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Though cleft palate, or palatoschisis, is relatively rare in horses, the congenital defect ranks as the most common craniofacial abnormality. Most frequently, cleft palate affects the caudal half or two-thirds of the soft palate. Incomplete fusion of tissues along the midline of the soft palate, which normally occurs at about day 47 of gestation, most commonly results in the defect.

Causes of cleft palate in domestic species runs the gamut from genetic factors to environmental, hormonal, and metabolic interactions. In cattle and swine, cleft palates are thought to be associated with consumption of certain plants, including lupine species, wild parsnip, poison hemlock, and the wild tobacco tree, though no clear association has been made with horses and ponies.

One of the most prevalent clinical signs of cleft palate involves difficulty or reluctance in swallowing, often accompanied by discharge of milk from the nostrils immediately after nursing, sometimes called nasal regurgitation. Signs of aspiration pneumonia are also usually observed, such as coughing, abnormal lung sounds, increased respiration rate, elevated heart rate, and fever. Definitive diagnosis of cleft palate is best achieved through endoscopic examination of the involved structures.

If the defect involves less than 20% of the soft palate and is symmetrical, surgical repair may be an option, though success is frequently blunted by postsurgical complications. Intensive postoperative care is required to circumvent aspiration pneumonia and meet nutritional requirements. Feeding through a nasogastric tube is often prescribed so irritation of the surgical site is reduced.

In a recent study* of 28 cases of cleft palate, short-term outcomes includes euthanasia (50%), surgical repair (11%), supportive care (4%), and no treatment (32%). Almost half of the animals (46%) survived to discharge from the hospital. Horses with aspiration pneumonia or defects of both the hard and soft palate had less favorable outcomes.

*Shaw, S.D, T.E. Norman, C.E. Arnold, and M.C. Coleman. 2015. Clinical characteristics of horses and foals diagnosed with cleft palate in a referral population: 28 cases (1988-2011). Canadian Veterinary Journal. 56:756-760.

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