Every day, veterinarians are confronted with diagnostic challenges in the form of dogs with symptoms and no way to tell them where it hurts. There are some diseases and illnesses that vets see often, like ear infections, hip dysplasia, allergic reactions, dental disease and hot spots. But then there are some rare diseases that seldom make it to every vet’s examination table.
In this article, we explore five rare diseases in dogs, the symptoms, how the diseases are diagnosed, and how they are treated.
Ectopic Ureters
Ectopic (outside; out of place) ureters (the tubes connecting the kidneys to the bladder) occur when the ureters don’t develop normally in a puppy. It is a congenital condition that the puppy is born with, in which the ureter(s) exit the kidneys, but they empty directly into the urethra – bypassing the bladder altogether. 
Ectopic ureters is a rare condition that affects females more so than male dogs, and while it is congenital, there are some breeds that appear to be more susceptible than others, such as golden and Labrador retrievers, Siberian huskies, Newfoundland dogs, poodles, and some terriers like Westies and wheaten terriers. The age of onset of symptoms can be any time from weaning to 10 months old. The condition is usually brought to the vet’s attention when the owner notices that the puppy is dribbling urine, even though they are house-trained. There may also be staining of the fur around the genitals because of urine constantly leaking and causing discolouration. The puppy may also develop recurring urinary tract infections (UTI) and/or be constantly licking the genitals.
To diagnose ectopic ureters, the vet will first need to rule out a UTI, bladder stones, or any other condition that presents with urinary incontinence. They will do a urinalysis (testing the chemical make-up of the urine), urine culture, and abdominal X-rays, ultrasound and/or CT scan. The vet can also perform a cystoscopy, which involves using a small camera to look inside the dog’s bladder and urethra while they are under general anaesthesia. The camera will reveal where the ureters are emptying into the urethra, and confirm that they are not emptying into the bladder.
Ectopic ureters can be treated during the cystoscopy if their position is uncomplicated. The ectopic ureters can be ‘intramural’ or ‘extramural’. Intramural ureters have tunnelled through the wall of the bladder, yet extend and open into the urethra. These can be corrected during the cystoscopy using laser technology. Extramural ectopic ureters will require an abdominal incision and surgery to section the ureters from the urethra and to re-attach each one to an incision in the bladder.
The surgery for ectopic ureters has a high success rate in curing the urinary incontinence typically seen in the condition. However, dogs with ectopic ureters sometimes have other abnormalities in their elimination system, and a small percentage of patients will develop kidney failure, or will remain incontinent. The vet can prescribe medication to help with the incontinence.
Canine Uveodermatologic Syndrome
Canine uveodermatologic syndrome (UDS) is also known as Vogt-Koyanagi-Harada-like syndrome in dogs and describes the way the disease presents in the eyes (uveitis) and in the skin (dermatologic). UDS is a genetic or inherited autoimmune disease in which the immune system attacks melanocytes (the skin cells that form melanin or skin pigment), causing the skin to go white and the eyes to become inflamed. The dog breeds that are most susceptible to inheriting this syndrome include Akitas, Siberian huskies, Alaskan Malamutes and Samoyeds. It does occur in a range of other breeds, but only very rarely.
The symptoms of canine uveodermatologic syndrome include depigmentation (whitening) around the eyes, poliosis (a patch of white or grey fur) on the face, inflammation in the eyes, leading to tearing, bloodshot eyes, photosensitivity, and squinting. In general, a black dog can slowly turn completely white, and, if the eye problems are not treated, it can lead to glaucoma, cataracts and eventually complete blindness.
A vet will do a physical examination and the dog may require an examination by a specialist ophthalmologist to correctly diagnose the eye symptoms. A skin biopsy (preferably from the lip) can help to confirm the dermatological part of the diagnosis of UDS. The first port of call for treatment involves suppressing the inflammation (immune response) through the administration of corticosteroids like prednisone. These cannot be used long-term, so when the inflammation has been reduced, the vet may prescribe non-steroidal immunosuppressive medication like cyclosporine. UDS cannot be cured. The vet will focus on keeping the dog’s eyes free of pain and inflammation. Sometimes, the owner may choose to have the dog’s eyes removed, especially if the disease has progressed too far and blindness is inevitable. The skin and fur changes do not hurt the dog and their comfort can be maintained with topical treatments.
Achromatopsia
Dogs can experience a dysfunction in the light cone receptors in their eyes, which leads to day blindness, colour blindness, or achromatopsia. They can completely lose their sight during the day, but then see fully or partially after sunset, in the shade or in low light. Achromatopsia is a genetically inherited disease and would be present from birth, with the main symptoms starting to show at around nine weeks of age.
The symptoms of achromatopsia include vision loss and photosensitivity, which manifest as behavioural symptoms of avoiding bright light (like daylight) and photophobia – showing actual pain or distress in light – and not being able to navigate obstacles in daylight. Dogs with achromatopsia may blink repeatedly, shake their heads and actively move into shade or darkened areas. Nystagmus – abnormal side-to-side movement of the eyes – may also be present.
