EQUINE VETERINARY JOURNAL Equine vet. J . (1978), 10 (3), 185-187
Tetralogy of Fallot and Cranial Mesenteric Arteritis in a Foal DEBORAH J. REYNOLDS; and T. K. NlCHOLLt University of Bristol, Langford House, Langford, Bristol BS18 7DU. Avon
SUMMARY A 5 month old colt foal with recurrent pyrexia and a loud pansystolic murmur later developed signs of cardiac failure. Peritoneal fluid and blood samples both demonstrated an extreme leucocytosis and neutrophilia. At post-mortem both a cranial mesenteric arteritis and the congenital cardiac anomaly, Tetralogy of Fallot were found. The detailed clinical and post-mortem findings contributing to the case are described.
CASE REPORT History and Clinical Signs A 5 month old part-Arab colt foal was reported to be dull, restless and anorexic. The rectal temperature was 106°F. There was no previous history of illness and the animal was well grown for its age. Three days later there appeared to be some clinical improvement and the temperature had fallen to 104°F. The following day, however, the foal relapsed, with difficulty in standing and rapid shallow respirations. The temperature was 107°F and the animal was inappetant; it was referred to the University of Bristol on the fifth day from the onset of illness. On examination the pulse rate was found to be 80 per min, respiratory rate 32 per min and temperature 1012°F. Clinical abnormalities were confined to the cardiovascular system. Auscultation of the cardiac and surrounding areas revealed a loud pansystolic heart murmur. It was discernible over a large area of the chest wal! and was loudest over the left atrio-ventricular valve, almost obscuring the normal heart sounds. No cough, oedema, jugular pulse or other signs of cardiovascular insufficiency were found. Daily monitoring of rectal temperature revealed a recurrent pyrexia with 2 major peaks in addition to that reported before admission. This is shown in fig. 1.
temperature had fallen to 101°Fand the foal appeared to be much brighter although the respirations were still laboured. The cardiac murmur remained obvious and lameness occurred once in this period. A deterioration in the foal's condition occurred over the next 4 days with a return of the pyrexia (IOYF), increase in pulse rate (100 per min) and rapid, abdominal respirations. The foal was lethargic and spent long periods in lateral recumbency. Treatment was changed again, to i.v. chloramphenicol (2 g daily) and within 5 days the temperature had fallen to 101.5"F. At this stage exercise tolerance was poor, dyspnoea and cyanosis was evident and a palpable cardiac thrill developed. Clinical Pathology The results of serial haematological examinations are shown in Table I and fig. 1. The red cell parameters were normal but there was gross leucocytosis, with a maximum total white cell count of 43 x 109/1largely due to polymorphoneutrophil leucocytes with a moderate shift to the left. Rnbitin
Treatment Intravenous treatment began with 500 mg ampicillin' twice daily. Four days later this seemed ineffective so was discontinued for 36 hours, when a sample of blood was taken for bacteriological examination. Treatment was resumed with trimethoprim and sulfadoxine* at a dose rate of 2 g daily for 10 days. After 6 days the Present addresses: Institute for Research on Animal Diseases, Compton, Nr. Newburv. Berkshire. England. t Shadowfox Stables,' Wgie Road RD5, West Chester, P.A. 19380, U.S.A. Penbritin, Beecham Animal Health. Trivetrin, Wellcome.
Fig. 1. (-)
11 15 Days from ometd ill-
Rectal temperature (- -) and total white cell count monitored during the periods of administration of 3 different antibiotics.
EQUINE VETERINARY JOURNAL
1ABLE I HAEMATOLOGICAL RESULTS-VALUES OBTAINED FOR TOTAL A N D DIFFERENTIAL WHITE CELL COUNTS
Parameter Total white blood cells x 109/1 Band neutrophils % Polymorphs % Eosinophils % Lymphocytes % Monocytes % Basophils %
Normal value* 5-9