Bovine congestive heart failure (BCHF) is an untreatable, deadly disease increasingly prevalent in feedlot cattle in North America’s Western Great Plains. The condition was first identified in the 1970s, and has since been reported in increasing frequency. BCHF mortality has reached 7% in severely affected cattle operations and, in some cases, annual losses have exceeded $250,000 for a single producer. Researchers have recently identified genetic variants associated with BCHF to help cattle producers make informed decisions about selective breeding and animal health management.
Bovine congestive heart failure epidemiology
Known congestive heart failure etiologies in cattle include exposure to high altitudes, traumatic reticulopericarditis, infectious endocarditis, lymphoma, ionophore toxicity, and congenital diseases such as ventricular septal defects. BCHF seems most similar to high altitude disease, also known as brisket disease or high mountain disease, which affects cattle raised on ranches at altitudes above 5,000 feet. Because of the lower oxygen content in the high altitude air, less oxygen reaches the pulmonary vasculature and the pulmonary artery constricts, producing a high pressure area, and making the heart pump harder to adequately circulate blood. While all mammals experience this response, cattle are particularly susceptible to low oxygen levels, because the contractive shunting response is more exaggerated in cattle, and the bovine lung does not allow free air passage between neighboring regions. Pulmonary arterial hypertension occurs, followed by arterial remodeling if the animal stays at a high altitude, leading to right-sided congestive heart failure. Signs include lethargy, weakness, decreased appetite, bulging eyes, jugular vein distention and pulsation, limb and brisket region swelling, and death.
BCHF also affects cattle at moderate elevations (i.e., 1,100 to 5,000 feet). A 2019 postmortem study examined 17 cattle that had developed right-sided heart failure at a western Nebraska feedlot. Histopathological analysis was performed on various tissues from each animal. Lesions noted on histopathology and at necropsy indicated hypoxia-induced pulmonary arterial hypertension, specifically intimal pulmonary elastic artery hyperplasia. Pneumonia was absent in 9 of the 17 cases, suggesting another cause for the hypoxia that led to pulmonary arterial hypertension in these animals. More research is needed to determine the exact cause of BCHF.
Genetic risk factors for bovine congestive heart failure
Cattle from different sources vary markedly in BCHF incidence, despite being the same breed and being raised in the same region with similar management conditions. In addition, cattle from the same sources have a fairly predictable BCHF prevalence in their feedlot environment. This information suggests that genetic factors may influence BCHF risk, and instigated U.S. Meat Animal Research Center researchers to conduct a retrospective genomic study. Starting in 2017, trained, experienced pen riders screened more than 140,000 Western Plains feedlot cattle for BCHF signs and chose 102 matched pairs of BCHF-affected and unaffected pen mates for genetic evaluation. Using matched pairs helped standardize their genetic background and environmental influences. The genetic information from 560,000 DNA markers for each BCHF case was compared to the genetic information from the unaffected pen mate to discover chromosomal regions associated with BCHF. The most significant association was in the arrestin domain-containing protein 3 gene (ARRDC3) and the nuclear factor IA gene (NFIA). Animals who had homozygous risk alleles at either gene were approximately eight times more likely to have BCHF than their matched pen mates without those risk alleles, and animals who had homozygous risk alleles at both genes were 28 times more likely to have BCHF. While the pathogenic roles for ARRDC3 and NFIA are unknown, their discovery can help identify animals at genetic risk, allowing cattle producers to make informed decisions to prevent perpetuating BCHF.
Genetic testing for bovine congestive heart failure
Genetic testing for predisposition to BCHF is available. Tests that evaluate the ARRDC3 and the NFIA genes most accurately identify the animals not likely to become BCHF cases in affected feedlots. If an animal exhibits no gene variants, they only have a 1% chance of developing BCHF. Knowing what animals have minimal BCHF risk may be useful in selective breeding. About 29% of BCHF cases had changes at both gene sites, compared to only 2% of the matched unaffected pen mates, which demonstrates that other genetic and environmental factors likely contribute to BCHF. Feedlot operators who have BCHF-affected cattle in similar environments may benefit from genetic testing by identifying high-risk animals. By selecting animals who do not carry risk factors in ARRDC3 and NFIA genes, the disease impact should be reduced in subsequent calf crops, but research on beneficial management options is ongoing. Research is also underway to identify and confirm causal variants for BCHF risk and their mode of action.
BCHF is a concerning issue increasingly affecting cattle operations at moderate elevations, but research is ongoing to find answers that will help cattle producers manage their operations to help prevent disease occurrence. Currently, genetic testing may be helpful for feedlot operations already affected by BCHF, so the animals who should be bred to reduce disease incidence can be determined.