Nutritional myopathies in ruminants and pigs are primarily represented by selenium/vitamin E–deficiency–associated nutritional myodegeneration (white muscle disease) and hypokalemic myopathy in dairy cattle. These syndromes cause clinically significant skeletal and cardiac muscle injury, leading to weakness, recumbency, respiratory compromise, and sometimes sudden death. This BCSE-focused note reviews pathophysiology, clinical presentation, diagnostic approach, treatment, and prevention to help veterinarians integrate nutrition, metabolism, and muscle pathology in food animal practice and exam scenarios.

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Laryngeal hemiplegia, commonly known as “roaring,” is a respiratory disorder in horses caused by paralysis of the recurrent laryngeal nerve—most often affecting the left side. This leads to incomplete abduction of the arytenoid cartilage, resulting in inspiratory noise and exercise intolerance. It is most frequently seen in large-breed performance horses.

Environmental diseases in aquatic systems result from poor water quality, including imbalances in temperature, pH, ammonia, nitrites, nitrates, oxygen levels, or pollutants. Fish and other aquatic animals are highly sensitive to these changes, which can lead to gill damage, immunosuppression, metabolic acidosis, and mass mortality events. Common clinical signs include erratic swimming, gasping at the surface, fin erosion, and increased susceptibility to secondary infections.

Primary canine glaucoma is an inherited condition characterized by increased intraocular pressure (IOP) due to impaired aqueous humor outflow, leading to optic nerve damage and eventual blindness. It can be classified as open-angle or angle-closure, with certain breeds predisposed (e.g., Cocker Spaniels, Basset Hounds). Clinical signs include ocular pain, corneal edema, mydriasis, vision loss, and a buphthalmic eye. Diagnosis involves tonometry and gonioscopy.

Infectious Bovine Rhinotracheitis (IBR) is a highly contagious respiratory disease caused by Bovine Herpesvirus-1 (BoHV-1). It affects cattle of all ages and is part of the bovine respiratory disease complex. Clinical signs include fever, nasal discharge, conjunctivitis, cough, tachypnea, and hyperemia of the nasal mucosa ("red nose"). The virus may also cause conjunctivitis, infectious pustular vulvovaginitis, balanoposthitis, abortions, and latent infections.

Urolithiasis is a common and life-threatening condition in male sheep and goats, particularly castrated males, due to urethral obstruction by urinary calculi. High-risk factors include high-concentrate, low-calcium, or imbalanced phosphorus diets, especially with inadequate water intake. Clinical signs include stranguria, dribbling urine, vocalization, abdominal pain, and distension. The urethral process and sigmoid flexure are common obstruction sites.

Canine osteomyelitis is an inflammatory condition of bone caused by bacterial or fungal infection, often secondary to open fractures, orthopedic implants, bite wounds, or hematogenous spread. Common pathogens include Staphylococcus spp., E. coli, and Aspergillus spp. Clinical signs include lameness, localized swelling, pain, fever, and draining tracts. Diagnosis relies on radiographs, culture, and biopsy, though early radiographic changes may lag behind clinical signs.

Radioactive iodine (I-131) is a gold-standard, curative treatment for feline hyperthyroidism caused by functional thyroid adenomas. I-131 selectively destroys hyperfunctional thyroid tissue while sparing normal tissue and parathyroid glands. It is administered subcutaneously or intravenously and requires temporary hospitalization due to radiation safety protocols. Clinical improvement is typically seen within weeks.

Antigen testing is the primary screening method for diagnosing heartworm disease in dogs and cats, detecting circulating antigens from Dirofilaria immitis adult female worms. Most tests are enzyme-linked immunosorbent assays (ELISAs) or rapid immunochromatographic tests. Antigen is typically detectable around 6 months post-infection, making timing crucial. False negatives may occur in early infections, single-sex male infections, or with immune complex interference.