Recurrence of Pharyngeal Pythiosis in a Horse

The image in Figure 1 is that of a "normal" larynx and pharynx in a horse. In Figure 2-4, the pharynx is filled with granulomas that are nearly completely obstructing the larynx. The images in Figures 2-4 belong to a middle-aged quarter horse mare that has been treated several times over 2 years for pythiosis of the pharynx. After each treatment with systemic anti-fungal medication, the granulomas shrink in size and the hemorrhagic discharge stops (Figure 4) . However, once the medication stops, the granulomas slowly begin to re-grow and the discharge returns. The image in Figure 4 was taken approximately 12 months prior to Figures 2 and 3. Although the granulomas are present and there is some drainage, the over-all condition of the pharynx is better than what we see in Figures 2 and 3!

Figure 1

Figure 2

Figure 3

Figure 4

 The most likely scenario in this case is that the pythiosis pathogen resides within the granulomas and although they shrink and appear to become inactive, the pathogen persists. Once the medication is stopped, the pathogen is allowed to multiply and the granulomas grown unabated!  Pythiosis was once believed to be a fungi put is now described as an algae that lives in stagnant water throughout the southeastern United States. The pathogen gains access to the horse through small wounds in skin or mucosa. I have diagnosed pharyngeal pythiosis in over a dozen horses in the past 10 years. Every case has involved horses with access to free standing water and all have responded favorably to the systemic anti-fungal. The case imaged in the figures above has been refractory and proven difficult to completely resolve!!

Cystic Calculi in a Horse

A teenage gelding presented for the complaint of increased urination (polyuria) and increased water intake (polydypsia). The increased urination had become a significant issue since it was happening at all times including when under saddle and showing. The physical exam was normal and a blood sample was collected for CBC and chemistry analysis. In addition, a free-catch (non-sterile) urine sample was collected during the exam. The CBC and chemistry results were normal suggesting that a primary problem of the kidneys may not have been the cause for the frequent urination. However, the urine sample contained traces of blood, moderate calcium crystals, and moderate white blood cells. These findings suggested an inflammatory process either in the urinary bladder or urethra. A endoscopic exam (cystoscopy) of the urinary bladder was performed. In Figure 1, the internal cavity of the urinary bladder is visualized. A pool of urine is present and a large, yellow object consistent with a urinary bladder stone (cystic calculi) is located in the center of the bladder. The surface of the bladder stone is rough and spiculated. In Figure 2, the inflammation caused by the abrasive stone can be visualized. 

Figure 1

Figure 2

In Figure 3, a pool of "debris" is noted surrounding the bladder stone. This debris is likely made up of calcium crystals, purulent matter (white blood cells), and some bacteria. The irritation caused by the bladder stone likely resulted in hemorrhage within the urinary bladder which is a great media for bacterial colonization! As such, chronic urinary bladder infection or cystitis is a common problem in these patients that will not resolve until the stone and debris is removed. A bladder stone this size can only be removed through a surgical procedure. There are two options regarding surgical approach: 1: bladder exploration via an abdominal incision or 2: through a urethrotomy within the perineum. The latter is performed in a standing horse and is limited to small bladder stones.

Figure 3

The cause of urinary bladder stones in horses is believed to be in part due to diet. Horses consuming diets high in calcium such as alfalfa and drinking water that has a high calcium content may be predisposed to developing urinary bladder stones. However, the condition is relatively rare when one considers how many horses are fed a pure alfalfa diet!  In addition, horses can develop stones in the bladder AND kidneys. These stones may travel and lodge within the ureters and the urethra. In my clinical experience, I have diagnosed urinary bladder stones in 2 geldings and 1 mare. In addition, I have diagnosed kidney and ureter stones in 2 geldings and 2 mares. If the stones obstruct the flow of urine from the kidneys into the urinary bladder they will ultimately result in compromise of kidney function. Common clinical signs include increased urination, increased water intake, recurrent low-grade colic, fever, blood in urine, and poor performance.

Arytenoid Chondritis in a Horse

A 12 year old quarter horse mare presented for a 2-3 month history of coughing and "wheezing". The mare had developed the symptoms some what suddenly and was responsive to systemic corticosteroids. As such, it was initially thought that the mare was developing signs of heaves or COPD (chronic obstructive pulmonary disease). Heaves is relatively common in the southeastern United States and is a chronic progressive condition that involves an allergic condition that affects the lungs and causes fibrosis and scarring.     At presentation, the client was interested in finding out for sure what was causing the coughing and wheezing. Re-breathing exam was essentially normal with no wheezing detected or coughing. The mare was currently being treated with corticosteroids and had been for the past 48 hours. The initial plan was to scope the mare and perform a bronchoalveolar lavage (BAL) to confirm the diagnosis of heaves. However, when the endoscope was passed to the point of the larynx, we discovered what was the true problem!

