Genetic and environmental factors associated with incidence of infectious bovine keratoconjunctivitis in preweaned beef calves

Infectious bovine keratoconjunctivitis (IBK) is one of the most economically important diseases in preweaned calves. This study examined the health records of 45,497 calves over a 20-yr period to determine environmental and genetic factors influencing the incidence of IBK. Three data sets were analyzed with an animal model. The first data set (n = 41,986) evaluated environmental factors and genetic differences among nine purebred (Angus, Braunvieh, Charolais, Gelbvieh, Hereford, Limousin, Pinzgauer, Red Poll, and Simmental) and three composite breeds (MARC I, MARC II, and MARC III). Weaning weights of calves diagnosed with IBK were 8.9 kg lighter (P < 0.05) than weights of healthy calves. Incidence of IBK was related to age of the calf and the seasonal life cycle of the face fly (Musca autumnalis). Incidence of IBK increased in the spring (June), peaked during the summer months (July to September), and then decreased in the fall. Herefords were the most susceptible breed (P < 0.05) compared with all other purebreds and composites. Estimates of direct heritability for the incidence of IBK were generally low and ranged from 0.00 to 0.28 by breed. The maternal permanent environmental and genetic effects of the dam on the incidence of IBK were not significant for most breeds. The second data set (n = 9,606) was used to estimate heterosis for the incidence of IBK from a Hereford and Angus diallel design. The heterosis effect for the incidence of IBK in reciprocal Hereford/Angus crossbred calves was slightly negative (P = 0.12) but not large. The higher incidence of IBK in Angus x Hereford calves compared with Hereford x Angus calves (13.3 vs. 8.9%) suggests a maternal effect related to the incidence of IBK. Incidence of IBK in crossbred calves sired by tropically adapted breeds (Brahma, Boran, Tuli) compared with purebred and crossbred Bos taurus types was investigated in the third data set (n = 2,622). Crossbred calves sired by tropically adapted breeds had a lower incidence of IBK than most Bos taurus types (P < 0.05), but they were not different than either reciprocal crosses of Hereford and Angus or purebred Angus calves. Response to selection for decreasing the incidence of IBK is likely to be slow because of low heritability and low incidence in most breeds. Significant breed differences for incidence of IBK may be important to some producers and management systems.     

Equine G3P[3] rotavirus strain E3198 related to simian RRV and feline/canine-like rotaviruses based on complete genome analyses

Equine group A rotavirus (RVA) strains are the most important cause of gastroenteritis in equine neonates and foals worldwide, and G3P[12] and G14P[12] are epidemiologically the most important genotypes. The genotype constellation of an unusual Argentinean G3P[3] RVA strain (RVA/Horse-wt/E3198/2008/G3P[3]) detected in fecal samples of a diarrheic foal in 2008 was shown to be G3–P[3]–I3–R3–C3–M3–A9–N3–T3–E3–H6. Each of these genotypes has been found typically in feline and canine RVA strains, and the genotype constellation is reminiscent to those of Cat97-like RVA strains. However, the phylogenetic analyses revealed only a distant relationship between E3198 and known feline, canine and feline/canine-like human RVA strains. Surprisingly, a rather close relationship was found between E3198 and simian RVA strains RVA/Simian-tc/USA/RRV/1975/G3P[3] for at least 5 gene segments. RRV is believed to be a reassortant between a bovine-like RVA strain and a RVA strains distantly related to feline/canine RVA strains. These analyses indicate that E3198 is unlikely to be of equine origin, and most likely represents a RVA interspecies transmitted virus, possibly in combination with one or more reassortments, from a feline, canine or related host species to a horse. Further studies are in progress to evaluate if this strain was a single interspecies transmission event, or if this strain started to circulate in the equine population.     

Influence of detomidine and buprenorphine on motor-evoked potentials in horses

Horses need to be sedated before they are investigated by transcranial magnetic stimulation because of the mild discomfort induced by the evoked muscle contraction and the noise of stimulation. This paper describes the influence of a combination of detomidine (10 microg/kg bodyweight) and a low dose of buprenorphine (2.4 microg/kg) on the onset latency and peak-to-peak amplitude of magnetic motor-evoked potentials in normal horses. There were no significant differences between measurements of these parameters made before the horses were sedated and measurements made 10 and 30 minutes after the drugs were administered.     

