. Data were collected frombroodmare cards, foaling notes and direct information was received from the generał farmmanager. Colts and fillies were divided into two groups. One of them we re foals dead untilthird day of life and another groups were foals dead from fourth day of life until weaning,which had place around 6 month of life. Causes of foals' death were diseases of the followingsystems: digestive, circulatory, nervous, respiratory and musculoskeletal. Injuries were alsoconsidered. Because of incomplete data in broodmare cards, a group of foals dead fromunknown causes was created. It was found that 4.55 % of foals died until third day of life and15.19% died until sixth months of life. Main causes of foals' deaths up to third day of lifewere diseases of circulatory system (16.16%) and from fourth day of life Rhodococcus equipneumonia (58.97 %).

KEY WORDS: foals / mortality / Thoroughbred horses

Highly specialized breeding has made Thoroughbreds the fastest horses in theworld, yet such a rigid selection for speed has also produced its negative effects.Intensive rising and training exert significant influence on young organisms, particularlyon their nervous excitability, which in tum affects the endocrine system and finallyreproductive functions. Thoroughbred mares are less fertile than other breeds; theysuffer from infertility more frequently or abort their foals. In addition, they are moreprone to multiple pregnancies [5, 8]. A high inbreeding coefficient is also a significantfactor here, as it conditions strong genetic feature transmission. Along with the desiredfeature, which is speed, certain other flaws, such as reduced immunity, are transmitted[6]. Immunological deficits are particularly dangerous in the case of diseases such asRhodococcus equi pneumonia [1].

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The aim of the study was to analyze Thoroughbred mortality caused by diseases orinjuries during the first six months of life.

Materiał and methods

Data was collected at one of Polish Thoroughbred National Studs. It was based onbroodmare cards, foaling notes and direct information received from the general farmmanager. Twelve breeding seasons during which 395 foals were bom, were analyzed.Dead colts and fillies were divided into two groups: dead foals until the third day oflife and dead foals from the fourth day of life up to weaning (around the sixth monthof life). Foals' deaths were caused by diseases of the following systems: digestive,circulatory, nervous, respiratory and musculoskeletal. Injuries were also tak en intoconsideration. The influence of prenatal factors has been already discussed in Part l ofthis study. Because of incomplete data in certain broodmare cards, a group of foals deadfrom unknown causes was created.

Results and discussion

I

I.J1Due to relatively significant difficulties in breeding and raising Thoroughbred

horses, identifying causes of foals' deaths becomes a very serious challenge. Table lpresents numbers and percentages of live-bom and dead foals. It can be seen that 4.55%of foals died up to the third day of life, while no difference between the number of deadfillies or colts was noted. On the other hand, many more colts than fillies died from dayforth up to weaning. Generally, 19.74% of all live-born foals died prior to their weaningage.

Most deaths, taking into consideration after birth diseases (until the third day oflife), were caused by impaired functioning of the circulatory system (16.66%). Inindividual cases, colts died as a result of nervous system disorders, neonatal isoeryth-rolysis and joint deformation; whilst the causes of filIies' deaths included circulatorysystem disorders (neonatal isoerythrolysis and eongenital heart defects) - Table 2.

Rhodococcus equi pneumonia was the most frequent cause of foal losses from thefourth day of life; it was more often suffered by colts (81.81 %) than fillies (70.37%).In three cases, no cause of filly's death was provided, whilst five other deaths werecause by the following: volvulus, e1eft palate, cerebral symptoms, fracture and septice-mia. For two colts, the cause of death has not been given, while single animals died asa result of congenitallung defect, peritonitis, croup paresis and joint deformation (Table 2).

