Equine Medicine

Incorrect answer for Equine Image Quiz: Neurologic deficits and vestibular dysfunction in a palamino

What's causing this horse's head tilt and facial nerve paralysis?

Correct answer for Equine Image Quiz: Neurologic deficits and vestibular dysfunction in a palamino

Bacterial septicemia is the leading cause of morbidity and mortality in equine neonates. Survival rates reported over the last 5 years in retrospective studies of septicemic foals are highly variable, ranging between 40 and 70%, and comparisons among studies are difficult because of differences in case definition.

Mechanical injuries to peripheral nerves occur because of compression, entrapment, transection, laceration, ischemia, crushing, stretching, or chemical or burn damage. Neurapractic lesions are characterized by a failure of conduction of the action potential across the injured axonal segment.

Hormonal management of mares is used to manipulate the onset of the breeding season, the timing of ovulation and in performance mares the prevention of estrus. Pasture breeding, hand breeding using teasing with estrus detection by a stallion, and artificial insemination (AI) of cooled and frozen semen are still commonly used in Canada.

Endoscopic examination in the stallions is indicated in cases where blood (hemospermia), pus or (pyspermia) in the semen or urine, treatment for seminal vesiculitis, pain on ejaculation, or there is an inability to emit semen.

Colic cases

Foaling problems are very stressful for most practitioners, mares, and horse owners. The maternal and fetal outcomes during dystocia are less successful for the mare compared to other species. An understanding of the underlying causes and strategies to remedy dystocia are essential for a successful outcome.

Vaccination is a critical component of an equine health maintenance program. Veterinarians play a crucial role in client education, risk assessment, and herd evaluation to determine which vaccination program is best suited for an individual horse or herd. Selection of vaccinations must take into account the horse's age, sex, geographic location, use of the horse, pregnancy status, risk for developing disease, and associated costs of immunization to the client.

Equine Cushings Disease (Pituitary Pars Intermedia Dysfunction [PPID]) is a disorder that likely affects more than half the population of horses aged 14 years and older. If unmanaged, affected horses are at risk for laminitis and insulin resistance (IR) and are immune-suppressed, increasing their risk of numerous infections.

Fermentation in the hindgut of the horse is similar to that in the rumen, resulting in the production of short-chain volatile fatty acids mainly acetic, propionic and butyric acids. The proportions of these acids are influenced by the availability and type of substrate, composition of the microbial community and the hindgut physiologic conditions.

Equine infectious diseases continue to emerge and re-emerge, infecting horses across the US and beyond. For the purpose of this discussion, we will discuss equine piroplasmosis (EP), methicillin-resistant Staphylococcus aureus, and Lyme Disease in the horse.

Sperm quality is the culmination of a variety of factors such as the total sperm number, sperm motility, sperm morphology, and sperm fertilizing ability. Presently in an assessment of the quality of a stallion's ejaculate, it is often based only on the volume, motility, and concentration of the sperm. These are relatively easy parameters to quantify.

Neonatal isoerythrolysis occurs when the foal inherits blood antigens (types) from the stallion that are different from that of the mare. As a result, the mare may produce antibodies to these antigens, which are then concentrated in her colostrum.

High risk mares are mares that are at significant risk of problems during pregnancy. This includes mares that are of advanced age, repeated history of unsuccessful foaling outcomes, mares with twin pregnancies, mares that have experienced a significant toxemia, or that suffer significant physical infirmaries including chronic founder, severe arthritis, or body wall injuries or mares that have placentitis,.

Endometritis is the most common infectious pathologic condition affecting the uterus in brood mares. Pathologic endometritis is an abnormal extension of a physiologic process. In the pathologic form excessive inflammation of the endometrium occurs and then persists.

Equine gastric ulcer syndrome (EGUS) is common in performance horses and in foals. Diagnosis of EGUS is based on history, clinical signs, endoscopic examination, and response to treatment. All ages and breeds of horses are susceptible to EGUS and current therapeutic strategies focus on blocking gastric acid secretion and raising stomach pH.

Reproductive problems of stallions occur frequently and may be related to physiologic, pathologic, and management processes. Relatively few colts are kept as stallions in the equine industry, and veterinarians may not have a great deal of exposure or experience with stallions.

Endoscopic examination of the mare's uterus is primarily used as tool to aid in the diagnosis of unusual conditions, such as intractable infections, tumors, abscesses, foreign bodies, adhesions, and congenital abnormalities.

One of the critical functions of the reticular formation of the brainstem is activation of the cerebral cortex for the awake state. This component of the formation, known as the ascending reticular activating system (ARAS), is an ill-defined meshwork of cells concentrated in the rostral brainstem that receives afferent input from all parts of the CNS and projects excitatory stimuli cortically.

The brainstem includes the diencephalon, mesencephalon (midbrain), and rhombencephalon (hindbrain). With the exception of the olfactory nerves (I), all cranial nerves are arrayed along the brainstem. The hindbrain is divided into metencephalon (cerebellum) and myelencephalon (pons and medulla oblongata).

Axons of the upper motor neuron (UMN) extrapyramidal and vestibular systems travel from cell bodies throughout the brain and pass predominantly in reticulospinal and vestibulospinal tracts to lower motor neurons (LMN) in the ventral and intermediate columns of the gray matter of the spinal cord.

Fungi are eukaryotic organisms with a cell wall made up of chitins, glucans and mannans. The plasma membrane contains ergosterol, which is a sterol that is targeted by several antifungal drugs. Fungal infections in horses are relatively uncommon, although geographic prevalence is highly variable.

The term "wobbler" or "wobbler syndrome" describes a group of developmental anomalies and degenerative conditions involving the cervical vertebrae of ataxic horses (Hahn et al. 1999; Mayhew 2009). Several more or less descriptive abbreviations are used in wobbler terminology.

Clostridial myositis results from rapidly progressive necrosis of muscle from infection with clostridial organisms, often with fatal consequences. The majority of equine cases are secondary to intramuscular injections or as a result of direct contamination of deep wounds with bacterial growth in an anaerobic environment.

Deciding when to refer a horse with colic can be a difficult decision and involves careful evaluation of clinical and laboratory parameters, surgical considerations, probability of survival, and other considerations that include worsening of clinical condition, unresolved pain, or to obtain a second opinion.

Diagnosis and treatment of horses with colic have certainly improved in the last 20 years. However, horses with recurrent colic continue to be a diagnostic and often management challenge for both owners and veterinarians.

New information cerebellar abiotrophy of Arabians, Severe Combined Immunodeficieincy (SCID) of Arabians, Lavender foal syndrome of Arabians, Lethal White Syndrome of overo Paints, Glycogen Branching Enzyme Deficiency (GBED) of Quarter Horses, hemophila and thrombobasthenia will be discussed.

If the foal is less than 12 hours, it can be given 1-3 liters of high quality (sp gr > 1.090) colostrum. (Frozen colostrum should be thawed in warm water, rather than the microwave. Ideally colostrum should be < 12 months old).