The vet will perform a physical examination and may refer the dog to a veterinary ophthalmologist to perform an electroretinogram, which will reveal the degeneration or underdevelopment of the cones. The vet can also perform a genetic test to detect the two mutated recessive genes responsible for the condition and make a definitive diagnosis. There is no cure for achromatopsia, but in 2010, gene therapy was used to successfully cure young dogs of the condition in a research setting. Owners of dogs with achromatopsia are encouraged to fit their dogs with tinted goggles that enable the dogs to function normally in daylight.
Immunoproliferative systemic intestinal disease
Immunoproliferative systemic intestinal disease (IPSID) is also referred to as immunoproliferative enteropathy – a gastrointestinal disease (similar to irritable bowel syndrome) to which Basenji dogs appear to be most susceptible. It does occur in other breeds, but is particularly genetically linked to the Basenji. There are numerous inflammatory diseases with the same symptoms as immunoproliferative enteropathy, so the diagnosis of this disease can be challenging. There can be a cancerous, bacterial, or allergic trigger, but the symptoms are caused by an over-reactive immune system that creates inflammation in the intestinal lining. This inflammation interferes with the normal absorption of protein and nutrients.
The onset of immunoproliferative enteropathy in Basenjis is from around 10 months to three years old. Dogs will show symptoms such as vomiting and diarrhoea for longer than three weeks, consequent weight loss, a coarse, dry coat as a result of malabsorption, abdominal oedema, depression, excessive sleeping, difficulty breathing, difficulty moving, and even death. If not treated timeously, dogs can appear emaciated, and the inability to absorb protein will have a ripple effect on vital organs and basic functioning. If left untreated, it will be fatal.
The diagnosis of immunoproliferative enteropathy is complicated because of the symptoms being so common in other diseases. Diagnosis is differential (ruling out other diseases) and will include a physical examination and medical history of the dog. The vet may perform a gastric endoscopy to take note of any lesions in the digestive tract. They can also biopsy the intestinal wall. Cultures may be taken to see which bacteria are present (and if there’s an overgrowth), and the vet may also do urinalysis and faecal analysis, and a complete blood count. The blood tests will show increased immune response and decreased protein absorption.
Treatment of immunoproliferative enteropathy involves suppressing the immune response, which is typically done with corticosteroids like prednisone, to reduce inflammation and the resulting tissue damage. The condition cannot be cured, but if treatment is started early, it can be managed with a clean, simple diet, reducing the dog’s stress, and maintaining their hydration. Medications will be provided based on the severity of the disease and the type of hypoallergenic diet the dog responds to best. If treatment is not started early, the prognosis is poor, leading to euthanasia within two years of diagnosis.
Dermoid Sinus
A dermoid sinus is a congenital defect that occurs when the neural tube (which develops into the spine) doesn’t separate completely from the skin. This happens when the puppy is still an embryo; therefore, they are born with this condition. A dermoid sinus is a tiny tract or opening that connects the dorsal skin to the spinal cord, and is graded as a category I to category V condition, depending on how deep the sinus penetrates the skin. A category V dermoid sinus does not open onto the skin’s surface, and presents as a bump or cyst under the skin; while a category IV descends down to the outer membrane of the spinal cord. If the sinus collects skin debris and bacteria, it can become infected, which can have dire consequences for the central nervous system. An infected dermoid sinus can lead to meningitis, myelitis and even encephalitis (inflammation of the spinal membranes, spinal cord, and brain, respectively). Dermoid sinus occurs most commonly in Rhodesian ridgebacks because of the visible ridge of fur on their back.
Some dermoid sinuses remain uninfected or uninflamed, and are not detected under the swirl of fur in the ridgeback. In a dog whose fur normally lies flat (like a boxer or French bulldog), the dermoid sinus may cause a whorl of fur, alerting the owner to its presence. It is not painful or a bother unless it becomes infected, which is usually when owners bring their affected dogs to the vet. All dogs will be affected differently by their dermoid sinus, which can be located anywhere along the neck, spine and tail of the dog, and at varying depths into the skin. Some owners will see a little opening or hole along their puppy’s back, or there may be a rope-like structure that can be felt under the skin. They might only become aware of it when an abscess forms as a result of infection, by which point it will be painful to the puppy.
An experienced veterinarian may suspect a dermoid sinus based on the history provided, and will know what to look for. They will use an exploratory catheter, may take an X-ray, or may need to use a CT scan or even an MRI to get a better idea of what they are dealing with.
Treatment for a dermoid sinus may include a course of antibiotics (if it is painful and infected) before the necessary surgery to remove the sinus. There may be complications with the surgery if the dermoid sinus is wrapped around the spinal cord or other joints. If it’s too risky to remove completely, the surgeon will tie it off, but then the risk is that the sinus may reopen and become infected again. If the dog already has neurological issues because of infection in the brain and CNS, the prognosis is guarded. Uncomplicated surgeries of puppies with dermoid sinus who are otherwise healthy, carry a better prognosis.
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