Rhodococcus equi pneumonia was the cause of more than half of deaths (58.97%);prenatal factors analyzed in Part l of this study folIowed - Table 2. No cause of deathwas recorded in 6.4% cases (5 animals). Two foals (2.56%) died due to each of thefollowing: neonatal isoerythrolysis, cerebral symptoms and deformation. Single deathswere caused by volvulus, peritonitis, e1eft palate, eongenital heart defect, eongenitallung defect, croup paresis, contractures, fracture and septicemia. The percentage valuein each of the above categories equalled 1.28%.

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Table 1 - Tabela 1Number and percentage of live-born and dead foalsLiczba i procent źrebiąt żywo urodzonych i padłych

Live-born

foals

Źrebięta

żywo

urodzone

Dead foals - Źrebięta padłe

up to third day of life

do trzeciego dnia życia ogólem

after fourth day of life until weaning

po czwartym dniu życia do odsadzenia

total

fillies

klaczki

colts

ogierki

subtotal fillies colts subtotal

suma klaczki ogierki suma

n % n % n % n % n % n % n % n %

395 100.0 8 2.02 10 2.53 18 4.55 27 683 33 8.35 60 15.19 78 19.74

00•.....

00 Table 2 - Tabela 2tvFoals mortality causesPrzyczyny upadków źrebiąt

Foals de ad up to third day of life Foals dead from fourth day of life Dead foals

Foals monality causes Źrebięta padle do 3. dnia życia Źrebięta padle od 4. dnia życia - total

Przyczyny upadków fillies colt s subtotal fillies colts subtotal Źrebięta padle

klaczki ogierki suma klaczki ogierki suma - ogólem

n % n % n % n % n % n % n %

Oigestive system 2 7.40 3.03 3 4.98 3 3.84Układ pokarmowyCirculatory system 2 25 10 3 16.66 3 3.84(neonatal isoerythrolysis included) (2) (2.56)Układ krwionośny(w tym konflikt serologiczny)

Nervous system 10 5.55 3.70 1.66 2 2.56Uklad nerwowyRespiratory system 19 70.37 28 8484 47 78.32 47 60.25(Rhodococcus equipneumonia included) (19) (70.37) (27) (81.81) (46) (76.66) (46) (58.97)Układ oddechowy

(w tym rodokokoza)Musculoskeletal system 10 5.55 3.70 2 6.06 3 4.98 4 5.12(joint deformation incJuded) (2) (2.56)Układ mięśniowo-szkieletowy(w tym deformacja stawu)Injuries 3.70 1.66 1.28

Urazy mechanicznePreriatal factors 6 75 7 70 13 72.22 13 16.66Czynniki prenatalne

Unknown reason 3 11.10 2 6.06 5 8.32 6.40

Brak podanej przyczyny

Total - Razem 8 100 10 100 18 100 27 100 33 100 60 100 78 100

__""--.......~~L -----..&.._J-, -----I.~_ _'-- l..~ __

Owing to an insignificant amount of other causes of foal death, Rhodococcus equipneumonia will be discussed in more details here. It is a bacterial disease affecting therespiratory system brought about by Rhodococcus equi [3]. In foals up to the sixthmonth of age, this microorganism causes pneumonia and sometimes also endoenteritis[2, 7]. Rhodococcus equi pneumonia can threaten breeding significantly as, accordingto Frymus [1] and previous research, 5-7% offoals suffer from it. Mortality rate amountsto 80%. Rhodococcus equi pneumonia is a cause of 5-17% of al! foal losses globally,which confirms an incredible scale of the problem [1]. The observed high mortality ratedue to Rhodococcus equi pneumonia is, as Max says [6], a result of its being an enzootieherd disease with difficulties in early diagnosis. That is why it would be important todraw particular attention to the prevention of Rhodococcus equi infections. As Grądzkiet al. [4] points out, successful active measures for Rhodococcus equi pneumoniaprevention have not been developed so far. Early diagnosis makes it possible to selectappropriate treatment and increases its effectiveness.

