Domestic sheep and bighorn sheep carry distinct gammaherpesviruses belonging to the genus Macavirus.

The genus Macavirus of the subfamily Gammaherpesvirinae comprises two genetically distinct lineages of lymphotropic viruses. One of these lineages includes viruses that can cause malignant catarrhal fever (MCF), which are known as MCF viruses (MCFV). All MCFVs are genetically and antigenically related but carried by different hosts. In this study, we report the recognition of new MCFV carried by bighorn sheep. The virus was first identified in a bighorn sheep from Banff National Park, Alberta, Canada. Analysis of a conserved region of the viral DNA polymerase gene of the virus carried by this bighorn sheep showed 85.88% nucleotide identity to the MCFV carried by domestic sheep, ovine herpesvirus 2 (OvHV-2). Further investigation of bighorn samples obtained from animals in the US and Canada showed 98.87-100% identity to the DNA polymerase sequence of the first bighorn in the study. Phylogenetic analysis indicated that the MCFV carried by bighorn sheep is closely related but distinct from OvHV-2. Epidemiological and virulence features of the newly recognized MCFV are still unknown and warrant further investigation. Considering the current nomenclature for MCFVs, we suggest a tentative designation of ovine herpesvirus-3 (OvHV-3) for this newly identified bighorn sheep MCFV.

Differential Susceptibility of Bighorn Sheep (Ovis canadensis) and Domestic Sheep (Ovis aries) Neutrophils to Mannheimia haemolytica Leukotoxin is not due to Differential Expression of Cell Surface CD18.

Bighornsheep ( Ovis canadensis ) are more susceptible to pneumonia caused by Mannheimia haemolytica than are domestic sheep ( Ovis aries ). Leukotoxin produced by M. haemolytica is the principal virulence factor involved in pneumonia pathogenesis. Although leukotoxin is cytolytic to all subsets of ruminant leukocytes, neutrophils are the most susceptible subset. Bighorn sheep neutrophils are four- to eightfold more susceptible to leukotoxin-induced cytolysis than are domestic sheep neutrophils. We hypothesized that the higher susceptibility of bighorn sheep neutrophils, in comparison to domestic sheep neutrophils, is due to higher expression of CD18, the receptor for leukotoxin on leukocytes. Our objective was to quantify CD18 expression on neutrophils of bighorn sheep and domestic sheep. Cell-surface CD18 expression on bighorn sheep and domestic sheep neutrophils was measured as antibody binding capacity of cells by flow cytometric analysis with two fluorochrome-conjugated anti-CD18 monoclonal antibodies (BAQ30A and HUH82A) and microspheres. Contrary to our expectations, CD18 expression was higher (P<0.0001) with monoclonal antibody BAQ30A and was higher (P<0.0002) as well with monoclonal antibody HUH80A on domestic sheep neutrophils in comparison to bighorn sheep neutrophils. These findings suggest that the higher in vitro susceptibility to leukotoxin of bighorn sheep neutrophils compared to domestic sheep neutrophils is not due to higher expression of the leukotoxin receptor CD18 on bighorn sheep neutrophils.

Potential disease agents in domestic goats and relevance to bighorn sheep (Ovis canadensis) management.

Domestic goats are raised for meat, milk and hair production, in herds for rangeland weed control, and as pack animals. Domestic sheep, goats and wild bighorn sheep are all susceptible to a multifactorial pneumonia. We sampled 43 herd goats from 7 herds and 48 pack goats from 11 herds for viral and bacterial serology, parasitology, and Pasteurellaceae microbiology. The goats in this study were in generally good health, although most goats did harbor various pathogens and parasites including several bacteria, specifically Pasteurellaceae, which have been associated with pneumonia in free-ranging bighorn sheep. It is not known if domestic goats can transmit the Pasteurellaceae or other pathogens found in this study readily to wild bighorn sheep. However, due the possibility of transmission, domestic goats in areas in or near bighorn sheep habitat should be managed to minimize the risk of spreading disease agents to bighorn sheep.

Assessing Timing and Causes of Neonatal Lamb Losses in a Bighorn Sheep ( Ovis canadensis canadensis ) Herd via Use of Vaginal Implant Transmitters.

We evaluated the use of vaginal implant transmitters (VITs) as a means of detecting, capturing, and radio collaring Rocky Mountain bighorn sheep ( Ovis canadensis canadensis) lambs to estimate survival and to facilitate carcass recovery to assess causes of mortality. We focused on one of several bighorn herds in Colorado, US, suffering from depressed recruitment that was not preceded by a classic all-age die-off. We captured, radio-collared, diagnosed pregnancy by ultrasound examination, and inserted VITs into 15 pregnant ewes from a herd residing near Granite, Colorado. We were subsequently able to collar a lamb from each of 13 VITs, and two additional lambs opportunistically from ewes without transmitters. As lambs died, we recovered and submitted carcasses for necropsy and laboratory assessment. All lambs captured and one additional lamb (carcass found opportunistically) were dead by about 130 d of age: 11 died of apparent pneumonia (all within 8-10 wk of age), one died from trauma after being kicked or trampled, one was killed by a mountain lion ( Puma concolor ), and three died of starvation likely caused by abandonment after capture. Pneumonic lambs had involvement of Mycoplasma ovipneumoniae and leukotoxigenic Bibersteinia trehalosi . The use of VITs and lamb collars enabled us to efficiently identify pneumonia as the predominant cause of depressed lamb recruitment in this herd; however, we urge care in neonatal lamb handling to minimize abandonment.

Sheep-Associated Malignant Catarrhal Fever-Like Skin Disease in a Free-Ranging Bighorn Sheep ( Ovis canadensis ), Alberta, Canada.

Malignant catarrhal fever-like clinical disease was diagnosed in a free-ranging bighorn sheep ( Ovis canadensis ) from Alberta, Canada, in June 2015. Antemortem and gross pathology findings included muscle atrophy, marked weight loss, and bilaterally symmetric alopecia with hyperpigmentation and crusting over the face, medial surfaces of the pinnae, dorsal trunk, distal limbs, perineal area, and tail. Histologically, the skin lesions were characterized by granulomatous mural folliculitis with numerous multinucleated giant cells and fewer lymphocytes and eosinophils consistent with previous reports of chronic ovine herpesvirus-2 (OvHV-2) infection. Multiple skin samples were positive for OvHV-2 DNA on PCR, and on partial sequencing of the viral DNA, there was 94% homology with reference GenBank OvHV-2. Quantitative PCR confirmed an increased level of OvHV-2 DNA in the lesional skin tissues. Based on exclusion of other disease processes, gross and histological lesions, PCR, and viral DNA sequencing results, a diagnosis of OvHV-2-mediated malignant catarrhal fever-like dermatitis was made.