Oesophageal electrocardiography in healthy horses

Reasons for performing study: In human medicine, oesophageal electrocardiography (ECG) is a well‐established technique that magnifies P waves with respect to the QRS complex. Objectives: To investigate the feasibility of oesophageal ECG recording in horses and its ability to produce larger P waves compared with base‐apex and unipolar recordings. Methods: Bipolar and unipolar ECG were performed using oesophageal and surface electrodes. Oesophageal ECG was obtained from 6 different recording configurations at different oesophageal depths. Amplitudes of P, Q, R, S and T waves were measured from 3 different cardiac cycles for each recording configuration and depth. Results: Oesophageal ECG was feasible in all horses. For all oesophageal recording configurations, significantly larger P waves were recorded from a depth that equalled ‘height of the withers + 10 cm’ (HW₊₁₀) than from any other depth. P/QRS_magn, the ratio between the P wave and QRS complex magnitudes, was largest for intraoesophageal recordings with an interelectrode distance of 10 cm, at HW₊₁₀, where it was significantly larger than base‐apex and unipolar recordings. Base‐apex recording resulted in significantly smaller P waves than all other recording configurations and significantly smaller P/QRS_magn ratios than all other recording configurations except one combined oesophageal‐surface recording (E/S_low). Conclusions: Oesophageal ECG recording is feasible in horses and effective in magnifying P wave amplitude. Potential relevance: The procedure is promising for diagnosis of supraventricular tachydysrhythmias and might be used in electrophysiological studies and for cardiac pacing.     

Neuritis of the cauda equina in a dog

This study presents the first case report of neuritis of the cauda equina in a dog, including characterisation of the inflammatory infiltrate. The dog in question, a 6-year-old Welsh springer spaniel, was presented with flaccid tail and faecal and urinary incontinence. The histological lesions included severe mononuclear cell infiltration of the nerve roots of the cauda equina and of the lumbar nerve roots. The infiltrate was composed of large numbers of T-lymphocytes and B-lymphocytes and small numbers of macrophages. Polymerase chain reactions of brain and spinal tissues were positive for Neospora caninum.     

Penile and preputial tumours in the horse: literature review and proposal of a standardised approach

Penile and preputial tumours are not uncommon in the horse, but can cause discomfort and lead to serious complications. Several types of tumour of the male external genitalia have been described. The most common type is the squamous cell carcinoma (SCC), which is found mainly in older horses. Reports of a breed predilection for penile tumour formation are equivocal, but castration, coat colour, poor hygiene and various infectious agents have all been suggested to predispose to the development of some types of tumour (e.g. SCC, papilloma and melanoma). Careful assessment of the primary tumour is an important first step in the design of an optimal treatment protocol. Invasiveness, differentiation grade, tumour size and presence of metastases are all relevant to the decision to pursue additional diagnostic procedures or specific treatment options. To date, no standard protocol has been reported for the approach to penile tumours in the horse and treatments range from minimally invasive therapies (e.g. topical use of 5-fluorouracil) to radical surgical interventions (e.g. en bloc penile and preputial resection with penile retroversion). Completeness of removal of the neoplasm and therefore risk of recurrence is highly dependent on the type of therapy chosen. However, the size and histopathological features of the primary tumour are also important factors with respect to the likelihood of recurrence. This review describes the most common penile and preputial neoplasms in the horse, and outlines a standard protocol aimed at arriving at a specific diagnosis and tailoring the therapeutic approach accordingly.     

Definitive‐intent intensity‐modulated radiation therapy provides similar outcomes to those previously published for definitive‐intent three‐dimensional conformal radiation therapy in dogs with primary brain tumors: A multi‐institutional retrospective study

Radiotherapy with or without surgery is a common choice for brain tumors in dogs. Although numerous studies have evaluated use of three‐dimensional conformal radiotherapy, reports of definitive‐intent, IMRT for canine intracranial tumors are lacking. Intensity‐modulated radiation therapy has the benefit of decreasing dose to nearby organs at risk and may aid in reducing toxicity. However, increasing dose conformity with IMRT calls for accurate target delineation and daily patient positioning, in order to decrease the risk of a geographic miss. To determine survival outcome and toxicity, we performed a multi‐institutional retrospective observational study evaluating dogs with brain tumors treated with IMRT. Fifty‐two dogs treated with fractionated, definitive‐intent IMRT at four academic radiotherapy facilities were included. All dogs presented with neurologic signs and were diagnosed via MRI. Presumed radiological diagnoses included 37 meningiomas, 12 gliomas, and one peripheral nerve sheath tumor. One dog had two presumed meningiomas and one dog had either a glioma or meningioma. All dogs were treated in the macroscopic disease setting and were prescribed a total dose of 45‐50 Gy (2.25‐2.5 Gy per fraction in 18‐20 daily fractions). Median survival time for all patients, including seven cases treated with a second course of therapy was 18.1 months (95% confidence of interval 12.3‐26.6 months). As previously described for brain tumors, increasing severity of neurologic signs at diagnosis was associated with a worse outcome. Intensity‐modulated radiation therapy was well tolerated with few reported acute, acute delayed, or late side effects.