The study revealed Rhodococcus equi pneumonia to be a more common cause ofdeath among colts than filIies. It can be presumed therefore that colts are more vulne-rabIe to this disease. No incident of Rhodococcus equi pneumonia among foals up tothe third day of life was noted, which can be explained by higher immunity at this stageprovided by colostrum.

Due to relatively high losses in Thoroughbred breeding, caused by infertility, foalabortion or multiple pregnancies, it is necessary to take all measures aiming at theelimination of factors conditioning foals' deaths. The conducted study revealed that4.55% of foals died until the third day of life and 15.19% died prior to weaning.Rhodococcus equi pneumonia was the most common cause of death in foals from thefourth day of life - 58.97% of al! deaths. The number confirms the incredible scale ofthe problem and the need for further research aiming at the improvement of diagnosticsand successful preventive measures.

BIBLIOGRAPHY

l. FRYMUS T., 1994 - Zwalczanie rodokokozy źrebiąt. Życie Weterynaryjne 2, 52-54.2. GIGUERE S., PRESCOTT J.F., 1997 - Clinical manifestations, diagnosis, treatment, and

prevention of Rhodococcus equi infections in foals. Vet. Microbiol. 56, 313-334.3. GRĄDZKI Z., ZIĘTEK A., BOGUTA L., WINIARCZYK S., WOŁOSZYN S., 2002 - Rodo-

kokoza źrebiąt. Medycyna Wet. 58 (12), 915-920.4. GRĄDZKI Z., ŻIĘTEK A., BOGUTA L., WINIARCZYK S., 2003 - Aktualne możliwości

przyżyciowej diagnostyki Rodococus equi u źrebiąt. Medycyna Wet. 59 (9), 773-777.5. KULISA M., PIESZKA M., FRYBES 0.,1999 - Ciąże bliźniacze w hodowli koni pełnej krwi

angielskiej w Polsce w latach 1987-1996. Medycyna Wet. 55 (l O), 13.6. MAX A., 2003 - Niewydolność oddechowa i zapalenie płuc u źrebiąt. Kall Polski 2 (225),

36-38.7. MElJER W.G., PRESCOTT r.r.. 2004 - Rhodococcus equi. Vet. Res. 35,383-396.8. PRUSKI W., 1960 - Hodowla koni. T. 1. PWRiL, Warszawa.

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Maria Kulisa, Katarzyna Makieła, Bogusława Długosz, Magdalena Gaj

Przyczyny śmiertelności źrebiąt pełnej krwi angielskiejw okresie pierwszych sześciu miesięcy życia.Cz. II. Schorzenia i urazy mechaniczne

Streszczenie

Celem badań była analiza przyczyn śmiertelności źrebiąt pełnej krwi angielskiej w okresiepierwszych sześciu miesięcy życia. Materiał do pracy zebrano w państwowej stadninie koni pełnejkrwi angielskiej. Dane uzyskano z kart klaczy matek, zeszytów porodowych oraz bezpośrednichinformacji udzielonych przez dyrektora stadniny. Przeanalizowano 12 sezonów rozrodczych,w których urodziło się 395 źrebiąt. Klaczki i ogierki padłe podzielono na dwie grupy. Pierwszągrupę stanowiły osobniki padłe do trzeciego dnia życia, drugą grupę - od czwartego dnia życia doodsadzenia, tj. do szóstego miesiąca. Powodem strat źrebiąt były choroby układu pokarmowego,krwionośnego, nerwowego, oddechowego i mięśniowo-szkieletowego. Uwzględniono również u-razy mechaniczne. Ze względu na braki w niektórych kartach klaczy matek wyłoniono grupęźrebiąt bez podanej przyczyny upadku. Stwierdzono, że w okresie do trzeciego dnia życia padło4,55% źrebiąt, a do czasu odsadzenia - 15,19%. Najczęstszą przyczyną upadków źrebiąt w pier-wszych dniach po porodzie były schorzenia układu krwionośnego (16,16%), a w późniejszymczasie - schorzenia układu oddechowego (76,66%).

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