Cairn Terrier nutrition: liver shunts, diabetes and weight

The American Kennel Club gives the Cairn Terrier's ideal weight as about 14 pounds for males and 13 pounds for females (roughly 6 kg), with a life expectancy of 13 to 15 years. The AKC's list of recommended health tests says a lot about what matters for this breed: a liver test for portosystemic shunts and microvascular dysplasia, a DNA test for globoid cell leukodystrophy, a kidney ultrasound, a cardiac exam, a kneecap evaluation and an eye exam for ocular melanosis. The liver shunt on that list, and diabetes, which is not on it, have the most direct bearing on how a Cairn is fed.

Liver shunts

Normally, blood from the intestines passes through the liver, which removes ammonia and other substances absorbed from the gut before the blood reaches the rest of the body. In a congenital portosystemic shunt, a blood vessel lets that blood bypass the liver. Ammonia then reaches the brain and causes hepatic encephalopathy.

In Cairns the condition is inherited. A Dutch program that screened 6,367 Cairn Terrier puppies at six weeks of age found shunts in 58 of them, just under 1%, with markedly higher rates in some family lines and in test matings of affected dogs. Males and females were affected equally. Microvascular dysplasia, a related abnormality of the small vessels inside the liver, is also covered by the AKC's recommended liver test.

Signs to watch for

The Merck Veterinary Manual describes the signs of hepatic encephalopathy as ranging from mild dullness and difficulty responding to basic commands to more obvious problems:

• Circling, head pressing or aimless wandering
• Weakness, wobbliness or disorientation
• Unexplained blindness
• Drooling
• Personality change or house soiling

In a puppy, poor growth alongside any of these, especially if they come and go around meals, needs a vet promptly. A seizure or collapse is an emergency.

Feeding a dog with a shunt

Many dogs with an extrahepatic shunt have it corrected surgically, and diet is used to stabilize them beforehand or when surgery is not an option. The old advice to cut protein hard has changed. Merck describes strict protein restriction for liver patients as a dogma that studies in people and clinical observations in dogs and cats have debunked. Protein should be set to what the individual dog tolerates, because muscle itself helps clear ammonia and a dog that loses muscle copes worse.

• Protein source matters. Merck's starting point is a protein-modified diet that limits red meat and fish and uses dairy, vegetable or white-meat chicken protein, with the amount increased gradually while the dog is monitored.
• Medication does part of the work. Lactulose, fermented in the colon, reduces ammonia absorption, and some dogs also need an antibiotic. These are prescribed and dosed by the vet.
• Small, regular meals spread the protein load across the day.
• No home experiments. A dog with a shunt should be on a diet chosen with the vet, often a prescription liver diet, not a home-made low-protein recipe.

Diabetes

Cairn Terriers are one of the breeds at highest risk of diabetes mellitus. A study of dogs from the UK Canine Diabetes Register described the Samoyed, Tibetan Terrier and Cairn Terrier as the three highest-risk breeds it included. None of the immune-gene types the study tested were associated with diabetes in those three breeds, which the authors took to mean these genes may not add obvious or strong risk there.

Diabetes in dogs usually means the pancreas no longer produces enough insulin, and affected dogs need insulin injections for life. Diet cannot undo that, but it does matter:

• Before diagnosis: keep a Cairn lean. Extra fat makes the body less responsive to insulin, and weight gain is the part of the risk an owner controls.
• After diagnosis: feed the same food, in the same amount, at the same times each day, matched to the insulin schedule the vet sets. Consistency matters more than any single ingredient.
• Food choice: the vet may recommend a particular diet. Avoid switching foods or adding treats without adjusting the plan with the vet.

Drinking and urinating more, eating well but losing weight, and new cloudiness in the eyes are all reasons for a blood and urine glucose test.

Itchy skin and food allergy

Scratching, paw licking, red skin and repeated ear infections in a Cairn can come from fleas, environmental allergy, infection or food. A vet should rule out parasites and infection first. If food allergy is suspected, the only reliable test is an elimination diet: a novel protein or hydrolyzed prescription diet fed with nothing else, including no treats or flavored medications.

A review of the published trials found that eight weeks on the diet brought complete remission in more than 90% of food-allergic dogs and cats, so the trial should last at least that long. If the skin improves, the old food or single ingredients are then reintroduced one at a time. A flare after a reintroduction points to the trigger.

For a Cairn that also has a shunt or diabetes, an elimination diet has to fit the other diet, so plan it with the vet rather than switching foods independently.

Globoid cell leukodystrophy

Globoid cell leukodystrophy (GLD), also called Krabbe disease, is an inherited disease of myelin, the insulating layer around nerve fibers, caused by a deficiency of the enzyme galactocerebrosidase. It occurs in Cairn and West Highland White Terriers. It is autosomal recessive, so an affected puppy has inherited a copy of the mutation from both parents. Researchers developing a DNA screening test identified more than 50 Cairn Terrier carriers.

There is no dietary treatment. Prevention is in the breeding: the AKC lists a DNA test for GLD among its recommended tests, and carriers are healthy themselves but should not be bred to other carriers. When choosing a puppy, ask for both parents' results.

Portions, treats and weight

The AKC notes that some Cairns are prone to getting overweight and describes the breed as needing a moderate amount of exercise, with dog sports and earthdog events as good outlets. Energy needs can be estimated with the formula in the Merck Veterinary Manual: 70 times body weight in kilograms to the power 0.75, multiplied by 1.8 for an intact adult, 1.6 for a neutered adult or 1.4 for a dog that gains weight easily.

Merck adds that dogs of the same weight can need 30% more or less, so treat the table as a first estimate. A Cairn's harsh coat hides the body, so check by hand: ribs easy to feel under a thin covering and a visible waist. Weigh the dog every month. On a 6 kg dog, a daily handful of cheese or a large biscuit is a big share of the day's calories, so use small treats, count them, and take training rewards out of the meal ration.

Two measured meals a day suit most adults. A dog with diabetes or a shunt follows the schedule its treatment needs instead.

Sources

1. Cairn Terrier dog breed information. American Kennel Club.
2. Inherited congenital extrahepatic portosystemic shunts in Cairn terriers. Journal of Veterinary Internal Medicine, 2005.
3. Hepatic encephalopathy in small animals. Merck Veterinary Manual.
4. Dog leucocyte antigen (DLA) class II haplotypes and risk of canine diabetes mellitus in specific dog breeds. Canine Medicine and Genetics, 2020.
5. Critically appraised topic on adverse food reactions of companion animals (1): duration of elimination diets. BMC Veterinary Research, 2015.
6. Globoid cell leukodystrophy in cairn and West Highland white terriers. Journal of Heredity, 1999.
7. Nutritional requirements of small animals. Merck Veterinary Manual.