Animal: Dog (Canis familiaris), adult, female.
History: No previous clinical signs were reported by neither the owner nor the vet. The dog passed away suddenly at home.
Diagnosis: Thoracic cavity. Diaphragmatic hernia with intestinal dislocation within the thoracic cavity.
Comment: A 1 x 2.5 cm defect was found on the right dorsal quadrant (muscular region). No evidence of acute nor chronic trauma to the diaphragm (no haemorrhages, fibrin, adhesions, etc.) was seen. It is thus highly likely that there was a previous clinically silent hernia, either congenital or chronic, as diaphragmatic hernias may have minimal clinical significance and therefore remain undetected for years1. Then, endogenous forces (most likely pregnancy) led to the herniation of the abdominal viscera into the thoracic cavity through such defect. This resulted in impaired breathing due to the compression of the lungs. Moreover, the strangulation of the caecum must have led to obstruction of efferent veins, venous infarction and eventually intestinal ischemia.
Congenital diaphragmatic clefts are commonly observed in dogs in the left dorsal quadrant and central areas, presumably due to failure of the pleuroperitoneal fold to fuse with the septum transversum2. However, considering the location of this one and the age of the dog, a chronic acquired diaphragmatic defect seems more likely. Although in the present case, the cause of the rupture remains unknown, in dogs they are usually the consequence of road traffic accidents (RTA)1.
Contributors: Esther Vazquez Fernandez and Guido Rocchigiani. Department of Veterinary Anatomy, Physiology and Pathology, University of Liverpool, Leahurst campus, Neston, United Kingdom
References:
Pereira GJ, Rahal SC, Melchert A, et al. Eleven-year retrospective analysis of acquired diaphragmatic hernia in 49 dogs and 48 cats. Can Vet J. 2023;64(2):149-152.
Cooper BJ, Valentine BA. Muscle and tendon. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. Vol. 1. Elsevier, 2016: pages 191, 192.