Figure 1

In Figure 1 and 2, the larynx of the horse in question appears grossly abnormal. In Figure 1, the horse is in between breaths and there is thin slit between the arytenoids which consists of her airway. In Figure 2, the mare is taking a deep breath and the full extend of her airway is probably the diameter of a sharpie pen! There is large linear ulcer that crosses the left arytenoid cartilage and the significant thickening of both left and right arytenoid cartilages suggest chronic inflammation. In Figure 3, a "normal" endoscopy demonstrates what the full extent of the airway should be during inspiration and what normal arytenoid cartilage should look like!

Figure 2

Figure 3

Arytenoid chondritis is a relatively common cause of coughing and nasal discharge in older horses. This mare was a bit on the young side to have developed this condition. The causative agent is not clear but it is believed to be a combination of chronic irritation that is made worse by bacterial infection. In my experience, I have diagnosed this problem in horses that were exposed to a chemical irritant in agriculture setting such as dairy farms and produce farms; however, I have not been able to determine what chemical is causing the problem. Unfortunately  once the condition becomes chronic and the arytenoids are permanently disfigured, the only viable option is to perform a permanent tracheotomy. Surprisingly  horses do very well with permanent tracheotomies as long as they do not go swimming!! Clinical signs will improve with systemic corticosteroids and throat spray however these treatments will NOT reverse the damage done!!  This case, once again, demonstrate the importance of an endoscopic exam EARLY in the disease process.

Guttural Pouch Mycosis in a horse!!

The endoscopic images in Figure 1 and 2 are that of a normal guttural pouch in a horse. There are 2 guttural pouches in the horse and their role is not clearly defined. However, there are several very important structures which course through the guttural pouches. These include large veins and arteries plus critical cranial nerves (Figure 2) . Each guttural pouch is divided into a medial and lateral compartment by a unique bone named the stylohyoid bone. This bone articulates with the base of the skull, just below the ear drum and is part of the support structure for the tongue and larynx! As such, when the horse moves its tongue the articulation between the stylohyoid bone and the base of the skull moves as well. The large blood vessels located within the guttural pouch are important for bringing oxygenated blood to the brain and draining deoxygenated blood from the brain. Equally important are the cranial nerves that course through the guttural pouches. These nerves are essential for a proper swallowing reflex, sensation to the face, and balance.

Figure 1

Figure 2

The endoscopic images in Figures 3-5 are from a gelding that presented for a history of purulent nasal discharge that responded to antibiotic treatment. The endoscopic exam was requested as a follow-up to make sure there was nothing lurking in the horse's upper airway. When the right guttural pouch was entered, a large white plaque was noted covering the entire stylohyoid bone. There was minimal discharge within the pouch and there appeared to be mold covering the surface of the plaque!!

Figure 3

Figure 4

In Figures 4 and 5, the proximity of the fungal plaque with the large blood vessels and important nerves can be seen. Normally, fungi seek out vascular tissue and slowly erode the walls of vessels which can result in low grade bleeding and if it is a large artery, sudden death!! Commonly, horses with fungal infection or mycosis of the guttural pouch present with a history of a bloody nose (epistaxis), however this horse did not. When the plaque was disturbed with the scope, the underlying tissue was exposed and the inflammation was evident.  A bacterial and fungal culture was performed on the fluid recovered during the guttural pouch lavage and a fungi was recovered yet the identity is still being worked out. This condition is difficult to treat and is currently being managed with systemic antifungals and guttural pouch lavage. Stay tuned!!!!

Figure 5

Cleft Palate!

Image 1

The first two images are from a yearling thoroughbred that presented for a long history of nasal discharge, coughing while eating, and the presence of water exiting from nostrils while drinking. The filly had been treated with antibiotics prior to the exam. Endoscopic exam revealed a defect within the soft palate that extended nearly the entire length of the soft palate. In addition, the epiglottis was entrapped by the aryepigltottic fold. 

Image 2

 The defect within the soft palate is known as a "cleft palate" and most likely has been there since birth. Fortunately, this is a relative rare condition! Normally, the palate plays the role of separating the nasal passages from the oral passage. Hence, a horse is an obligate nasal breather and the palate keeps water and feed from entering the airway. When a cleft palate exists, there is communication between the air passage and oral passage resulting in feed and water going the "wrong way". This may consist of feed material exiting the nostril and/or traveling down the trachea into the lungs. If these horse go undiagnosed they are typically "poor doers" with failure to thrive secondary to chronic respiratory infections. Sadly, there is little to be done to help such a severe cleft palate. Less severe cases may be addressed with surgical intervention with mixed results. 

Image 3

The third image if that of a "normal" horse. The epiglottis is visible and is resting on top of the complete soft palate. Diagnosis of a cleft palate is often made immediately after birth during a thorough post-foaling exam. The veterinarian should palpate the length of the hard and soft palate with their finger to make sure it is normal. If missed at foaling, the diagnosis can be made quite simply with an endoscopic exam.